Medicinal allergy - allergic reaction of an organism caused by various components of medicinal preparations. Nowadays, allergy to medicines is an urgent problem not only of allergic people, but also of the doctors treating them, since they are directly responsible for the appointment of each drug. More often than not, people take medicines themselves, relying on advice received from television advertising on the treatment of a particular disease. The most dangerous and these are exactly these drugs, and they are released in pharmacies without the prescription of a doctor. In almost 90% of people susceptible to this allergic manifestation, medicinal allergy is caused by over-the-counter antibiotics (cefuroxime, penicillin), sulfanilamide preparations (biseptol, septrin, trimethoprim) or regular aspirin.
Drug allergy in children is not a side effect of a particular drug. In fact, this is a reaction that is caused by the individual intolerance of a particular drug substance. The development of an allergic reaction is absolutely independent of the amount of medication that has entered the body, for the development of an allergic reaction, a truly microscopic amount of an allergen-induced drug substance, which is sometimes tens of times less than the generally prescribed therapeutic dose, is sufficient. In some cases, it is enough to inhale a couple of drugs to develop an allergy.
Drug allergy in the vast majority of cases develops only after repeated contact with the drug component provoking its development, whereas during the first contact of immunity with the drug, a period of sensitization
Causes of a drug allergy
Different people have a medicinal allergy. In one case, it is a purely occupational disease that develops in quite healthy people due to prolonged contact with drugs and is often the cause of partial or complete disability. The most common occupational drug allergy is observed in people engaged in the production of medical drugs and medical workers. In another case, LA is a complication of the therapeutic treatment of a certain disease (often of an allergic nature), and it significantly aggravates its course and can cause both disability of the patient and lead to death.
According to the statistics of the center for studying the development of side effects after taking medications, it was found that in more than 70% of registered cases, the side effect on medications is allergy. According to the data of the majority of participating countries, drug allergy occurs in more than 10% of patients, and these indicators only increase annually.
Most often, LA is observed in women, in relation to men 2: 1. Residents of rural areas allergy to medicines suffer much less. Most often, LA is observed in people who have overcome the thirty-year age limit. The most common allergic response occurs after taking non-steroidal anti-inflammatory drugs, sulfonamides, antibiotics, and after tetanus vaccinations. In addition, I want to note that for the same drug LA can develop repeatedly even after many years from the first case.
The greatest risk of drug allergy development is experienced by long-term medical patients and workers in the pharmaceutical industry. Often, LA is observed in genetically predisposed people, as well as in patients with allergic and fungal diseases.
Immunoglobulins, vaccines and serum preparations are of a protein nature, thus being allergens due to the fact that they are capable of inducing the production of antibodies independently, after which they go into appropriate reaction with them. The vast majority of existing medical products are so-called haptens, i.e. substances that acquire their antigenic properties exclusively after binding to serum proteins or tissues. As a result of this reaction, antibodies are formed, which upon repeated ingress into the body of the antigen form an antibody-antigen complex, which triggers an allergic reaction. Pharmaceutical allergy, in principle, can cause any medications, and unfortunately even those that have to fight it!
In some cases, after taking a certain medication, a false allergic reaction may develop, which in its symptoms is very similar to the symptoms of anaphylactic shock. Despite the similarity of symptoms with drug allergy, with a false allergic sensitization reaction to a medical product does not occur, and as a result, the antibody-antigen reaction does not develop. In this case, there is a nonspecific release of mediators like histamine and histamine-like substances.
Drug pseudo allergies, in contrast to true LA, can develop after the first administration of the drug, and with a slow enough introduction of the drug, it appears extremely rare, because the concentration in the blood of the administered substance remains below the critical threshold, and the rate of histamine release is not increased. With drug pseudoallergies, pre-allergotests for future drug administration give a negative result.
Provocators of histamine release may be blood substitutes (dextran), alkaloid preparations (papaverine), opiates, desferal, polymyxin B, no-shpa, etc. An indirect sign of a pseudoallergic reaction is the absence of a weighed allergic anamnesis. A favorable background for the development of drug pseudoallergies are chronic infections, gastrointestinal tract diseases, vegetovascular dystonia, liver diseases, diabetes mellitus . Also, the development of pseudoallergia can trigger uncontrolled excessive administration of medications
Drug Allergies - Symptoms
When treating with drugs, the following complications and reactions of the body are possible:
• Side effects (abdominal pain, headache , etc.). A list of all possible side effects is indicated in the instructions of each medication. For example - after taking antihistamines, there may be dizziness and drowsiness
• Toxic reactions. These manifestations occur when the permissible dosage of the drug is exceeded. Most often, toxic reactions develop in patients with diseases of the kidneys and liver, as in these cases, the excess dose of the medication occurs with damage to the kidneys and the liver due to deterioration of the excretion of the drug from the body
• Allergic reactions
• Cancellation reaction. This reaction occurs if the long-term treatment with certain drugs is stopped
• Secondary effects. These include fungal lesions of the mucous membranes, a violation of normal intestinal microflora, and so forth.
