All routes of administration medicines into the body can be divided into enteral and parenteral. Enteral routes of administration ( enteros- intestines) ensure the introduction of the drug into the body through the mucous membranes gastrointestinal tract. Enteral routes of administration include:

• Oral administration (orally, per os)- introduction of medicine into the body by ingestion. In this case, the medicine first enters the stomach and intestines, where it is absorbed into the portal vein system within 30-40 minutes. Next, through the bloodstream, the medicine enters the liver, then the inferior vena cava, the right side of the heart and, finally, the pulmonary circulation. Having passed a small circle, the medicine reaches the left parts of the heart through the pulmonary veins and, with arterial blood, enters the tissues and target organs. This route is most often used to administer solids and liquids. dosage forms(tablets, dragees, capsules, solutions, lozenges, etc.).

• Rectal route (>per rectum)- administration of medication through the anus into the ampulla of the rectum. This way, soft dosage forms (suppositories, ointments) or solutions (using microenemas) are administered. The substance is absorbed into the system of hemorrhoidal veins: upper, middle and lower. From the superior hemorrhoidal vein, the substance enters the portal vein system and passes through the liver, after which it enters the inferior vena cava. From the middle and inferior hemorrhoidal veins, the medicine enters directly into the inferior vena cava system, bypassing the liver. The rectal route of administration is often used in children of the first three years of life.

• Sublingual (under the tongue) and subbucal (into the cavity between the gum and cheek) administration. In this way, solid dosage forms (tablets, powders), some liquid forms (solutions) and aerosols are administered. With these methods of administration, the drug is absorbed into the veins of the mucous membrane oral cavity and then sequentially enters the superior vena cava, the right side of the heart and the pulmonary circulation. After this, the medicine is delivered to the left side of the heart and travels with arterial blood to the target organs.

Parenteral administration is a route of administration of a drug in which it enters the body bypassing the mucous membranes of the gastrointestinal tract.

• Injection administration. With this route of administration, the drug immediately enters the systemic circulation, bypassing the tributaries of the portal vein and the liver. Injection includes all methods in which the integrity of the integumentary tissue is damaged. They are carried out using a syringe and needle. The main requirement for this route of administration is to ensure the sterility of the drug and aseptic injection.
• Intravenous administration. With this method of administration, the syringe needle pierces the skin, hypodermis, and vein wall, and the medicine is directly injected into the systemic bloodstream (inferior or superior vena cava). The medicine can be administered slowly or quickly (bolus), as well as by drip. In this way, liquid dosage forms are administered, which are true solutions or lyophilized powders (after dissolving them).

• Intramuscular administration. All types of liquid dosage forms and powder solutions are administered this way. The needle of a syringe pierces the skin, hypodermis, muscle fascia and then its thickness, where the medicine is injected. Absorption of the drug occurs in the vena cava system. The effect develops after 10-15 minutes. The volume of the injected solution should not exceed 10 ml. At intramuscular injection the medicine is absorbed less completely compared to intravenous administration, but better than with oral administration(however, there may be exceptions to this rule - for example, diazepam when administered intramuscularly is absorbed less completely than when administered orally).

• Subcutaneous administration. Liquid dosage forms of any kind and soluble powders are administered this way. The syringe needle pierces the skin and enters the hypodermis; after injection, the medicinal substance is absorbed immediately into the vena cava system. The effect develops after 15-20 minutes. The volume of the solution should not exceed 1-2 ml.

• Intrathecal administration- administration of a medicinal substance under the membranes of the brain (subarachnoid or epidural). Performed by injecting a substance at the level of L4-L5 lumbar vertebrae. In this case, the needle pierces the skin, hypodermis, interspinous and yellow ligaments of the vertebral processes and approaches the meninges. With epidural administration, the medicine enters the space between the bony canal of the vertebrae and the dura mater of the brain. With subarachnoid injection, the needle pierces the dura and arachnoid membranes of the brain and the medicine is injected into the space between the brain tissue and soft tissue. meninges. The volume of administered medication cannot exceed 3-4 ml. In this case, it is necessary to remove the appropriate amount of liquor. Only true solutions are administered.

• Inhalation administration- administration of a medicinal substance by inhalation of its vapors or tiny particles. Gases (nitrous oxide), volatile liquids, aerosols and powders are introduced through this route. The depth of introduction of aerosols depends on the size of the particles. Particles with a diameter of more than 60 microns settle in the pharynx and are swallowed into the stomach. Particles with a diameter of 40-20 µm penetrate the bronchioles, and particles with a diameter of 1 µm reach the alveoli. The medicine passes through the wall of the alveoli and bronchi and enters the capillary, then through the bloodstream it enters the left side of the heart and, through the arterial vessels, is delivered to the target organs.

