Medicinal substances can be introduced into the body in various ways. There are many of them, but they are all divided into two large groups:

• enteral routes of administration, in which drugs enter the body through the gastrointestinal tract;
• parenteral routes of administration, when the drug is administered without passing through the gastrointestinal tract.

Methods of introducing drugs into the body include:

• enteral (orally (through the mouth), sublingual (under the tongue), rectal (into the rectum), into the stomach and intestines (using a probe);
• parenteral (injection (under the skin, into a muscle, into a vein, into the spinal canal, etc.), on the skin and mucous membranes, inhalation (by inhalation).

All of these methods have positive and negative sides, however, the speed of onset of the pharmacological effect, its strength and duration depend on the correctly chosen route of administration of the drug into the patient’s body.

ATTENTION! When analyzing in detail individual routes of administration, note the advantages and disadvantages of each of them.

ENTERAL ROUTES OF ADMINISTRATION

Orally (per os), or orally, is the most convenient and simplest route of administration. It does not require sterilization of medicinal substances and is convenient for taking most dosage forms.

Medicinal substances taken orally pass through the esophagus, stomach, duodenum, are absorbed in the small intestine, enter the portal vein, then into the liver and then into the general bloodstream. The effect of medicinal substances, or, as they say, “pharmacological effect,” when administered orally, begins within 15-30 minutes. However, this route of administration cannot always be used. Some medicinal substances (adrenaline, insulin) are easily destroyed under the influence of enzymes and stomach acids, others strongly irritate the mucous membrane, and others are not absorbed from gastrointestinal tract and cannot have an effect on the entire body, and, finally, medicinal substances, such as tetracycline, can partially or completely bind to food elements and lose their effect. In addition, the liver, performing a protective function, partially neutralizes (inactivates) drugs when they pass through it. The slow onset of the pharmacological effect after taking the drug by mouth also does not allow, in most cases, the use of this route of administration. emergency care.

Rectal route of administration, or into the rectum ( per rectum), used for administering medicinal enemas (solutions, mucus, etc.) and suppositories. In this case, the absorption of drugs occurs faster than when taken orally. After administration, medicinal substances enter first the hemorrhoidal veins, then the inferior vena cava and, bypassing the liver, into the general bloodstream.

This route of administration is used if it is impossible to administer the drug by mouth, for diseases of the lower intestine and pelvic organs, and also if they want to avoid undesirable effects of the drug on the liver. Doses of medicinal substances when administered into the rectum should be slightly less than when taken orally. It should be remembered that if a medicinal substance has an irritating effect, it is injected into the rectum with enveloping agents, for example, starch mucus.

The sublingual (sub - under, lingua - tongue) route of administration is used for drugs that are easily absorbed through the mucous membrane of the oral cavity, while they quickly enter the bloodstream, bypassing the liver and almost without being exposed to digestive enzymes. However, the absorption surface of the sublingual region is limited, which allows only highly active substances, such as nitroglycerin during angina attacks, to be administered in this way. Sometimes it is recommended to use Corvalol, Cordiamine and other drugs in this way.

Medicinal substances are administered into the stomach and intestines using special rubber tubes. These routes of administration are used mainly in laboratory practice when studying gastric juice or bile.

PARENTERAL ROUTES OF ADMINISTRATION

Injection routes of administration are considered one of the most rational and effective. With relatively lower doses than when taken orally, in these cases it is possible to obtain a good pharmacological effect much faster and often for a longer period. Let us remind you that sterile aqueous and oil solutions, suspensions and powders, which are dissolved in special solvents (water for injection, novocaine solutions, isotonic sodium chloride solution, etc.) before administration. Each injection route has its own characteristics that must be taken into account when introducing drugs into the patient’s body.

By subcutaneous administration, sterile medicinal substances are delivered using a syringe, special system(droppers) or needleless injector. Aqueous solutions are administered more often, and oil solutions less frequently. To avoid infiltrates, it is recommended to warm the latter to body temperature, and massage the injection site after administering the drug.

The absorption of drugs into the blood when administered subcutaneously is relatively slow, and therefore the pharmacological effect develops after 5-15 minutes.

For subcutaneous administration The area of ​​the shoulder and shoulder blade is most often used, and for drip administration - the area of ​​the thigh and abdomen. 1-2 ml of solution is injected simultaneously under the skin, and up to 500 ml by drop.

REMEMBER! Oil solutions in the form of injections are injected into the muscle or under the skin in a heated form.

The intramuscular route of administration is used for aqueous, oily solutions and suspensions. The former in this case are absorbed faster than when they are injected under the skin. Suspensions form a kind of reserve (depot) of the medicinal substance, from which they are gradually absorbed and significantly increase the time of its action. When injecting oil solutions and suspensions into the muscle, it is necessary to ensure that the needle does not enter a blood vessel, since in this case blockage of the blood vessels (embolism) is possible, and this can cause disruption of vital functions. important functions body.

Medicinal substances are generally injected into the muscle simultaneously from 1 to 10 ml, using large muscles, such as thighs and buttocks. If the gluteal muscle is used, then it is conventionally divided into four parts and the medicine is injected into the upper outer left or upper outer right square.

REMEMBER! When administering oil solutions and suspensions intramuscularly, care must be taken to ensure that the needle does not enter a blood vessel. Possible embolism!!!

With the intravenous route of administration, in contrast to the subcutaneous and intramuscular route, in which the drug substance is partially retained and destroyed in the tissues, the entire amount of the administered substance immediately enters the blood. This explains the almost immediate development pharmacological effect.

It is mainly injected into a vein aqueous solutions, as well as hypertonic solutions and irritating substances that cannot be injected under the skin and into the muscle. True, irritating substances in some cases should be diluted before administration to reduce the unpleasant effect.

It is unacceptable (!) to inject oil solutions and suspensions into a vein due to possible embolism.

Medicinal substances are injected into a vein slowly, sometimes for several minutes, and by drip for several hours. From 1 to 20 ml are injected into a vein at the same time, and from 50 ml to 1 liter or more by drip. For intravenous administration, the ulnar veins are most often used, other veins (temporal, popliteal) are used less frequently.

The disadvantage of the intravenous route of administration is the possibility of blood clots, especially with prolonged administration of drugs.

