What Is a Fixed Drug Reaction?

After drugs enter the body through various pathways, they cause organ and tissue reactions, called drug reactions. Among the drug side effects, about 1/3 to 1/4 affect the skin, so some people have suggested cutaneous drug reactions. Among all skin and mucosal drug reactions, drug eruption or dermatitis medicamentosa are more prominent.

Drug response

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After drugs enter the body through various pathways, they cause organ and tissue reactions, called drug reactions. Among the drug side effects, about 1/3 to 1/4 affect the skin, so some people have suggested cutaneous drug reactions. Among all skin and mucosal drug reactions, drug eruption or dermatitis medicamentosa are more prominent.

Whether prescription drugs

prescription

Athletes use with caution

Use with caution

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Incorporate

Since the founding of the People's Republic of China, due to the rapid development of medical and health services, the number of new medicines has continued to increase, and the opportunities for patients to use medicines have been increasing. Therefore, there has been a significant increase in drug response.

According to the statistics of the dermatology department of our school 10 years after the founding of the People's Republic of China, the medicinal rash alone increased from 0.1% of newly diagnosed dermatology patients in 1949 to 1.2% in 1958, an increase of 12 times. Statistics from several major hospitals in Shanghai show that drug rash increased from 0.5% of 200,000 newly diagnosed patients in dermatology from 1949 to 1954 to 1.2% of 280,000 patients from 1955 to 1958, which is basically the same as the former.

Recently, our school's dermatology department counted 380,000 newly diagnosed patients in the five years from 1982 to 1986, and the number of patients with drug rash increased to 2.37%. From 1983 to 1991, there were 208 cases of drug rash in 2418 people in the Department of Dermatology, Huashan Hospital, 8.6%.

In the past, drug reactions were more common in cities. In recent years, drug reactions have become more common in rural areas due to the popularity of medicine. Due to the widespread use of Chinese herbal medicine, the drug response caused by Chinese medicine has increased.

In fact, almost everyone has the opportunity to be exposed to this or that drug in their lifetime, so almost everyone may have some kind of drug response under certain circumstances. With the continuous increase of drug varieties, the types and performance of drug reactions have also changed accordingly. Drugs are mostly given by doctors, so drug reactions are mainly iatrogenic diseases. If doctors can be cautious when taking medicine, although the drug reaction cannot be completely avoided, it can certainly be greatly reduced.

The prerequisite for a drug response is that the drug must first enter the body. The most common way for drugs to enter the human body is oral, followed by injection, including intramuscular, intradermal, subcutaneous, intravascular, intra-articular, spinal canal, intraluminal and diseased tissue injection. Others include anal or vaginal plugging, bladder or vaginal irrigation, enemas, eye drops, nose drops, mouthwash, lozenges, fumigation, vaccination and skin tests. In addition, in special cases, topical liquids and ointments can also be absorbed through the skin to cause reactions. In addition, some drugs or chemicals can cause reactions by entering the body in a more subtle way, such as drinking milk from cows injected with penicillin antibiotics and eating pastries, sweets, preservatives, disinfectants, spices or dyes Canned food and beverages. These are often overlooked by patients and health care professionals and lead to misdiagnosis.

Needless to say, the direct cause of drug reactions is of course drugs.

According to statistics from the 1960s statistics of the undergraduate, the drugs that cause drug rash are mainly the following 4 categories: sulfa drugs (accounting for 21.6%), antipyretic and analgesics (accounting for 14.3%), antibiotics (accounting for 12.3%) and sedative sleeping pills (accounting for 11 %), Which together account for nearly 60% of the causative drugs.

According to the analysis of 104 cases of severe drug rash hospitalized from 1983 to 1992, the top 4 categories of pathogenic drugs are mainly antibiotics, anti-gout drugs (26 cases each, accounting for 25%), and antipyretic analgesics (20 cases, accounting for 19.2). %) And sulfa drugs (12 cases, 11.5%).