• Transdermal administration- application of a medicinal substance to the skin to ensure its systemic effect. Use special ointments, creams or TTS (transdermal therapeutic systems - patches).

• Local application. It involves the application of medication to the skin, mucous membranes of the eyes (conjunctiva), nose, larynx, and vagina in order to provide a high concentration of the drug at the site of application, usually without systemic action.

The choice of route of administration of the drug depends on its ability to dissolve in water or non-polar solvents (oils), on the localization of the pathological process and the severity of the disease. Table 1 shows the most common methods of using drugs for various types of pathology.
Table 1. Choice of route of drug administration for various pathologies.

There are several ways to administer drugs: externally - through the skin, mucous membranes or respiratory tract, internally (enteral) - through the mouth or rectum and parenterally, bypassing the gastrointestinal tract.

External use of drugs is designed mainly for their local effect, since the absorption capacity of intact skin is very small.

Remember! Application of medications should always be done on clean skin, with clean tools and thoroughly washed hands.

There are the following methods of administering medicinal substances through the skin: rubbing, wiping, lubricating, bandages. Rubbing is the administration of medications through the skin in the form of liquids or ointments. Rubbing is done into areas of healthy skin, mainly where it is thinner and not covered with hair: the flexor surface of the forearms, back surface hips, side surface chest and belly. For rubbing, a small amount of ointment is placed on the palm (or a warm medicinal substance is poured onto the palm) and longitudinal movements combined with circular movements are made until the palm becomes dry and the skin turns red (about 20 minutes). Remember! Nitromast does not rub in.

Rubbing - used for skin diseases(urticaria, neurodermatitis, prurigo) as a preventive measure purulent complications. Wring out a cotton (gauze) swab soaked in the required solution and apply it to the skin with longitudinal movements (where the hair is - in the direction of its growth). For purulent diseases, the skin is wiped around the lesions in the direction from the periphery to the center.

Lubrication is a method of applying medicinal substances contained in ointments, pastes, and mash to the skin. Ointments and pastes are applied with a clean spatula to the affected surface and lightly smeared. Talkers are used for extensive skin lesions; before use, they should be shaken, applied with a cotton swab, and sprinkled with talcum powder. Talkers and pastes should not be applied to hair areas. Potent ointments that are prepared without bases (tar, ichthyol) are applied with a cotton swab strictly to the affected area.

Bandages are often used to fix the drug and create conditions for it to penetrate deeper into the skin. Ointment and wet-dry dressings are used. Ointment bandage technique: the ointment is placed with a spatula on the lesion or on a sterile napkin and tightly fixed with 2-3 rounds of bandage. You can put a layer of cotton wool on top of the napkin. If you need an ointment compress, apply compress paper under a layer of cotton wool and bandage it. Contraindicated in acute inflammatory processes with weeping. Wet-dry dressing technique: gauze, folded in 10-15 layers, is moistened in medicinal solution, squeeze out and apply to the affected area. Compress paper is applied over the gauze and bandaged for 4-5 hours. Remember! Do not remove by force, but when removing, moisten with the same solution.

Inhalation is a method of administering drugs through the respiratory tract. Inhalations based on the method of sublimation of the medicinal substance are divided into aerosol, steam and steam-oil. Aerosol inhalations are the delivery of finely dispersed substances into the airways using special devices designed like a spray gun. Steam inhalations - delivery using steam. When inhaling steam, remember that the escaping steam can cause burns. The steam should be inhaled through the nose and exhaled through the mouth. Oil inhalation is used after steam inhalation and very rarely on its own (to protect against chemical substances). The advantages of medicinal inhalations are that: a) the medicine is delivered directly to the site of the pathological process; b) the medicine is quickly absorbed; c) the medicine enters directly into the blood, bypassing the liver, so lower concentrations can be used for a longer period.

Internal (enteral) administration of drugs is the most common, simple and convenient method of administration. The following dosage forms are administered using this method: powders, tablets, pills, dragees, mixtures, drops, infusions, etc. Almost all of them have general action on the body, and often locally on the gastrointestinal tract. Most often, the medicine is given before meals, since interaction with food slows down its absorption. After meals, drugs are used that irritate the gastrointestinal mucosa (iron, aspirin, calcium chloride, iodine, etc.). Enzyme preparations (festal, panzinorm) are used directly during meals. The advantage of this method is that the medicinal substances are used in various forms and do not require sterility. The disadvantages include the following: a) partial and sometimes complete inactivation in the liver and stomach; b) dependence of the action on age, weight; c) slow and incomplete absorption into digestive tract, and, consequently, late entry into the blood.

