Oral medication. Orally - how is it? Oral route of drug administration

Greetings, dear readers! During treatment various diseases we often have to deal with medical terms, many of which remain incomprehensible to us. For example, when prescribing a drug, the doctor recommends oral administration. And only when we begin to fulfill the prescriptions, the question arises: orally - what does this mean and how to take the medicine. Let's figure it out.

What does oral mean?

I immediately answer the question: orally, this means in the mouth, that is, the pill must be swallowed.

There are two main ways of introducing drugs into the body: enteral and parenteral. The enteral method is directly connected with the gastrointestinal tract, the parenteral method bypasses the gastrointestinal tract. oral route belongs to the first type.

Traditionally, medicines are taken orally, produced in the form of:

  • tablets;
  • powders;
  • solutions;
  • capsules;
  • tinctures.

These drugs can be swallowed, chewed, drunk. Most often, patients have to drink tablets: this is the most popular form of application. They give effect within a quarter of an hour after taking.

Drugs taken orally pass through the body in the following way:

  • The medication enters the stomach and begins to be digested.
  • The drug is actively absorbed into the blood and gastrointestinal tract.
  • Molecules of the drug are carried throughout the body.
  • Passing through the liver, some of the substances that enter the body become inactive and are excreted by the liver and kidneys.

Application oral medication known in medicine since ancient times. Psychologically, this is the most comfortable way to take medicines even for children, especially if the drug has pleasant taste. Being conscious, a person of any age can take a pill or tincture and alleviate his condition.

However, despite the high popularity, drugs taken orally have their drawbacks along with the advantages.

How do they act?

Today, many patients prefer to inject themselves medical preparations in the form of injections, especially when it comes to antibiotics. The motivation is simple: when injected active substance immediately enters the bloodstream, bypassing the stomach, while with internal use, the intestinal microflora suffers.

However, injections are always associated with psychological discomfort, and drugs are no less capable of harming the stomach than when taken orally.

Medications for oral use (i.e. oral administration) are well absorbed through the mucous membranes of the gastrointestinal tract. The advantages of such an administration are that in some diseases it is possible to use drugs that are poorly absorbed in the intestine, thereby achieving their high concentration. This method of treatment is very popular for gastrointestinal diseases.

There are quite a few disadvantages of this method of taking medications:

  • compared to some other methods of administering drugs, this one acts rather slowly;
  • the duration of absorption and the result of exposure are individual, since they are affected by the food taken, the state of the gastrointestinal tract and other factors;
  • oral administration is not possible if the patient is unconscious, or he has vomiting;
  • some drugs are not rapidly absorbed into the mucous membranes, so they require a different form of application.

The intake of many drugs is tied to food intake, which allows you to achieve the best therapeutic effect. For example, many antibiotics are recommended to be drunk after meals in order to injure the intestinal microflora to a lesser extent.

Wash down the preparations, as a rule, with water, less often with milk or juice. It all depends on what effect is expected from the medication, and how it interacts with fluids.

Despite obvious shortcomings, internal use continue to be actively used in medicine, forming the basis of home treatment.

If the article was useful to you, advise your friends to read it. In the social networks. The information has been provided for informational purposes. We are waiting for you on our blog!

Big hello to everyone. Today I have an unusual article. The fact is that my cousin Zhenya has been living and working in Denmark for two months now. And now, on Christmas Eve, real miracles happen there. I asked Zhenya to tell us about her observations in new country. And the topic of today's conversation

Hello dear parents! Most likely, you are very interested in knowing how your baby should develop. When and in what sequence certain skills, movements appear, what is a variant of the norm, and in which case it is urgent to sound the alarm.

Good afternoon dear parents! Today we invite you to talk about water. Do not be surprised! Water is the basis of life on Earth. The human body has the most water. Amniotic fluid surrounds the baby during fetal development. And although after birth we are surrounded by air, being in

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How is it orally?

Often, when reading the instructions for use, some medicine or on TV, we come across the phrase "take the drug orally." The natural question, which, for sure, everyone once asked, was “but, in fact, how is it orally?”