REMEMBER! Rapid administration of drugs into a vein can cause undesirable changes in the respiratory system, cardiovascular system and central nervous system.

In addition to the indicated injection routes of administration, there are also intradermal and intra-arterial routes of administration, the route of administration into the spinal canal, as well as into various cavities, for example abdominal, pleural, etc.

The cutaneous route of administration is suitable for ointments, pastes, liniments, solutions, infusions, decoctions, etc.

This route of administration is designed mainly for local action and less often for general action, because the absorption of medicinal substances through the skin occurs only if they are well dissolved in the fats (lipids) of the skin. It is believed that ointments and pastes prepared with Vaseline have only a superficial local effect and are not absorbed through the skin. These same dosage forms, but prepared with lanolin, are well absorbed and can have not only local, but also general action. Moreover, depending on pharmacological properties of the medicinal substances used, they can have a local irritant, analgesic, drying or some other effect. With the cutaneous route of administration, absorption of medicinal substances occurs relatively slowly. Rubbing, warm baths, compresses, as well as the creation of hyperemia (redness) in this area contribute to the acceleration of the absorption process. For this purpose, appropriately converted electricity in physical therapy rooms. Good absorption of medicinal substances is facilitated by a violation of the integrity of the skin, so introducing the drug into a wound or applying it around it gives a different pharmacological effect.

The inhalation route of administration is most often used for respiratory diseases. The area of ​​the lungs is large, almost 100 m2, and therefore medicinal substances can easily penetrate into the blood and have a general effect. Inhalation, i.e. by inhalation, gaseous substances (oxygen), vapors of liquid, highly volatile substances (ether for anesthesia), as well as aerosols are administered, for example during attacks of bronchial asthma.

The pharmacological effect on the respiratory system with this method of administration is achieved faster than, for example, with intramuscular administration.

Existing methods of administering drugs are divided into enteral (through digestive tract) and parenteral (bypassing the digestive tract).

From the method of administration medicinal product It largely depends on its entry into a certain place (for example, into the site of inflammation), the speed of development of the effect, its severity and duration, as well as the effectiveness of treatment in general. IN in some cases The method of drug administration is determined by the nature of the drug’s action. An example is Diclofenac tablets with enteric coating and injections of the same drug: tablets begin to act, as a rule, after 2-4 hours, and the drug administered by injection already after 10-20 minutes.

Another example is antibiotics. When taking antibiotics orally, it is advisable to use capsules rather than tablets whenever possible, since the drug from the capsule is absorbed much more quickly. The therapeutic effect appears even faster when injecting antibiotics; in addition, with this method of administration it is possible to avoid many side effects from the gastrointestinal side intestinal tract and liver, which occur when taken orally.

Enteral methods include the administration of drugs through the mouth (orally), under the tongue (sublingual), behind the cheek (buccal), into the rectum (rectally) and some others. The advantages of the enteral route of administration are its convenience (no assistance from medical personnel is required), as well as comparative safety and the absence of complications characteristic of parenteral use.

Drugs administered enterally can have both local (some antimicrobial, antifungal and anthelminthic agents) and systemic (general) effects on the body. Most medications are administered enterally.

Oral route of administration

• The simplest and most common way to take medications.
• Most drugs are taken orally (tablets, capsules, microcapsules, dragees, pills, powders, solutions, suspensions, syrups, emulsions, infusions, decoctions, etc.). The active substance contained in the drug enters the bloodstream, absorbed from the gastrointestinal tract.
• To prevent irritation arising from contact of the drug with the mucous membrane of the mouth and stomach, as well as to avoid the destructive effect of gastric juice on the drug itself, dosage forms (tablets, capsules, pills, dragees) coated with coatings resistant to the action of gastric juice are used. , but disintegrating in the alkaline environment of the intestine. They should be swallowed without chewing unless otherwise stated in the instructions.
• The oral route of administration is characterized by a relatively slow onset of action of the drug (within a few tens of minutes, rarely - a few minutes after administration), which, in addition, depends on individual characteristics (the condition of the stomach and intestines, the regimen of food and water intake, etc.). However, this property is used to create drugs with prolonged (long) action. Their description contains the word “retard” (for example, retard tablets, retard capsules). Retard dosage forms cannot be crushed if they do not have a dividing strip, since this will lose their properties. For example, tablets containing the digestive enzyme pancreatin (Festal, Mexaza, Panzinorm, etc.) should never be divided into parts, since if the integrity of the coating of the tablet is damaged, already in the oral cavity and then in the stomach, pancreatin is inactivated by saliva and the acidic contents of the stomach.
• Some substances, such as insulin and streptomycin, are destroyed in the gastrointestinal tract, so they cannot be taken orally.
• It is most rational to take drugs orally on an empty stomach, 20-30 minutes before meals. At that time digestive juices are almost not released, and the likelihood of loss of drug activity due to their destructive effect is minimal. And in order to reduce the irritating effect of the drug itself on the gastric mucosa, the medicine should be taken with water. However, it must be remembered that each drug has its own recommendations for use, which are indicated in the instructions for it.

Sublingual and buccal routes of administration

When the drug is administered sublingually and buccally, its effect begins quite quickly, since the mucous membrane of the mouth is abundantly supplied with blood, and substances are absorbed into it faster.

• Some powders, granules, dragees, tablets, capsules, solutions and drops are taken sublingually.
• When administered sublingually, medications are not exposed to the destructive effects of gastric juice and enter the bloodstream, bypassing the liver.
• Nitroglycerin is especially often used sublingually to relieve angina attacks, Nifedipine and Clonidine for hypertensive crises, and other fast-acting vasodilators.
• The drug should be kept under the tongue until completely absorbed. Swallowing the undissolved part of the medicine with saliva reduces the effectiveness of the action.
• For buccal administration of drugs, special dosage forms are used, which, on the one hand, ensure rapid absorption in the oral cavity, and on the other hand, allow prolongation of absorption to increase the duration of action of the drug. This is, for example, Trinitrolong - one of the dosage forms of Nitroglycerin, which is a plate made of a biopolymer base, which is glued to the mucous membrane of the gums or cheeks.
• It should be remembered that with frequent sublingual and buccal use of drugs, irritation of the oral mucosa is possible.