Compared with the previous data, the major and minor sequences and types of pathogenic drugs have changed notably. For example, the sulfonamide drug has a significantly reduced pathogenic ratio, and it is only a compound SMZ. Yin alcohol; Cephalosporins are the main antibiotics.

In the past few years, there have been more reports of panterine, thiazide drugs, non-steroidal anti-inflammatory agents, isoniazid, p-aminosalicylic acid, chlorpromazine, carbamazepine, immunosuppressants, and anticancer drugs. , Serum biological products and Chinese herbal medicines, especially some Chinese patent medicine preparations.

The mechanism of drug reaction is quite complicated, there are allergic, non-allergic or other special mechanisms.

(A) allergic reactions

Most drug rashes occur in connection with this. Its main basis is:

Almost all occur in the amount allowed by pharmacology;

Have a certain incubation period;

The patient is allergic to only one or a certain class of drugs and is highly specific;

For those who have been sensitized with a certain drug, if the same drug is used again, even a small amount, it often causes a recurrence of the drug rash;

Cross-allergic reactions may occur with drugs that have a similar structure to the sensitizing drug;

A skin test with an allergenic drug will yield a positive result;

Drug sensitization caused by a small number of drugs, mainly type I reactions, can be desensitized for a short time;

Antiallergic drugs, especially corticosteroids, are often effective.

Chemical drugs are mostly haptens. After entering the body, they must first covalently bind to certain protein components in the tissue to form a full antigen (hapten-carrier complex) before they can begin to function. The strength of a drug's antigenicity is related to its own chemical structure. Generally, drugs with a high molecular weight or a benzene or pyrimidine nucleus have strong antigenicity, such as penicillin G and its derivatives, polymers, long-acting sulfonamides, Drug rashes caused by phenobarbital and compound aspirin are more common; drugs with weak or non-antigenic properties, such as potassium chloride and sodium bicarbonate, rarely cause or do not cause drug rashes.

The type of allergic drug response is different, it can be expressed in any type of type I to IV, sometimes in the same patient can have more than two types of reactions.

(2) Non-allergic reactions and others

1. Toxic effects are mostly caused by excessive dosages, such as central nervous system depression caused by high-dose barbiturates; sleeping bone marrow suppression or liver damage caused by nitrogen mustard and Baixuening; poisoning reactions caused by the absorption of pesticides 1059 and 1605.

2. Pharmacological effects such as drowsiness caused by antihistamines; euphoria caused by corticosteroids; facial flushing caused by niacin.

3 Photosensitivity After taking chlorpromazine and sulfa drugs, and then exposure to sunlight, it can cause dermatitis that mainly occurs in exposed areas. According to its mechanism, there are two types of photoallergenic and phototoxic reactions.

4 Disruption of the enzyme system, such as galentin, can cause oral ulcers by interfering with the absorption and metabolism of folate; 13-cis retinoids can change lipid metabolism and cause xanthomas; isoniazid can affect vitamin B6 metabolism and cause multiple Peripheral neuritis.

5. Deposition The reaction caused by the deposition of drugs or their products in special tissues, such as bismuth, mercury, silver, lead and other heavy metal salts deposited on the gums, arsenic deposited on the skin (pigmentation, keratinization), and the skin caused by Apin Yellowing and so on.

6. Special local stimulating effects such as aspirin can directly corrode the gastric mucosa, causing gastric bleeding and gastric ulcers; sulfa crystals block the renal tubules, renal pelvis and ureters, causing dysuria, hematuria, oliguria, and even urinary closure.

7. Bacterial flora: The normal flora in the human body can adapt to each other during many years of co-evolution. Some flora can inhibit the excessive reproduction of others. Some flora can still synthesize vitamin B family and vitamin K, which are needed for the health of the body. . In short, there is a contradictory unity between microorganisms and microorganisms, and between microorganisms and organisms. But long-term or heavy use of antibiotics, corticosteroids, or immunosuppressants can disrupt these balances. Such as the application of broad-spectrum antibiotics can often lead to bacterial infections of conditional pathogens.