Oral means through the mouth, that is, in other words, the medicine must be swallowed.

There are many ways for the drug to enter the body, oral is usually prescribed with the condition that the drug will be well absorbed by the stomach.

If these are tablets, then a special outer capsule is made for them - a special shell that increases the absorption of the drug by the food system.

The oral route has its drawbacks.

Before the therapeutic effect of the drug occurs, enough a large number of time, since the stomach does not immediately determine where exactly, it is necessary to “deliver” the drug.

The absorption rate, as well as the absorption process, are strictly individual for each patient, since the body has individual, only one of them. inherent features digestive system.

Drugs can form ineffective metabolites that are very poorly absorbed by the stomach. In addition, the liver and pancreas can simply not “pass” the drug into the blood, thereby blocking any manifestation of the therapeutic effect of the drug.

The oral route of administration of drugs is ineffective if the patient has an increased level of gag reflexes or if the person is unconscious.

Oral medications are most often prescribed for medicines that are available in the following dosage forms: tablets, solutions, capsules, pills and powders.

Well, now we can say with confidence that you are familiar with the term "oral" and, if necessary, will be able to deal with the features of the annotations.

The article was prepared specifically for the site - http://zhenskiy-sait.ru

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Types of medication

Of the shortcomings, it should be noted, firstly, possible problems when using children's medicines. Even sweet-tasting fruit mixtures are not always readily accepted by babies, not to mention bitter pills or powders. Secondly, some drugs, when interacting with gastric juice lose their properties, and some, on the contrary, can harm the digestive organs. Thirdly, it takes time for orally administered substances to enter the bloodstream, which sometimes simply does not exist in stock. It is for this reason that the method of administering medications should be prescribed by a specialist, based on the current situation.

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Taking medications orally - how is it?

Majority prophylactic and vitamins are usually prescribed to patients orally. This, as a rule, allows you to carry out the course with minimal discomfort. After all, the patient simply consumes powders, tablets or capsules, drinking them enough liquids.

If a medicine is prescribed to be taken orally, how is it?

Unfortunately, some patients do not understand medical terminology, and are embarrassed to ask when prescribing treatment (or do not want to look stupid). Therefore, having received a prescription, they try to figure out what oral medication means. Well, if we are talking about pills (here, as a rule, everything is clear anyway). And if incomprehensible powders or liquids in ampoules are prescribed, you can get confused.

But everything is not so difficult. This method of treatment is perhaps the simplest of all available. And it means elementary ingestion, that is, the introduction into the body through the mouth. So taking medicine orally is like simply swallowing food. Usually when assigned similar treatment the specialist also indicates the dosage, the number of doses per day and recommends treatment before, after or during meals.

Types of medication

When are oral medications given? These are, as a rule, cases of the patient being on home (outpatient) treatment, as well as in a hospital in cases where immediate administration of the drug is not required, there are no contraindications to this method of application. In more difficult situations when the patient is unconscious, there are certain problems with digestion, preventing the normal ingestion of drugs, another is used - enteral administration of drugs (already using probes and other devices). The same method can supply nutrient mixtures directly into the stomach of patients who, for one reason or another, are unable to swallow food on their own.

In the case when instant administration of the drug is required, parenteral routes of its administration (subcutaneous, intravenous or intramuscular) are used. They are also used for drugs whose contact with digestive tract undesirable or contraindicated.

Advantages and disadvantages of oral medication

Undoubtedly, this is the simplest and least unpleasant way introduction of a substance into the body. Its main advantage is naturalness. A person eats food every day to get enough useful substances, water and other drinks to replenish fluids. Therefore, it will not be difficult for him to swallow an additional few tablets or capsules. With powders and liquids, things are a little more complicated, but they can also be drunk.

Greetings, dear readers! In the process of treating various diseases, we often have to deal with medical terms, many of which remain incomprehensible to us. For example, when prescribing a drug, the doctor recommends oral administration. And only when we begin to fulfill the prescriptions, the question arises: orally - what does this mean and how to take the medicine. Let's figure it out.

What does oral mean?

I immediately answer the question: orally, this means in the mouth, that is, the pill must be swallowed.