Rectal, vaginal and urethral routes of administration

• When administered rectally, the active substances are absorbed into the blood faster than when taken orally, without being subject to the destructive effects of gastric juice and liver enzymes.
• Suppositories are administered rectally ( rectal suppositories), ointments, capsules, suspensions, emulsions and solutions using microenemas, as well as enemas, no more than 50-100 ml for adults; for children - volume 10-30 ml. It should be remembered that absorption active substance from suppositories it is carried out more slowly than from a solution.
• The main disadvantages of the rectal route of drug administration are inconvenience in use and individual variations in speed and completeness. drug absorption. Therefore, drugs are mainly used rectally in cases where their administration through the mouth is difficult or impracticable (vomiting, spasm and esophageal obstruction) or when rapid entry of the drug into the blood is required, and the injection method is undesirable or impracticable due to the lack of necessary dosage form.
• Suppositories, tablets, solutions, creams, emulsions and suspensions are administered vaginally.
• Vaginal and urethral routes of administration are most often used to treat an infectious process in these organs or for diagnostic purposes - for example, administration contrast agents(iodamide, triomblast, etc.).

Parenterally, drugs are usually administered subcutaneously, intramuscularly, intravenously (sometimes intraarterially), but always with a violation of the integrity of the skin.

With parenteral routes of administration, the drug enters directly into the blood. This eliminates its side effects on the gastrointestinal tract and liver. Parenteral methods are used to administer drugs that are not absorbed from the gastrointestinal tract, irritate its mucous membrane, as well as those that are destroyed in the stomach under the influence of digestive enzymes.

Most of the listed parenteral routes of drug administration require the use of sterile additional equipment(syringe). The dosage form must also be sterile, and infusion solutions (i.e., solutions administered intravenously in large quantities - more than 100 ml) must, in addition, be necessarily pyrogen-free (i.e., not containing waste products of microorganisms). All infusions are carried out by drip under strict medical supervision.

Injections can be carried out on an outpatient basis (i.e. in a clinic, medical center), in a hospital (hospital) or at home, inviting a nurse. Insulin preparations, as a rule, are administered by patients themselves using special single-dose devices - “penfills”.

Intravenous administration

• Intravenous administration of the drug ensures rapid achievement of the effect (from several seconds to minutes) and accurate dosing.
• Methods of intravenous administration depend on the volume of the injection solution: up to 100 ml can be administered using a syringe, more than 100 ml (infusion) - using a dropper. Intravenous medications are usually administered slowly. Single, fractional, drip administration is also possible.
• It is prohibited to administer intravenously:
  • insoluble compounds (suspensions - for example, insulin preparations, Bismoverol, Zymozan, etc., as well as oil solutions), since in this case there is a high probability of embolism - blockage of a vessel, formation of a blood clot;
  • means with pronounced irritating effect(can lead to the development of thrombosis, thrombophlebitis). Eg, concentrated solution alcohol (more than 20%);
  • drugs that cause accelerated blood clotting

Intramuscular and subcutaneous administration

• Intramuscular and subcutaneous injections usually contain up to 10 ml of the drug. The therapeutic effect develops more slowly than with intravenous administration (soluble active ingredients are absorbed within 10-30 minutes). Intramuscular drugs are administered, as a rule, into the gluteal muscle or forearm; subcutaneously - in the forearm or in the abdominal area.
• Subcutaneous injections are usually performed (Fig. 2.) in the subscapular region (A) or outer surface shoulder (B). For independent subcutaneous injections, it is recommended to use the anterolateral abdominal region (D). Intramuscular injections are carried out in the upper outer quadrant of the buttock (B). For independent intramuscular injections, it is convenient to use the anterolateral surface of the thigh (D).
• When the drug is administered intramuscularly, the therapeutic effect occurs relatively quickly if the active substance is soluble in water. However, in the presence of an oil solution, the absorption process slows down due to to a greater extent its viscosity (compared to water).
• To prolong the effect of the drug, medicinal substances are injected into the muscle in a slightly soluble form (suspension or suspension), in oil or other bases that delay the absorption of substances from the injection site.
• Thus, by changing the solvent or solubility of the active substance, drugs are created with its delayed release and absorption into the body tissues. When such a medicine is administered, a “depot” of the drug is created in the body (i.e., the bulk of the active substance is localized in one place in the body). From this place the drug enters the blood at a certain speed, creating the necessary concentration of the active substance in the body.
• After intramuscular administration, local soreness (redness of the skin, itching) and even abscesses - suppuration inside the muscle layer, which are later opened surgically, may appear. This is possible, for example, with the introduction of oily, suspension preparations that are absorbed rather slowly (for example, Bismoverol, camphor oil, hormonal agents: Sinestrol, Diethylstilbistrol propionate, etc.).
• Substances that have a pronounced irritant effect are not administered intramuscularly or subcutaneously, as this can cause inflammatory reactions, infiltrates, the formation of compactions and suppuration, and even necrosis (tissue death).

Intra-arterial administration

Medicines are injected into the arteries, which quickly break down in the body. Wherein high concentration the drug is created only in the appropriate organ, and overall impact on the body can be avoided.

Medicines are administered intra-arterially for the treatment of certain diseases (liver, limbs, heart). For example, the introduction of thrombolytics into the coronary artery (injections of Heparin, Streptokinase, etc.) can reduce the size of the blood clot (up to its resorption) and thereby relieve the inflammatory process.

X-ray contrast agents are also administered intra-arterially, which makes it possible to accurately determine the location of a tumor, blood clot, narrowing of a vessel, or aneurysm. For example, the introduction of a radiopaque substance based on an iodine isotope makes it possible to determine the location of the stone in the urinary system and, based on this, use one or another type of treatment.

For gaseous and volatile compounds, the main method of administration is inhalation, which requires a special device - an inhaler. They are usually supplied with a medicinal product in an aerosol package, or the package itself (aerosol can) has a valve-spray dosing device.

When administered by inhalation, the active substances are quickly absorbed and have both local and systemic effects on the entire body, depending on the degree of their dispersion, i.e., the grinding of the drug. Medicines can penetrate the alveoli of the lungs and enter the blood very quickly, which necessitates their precise dosage.