8. Teratogenic and carcinogenic effects Some drugs may have teratogenic and carcinogenic effects after long-term application, such as thalidomide and tretinoin.

(Three) influencing factors

In addition to the drugs mentioned above as direct causative factors and their possible pathogenic mechanisms, the following factors also often play a role in the occurrence and development of drug reactions.

1. Medication

(1) Abuse: Most of them are due to the poor grasp of the principle of drug use by doctors, and they are arbitrarily administered. There is also a part of the drug response caused by patients using self-provided drugs or self-purchased drugs.

(2) Misuse: The doctor prescribes the wrong prescription, or the pharmacy issues the wrong medicine, or the patient takes the wrong medicine. Of course, these are accidents.

(3) Suicide by taking medicine: This is a rare phenomenon.

(4) Dosage: Too much medication can cause serious reactions and even death. However, sometimes the normal dose can also have a drug response, which is related to the different rates of drug absorption, metabolism and excretion by different individuals, especially elderly patients should pay close attention.

(5) Medication course: Acute illness, the medication time is generally not long, even if the drug used is more toxic, its harm may be less. However, chronic diseases, especially patients with cancer, use anticancer drugs for a long period of time, often accumulating drugs and producing toxic reactions. Of course, some drugs such as sleeping pills and sedatives can cause drug addiction after repeated application for a long time.

(6) Too many types of medications: For people with allergies, the more types of medications there are, the more chances of reactions occur. This may be due to cross-reactions or synergies between the drugs.

(7) Medication route: Generally speaking, drugs are more likely to cause reactions by injection than by oral administration. Topical antigenic ointments, such as sulfa and tetracycline ointment, have a much higher incidence of drug reactions after absorption than those who take it orally. Cases of infant death due to excessive absorption of drugs by topical boric acid solution wet application have been reported. Medications taken by pregnant or lactating women can enter the fetus or infant and cause a reaction.

(8) Cross-allergy: Many drugs that have structural similarities, such as sulfa drugs that contain a common "aniline" core, procaine, p-salicylic acid, etc. can cause the same reaction, which is called cross-allergy . This reaction can occur about 10 hours after the first application, without the need to go through an incubation period of more than 4 to 5 days.

(9) Reuse of sensitizing drugs: If the patient is allergic to a certain drug and then repeat application, a more serious reaction may occur. The reuse of sensitizing drugs is usually due to:

The doctor's negligence and no understanding of the patient's past drug reaction history;

The patient did not take the initiative to tell the doctor about his drug allergy history;

used drugs that can cause cross-allergies;

Individual patients with drug rash in a high-sensitivity state are prone to allergic reactions to drugs that are not sensitive to the drug.

(10) Unclean syringes: Unclean syringes, needles, syringes, medicine bottles, leather tubes, etc. may cause adverse reactions due to the introduction of certain pyrogens into the body.

2. Body condition

(1) Gender: Drug reactions can occur in both men and women, but slightly more men than women (3: 2). Due to gender differences, estrogen and griseofulvin can cause male breast development, and male hormones can cause virilization in female patients.

(2) Age: In addition to being more sensitive to narcotics than adults, children are more tolerant to general drugs. Children's allergic reactions to the drug are also rare.

(3) idiosyncrasy: an abnormal response to a drug that does not occur through an immune mechanism. The cause is unknown.

(4) Genetic factors: Patients with genetic allergies (atopy) have a potential risk of serious reactions to penicillins.

(5) Allergic or allergic constitution: Most drug reactions occur in patients with a certain allergic constitution. Its allergic pathogenesis has been discussed previously.

Because the drug response can affect various systems and organs, it has a wide range, both systemic and local. This section only discusses some typical drug rashes and a few specific types of drug reactions.