Dragees, capsules, pills are taken unchanged, placing them on the root of the tongue. Infusions, solutions, mixtures, and decoctions are often prescribed in tablespoons. Alcohol tinctures, extracts are in drops, and often droppers are built into the bottles directly into the stopper. If it is not there, then you need to use your own pipette for each bottle.

Patients with swallowing disorders, vomiting, who are in unconscious, children, and mental patients prefer to administer medicinal substances into the rectum. This method has its advantage, since the drug is not influenced by gastric juice enzymes and, when absorbed, enters through the hemorrhoidal veins directly into the inferior vena cava, bypassing the liver. Forms of administration into the rectum - suppositories, medicinal microenemas. The suppositories are stored in the refrigerator and inserted with a rounded end into the rectum, where under the influence of body temperature they quickly become liquid. Remember! Before introducing medications into the rectum, you should do a cleansing enema 20-30 minutes before!

Technique for inserting a suppository: the patient lies on his side, the legs bent at the knees should be pressed to the stomach, the buttocks should be spread apart with the left hand, and the suppository should be quickly inserted with the right hand.

Technique for administering liquid dosage forms into the rectum: heat the drug to 37-38 o C, use a rubber balloon with a gas outlet tube to administer the drug in an amount of 50-100-200 ml to a depth of 15-20 cm. The patient should lie down for half an hour, to keep the medicine. Sterilize the gas outlet tube and store it in a dry container.

Parenteral administration of drugs is the administration of a medicinal substance using a syringe by injection (injectio - injection) into tissues (into the skin, subcutaneously, into muscles), into vessels or into cavities (abdominal, pleural, articular). The main advantages of this method are speed and dosage accuracy. This method requires strict adherence to the rules of asepsis, if violated, they may enter the body. pathogenic microbes, as a result of which it is possible to develop infectious complication. Currently, only disposable syringes are used, but certain rules must be followed regarding them:

1. Choose a syringe depending on the type of injection: intradermal - no more than 0.5 ml; subcutaneous - 0.5-2 ml; intramuscular - 1-10 ml; intravenous - 20 ml.

2. Accurately navigate the price of syringe divisions - usually the total capacity of the syringe is divided by the number of divisions.

It is advisable to use needles and syringes strictly for their intended purpose.

Intradermal administration of drugs is used for local anesthesia, and also with diagnostic purpose, more often, if necessary, determine sensitivity to medications. Features of the technique: the needle is directed parallel to the surface of the skin to a depth of 5 mm. Control correct administration is the formation of a whitish tubercle in the form of a lemon peel. Determining the patient's reaction to the administration of antibiotics: after administering 0.1 ml of the substance, the reaction is checked after 20 minutes; if there are no rashes and blood pressure does not decrease, then another 0.5 ml of solution is administered. Further administration of the substance is possible only after 20 minutes in the absence of any unpleasant sensations.

Subcutaneous injections are made into the subcutaneous fat layer, rich in blood vessels, to a depth of 15 mm. The most convenient areas: outside surface shoulder or radial edge of the forearm, subscapular space, anterior outer surface of the thigh, lateral surface abdominal wall and lower part armpit. In these areas, the skin is well captured in the fold and there is no danger of damage to blood vessels, nerves and periosteum. Particularly dangerous if it gets into blood vessels oil solutions. Remember! It is not recommended to inject into areas with swollen subcutaneous tissue or into seals after previous injections.

Intramuscular administration of medicinal substances creates conditions for faster and more complete absorption, since muscles have a wide network of blood and lymphatic vessels. Intramuscular injections should be performed in certain areas of the body where there is a significant layer muscle tissue, away from large blood vessels and nerve trunks: muscles of the buttocks, abdomen and thighs. The sciatic nerve and large vessels pass through the gluteal region, so injections should be made only in the upper outer quadrant, which is determined by mentally dividing the buttock into 4 parts. Features of the injection technique: after inserting the needle, it is necessary to pull the piston towards you to make sure that the needle is not in the blood vessel.

Intravenous administration of medicinal substances is carried out by venipuncture and venesection only by specially trained medical personnel.