There are two main ways of introducing drugs into the body: enteral and parenteral. The enteral method is directly connected with the gastrointestinal tract, the parenteral method bypasses the gastrointestinal tract. The oral route belongs to the first type.

Traditionally, medicines are taken orally, produced in the form of:

  • tablets;
  • powders;
  • solutions;
  • capsules;
  • tinctures.

These drugs can be swallowed, chewed, drunk. Most often, patients have to drink tablets: this is the most popular form of application. They give effect within a quarter of an hour after taking.

Drugs taken orally pass through the body in the following way:

  • The medication enters the stomach and begins to be digested.
  • The drug is actively absorbed into the blood and gastrointestinal tract.
  • Molecules of the drug are carried throughout the body.
  • Passing through the liver, some of the substances that enter the body become inactive and are excreted by the liver and kidneys.

The use of oral agents has been known in medicine since ancient times. Psychologically, this is the most comfortable way of taking medicines, even for children, especially if the drug has a pleasant taste. Being conscious, a person of any age can take a pill or tincture and alleviate his condition.

However, despite the high popularity, drugs taken orally have their drawbacks along with the advantages.

How do they act?

Today, many patients prefer to administer their medications in the form of injections, especially when it comes to antibiotics. The motivation is simple: when injected, the active substance immediately enters the bloodstream, bypassing the stomach, while when administered internally, the intestinal microflora suffers.

However, injections are always associated with psychological discomfort, and drugs are no less capable of harming the stomach than when taken orally.


Medicines for oral administration (that is, oral administration) are well absorbed through the mucous membranes of the gastrointestinal tract. The advantages of such an administration are that in some diseases it is possible to use drugs that are poorly absorbed in the intestine, due to which their high concentration is achieved. This method of treatment is very popular for gastrointestinal diseases.

There are quite a few disadvantages of this method of taking medications:

  • compared to some other methods of administering drugs, this one acts rather slowly;
  • the duration of absorption and the result of exposure are individual, since they are affected by the food taken, the state of the gastrointestinal tract and other factors;
  • oral administration is not possible if the patient is unconscious, or he has vomiting;
  • some drugs are not rapidly absorbed into the mucous membranes, so they require a different form of application.

The intake of many drugs is tied to food intake, which allows you to achieve the best therapeutic effect. For example, many antibiotics are recommended to be drunk after meals in order to injure the intestinal microflora to a lesser extent.

Wash down the preparations, as a rule, with water, less often with milk or juice. It all depends on what effect is expected from the medication, and how it interacts with fluids.


Despite the obvious shortcomings, internal use continues to be actively used in medicine, forming the basis of home treatment.

If the article was useful to you, advise your friends to read it. In the social networks. The information has been provided for informational purposes. We are waiting for you on our blog!

This method of administration involves the use medicines through oral cavity followed by swallowing, i.e. through the mouth.

oral intake medicinal components is one of the most traditional and easy to implement. Most of the drugs produced in the form of tablets, capsules, powders, mixtures, and syrups undergo maximum dissolution and absorption in the stomach cavity. To achieve local therapeutic effect in diseases of the stomach, oral administration of drugs is carried out, the absorption of which is almost impossible through the wall of the stomach.

What are the main advantages and disadvantages this method taking medicinal substances, as well as in relation to which dosage forms the use of the oral route of administration is acceptable, will be detailed below.

In the process of selecting possible dosage forms for oral administration, those medicines that can be easily dissolved and quickly absorbed through the wall of the stomach have advantages. A natural exception are medicinal substances for the treatment of diseases of the stomach. IN this case the main goal is to achieve the maximum concentration of these substances in the stomach cavity, with the subsequent provision of a local therapeutic effect.

Available for oral administration are dosage forms as dragees, capsules, tablets, solutions, powders, decoctions, syrups, infusions, and also pills.

Do not forget that there are drugs, the action of which can be aimed at treating one disease, and at the same time provoking another. A striking example is Diclofenac, which perfectly copes with inflammation in the joints, but at the same time provokes the development peptic ulcer stomach.