Inhalation administration of drugs allows you to reduce the absorption time, introduce gaseous and volatile substances, and also has a selective effect on the respiratory system.

Source: Encyclopedic reference book. Modern medicines. - M.: Russian Encyclopedic Partnership, 2005; M.: OLMA-PRESS, 2005

There are many ways to introduce drugs into the body. The route of administration largely determines the speed of onset, the duration and strength of the drug, the spectrum and severity of side effects. IN medical practice It is customary to divide all routes of administration into enteral, that is, through the gastrointestinal tract, and parenteral, which includes all other routes of administration.

Enteral routes of drug administration

Enteral route includes: administration of the drug orally (per os) or orally; under the tongue (sub lingua) or sublingually, into the rectum (per rectum) or rectally.

Oral route

The oral route (also called taking the drug orally) is the most convenient and simplest, therefore it is most often used for administering medications. Absorption of drugs taken orally occurs primarily by simple diffusion of non-ionized molecules into small intestine, less often - in the stomach. The effect of the drug when taken orally develops after 20–40 minutes, so for emergency therapy this route of administration is not suitable.

Moreover, before entering the general bloodstream, drugs pass through two biochemically active barriers - the intestines and the liver, where they are affected by hydrochloric acid, digestive (hydrolytic) and liver (microsomal) enzymes, and where most drugs are destroyed (biotransformed). A characteristic of the intensity of this process is bioavailability, which is equal to the percentage of the amount of drug that reaches the bloodstream to total number medicine introduced into the body. The greater the bioavailability of a drug, the more completely it enters the bloodstream and the greater the effect it has. Low bioavailability is the reason why some drugs are ineffective when taken orally.

The speed and completeness of absorption of drugs from the gastrointestinal tract depends on the time of food intake, its composition and quantity. Thus, on an empty stomach, acidity is less, and this improves the absorption of alkaloids and weak bases, while weak acids are absorbed better after eating. Medicines taken after meals can interact with food components, which affects their absorption. For example, calcium chloride taken after a meal can form fatty acids insoluble calcium salts, limiting the possibility of its absorption into the blood.

Sublingual route

Rapid absorption of drugs from the sublingual area (with sublingual administration) is ensured by the rich vascularization of the oral mucosa. The effect of the drugs occurs quickly (within 2-3 minutes). Nitroglycerin is most often used sublingually for an attack of angina, and clonidine and nifedipine to relieve a hypertensive crisis. When administered sublingually, drugs enter the systemic circulation, bypassing the gastrointestinal tract and liver, which avoids its biotransformation. The drug should be kept in the mouth until it is completely absorbed. Often, sublingual use of drugs can cause irritation of the oral mucosa.

Sometimes, for rapid absorption, drugs are used behind the cheek (buccal) or on the gum in the form of films.

Rectal route

The rectal route of administration is used less frequently (mucus, suppositories): for diseases of the gastrointestinal tract, for unconscious sick. The bioavailability of drugs with this route of administration is higher than with oral administration. About 1/3 of the drug enters the general bloodstream, bypassing the liver, since the inferior hemorrhoidal vein flows into the inferior vena cava system, and not into the portal vein.

Parenteral routes of drug administration

Intravenous administration

Medicinal substances are administered intravenously in the form of aqueous solutions, which provides:

• rapid onset and precise dosing of the effect;
• rapid cessation of drug entry into the blood when adverse reactions;
• the possibility of using substances that degrade, are not absorbed from the gastrointestinal tract or irritate its mucous membrane.

When administered intravenously, the drug immediately enters the bloodstream (there is no absorption as a component of pharmacokinetics). In this case, the endothelium comes into contact with a high concentration of the drug. When administered into a vein, the drug is absorbed very quickly within the first minutes.

To avoid toxic effects, potent drugs are diluted isotonic solution or glucose solution and is administered, as a rule, slowly. Intravenous injections often used in emergency care. If it is not possible to administer the medicine intravenously (for example, in burnt patients), it can be injected into the thickness of the tongue or into the floor of the mouth to obtain a quick effect.

Intra-arterial administration

It is used in cases of diseases of certain organs (liver, blood vessels, limbs), when medicinal substances are quickly metabolized or bound by tissues, creating a high concentration of the drug only in the corresponding organ. Arterial thrombosis is a more serious complication than venous thrombosis.

Intramuscular administration

Aqueous, oily solutions and suspensions of medicinal substances are administered intramuscularly, which gives relatively quick effect(absorption is observed within 10-30 minutes). The intramuscular route of administration is often used in the treatment of depot drugs that provide a prolonged effect. The volume of the administered substance should not exceed 10 ml. Suspensions and oil solutions, due to slow absorption, contribute to the formation of local soreness and even abscesses. Injecting drugs near nerve trunks can cause irritation and severe pain. Accidental penetration of a needle into a blood vessel can be dangerous.

Subcutaneous administration

Aqueous and oil solutions are injected subcutaneously. With subcutaneous administration, absorption of the drug occurs more slowly than with intramuscular and intravenous administration, and the manifestation therapeutic effect develops gradually. However, it lasts longer. Solutions of irritating substances that can cause tissue necrosis should not be injected under the skin. It should be remembered that in case of peripheral circulatory failure (shock), subcutaneously administered substances are poorly absorbed.

Local application

To obtain a local effect, medications are applied to the surface of the skin or mucous membranes. When applied externally (lubrication, baths, rinses), the drug forms a complex with the biosubstrate at the injection site - a local effect (anti-inflammatory, anesthetic, antiseptic, etc.), in contrast to the resorptive one that develops after absorption.

Some drugs used externally for a long time (glucocorticoids), in addition to the local effect, can also have a systemic effect. IN last years Adhesive dosage forms have been developed that provide slow and long-term absorption, thereby increasing the duration of action of the drug (patches with nitroglycerin, etc.).