Complications. Most of the complications are due to the fault of the person injecting, and the cause is usually severe chemical irritation of tissues, especially subcutaneous tissue, slow absorption due to the use of a blunt needle or a needle that is too short, inappropriate for the type of injection, inaccurate choice of injection site, frequent injections to the same place.

Possible complications:

1. Formation of infiltrate (reactive proliferation of cells around a mechanical injury when using a blunt needle, after the introduction of unheated oil solutions, or when asepsis rules are not followed). Treatment - local warming compress of 40% alcohol solution or a heating pad (if in the buttock area);

2. Abscess formation ( purulent inflammation soft tissues with the formation of a cavity) as a result of violation of asepsis rules. Treatment is surgical;

3. Incorrect administration of medications. Most often it can lead to tissue necrosis (cell death). For example, introducing 10% sodium chloride instead saline solution. Treatment: inject 0.9% sodium chloride solution up to 50-80 ml into the injection site and around it and put an ice pack. If the drug is mistakenly administered subcutaneously, then before administering the isotonic solution, a tourniquet should be applied above the injection site to slow down absorption.

4. Damage to the nerve trunks due to incorrect choice of injection site and blockage of the vessel supplying the nerve leads to the development of neuritis or paralysis. Prevention of this complication is to improve the insertion technique.

5. Needle fracture due to sudden muscle contraction. Treatment is surgical;

6. Drug embolism when oil solutions get into blood vessels or when they are introduced into the infiltrate from previous injections, since the vessels in them are inactive and their lumen gapes. This is the most formidable complication, because the embolus can enter the pulmonary vessels. At following signs- sudden attack of suffocation, cough, blueness of the upper half of the body, feeling of tightness in the chest - call a doctor immediately.

Remember! When performing injections, the patient should not stand!

Never inject into the infiltrate! Before you inject a medicinal substance (especially an oil solution), you must pull the plunger up to ensure that no blood enters the syringe!

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 in the small intestine, and less commonly in the stomach. The effect of the drug when taken orally develops after 20–40 minutes, so this route of administration is not suitable for emergency therapy.

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 for relief 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, when the patient is unconscious. 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 with an isotonic solution or glucose solution and 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 high concentration the drug only in the appropriate authority. 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 a 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. Irritating substances 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

With 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 pharmacokinetic stages is reflected in the concentration and duration of stay 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.

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 to the liver and further 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 orally also prevents the use of this route of administration in emergency care in most cases.

The rectal route of administration, or into the rectum (per rectum), is used to administer 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 when it is impossible to administer the drug by mouth, in case of diseases lower section intestines and pelvic organs, as well as if they want to avoid unwanted 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 for injections, sterile aqueous and oily solutions, suspensions and powders are used, 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 of the pharmacological effect.

Mostly aqueous solutions are injected into the vein, as well as hypertonic solutions and irritating substances that cannot be injected under the skin or 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 a local, but also a general effect. In addition, depending on the 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.

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

Medicines can be administered naturally(inhalation, enteral, cutaneous) and using technical means. In the first case of transporting them to internal environments The body is provided with the physiological absorption ability of the mucous membrane and skin, in the second it occurs by force.

It is rational to divide the routes of drug administration into enteral, parenteral and inhalation.

Enteral gilah involves the administration of drugs through various parts of the digestive canal. With sublingual (administration of medications under the tongue) and subbucal (administration of medications on the buccal mucosa) routes of administration, absorption begins quite quickly, the drugs exhibit a general effect, bypass the liver barrier, and do not come into contact with hydrochloric acid of the stomach and enzymes of the gastrointestinal tract. Fast-acting drugs with high activity (nitroglycerin), the dose of which is quite small, are prescribed sublingually, as well as drugs that are poorly absorbed or destroyed in the digestive canal. The drug should be in the oral cavity until completely absorbed. Swallowing it with saliva reduces the benefits of this route of administration. Frequent use of drugs sublingually can lead to irritation of the oral mucosa.

The oral route of administration involves swallowing the drug and then passing it through the digestive canal. This method is the simplest and most convenient for the patient; it does not require sterile conditions. However, only a small part of the drugs begins to be absorbed in the stomach. For most drugs, the slightly alkaline environment of the small intestine is favorable for absorption, so when oral administration the pharmacological effect occurs only after 35-45 minutes.