Advantages

To the main poles of this method of reception medicinal medicines can be attributed:

Flaws

In addition to the existing advantages, oral medication has its own disadvantages, among which are:

  • compared with other methods of taking medicinal substances, this method is particularly slow, which is expressed in an increase in the time of absorption and the onset of a therapeutic effect;
  • how quickly and thoroughly the drug will be absorbed when taken orally, directly depends on individual characteristics, as well as from the influence that food and liquid consumed have;
  • oral administration of drugs is absolutely meaningless in relation to those drugs that are poorly dissolved and absorbed in the stomach cavity, this is how to use pacifiers (placebo);
  • using this method is not possible organic pathologies gastrointestinal tract, in particular, the esophagus (stenosis, tumors), during vomiting, and in an unconscious state;
  • in newborns and children infancy, oral administration of drugs can be significantly difficult;
  • getting into the gastrointestinal tract, many medicinal substances undergo biochemical transformations, resulting in harmful metabolites that have toxic effect on the body.

Another significant disadvantage of this method is the low bioavailability of many medicinal components, which, when taken orally, will not have any therapeutic effect. Precisely for similar drugs created alternative ways introduction into the body.

General admission rules

  1. Before taking the tablet orally, you should carefully read the instructions attached to it. Medicines produced in the form of tablets can be taken whole or chewed with a sufficient amount of any liquid. Not recommended as a liquid fruit juices, coffee, and especially alcohol. The best for this purpose is the usual or mineral water.
  2. Drugs produced in the form of capsules are used unchanged and washed down with plenty of water in order to ensure their fastest passage throughout the entire length of the esophagus.
  3. Before oral administration of several medicinal substances, attention should be paid to their compatibility. Combinations of certain drugs can cause serious side effects from organs and systems.

The choice of the method of taking medications should be carried out exclusively by the attending physician, taking into account the individual characteristics of a particular person, as well as the clinical case.

All routes by which drugs enter the human body, can be divided into two subgroups: parenteral and enteral.

The former include intravenous, intramuscular, subcutaneous and others. The latter ensure that the drug enters the human body through the mucous membrane of the stomach and intestines. This subgroup includes the method orally. It's like putting a pill on your tongue and swallowing it. In addition, there are rectal (through the rectum), sublingual (under the tongue), subbucal (into the space between the cheek and gums) entry of drugs into the body.

Oral administration is like swallowing a drug, which helps it enter the human body in this way, followed by absorption in the stomach, intestines.

Pharmacokinetics

The drug makes a dizzying flight through the esophagus and enters the stomach, and then the intestines, where it is slowly absorbed over thirty to forty minutes. After absorption, the active principle enters the bloodstream of the portal vein. Further, the blood flow carries the drug to the liver, and there straight into the inferior vena cava, then into right side working heart and from there - to the pulmonary circulation.

Passing in a small circle, medicinal substance travels through the pulmonary veins to left side working heart, where from arterial blood carried to target organs and tissues.

In a similar way, which means orally, liquid and solid dosage forms enter the human body.

Advantages of the method

  • Oral administration is simple, convenient and most physiological. The medicinal substance enters the body in a natural way.
  • No special training is required to use this method. Any patient can use this method independently.
  • Oral administration is absolutely safe.

Disadvantages of the method

  • The medicinal substance enters the systemic circulation very slowly, and also slowly reaches the target organ.
  • Inconsistent absorption rate. It depends on the presence of contents in the intestines and stomach, the degree of their fullness, motility of the gastrointestinal tract. With reduced motility, the rate of absorption also decreases.
  • Medicines enter the stomach, intestines, orally. This properly exposes them to the enzymes of the stomach, intestinal juice, and later the metabolic enzymes of the liver system. All these enzymes destroy most drugs even before it enters the systemic circulation (for example, nitroglycerin is destroyed by ninety percent when taken orally).
  • You can not use those drugs that are poorly absorbed in the intestines and stomach (antibiotics aminoglycosides, for example) or are destroyed there (growth hormone, alteplase, insulin, for example).
  • Some drugs irritate the intestines with the stomach up to ulcerative lesions(salicylates, corticosteroids).
  • In this way, it will not be possible to administer the drug if the patient is unconscious (if only one resorts to intragastric administration using a probe), when the patient constantly and continuously vomits, when there is a tumor in the esophagus, there is massive edema that disrupts the absorption of the drug in the intestine.