Inhalation

In this way, gases (volatile anesthetics), powders (sodium chromoglycate), and aerosols (beta-adrenergic agonists) are introduced into the body. Through the walls of the pulmonary alveoli, which have a rich blood supply, medicinal substances are quickly absorbed into the blood, exerting local and systemic effects. When the inhalation of gaseous substances is stopped, a rapid cessation of their action is observed (ether for anesthesia, fluorotane, etc.). By inhaling an aerosol (beclomethasone, salbutamol) their high concentration in the bronchi is achieved with minimal systemic effect. Irritants they are not introduced into the body by inhalation; in addition, drugs entering the left side of the heart through the veins can cause a cardiotoxic effect.

Intranasally (through the nose) drugs are administered that have a local effect on the nasal mucosa, as well as some drugs that affect the central nervous system.

Electrophoresis

This pathway is based on the transfer of medicinal substances from the surface of the skin to deep-lying tissues using galvanic current.

Other routes of administration

In and for spinal anesthesia, subarachnoid drug administration is used. In case of cardiac arrest, adrenaline is administered intracardially. Sometimes medications are injected into the lymphatic vessels.

Movement and transformation of drugs in the body

A drug is introduced into the body in order to provide some therapeutic effect. However, the body also influences the drug, and as a result, it may or may not enter certain parts of the body, pass or not pass certain barriers, modify or maintain its chemical structure, and leave the body in certain ways. All stages of the movement of a drug through the body and the processes occurring with the drug in the body are the subject of study of a special branch of pharmacology, which is called pharmacokinetics.

There are four main stages pharmacokinetics drugs - absorption, distribution, metabolism and excretion.

Suction- the process of entry of a drug from outside into the bloodstream. Absorption of drugs can occur from all surfaces of the body - skin, mucous membranes, from the surface of the lungs; When taken orally, drugs enter the bloodstream from the gastrointestinal tract using absorption mechanisms nutrients. It should be said that drugs that have good solubility in fats (lipophilic drugs) and have a small molecular weight are best absorbed in the gastrointestinal tract. High molecular weight drugs and fat-insoluble substances are practically not absorbed from the gastrointestinal tract and therefore must be administered by other routes, such as injections.

After the drug enters the bloodstream, the next stage begins - distribution. This is the process of penetration of a drug from the blood into organs and tissues, where the cellular targets of their action are most often located. The distribution of a substance occurs faster and easier, the more soluble it is in fats, as at the absorption stage, and the lower its molecular weight. However, in most cases, the distribution of the drug among the organs and tissues of the body is uneven: more of the drug gets into some tissues, and less into others. There are several reasons for this circumstance, one of which is the existence of so-called tissue barriers in the body. Tissue barriers protect against entry into certain tissues foreign substances(including medications), preventing them from damaging tissues. The most important are the blood-brain barrier, which prevents drugs from entering the central nervous system (CNS), and the blood-placental barrier, which protects the fetus in the uterus. Tissue barriers, of course, are not completely impermeable to all drugs (otherwise we would not have drugs that affect the central nervous system), but they significantly change the distribution pattern of many chemicals.

The next step in pharmacokinetics is metabolism, that is, modification chemical structure medicines. The main organ where drug metabolism occurs is the liver. In the liver, as a result of metabolism, the drug substance in most cases is converted from a biologically active to a biologically inactive compound. Thus, the liver has antitoxic properties against all foreign and harmful substances, including drugs. However, in some cases, the opposite process occurs: the drug substance is transformed from an inactive “prodrug” into a biologically active drug. Some drugs are not metabolized at all in the body and leave it unchanged.

The last stage of pharmacokinetics is excretion. The drug and its metabolic products may be excreted in various ways: through the skin, mucous membranes, lungs, intestines. However, the main route of elimination for the vast majority of drugs is through the kidneys through urine. It is important to note that in most cases the drug is prepared for excretion in the urine: when metabolized in the liver, it not only loses biological activity, but also turns from a fat-soluble substance into a water-soluble one.

Thus, the drug passes through the entire body before leaving it in the form of metabolites or unchanged. The intensity of the stages of pharmacokinetics is reflected in the concentration and duration of presence of the active compound in the blood, and this in turn determines the strength of the pharmacological effect of the drug. In practical terms, to assess the effectiveness and safety of a drug, it is important to determine a number of pharmacokinetic parameters: the rate of increase in the amount of drug in the blood, the time to reach maximum concentration, the duration of maintaining therapeutic concentration in the blood, the concentration of the drug and its metabolites in urine, feces, saliva and other secretions, etc. .d. This is done by specialists - clinical pharmacologists, who are called upon to help attending physicians choose the optimal pharmacotherapy tactics for a particular patient.

The use of drugs with medicinal or for preventive purposes begins with their introduction into the body or application to the surface of the body.

Existing routes of administration are usually divided into enteral (through the digestive tract) and parenteral (bypassing the gastrointestinal tract).

TO enteral routes include: oral (sublingual, buccal (buccal), supragingival), rectal, into the duodenum (through a probe).

The advantage of this route is its ease of use (no assistance from medical personnel is required), as well as comparative safety and the absence of complications characteristic of parenteral administration. In this way, natural barriers are not violated.

ORAL ADMINISTRATION (PER OS)

The most common way to use drugs. In the treatment of diseases internal organs Medicines that are well absorbed by the mucous membrane of the stomach or intestines should be prescribed orally. If it is necessary to create a high concentration of the drug in the gastrointestinal tract, on the contrary, they use drugs that are poorly absorbed, which makes it possible to obtain good effect in the absence of systemic adverse reactions.

Advantages:

· Various dosage forms (powders, tablets, dragees, mixtures, tinctures)

· Simplicity and accessibility

Does not require sterility

· Does not require special training

Disadvantages oral administration medicines are the following:

· relatively slow development of therapeutic action (15-30 min.);

· the possibility of large individual differences in the speed and completeness of absorption (dependence of the effect on age, condition of the body);

· influence of food on absorption;

· impossibility of using medicinal substances that are poorly adsorbed by the mucous membrane of the stomach and intestines (for example, streptomycin) and are destroyed in the lumen of the stomach and intestines (insulin, oxytocin, etc.) or when passing through the liver (hormones), as well as substances that have a strong irritating effect .

· administering medications by mouth is impossible if the patient is vomiting and unconscious.

To prevent the irritating effect of certain drugs on the gastric mucosa, tablets are used that are coated with films (coatings) that are resistant to the action of gastric juice, but disintegrate in the alkaline environment of the intestine. If possible, take the tablets while standing and drink plenty of water.