(1) Allergic drug rash This is the most common type of drug rash. According to its incubation period, occurrence and development, rash manifestations and outcomes, it can be divided into at least 10 subtypes, such as fixed erythema, scarlet fever-like erythema, measles-like erythema, urticaria-like, erythematous erythema-like, nodular erythema Samples, pityriasis rosea, purpura, and bullous epidermal necrolysis. They have the following common features: have a certain incubation period, generally 4 to 20 days, with an average of 7 to 8 days, if they have been sensitized, the same drug is used again, usually within 24 hours, and the disease can occur within an average of 7 to 8 hours . The shortest is only a few minutes, and the late one does not exceed 72 hours. Most of the onset is sudden, and there may be precursor symptoms such as chills, discomfort, and fever. The rash occurs and develops. In addition to fixing the erythema, it is general and symmetrical. Sexual distribution; Often accompanied by systemic reactions of varying severity, which may not be obvious, and severe cases may have headache, chills, high fever, etc .; The course of the disease is self-limiting. The mild one is about one week, and the severe one does not exceed one. Months; except for the prognosis of bullous epidermal necrosis and loosening, the rest are better. Several representative subtypes are introduced below.

1. Fixed erythema (fixed rash) is the most common form of drug eruption, accounting for 22% to 44% of drug eruption. Of the 909 drug eruption among undergraduates, 318 were in the shape, accounting for 34.98%. Common disease-causing drugs are sulfa drugs (with long-acting sulfa drugs in the first place), antipyretic analgesics, tetracyclines, and sedative sleeping pills (mainly barbiturates). It usually starts with bright red to purplish red edema patches, round or oval, with clear edges, and one to several blisters or bullae on severe patches. The number of erythema varies from one to several, and the distribution is asymmetric. Can occur in any part, often occur at the junction of skin and mucous membranes such as lips and external genitalia, often caused by erosion caused by friction. If it recurs, it usually still occurs in situ, completely or partially overlaps with the pigmentation spots left over from the previous one, and often enlarges and increases compared with the previous one. Localized skin lesions may be accompanied by itching, and there are different degrees of fever among those with extensive skin lesions. After the erythema recedes, it often leaves obvious purple-brown pigmentation spots, which do not recede for many years, and have diagnostic value. A few edematous erythema without purple fade quickly and leave no traces. Individual cases may be accompanied by erythema polymorpha, urticaria-like, or measles-like erythema.

2. Scarlet fever-like erythema rash occurs suddenly, often accompanied by chills, fever (above 38 ° C), headache, and general discomfort. The rash begins as large and small patches of erythema. It develops from the face and neck, torso, and upper limbs to the lower limbs. It can be spread throughout the body within 24 hours. The distribution is symmetrical, edematous, bright red, and can fade. In the future, the rash will increase and expand and merge with each other, which can affect the entire skin, just like scarlet fever. However, patients were generally in good condition without other manifestations of scarlet fever. After the rash developed to orgasm, the swelling gradually disappeared, followed by large scale desquamation, and the temperature gradually decreased. At the beginning of desquamation, it looks like wearing broken gloves and socks. After that, the scales gradually become thinner and thinner, like pityriasis, and the skin returns to normal. The whole course of disease does not exceed one month. There is generally no visceral damage. If the rash is like measles, it is called measles-like erythema; like urticaria, it is called urticaria-like drug rash; like pityriasis rosea, it is called pityriasis rosea; etc.

3 Severe erythema (Stevens-Johnsonsyndrome) This is a severe bullous erythema, in addition to skin damage, serious mucosal damage to the eyes, mouth, and external genitalia, with obvious erosion and exudation. Often accompanied by chills and high fever. Can also be complicated by bronchitis, pneumonia, pleural effusion, and kidney damage. Eye damage can cause blindness. Children with this type of drug rash are more common. However, it must be pointed out that this syndrome is sometimes not caused by drugs.