Types of diseases for which this method is preferable

The choice of the method of administration of the drug depends on the ability of the latter to dissolve in water or non-polar solvents, on the severity of the disease, on the location of the pathological process.

  • With a disease of the respiratory system of mild / moderate severity.
  • With diseases of the intestines, stomach of any severity.
  • With diseases of the heart, blood vessels
  • In diseases of soft tissues, skin of moderate / mild severity.
  • With ailments of the endocrine system of moderate / mild severity.
  • In diseases of the musculoskeletal system of moderate / mild severity.
  • In diseases of the mouth, ears, eyes - in severe cases.
  • For diseases genitourinary system moderate/mild severity.

Dosage forms taken by mouth

Many drugs can be given orally to the patient. These are both tablets and powders, both tinctures and decoctions.

Powders - the simplest dosage form, which is a drug crushed in a mortar (coffee grinder). When taken orally, it is better to drink the powder with the required amount of mineral or plain water. Powders are rarely used in medical practice.

Infusions and decoctions - often found dosage forms that are prepared by water extract from medicinal raw materials plant origin. Infusions and decoctions are not stored for a long time and quickly deteriorate. They need to be stored in the refrigerator for no more than two days.

Tinctures - alcohol-water, alcohol-ether and alcohol extracts, without the use of heat treatment, are prepared from medicinal raw materials. The dosage is made in drops, which can be diluted in a small amount of water before taking. Their difference from infusions and decoctions is that tinctures are able to retain their therapeutic effect for a long time.

Syrups are a child-friendly dosage form that is a mixture of a drug and a concentrated sugar solution. Stored in a glass container, closed after boiling.

Pills - oral preparations oval, round or other shape. Usually biconvex. They are made by pressing the drug with special machines. Easy to use, retain their properties long time, portable. The taste of the drug in them is not so noticeable.

Conclusion

The oral method is simple and convenient, easy to use and does not require special training. Allows you to easily control the intake of the drug. It is enough for the doctor to write out a prescription - and the patient will continue the treatment on his own.

There are many ways to introduce drugs into the body. The route of administration largely determines the rate of onset, the duration and strength of drug action, the spectrum and severity of side effects. IN medical practice It is customary to subdivide 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: the introduction of the drug inside through the mouth (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 oral administration) is the most convenient and simplest, therefore it is most often used for drug administration. Absorption of drugs taken by mouth occurs predominantly 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.

At the same time, before entering the general circulation, drugs pass through two biochemically active barriers - the intestines and the liver, where they are affected hydrochloric acid, digestive (hydrolytic) and hepatic (microsomal) enzymes, and where most drugs are broken down (biotransformed). A characteristic of the intensity of this process is bioavailability, which is equal to the percentage of the amount of drug that has reached the bloodstream, to total medicine introduced into the body. The greater the bioavailability of the 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 rate and completeness of absorption of drugs from the gastrointestinal tract depends on the time of the meal, its composition and quantity. So, 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. Medications taken after a meal may interact with food ingredients, which affects their absorption. For example, calcium chloride taken after a meal can form with fatty acids insoluble calcium salts limiting its ability to be absorbed into the blood.

sublingual way

The rapid absorption of drugs from the sublingual region (with sublingual administration) is provided by the rich vascularization of the oral mucosa. The action of drugs comes quickly (after 2-3 minutes). Sublingually, nitroglycerin is most often used for an attack of angina pectoris, and clonidine and nifedipine for relief. hypertensive crisis. With sublingual administration, 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 quick absorption, drugs are used on the cheek (buccally) or on the gum in the form of films.

rectal route

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

Parenteral routes of drug administration

Intravenous administration

Drugs are administered intravenously in the form aqueous solutions, which provides:

  • rapid onset and precise dosing of the effect;
  • rapid cessation of the drug's entry into the blood in the event of adverse reactions;
  • the possibility of using substances that are collapsing, non-absorbable from the gastrointestinal tract or irritating its mucous membrane.