SUBLINGUAL APPLICATION

The mucous membrane of the oral cavity has an abundant blood supply, so substances absorbed through it quickly enter the systemic circulation and begin to act through a short time. When administered sublingually, the drug is not exposed to gastric juice and enters the systemic bloodstream through the veins of the esophagus, bypassing the liver, which avoids its biotransformation.

The drug should be kept under the tongue until completely absorbed. Therefore, only drugs with a pleasant taste are used sublingually, in small doses. With frequent sublingual use of drugs, irritation of the oral mucosa may occur.

TRANSBUCCAL ADMINISTRATION

Buccal forms of drugs are used in the form of plates and tablets glued to the mucous membrane upper gum. It is believed, for example, that buccal forms of nitroglycerin (the domestic drug Trinitrolong) are one of the most promising dosage forms of this drug. The Trinitrolong plate is glued to a specific place - the mucous membrane of the upper gum above the canine, small molars or incisors (right or left). The patient should be explained that the plate should under no circumstances be chewed or swallowed, since in this case it will enter the bloodstream through the mucous membrane of the oral cavity excessively. a large number of nitroglycerin, which can be dangerous. A patient with angina pectoris should be explained that if he needs to increase the flow of nitroglycerin into the blood due to the need to increase physical activity(acceleration of steps, etc.), it is enough to lick the plate with the drug 2-3 times with the tip of your tongue.

INTRODUCTION INTO THE RECTUM (RECTAL)

The rectum has a dense network of blood vessels and lymphatic vessels, therefore, many medicinal substances are well absorbed from the surface of its mucous membrane. Substances absorbed in the lower part of the rectum enter the systemic circulation through the inferior hemorrhoidal veins, largely bypassing the liver. Rectal administration of drugs avoids stomach irritation. In addition, in this way it is possible to use drugs in cases where their administration per os is difficult or impracticable (nausea, vomiting, spasm or obstruction of the esophagus, unconsciousness of the patient, children, mental patients). This does not require the assistance of medical personnel.

TO shortcomings this path is attributed

· pronounced individual fluctuations in the speed and completeness of drug absorption,

· psychological difficulties and inconveniences of use.

· drugs that have an irritating effect have a laxative effect.

Suppositories and liquids are administered rectally using enemas.

This route of administration is used both to obtain local (for example, for ulcerative colitis), and systemic effects.

Parenteral routes include: various types of injections (intravenous, intraarterial, intradermal, subcutaneous, intramuscular, subarachnoid (intrathecal) methods of administration), inhalation, application of drugs to the skin and mucous membranes, electro-, iontophoresis, administration of drugs into the urethra, vagina.

Advantages:

· Speed ​​of action

Dosage accuracy

The barrier role of the liver is excluded

· Indispensable in emergency situations

Flaws:

Requires sterility and special preparation

INTRAVENOUS ADMINISTRATION

The introduction of medicinal substances into a vein ensures a rapid onset and precise dosing of the effect; rapid cessation of the drug entering the bloodstream if adverse reactions occur; the possibility of introducing substances that are not absorbed from the gastrointestinal tract or irritate its mucous membrane.

Only sterile solutions are administered intravenously. Do not introduce suspensions or oil solutions. With long-term treatment, venous thrombosis may occur. Since the effective concentration is quickly reached and there is a danger of overdose, before intravenous administration, the drug must be diluted with saline (unless special instructions are provided) and administered slowly. This route of administration, like intramuscular, subcutaneous, intradermal, is quite complex, requires the participation of medical personnel, special equipment, and is painful.

INTRAARTERIAL ADMINISTRATION

To treat diseases of certain organs, drugs that are quickly metabolized or bound by tissues are injected into the artery. In this case, a high concentration of the drug is created only in the corresponding organ, and systemic action can be avoided.

But it should be remembered that possible thrombosis artery is much more serious complication than vein thrombosis. (X-ray contrast agent VISIPAK)

INTRAMUSCULAR ADMINISTRATION

When administered intramuscularly, the drug provides a relatively rapid onset of effect (soluble drugs are absorbed within 10-30 minutes). In this way, depot medications can be used. The volume of the administered substance should not exceed 10 ml. After administration of drugs intramuscularly, local soreness and even abscesses may appear.

SUBCUTANEOUS ADMINISTRATION

With subcutaneous administration, the absorption of medicinal substances, and therefore the manifestation of the therapeutic effect, occurs more slowly than with intramuscular and intravenous administration. However, the effect lasts longer. It should be remembered that subcutaneously administered substances are poorly absorbed in case of peripheral circulatory failure (for example, in shock). Do not administer medications that have an irritating effect.

INTRADERMAL ADMINISTRATION

Use different quantities medicines; Thus, small volumes (0.1-0.2 ml) of solutions or suspensions are administered intradermally (allergens, vaccines) or cutaneously (with possible incision);

INTRACAVITY ADMINISTRATION

Intraperitoneal injections are rarely used in practice, punctures abdominal wall produced in compliance with all aseptic rules using sterile instruments;

· in emergency or special cases ( surgery) the medicine is injected directly into the heart muscle or into a cavity, for example, the right ventricle, into the articular cavities;

Aqueous solutions are injected into the bladder antimicrobial agents through the urethra, using non-irritating bougies (probes), to influence, for example, pathogens infectious diseases lower sections urinary tract;

· intrapleural and intratracheal routes are used for the administration of antimicrobial drugs and a number of hydrolytic enzymes for certain lung lesions ( chronic pleurisy, bronchiectasis);

· intrauterine solutions of drugs (for example, chemotherapy) must be sterile and prepared in pyrogen-free water.

INTRODUCTION TO THE SUBARACHNOID SPACE

Spinal anesthesia– method of central neuraxial anesthesia, which consists of administering local anesthetic into the subarachnoid space.

INTRAOCONEAL ADMINISTRATION OF DRUGS

Indications: extensive burns of the torso and limbs, in pediatric practice- in cases where the child’s saphenous veins are not pronounced, and the deep ones (subclavian, femoral) are inaccessible due to the technical unpreparedness of the person providing assistance or the presence of a suppurative process in the injection area. Introduction to calcaneus

Contraindications: acute blood loss, traumatic shock of the III-IV degree, when rapid replenishment of the deficit in circulating blood volume is required.