4 Bullous epidermal necrolysis loosening drug rash This is a type of drug rash we first saw in China in 1958. It is relatively rare in clinical practice, but it is quite serious. The onset was urgent and the rash spread throughout the body within 2 to 3 days. Initially bright red or purple-red spots, sometimes erythema-formed at the onset, increased and expanded later, and merged into large brown-red patches. In severe cases, the mucosa is involved at the same time, which can be said to be incomplete. Large blister appears on the large film, forming a lot of parallel 3 ~ 10cm long wrinkles, which can be pushed from one place to another. The epidermis is very thin and breaks with a little rubbing, showing obvious spinous layer loosening. The whole body is often accompanied by a high fever of about 40 ° C. Severe cases can involve the stomach, intestine, liver, kidney, heart, brain and other organs at the same time or successively. A case of death due to this disease was seen in which the lining of the nasal feeding tube was densely covered with mucous membranes. The course of the disease is self-limiting, and the rash usually subsides after 2 to 4 weeks. If serious complications or severe involvement of some important organs occur, or due to improper treatment, they can die in about 2 weeks.

The total number of white blood cells in the blood is more than 10 × 109 / L (10000 / mm3), about 80% of neutrophils, and the absolute count of eosinophils is 0 or very low. The pathological anatomy of severe death cases found that: The epidermis was significantly atrophied, only 1 or 2 layers of spinous layer cells were even disappeared, intercellular and intracellular edema, dermal congestion and edema, infiltration of peripheral small round cells, and degeneration of collagen fibers. Oral mucosal lesions are similar to skin. Lymph node enlargement, medullary hyperplasia, endothelial cell hyperplasia, and cortical follicle atrophy. Yellow and red liver section, blood stasis and liver cell degeneration can be seen. Microscopic examination showed severe blood stasis in the central lobules of the liver, lipid changes and dissociation of the remaining hepatocytes; the boundary between the liver parenchyma and the manifold was unclear; the borders of some hepatocytes were blurred; some necrotic cells were dissolved and absorbed. The kidney section was swollen and the capsule was eversion. Microscopic examination showed vascular congestion, curved tube edema, and focal infiltration of lymphocytes and monocytes in the cortex. Brain gray matter nerve cells showed various degenerations, and leaf nerve cells showed water-like degeneration and swelling, with satellite cell phenomenon in between. Nerve cells in the basal nucleus and cerebellum swell, blur, and even disappear. Focal microglia hyperplasia in the basal nucleus. Myocardium has interstitial edema and diffuse small round cell infiltration.

Bullous epidermal necrotizing drug eruption has many similarities to the toxic epidermal necrolysis reported by Lye1l (1956). The local pain is obvious, there is no obvious visceral damage, and often recurrence. However, some people think that the two may be the same disease.

(2) The etiology of other types of drug rash and drug response has not been fully identified. There are many types, which are selected as follows:

1. Systemic exfoliative dermatitis type is one of the more serious types of drug eruption, its severity is second only to bullous epidermal necrosis and loosening drug eruption, and its fatality rate is very high in the age when corticosteroids are not used. Due to the large dose or long course of treatment that causes this type of drug rash, it may be combined with certain toxic reactions based on allergic reactions.

This type of drug rash is uncommon. According to incomplete statistics of our department, 2.53% of the 909 drug rash cases from 1949 to 1958 and 7.9% of the 418 hospitalized drug rash cases from 1959 to 1975. Of the 104 patients with severe drug rash treated in 1983-1992, 23 were of this type, accounting for 22%. Due to the serious condition, if not rescued in time, it can lead to death.

This disease is characterized by a long incubation period, usually more than 20 to 30 days; the course of the disease is usually at least one month. The entire course of disease development can be divided into 4 stages:

The prodromal stage is manifested as a transient rash, such as symmetrical erythema confined to the chest, abdomen, or thigh, conscious pruritus, or accompanied by fever. This is a warning symptom. If the drug is stopped at this time, the disease may be avoided.