Medicines taken orally are exposed to digestive juices and may lose their activity. An example would be the destruction of insulin and other protein drugs by proteolytic enzymes. Some drugs are affected of hydrochloric acid stomach and alkaline intestinal contents. In addition, substances that are absorbed from the stomach and intestines enter through the portal vein system into the liver, where they begin to be inactivated by enzymes. This process is called the first pass effect. That is why, and not because of poor absorption, the doses of some drugs (narcotic analgesics, calcium antagonists) when administered orally should be significantly higher than when administered into a vein. The biotransformation of a substance during its initial passage through the liver is called systemic metabolism. Its intensity depends on the speed of blood circulation in the liver. It is recommended to take medications orally 30 minutes before meals.

Medicines are administered orally in the form of solutions, powders, tablets, capsules, and granules. To prevent the destruction of certain medicinal substances in the acidic environment of the stomach, tablets are used that are coated with a coating that is resistant to the action of gastric juice, but soluble in the alkaline environment of the intestine. There are dosage forms (multilayer-coated tablets, capsules, etc.) that provide gradual absorption of the active substance, which allows the therapeutic effect of the drug to be prolonged (retarded forms of drugs).

It should be remembered that in patients (especially the elderly) with impaired esophageal peristalsis or in those who have been in the horizontal position, tablets and capsules can linger in the esophagus, forming ulcers in it. To prevent this complication, it is recommended to take tablets and capsules with plenty of water (at least 200 ml). Reducing the irritating effect of drugs on the gastric mucosa can be achieved by preparing them in the form of mixtures with the addition of mucus. In case of significant irritant (or ulcerogenic) effect, drugs, especially those that require long-term course use (for example, diclofenac sodium), should be taken after meals.

Administration of medications by mouth is impossible or difficult during vomiting, during convulsions, or in a state of fainting.

Sometimes drugs are administered duodenally (through a tube into the duodenum), which makes it possible to quickly create a high concentration of the substance in the intestine. This is how, for example, magnesium sulfate is administered (to achieve a choleretic effect or for diagnostic purposes).

Medicines are administered rectally (into the rectum) in the form of suppositories (candles) or enemas (for adults - no more than 50-100 ml in volume). Rectal administration avoids the irritating effect of substances on the gastric mucosa, and also makes it possible to use them in cases where oral administration is difficult or impossible (nausea, vomiting, spasm or esophageal obstruction). Absorbed from the lumen of the rectum, drugs enter the blood not through the portal vein, but through the system of the inferior vena cava, thus bypassing the liver. Therefore, the strength of the pharmacological action of drugs and the accuracy of dosage for rectal administration are higher than for oral administration, which makes it possible to administer drugs not only preferentially local action(microanesthetic, anti-inflammatory, disinfectant), but also general action (hypnotics, analgesics, antibiotics, cardiac glycosides, etc.).

Parenteral route (bypassing the digestive canal). All types of parenteral administration pursue the same goal - to deliver the active substance of the drug to the internal environment of the body or directly to the pathological focus faster and without loss.

Inhalation is the most physiological of natural routes of drug administration. In the form of aerosols, substances are prescribed primarily to obtain a local effect (with bronchial asthma, inflammatory processes of the respiratory tract), although most substances (adrenaline, menthol, most antibiotics) administered in this way are absorbed and also have a resorptive (general) effect. Inhalation of gaseous or dispersed solid and liquid drugs (aerosols) ensures their entry into the blood almost as quickly as injection into a vein, is not accompanied by injury from an injection needle, and is important for children, the elderly and debilitated patients. The effect is easy to control by changing the concentration of the substance in the inhaled air. The rate of absorption depends on the volume of respiration, the active surface area of ​​the alveoli, their permeability, the solubility of substances in lipids, the ionization of drug molecules, the intensity of blood circulation, etc.

To facilitate the inhalation use of non-volatile solutions, special nebulizers (inhalers) are used, and the administration and dosing of gaseous substances (nitrous oxide) and volatile liquids (ether for anesthesia) is carried out using machines (anesthesia) artificial ventilation lungs.

Cutaneous route widely used in dermatology to directly affect pathological process. Some substances are highly lipophilic, can partially penetrate the skin, be absorbed into the blood and have a general effect. Rubbing ointments and liniments into the skin promotes deeper penetration of medicinal substances and their absorption into the blood. With ointment bases lanolin, spermaceti and pork fat provide deeper penetration of medicinal substances into the skin than petroleum jelly, since they are closer in composition to body lipids.

IN Lately Special pharmacotherapeutic systems have been developed for transcutaneous delivery of a drug (for example, nitroglycerin) into the systemic circulation. These are special dosage forms that are fixed with an adhesive substance on the skin and ensure slow absorption of the drug, thereby prolonging its effects.