At intravenous administration the drug immediately enters the bloodstream (absorption as a component of pharmacokinetics is absent). In this case, the endothelium is in contact with a high concentration of the drug. The absorption of the drug when injected into a vein is very fast during the first minutes.

To avoid toxic manifestations potent drugs bred isotonic saline or glucose solution and administered, as a rule, slowly. Intravenous injections often used in emergency care. If the drug cannot be administered intravenously (for example, in burned patients), it can be injected into the thickness of the tongue or into the bottom 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 rapidly metabolized or bound by tissues, creating a high concentration of the drug only in the corresponding organ. Arterial thrombosis - more serious complication than venous thrombosis.

Intramuscular administration

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

Subcutaneous administration

Water and oil solutions are injected subcutaneously. With subcutaneous administration, the absorption of the drug substance occurs more slowly than with intramuscular and intravenous injections, and the manifestation of the 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 insufficiency peripheral circulation(shock) subcutaneously administered substances are poorly absorbed.

Local application

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

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

Inhalation

In this way, gases (volatile anesthetics), powders (sodium chromoglycate), aerosols (beta-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, providing a local and systemic effect. When you stop inhalation gaseous substances there is also a rapid termination of their action (ether for anesthesia, ftorotane, etc.). By inhalation of an aerosol (beclomethasone, salbutamol), their high concentration in the bronchi is achieved with a minimal systemic effect. Irritants by inhalation are not introduced into the body, in addition, incoming drugs to the left heart through the veins can cause a cardiotoxic effect.

Intranasal (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 path 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

For and for spinal anesthesia subarachnoid drug administration is used. In cardiac arrest, adrenaline is administered intracardiac. Sometimes drugs are injected into the lymphatic vessels.

Movement and transformation of drugs in the body

The drug is introduced into the body in order to have any therapeutic effect. However, the body also affects the drug, and as a result of this, it may or may not enter certain parts of the body, pass or not pass certain barriers, modify or retain its chemical structure, leave the body in certain ways. All stages of the movement of the drug through the body and the processes that occur with the drug in the body are the subject of study of a special section of pharmacology, which is called pharmacokinetics.

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

Suction- the process of entry of the drug from the 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, the entry of drugs from the gastrointestinal tract into the blood occurs using absorption mechanisms nutrients. It must be said that the best gastrointestinal tract drugs are absorbed that have good solubility in fats (lipophilic agents) and have a small molecular weight. Macromolecular agents and substances insoluble in fats are practically not absorbed in the gastrointestinal tract, and therefore they must be administered by other routes, for example, in the form of injections.

After the drug enters the blood, 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 the substance is the faster and easier, the more it is soluble in fats, as in the stage of absorption, and the lower its molecular weight. However, in most cases, the distribution of the drug over the organs and tissues of the body occurs unevenly: more drugs get 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 specific tissues foreign substances(including drugs), preventing tissue damage. The most important are the blood-brain barrier, which prevents the penetration of drugs into the central nervous system (CNS), and the hematoplacental barrier, which protects the body of the fetus in the uterus of a pregnant woman. Tissue barriers, of course, are not completely impenetrable to all drugs (otherwise we wouldn't have drugs that affect the CNS), but they significantly change the distribution pattern of many chemicals.

next step pharmacokinetics is metabolism, that is, the 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.

Final stage pharmacokinetics - breeding. The drug and its metabolic products can be excreted different ways: through the skin, mucous membranes, lungs, intestines. However, the main route of excretion of the vast majority of drugs is through the kidneys with 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 is also converted from a fat-soluble substance to a water-soluble one.

Thus, the drug passes through the entire body before leaving it as metabolites or unchanged. The intensity of the pharmacokinetic steps is reflected in the concentration and duration of the presence of the active compound in the blood, and this in turn determines the strength pharmacological effect medicines. In practical terms, to assess the efficacy 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 the maximum concentration, the duration of maintaining the 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 designed to help attending physicians choose the optimal tactics of pharmacotherapy for a particular patient.