The rash period can slowly develop from the face down, or start to be an acute attack. Later, the rash may spread to the whole body quickly or slowly. At the climax of the rash, the whole body's skin was red and swollen, and facial edema was significant. Frequent scabs were associated with chills and fever. Some patients may have internal organ damage such as liver, kidney, and heart. The total number of white blood cells in peripheral blood is usually increased, generally between 15 × 109 20 × 109 / L (15000 20,000 / mm3).

exfoliation period , which is a characteristic manifestation of this disease. The rash and swelling began to subside, followed by fish scales to large scale desquamation. The scales could be covered with sheets every morning, hands like wearing gloves, feet like wearing socks, and repeatedly falling off, which could last for one to several months. Hair and fingernails often fall off at the same time.

During the recovery period , the fish scale-like desquamation turned into pityriasis, then gradually disappeared, and the skin returned to normal. Since the application of corticosteroids, the course of disease can be significantly shortened, and the prognosis is greatly improved.

2. Short-range antimony dermatitis type This is a mild toxic dermatitis seen in China in the 1950s when short-term intravenous treatment with antimony potassium tartrate was used to treat schistosomiasis in Japan. Its characteristics are:

The prevalence is high, generally above 30% to 40%, and some can be as high as 60% to 70%;

The incubation period is short, and they all develop within 2 to 3 days after starting treatment; The rash occurs after the antimony dosage reaches 0.3g;

More common in summer;

The rash is symmetrically distributed on the face, neck, back of the hand and the extended face of the fingers. Occasionally it appears in the chest and abdomen, resembles a mule, dense but not fused, mild inflammation, conscious slight itching or burning sensation, and individual symptoms such as fever;

The course of the disease is self-limiting. Even if the drug is not stopped, the rash mostly disappears within 3 to 5 days, accompanied by psoriasis-like desquamation;

Retreatment occasionally has recurrence. No complications or sequelae were seen. Histochemical examination revealed no significant difference in antimony content between the rash and normal skin (both approximately 2.5 g / dl). Histopathology was similar to contact dermatitis and was nonspecific.

3 Papillary hyperplasia is caused by long-term use of iodine and bromine. The incubation period is usually around January. We have seen 2 cases of scattered, irregular, significantly irregular skin on the basis of erythematous drug eruption, which is significantly higher than the skin surface and has a mushroom-like papillary proliferative granuloma with a diameter of about 3 to 4 cm. In the trunk. It gradually subsided after symptomatic treatment. The journey takes about 3 weeks.

4 Lupus erythematosus-like reactionSince hydralazine was found to cause lupus erythematosus-like reactions in the early 1960s, more than 50 drugs are known to date such as penicillin, procainamide, isoniazid, p-aminosalicylic acid, and batam , Methylthiouracil, reserpine, metronidazole, and oral contraceptives can cause such reactions. Clinical manifestations include polyarthralgia, myalgia, polyserositis, pulmonary symptoms, fever, hepatosplenomegaly and lymphadenopathy, cyanosis of the extremities, and rash. This disease is different from real lupus erythematosus in that fever, cast urine, hematuria, and azotemia are rare, and the condition is relatively mild. It often disappears after stopping treatment. Caused by hydralazine, laboratory positives can persist for months to years after symptoms disappear.

5. Mycotic disease response Due to the application of a large number of antibiotics, corticosteroids and immunosuppressants, it often causes disturbances of the internal environment balance and bacterial flora imbalance, and mycotic disease reactions occur, including Candida albicans and dermatophyte infection. The former two may have Gastrointestinal, lung, or other visceral infections can affect multiple organs at the same time. It is not uncommon to find severe systemic fungal infections during autopsy of immunosuppressant patients during their lifetime. It is worth noting that some patients with dermatophytosis, due to the application of the above-mentioned drugs, the skin lesions of ringworm have become more extensive and difficult to treat. Even if cured, it is easy to relapse, causing difficulties in the prevention and treatment of ringworm.