INHALATION METHOD OF ADMINISTRATION

At various diseases respiratory tract and lungs use the administration of drugs directly into Airways. In this case, the medicinal substance is administered by inhalation - inhalation (lat. inhalatum - breathe). When drugs are administered into the respiratory tract, local, resorptive and reflex effects can be obtained.

Inhalation method administer medicinal substances, both local and systemic impact:

Gaseous substances (oxygen, nitrous oxide);

Vapors of volatile liquids (ether, fluorotane);

Aerosols (a suspension of tiny particles of solutions).

Balloon metered aerosol preparations currently used most often. When using such a canister, the patient must inhale while sitting or standing, tilting his head back slightly so that the airways straighten and the drug reaches the bronchi. After vigorous shaking, the inhaler should be turned upside down. Having exhaled deeply, at the very beginning of the inhalation the patient presses the canister (with the inhaler in the mouth or using a spacer - see below), then continuing to inhale as deeply as possible. At the height of inhalation, you should hold your breath for a few seconds (so that the particles of the drug settle on the walls of the bronchi) and then calmly exhale.

Spacer is a special chamber-adapter from the inhaler to the mouth, where the drug particles are suspended for 3-10 s. The patient can make the simplest spacer independently from a sheet of paper about 7 cm long rolled up into a tube. The advantages of using a spacer are as follows.

Reducing the risk of local side effects: for example, cough and oral candidiasis with inhalation use glucocorticoids.

The ability to prevent systemic exposure to the drug (its absorption), since non-inhaled particles settle on the walls of the spacer and not in the oral cavity.

Possibility of prescribing high doses of drugs during attacks of bronchial asthma.

Nebulizer. In the treatment of bronchial asthma and chronic airway obstruction, a nebulizer (lat. nebula - fog) - a device for converting a solution of a medicinal substance into an aerosol for delivering the drug with air or oxygen directly into the bronchi of the patient. The formation of an aerosol is carried out under the influence of compressed air through a compressor (compressor nebulizer), which turns the liquid medicinal product into a foggy cloud and supplying it with air or oxygen, or under the influence of ultrasound (ultrasonic nebulizer). To inhale the aerosol, use a face mask or mouthpiece; the patient does not make any effort.

The benefits of using a nebulizer are as follows.

Possibility of continuous supply of the drug for a certain time.

Medicines can have resorptive (through the blood) and local effects. Depending on the mechanism of action of drugs, the routes of their administration are distinguished. The resorptive effect is carried out enterally (through the digestive tract), parenterally (bypassing the digestive tract) and sublingual route.

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Lecture No. 7 Topic “Routes of drug administration”

Goals

Educational:Study the ways of introducing drugs into the body. Advantages and disadvantages.

Developmental: Contribute to the formation of OK 1. Understand the essence and social significance of your future profession, show a steady interest in her.

Educational: contribute to the formation of OK 11. Be ready to take on moral obligations towards nature, society and people.

Plan

1. Main routes of drug administration.

2.Enteral route of administration. Advantages and disadvantages.

3. Parenteral route of administration. Advantages and disadvantages.

External To the skin

Inhalation - through the respiratory tract

On mucous membranes : in the eyes, ear, nose, vagina

Parenteral

Intradermal

Subcutaneously

Intramuscularly

Intravenous

Intra-arterial

Into the cavity

Intraosseous

Into the subarachoid space

Medicines can have resorptive (through the blood) and local effects. Depending on the mechanism of action of drugs, the routes of their administration are distinguished. The resorptive effect is carried out enterally (through the digestive tract), parenterally (bypassing the digestive tract) and sublingual route.

Local action provide medications used externally. Fat-soluble drugs are absorbed through the skin (nursing staff should take this into account to ensure their own safety!).

External path. Compresses, lotions, powders, lubricants, rubbing, bandages on the wound surface, instillation of drops, inhalations - all these are methods of external administration of various dosage forms: ointments, emulsions, solutions, mash, powders, tinctures, etc. Externally, you can influence not only skin, but also on the mucous membranes of the eye, ear, nose, etc.

For any method of drug administration, nursing staff must inform the patient:

About the name and purpose of the drug;

About possible side effects;

About the timing and signs of the onset of the effect of the drug used;

About the method of using the drug.

The doctor provides complete information about the drug to the patient and/or his relatives. He also obtains the patient’s consent to carry out drug therapy. The sister makes sure that there is informed consent.

Enteral route

Enteral routes of drug administration:

Oral

Sublingual and buccal

Rectal

Preudenal

Intragastric

Through the mouth (per os);

Through the rectum (per rectum);

Sublingually (sub lingua, in some cases refers to the enteral route).

Administration of medications by mouth

The use of drugs by mouth is most convenient and widespread, since various dosage forms (powders, tablets, pills, dragees, mixtures, etc.) can be administered in this way.

However, this method of administration has a number of disadvantages:

Partial inactivation of the drug in the liver;

Dependence of action on age, condition of the body, individual sensitivity and pathological processes in organism;

Slow and incomplete absorption in the digestive tract.

In addition, administering medications orally is not possible if the patient is vomiting or unconscious.

Method of distributing medicines:

1. Place containers with solids, bottles with liquid dosage forms, pipettes (separately for each bottle with drops), beakers, a container with water, scissors, and place prescription sheets on the mobile table;

2. Moving from patient to patient, give the medicine directly at his bedside, according to the prescription sheet (the medicine is dispensed from the package in which it was received at the pharmacy);

Remember! Before giving the patient the medicine:

Read the appointment sheet carefully;

Make sure that the patient in front of you is the one whose name is indicated on the appointment sheet;

Check the name of the medicine, its dose and method of administration;

Check the label on the package for compliance with the doctor's prescription;

Be especially careful in the case of patients with the same last name and/or on the same medications.

3. never give medicine without packaging;

Remember! Do not touch the tablets with your hands, as this is unsafe for your health.

