A retard in medicine is an extension of the validity of something, of a process: treatment, taking medication. In Russian, the term “retard” is sometimes used not only in the medical, legal and financial fields, but also in the general sense of extending something.
Recently, studies have been widespread to prolong the effect of drugs. Prolonged are forms having a modified release, which provides an increase in the duration of action of the substance by reducing the rate of its release.
The benefits of such drugs
Thanks to the use of drugs of prolonged action (this concept is now being used more and more often), it is possible not only to reduce the total amount of the drug that is ingested throughout the entire therapeutic course and the number of injections or doses due to the improved use, but also highlight a number of other significant advantages.
In addition, their use eliminates or reduces variations in the concentration of the active component in the tissues and blood, which are inevitable companions of repeated periodic doses of ordinary drugs. Thanks to compounds with a prolonged effect, it is possible to reduce the incidence of side effects in the patient (this also occurs due to the elimination of the irritating effect of drugs on the gastrointestinal tract), and the likelihood of negative consequences if the medicine is not taken at the appointed time.
Also, the use of these drugs can significantly save time spent on procedures (one dose or injection instead of four to five). This is important when conducting therapy in a clinic. The very same word retard in translation from English means "slow down", "delay".
Importance in Pharmacology
An increase in the duration of the influence of drugs is one of the areas of current interest in pharmaceutical technology , since in some cases it is necessary to ensure the availability of a certain level of drugs in the tissues and biological fluids of the human body. This requirement is especially necessary to adhere to while taking sulfonamides and antibiotics, other antibacterial agents.
With a decrease in their concentration, accordingly, the effectiveness of therapy decreases, resistant strains of various microorganisms are produced, the elimination of which will require an even higher dosage, which means that the side effect will increase. That is why the problem of prolonging the effect of drugs remains important and relevant.
Classification and characterization of prolonged forms
Retard are special prolonged dosage forms that must meet the following requirements:
- the concentration of the substance in accordance with the release of the drug should not fluctuate significantly and be in optimal condition in the body for a certain period of time;
- excipients that are included in the dosage form must be excreted in full or deactivated;
- prolongation methods should be affordable and easy to use and should not adversely affect the patient.
The drug "Cortexon" (retard) is an example of this kind of medical device.
Types
Depending on the way in which prolonged forms are introduced, they are divided into the following types:
- dosage forms (hereinafter - LF) depot;
- LF retard.
By the nature of the kinetic features of the process, dosage forms are released with the release of:
- periodic;
- continuous
- deferred.
Periodic release
Retard is now a very common form of drugs. LF with a periodic release (also multiple or intermittent release) is a prolonged dosage form, with the introduction of which the body takes a batch release of the active substance, which resembles inherently plasma concentrations that are created by the simple use of tablets every four hours. They also contribute to the re-action of a drug.
Continuous
Dosage forms of the retard with the release of continuous (long) - prolonged LF, with the ingestion of which the substance is released in its initial dose, the remaining doses, that is, the supporting ones, are released at a constant rate, that is, in accordance with the elimination rate, which ensures constancy necessary therapeutic concentration. Thus, the drug acts as a supportive drug.
Deferred
Delayed-release LFs are sustained release LFs with which the drug is released later, and this process continues longer than from a simple dosage form. Thus, a slowdown in the onset of the effect of the drug is provided.
Features
Retard - these are dosage forms that are prolonged enteral dosage forms that provide the creation in the human body of a stock of the drug and its subsequent gradual release. They are most often administered orally, but there are also rectal forms.
Depending on what technology was used to obtain them, there are two principal types of retard dosage forms (the translation is presented above), such as matrix and reservoir. The matrix type forms contain a polymer matrix with a drug substance distributed in it. Often they look like regular tablets.
The reservoir type is the core in which the drug substance is included, as well as the polymer or membrane membrane, which determines the speed of the release process. A single form (capsule, tablet) or microform, the combination of which forms the final form (for example, microcapsules, etc.), can act as a reservoir.
The general meaning of the word "retard" is of interest to many.
What are the forms?
Sustained-release dosage forms include:
- Enteric granules.
- Capsules retard and retard forte.
- Enteric coated retard tablets.
- Enteric coated capsules.
- Solution retard and rapid retard.
- Enteric-soluble, bilayer, scaffold and multilayer tablets.
- Suspension retard.
- Tablets retard, retard mete, rapid retard, ultra retard and retard forte.
- Multi-phase and film coated tablets.
There are also retard tablets that have other release methods — continuous, delayed, and extended evenly. In addition, they have such varieties as structural pills and duplex. These include the preparations Potassium-Normin, Dalfaz SR, Ketonal, Diklonat Pretard 100, Tramal Retard, Kordafleks, and in Cortexon Retard veterinary medicine.
What methods can prolong the effect of drugs?
At the moment, it has been established that it is possible to ensure a prolonged effect (this means long-term) of therapeutic agents by reducing the rate of their release from the dosage form, reducing the rate and degree of deactivation of substances by enzymes, removing them from the body, and depositing the drug in tissues and organs. The fact is known that a medicinal substance reaches its maximum concentration when its content in the blood is directly proportional to the dose introduced into the body and absorption rate, and also inversely proportional to the rate at which the substance is excreted from the body.
To achieve the prolonged effect of drugs, various methods can be used, including chemical, physiological and technological.
We got acquainted with the concept of "retard", which is in drugs, is now known.
Chemical methods
Chemical methods include such prolongation methods, which include changing the chemical structure of the drug through complexation, polymerization, replacement of functional groups, the formation of sparingly soluble salts, esterification, etc.
Physiological methods
Physiological methods include methods that provide changes in the rates of absorption or elimination of a drug substance due to the influence of various kinds of factors (chemical, physical) on the body.
This is mainly achieved by the following methods:
- tissue cooling at the place where the drug injection was introduced;
- use of a blood-sucking jar;
- the introduction of hypertonic solutions into the body;
- the use of vasoconstrictors, that is, agents that contribute to vasoconstriction;
- inhibition of excretory function of the kidneys (for example, ethamide is used for this purpose to slow the elimination of penicillin from the body), etc.
But it is worth noting that these methods can become unsafe for the patient, which is why they are rarely used. For example, in dentistry, vasoconstrictors and local anesthetics are used together to prolong the local anesthetic effect of the latter by reducing the lumen of the blood vessels. In this case, an adverse reaction such as tissue ischemia develops, due to which the oxygen supply decreases, and this leads to hypoxia, which can eventually cause tissue necrosis.
Technological methods
Technological methods have become the most common and most often get practical application. In this case, the effect of the drug substance is prolonged with the help of such methods:
- increasing the viscosity of the dispersion medium: this method is based on the fact that with an increase in this indicator of solutions, the process of absorption of the drug from the dosage form slows down;
- In addition to the use of non-aqueous media, aqueous solutions are also used, to which are added substances that contribute to an increase in viscosity - polymers semi-synthetic, natural and synthetic.
In pharmaceutical practice, the placement of active substances in the hydrolysis of macromolecular compounds and in gels has also gained considerable popularity recently. They are used as prolongators having a soft dosage form (liniments, ointments, plasters), and also serving as components, or reservoirs, of macromolecular systems of not only a matrix, but also a membrane type.
We now know that this is a retard.