Introduction of medicinal substances into conjunctival sac, outdoor ear canal, into the nasal cavity most often involves a local effect on the pathological process in the relevant organs (conjunctivitis, otitis media, rhinitis). Some drugs for local application tend to exhibit a resorptive effect (for example, m-anticholinergics and anticholinesterase drugs for glaucoma).

The introduction of medicinal substances into body cavities is rarely used. IN abdominal cavity Antibiotics are usually administered during surgical operations. Administration into the cavities of the joints and pleura is advisable for eliminating inflammatory processes (arthritis, pleurisy).

Among the parenteral routes of drug administration, injection is common: into the skin, subcutaneously, into a muscle, into a vein, into an artery, subarachnoid, subdural, suboccipital, intraosseous, etc.

Injection into the skin is used primarily for diagnostic purposes (for example, a test for increased individual sensitivity to antibiotics and local anesthetics), as well as for vaccination.

Often drugs are administered subcutaneously and intramuscularly. These methods are used when it is impossible to administer substances by mouth or into a vein, as well as to prolong the PHARMACOTHERAPEUTIC effect. Slow absorption of the drug (especially oil solutions) allows you to create a depot in the subcutaneous tissue or muscles, from which it gradually enters the blood and is there in the required concentration. Substances that have a significant local effect should not be injected under the skin and into the muscle, as this can lead to inflammatory reactions, the formation of infiltrates and even necrosis.

Administration into a vein saves the time required for the absorption of medications through other routes of administration, makes it possible to quickly create their maximum concentration in the body and obtain a clear healing effect, which is very important in cases of emergency care.

Only aqueous sterile solutions of drugs are injected into the vein; the introduction of suspensions and oil solutions is strictly prohibited (to prevent vascular embolism, vital important organs), as well as substances that cause intense blood thickening and hemolysis (gramicidin).

Medicines can be injected into a vein quickly, slowly in a stream or slowly in a drip. It is often administered slowly (especially to children), since many drugs tend to cause an effect too quickly (strophantine, ganglion blockers, plasma replacement fluids, etc.), which is not always desirable and can be life-threatening. It is rational to administer solutions by drip, usually starting with 10-15 drops per minute. and gradually increase the speed; maximum speed administration - 80-100 drops per 1 minute.

The medication, which is injected into a vein, is dissolved in isotonic solution(0.9%) NaCl or 5% glucose solution. Dilution in hypertonic solutions (for example, 40% glucose solution), except individual cases, less appropriate due to possible damage vascular endothelium.

Recently, they have been using rapid (within 3-5 minutes) administration of drugs into a vein in the form of a bolus (Greek. Bolos - com). The dose is determined in milligrams of the drug or in milliliters of a certain concentration of the substance in solution.

Introduction into an artery allows you to create a high concentration of the drug in the area of ​​​​the blood supply to this artery. Antineoplastic agents are sometimes administered this way. To reduce their overall toxic effect, the blood flow can be artificially slowed down (compression of the veins). X-ray contrast agents are also injected into the artery to clarify the location of the tumor, thrombus, aneurysm, etc.

Medicines that do not penetrate well through the blood-brain barrier can be administered under the membranes of the brain - subarachnoid, subdural, suboccipital. For example, some antibiotics are used in cases infectious lesion tissues and membranes of the brain.

Intraosseous injections are used if it is technically impossible to administer into a vein (children, elderly people), and also sometimes to inject large amounts of plasma-substituting fluids (into the spongy substance of the heel bone).

Advantages of parenteral routes of drug administration:

1. The pharmacological effect develops quickly (magnesium sulfate reduces arterial pressure during hypertensive crisis).

2. High dosing accuracy (mg/kg body weight can be calculated).

3. The possibility of administering drugs that are destroyed by the enteral route (insulin, heparin).

4. The medicine can be administered to patients in an unconscious state (insulin for diabetic coma).

Disadvantages of parenteral routes of drug administration:

1. The drug must be sterile.

2. You need equipment and the skills of medical personnel.

3. Danger of infection.

4. Injection of medications often causes pain.

Electrophoresis is often called bloodless injection. Anions and cations of ionized drugs are able, under the influence of an electric field, to penetrate into the body through intact skin (ducts of sweat and sebaceous glands) and mucous membrane. They are partially retained in tissues, bind to proteins of cells and intercellular fluid, and partially are absorbed further and enter the general bloodstream.