As it occurs, the drug allergy is divided into two types:
• Immediate. It occurs almost immediately after the administration or reception of a provoking substance. Immediate reactions include allergic edema, hives and anaphylactic shock. In most cases, such reactions develop after the introduction of penicillin, as well as its analogues. Due to the similar chemical structure of penicillin antibiotics, when a drug allergy occurs to one of them, a reaction to other drugs of this group is also possible. Immediately after the introduction of penicillin, the appearance of a rash, which is manifested by red spots rising above the surface of the skin. Unfortunately, the allergic response of the immune system to the rash may not be limited, and after a while such a much more serious reaction as anaphylactic shock may develop
• Slowed down. Occurs after a few days and as a result, it is often impossible to establish the exact cause of the allergic reaction. Slowed drug allergy changes in blood composition, joint pain, hives, fever. In addition, a few days after taking the drug, reactions such as: purpura, allergic vasculitis, allergic hepatitis, allergic nephritis, lymphadenopathy, astralgia, polyarthritis and serum sickness can occur.
Medicinal allergy - treatment
Treatment of drug allergy should first begin with the complete cessation of the allergy-causing drug. In the event that at the moment the patient is taking a number of drugs, all should be canceled, until the immediate "culprit" of the allergy is identified.
Often in patients with drug allergy, there are manifestations of food allergy, as a result of which a hypoallergenic diet with restriction of spices, smoked products, acidic, sweet and salty foods, as well as carbohydrates is shown. In some cases, food allergy implies the appointment of an elimination diet, which involves the use of large quantities of tea and water.
If the patient has a mild degree of allergy, it is already much better that he begins to feel after the withdrawal of the provoking drug. In the event that allergies are accompanied by urticaria and angioedema, treatment with antihistamine drugs (diphenhydramine, suprastin, tavegil) is indicated, although it is necessary to take into account their tolerability in the past. If after treatment with antihistamines, the symptoms of drug allergy do not subside, the use of parenteral injections of glucocorticosteroids is indicated.
When choosing an antihistamine drug should take into account the properties of all drugs in this group. An ideally selected drug for allergy besides high antiallergic activity should have a minimum of side effects when taken. These requirements are best suited to antihistamines such as Eryus, Telfast and Cetirizine.
In case of toxic-allergic reactions, the drugs of choice are such newest antihistamines as Fexofenadine and Desloratadine. If the severe course of the drug allergy is accompanied by the development of lesions of internal organs, dermatitis and vasculitis, a good effect is achieved by taking oral glucocorticosteroids. In case of lesions of internal organs, taking into account the probability of adverse reactions and allergic anamnesis, syndrome therapy is used.
In the case of severe allergic manifestations ( Lyell's syndrome ), the treatment consists of applying large doses of glucocorticosteroids, when the injections are given every 5 hours. In such cases, treatment is mandatory in a specialized intensive care unit, as severe lesions of the skin and internal organs are observed in such patients. In addition, therapy of such conditions implies the implementation of measures that are aimed at restoring acid-base and electrolyte balance, hemodynamics and general detoxification of the body.
Often at the same time as toxic skin damage, the development of the infectious process is observed, so the appointment of antibiotics is additionally shown, and the choice of the optimal antibiotic is very difficult, since it is possible to develop cross-allergic reactions.
With the purpose of detoxification and in the case of a large loss of fluid, the introduction of plasma-substituting solutions is indicated. However, it should be taken into account that these solutions also may develop an allergic or pseudoallergic reaction.
In case of extensive skin lesions, patients are treated in absolutely sterile conditions as burn patients. The affected skin is treated with sea buckthorn oil or rose hips, antiseptics, r-rum greens or blue eyes. In case of damage to the mucous membranes, the lesions are treated with an anti-burn emulsion, carotolin, hydrogen peroxide. With stomatitis apply water infusions of aniline dyes, chamomile infusions, etc.