4. Cut off the packaging of foil or paper tablets with scissors; Gently shake the tablets from the bottle into a spoon;

5. The patient must take the medicine in your presence, and also discuss any doubts with you;

6. Liquid medicines should be mixed thoroughly;

7. Bottles with protein preparations must be carefully rotated while mixing to prevent protein denaturation and foam formation; make sure that the drug has not changed color; pay attention to its expiration date.

The benefits of this type of drug distribution are obvious. First, the nurse monitors whether the patient has taken the drug. Secondly, she can answer his questions. Thirdly, errors during the distribution of medicines are excluded. When giving them to the patient, you should warn him about the features of this or that remedy: bitter taste, strong smell, duration of action, change in color of urine or feces after taking it.

Explain to the patient how to take medications:

a) solid dosage forms:

Take only while standing or sitting;

Place the tablet (dragee, capsule, pill) on the root of the tongue and wash it down with at least 100-150 ml of water (dragees, capsules, pills unchanged, if necessary, break the tablets into small pieces or crush them, the powder can be diluted with water beforehand);

b) liquid dosage forms - infusions, decoctions, mixtures:

Pour the medicine into a graduated beaker or tablespoon (15 ml), drink and wash down with water;

c) liquid dosage forms in alcohol - tinctures, extracts:

Pipette the required number of drops into a beaker, dilute 10-15 ml with water, drink and wash down with water.

Remember! The patient has the right to know the name, purpose and dose of the drug.

The patient needs to be told how to take the medicine.

The patient should be informed about the peculiarities of the interaction of the drug he is using with food.

8. After taking the medication, mark on the prescription sheets the time, dose and route of administration, and put your signature.

If the medicine is given in error or if it is exceeded single dosage notify your doctor immediately;

The nurse does not have the right to prescribe or replace some medications with others without the doctor’s knowledge.

Administration of drugs under the tongue

Rapid-acting drugs are usually prescribed sublingually. Dosage forms are different (tablets, capsules, solutions). Taking them under the tongue is usually associated with pain in the patient's heart, which sometimes poses a threat to life, so he is forced to constantly wear the prescribed medication.

Nursing staff (as prescribed by the doctor) must teach the patient the rules for taking and storing these drugs. It should be taken into account that pain in the heart is often accompanied by a feeling of fear and anxiety in the patient.

Remember!

If a person is forced to constantly carry pills with him, they should be in a hermetically sealed package in a clothing pocket (nitroglycerin decomposes in light and air).

If a painful attack occurs, a person should stop (if he was walking) and, if possible, sit down.

To relieve a painful attack, a person must put the number of tablets prescribed by the doctor under the tongue and keep them under the tongue until completely dissolved.

A person should seek help if the attack of pain does not go away.

A person should be aware of the start and end times of the drug.

Solutions of validol and nitroglycerin are also taken sublingually. To do this, 5 - 6 drops of validol solution or 2 - 3 drops of nitroglycerin solution should be dripped onto small piece sugar or bread and keep under the tongue without swallowing: sugar until completely absorbed, and bread for 10 - 15 minutes. To speed up the effect, you can drop 1 - 2 drops of 1% nitroglycerin solution under the tongue, and crush the capsule with nitroglycerin with your teeth and keep it under the tongue.

Medicines taken under the tongue are quickly absorbed, are not destroyed by enzymes of the digestive tract and enter the bloodstream, bypassing the liver.

Rectal method- This is the administration of drugs through the rectum. This is how suppositories and medicinal enemas are administered.

Advantages.

1. Absorption occurs quite quickly through the venous plexuses of the rectum.

2. They quickly enter the bloodstream, bypassing the liver.

Parenteral route

Parenteral administrationmedications (bypassing the digestive tract) are carried out by injection: intradermal, subcutaneous, intramuscular, intravenous, intra-arterial; into the abdominal, pleural cavities, into the heart, into the spinal canal, into the painful focus, into the bone marrow.

Benefits parenteral administration is: speed of action, accuracy of dosage, entry of the drug into the blood unchanged.

Disadvantages administration is: the mandatory participation of trained medical personnel, compliance with asepsis and antisepsis, difficulty or impossibility of administering the drug in case of bleeding, damage to the skin at the injection site.

Injection method.

Injection methods of administering drugs include intravenous, intramuscular and subcutaneous administration.

Intravenous administration of drugs.

Advantages.

1. Rapid achievement of a therapeutic effect.

3. The possibility of injecting drugs that are destroyed by other routes of administration.

Flaws.

1. Soreness.

2. The need for the participation of qualified medical personnel.

3. There is a possibility of infection of the patient.

4. Injection complications may develop, for example, thrombosis, embolism, phlebitis.

Intramuscular administration of drugs.

Advantages.

1. Rapid achievement of maximum concentration in blood plasma and rapid development of the therapeutic effect.

2. Possibility of administering drugs that are destroyed by other routes of administration.

3. The possibility of creating a “depot” of the drug at the injection site.

Flaws.

1. Soreness. Possibility of developing a post-injection abscess.

2. Possibility of damage to blood vessels or nerves.

3. Dependence of absorption rate on capillary blood flow.

4. The need for the participation of medical personnel.

Subcutaneous administration of drugs.

Advantages.

1. Slow absorption.

2. Achieving a concentration of the drug in the blood plasma close to the stationary level, which ensures a stable therapeutic effect.

3. Possibility of administering drugs that are destroyed by other routes of administration.

4. Possibility of creating a “depot” of the drug at the injection site.

Flaws.

1. Soreness

2. Dependence of absorption rate on local blood flow.

3. Ineffectiveness serious violations local circulation, for example, in shock, diabetes.

4. Possibility of developing inflammation and hematoma at the injection site.

5. The need for the participation of medical personnel.

Percutaneous method.

Advantages.

1.Convenience for the patient.

2. There is no need for the participation of medical personnel.

3. Ensuring a constant concentration of the drug in the blood plasma.

4. Reducing the frequency of use of the dosage form.

5. Possibility of quickly stopping the supply of the drug if adverse reactions develop.

6. Possibility of use in case of destruction of the active substance through other routes of administration.

Flaws.

1.Increasing cost of therapy.

2. Opportunity for development contact dermatitis. Limited range of drugs.

3. Increased time for development of the therapeutic effect compared to intravenous administration.