6. Corticosteroid-type reactions If hormones are used in larger doses and for longer periods of time, they can often cause a variety of adverse reactions and even cause death. The main side effects it causes are:

secondary bacterial or fungal infection: most common;

Gastrointestinal tract: "Steroid ulcer", even with blood and perforation;

Central nervous system: euphoria, irritability, dizziness, headache, insomnia, etc .;

Cardiovascular system: palpitations, elevated blood pressure, thrombosis, arrhythmia, etc .;

Endocrine system: Kexing-like syndrome, osteoporosis, diabetes, hypocortex, and growth and development inhibition in children;

Skin: acne, hairy, dilated capillaries, ecchymosis, skin atrophy, etc .;

Squint: blurred vision, increased intraocular pressure, cataracts and glaucoma.

In recent years, with the emergence of a large number of new drugs, the concept of "new drug rash" was proposed in the 1980s, so that people have a better understanding of drug response. Almost all new drugs can cause a variety of different drug reactions. There are many types of -lactam antibiotics, and various cephalosporins and penicillins can cause macular rash or maculopapular rash. Cytotoxic drugs can cause hair loss, urticaria, toxic epidermal necrosis, photosensitive dermatitis, and stomatitis. There are also many new anti-rheumatic drugs, which can cause photosensitive dermatitis, urticaria, purpura, maculopapular rash, and stomatitis. Rifampicin, D-penicillamine, and captopril can cause maculopapular rash, urticaria, and erythematous pemphigus (deciduous type). -blockers such as alpronol (alprenolol), oxenolol (oxprenolol), propranolol (propranòlol) and other long-term application can appear psoriasis-like rash, Some patients with hyperkeratosis of palmar plantar can also cause eczema, lichenoid rash and other types of rash. The antihypertensive drug minoxidil (minoxidil) can cause reversible hirsutism, can also reverse male pattern hair loss, and can cause Stevens Johnson syndrome.

Given the wide range of drug responses, their complexity, and the lack of specificity, it is sometimes difficult to make a diagnosis. For the diagnosis of drug rash, the clinical history is still the main basis, combined with the rash performance and laboratory tests, and the possibility of other diseases is excluded, and comprehensive analysis and judgment are performed. In terms of laboratory tests, such as skin scratches and intradermal tests, it is often used to detect whether patients are sensitive to penicillin or iodide, which is of certain value in preventing anaphylactic shock, but it has little significance in preventing the occurrence of drug rash. In vitro tests such as lymphocyte transformation test and radioallergosorbent test (RAST) have been used for the detection of allergens, but they are only reliable for some drugs and can be used under certain conditions, and have certain reference value.

[Treatment instructions]

(1) Eliminating the cause and discontinuing all suspicious disease-causing drugs is the first step that must be taken. It is forbidden to discontinue the drug when the aura manifestations of the drug reaction have occurred.

(2) Supportive therapy provides patients with favorable conditions and avoids unfavorable factors in order to successfully pass through their self-limiting course of disease, such as bed rest, rich diet, maintaining a suitable warm and cold environment, and preventing secondary infections.

(3) Strengthen excretion Use laxatives and diuretics as appropriate to promote the excretion of drugs in the body.

(4) Drug treatment requires different measures according to the severity of the disease.

1. Mild cases 1 or 2 antihistamines are administered orally; Vitamin C1g is given intravenously once a day; 10% calcium gluconate or 10% sodium thiosulfate is given intravenously 10m1 once or twice a day; Calamine lotion, oscillating lotion or powder powder containing camphor or mint, multiple times a day to relieve itching, heat dissipation and anti-inflammatory, usually healed in about a week.

2. Slightly more severe cases refer to those with extensive rashes and fever. Rest in bed; apply the above drugs; prednisone 20-30mg daily, orally divided into 3 to 4 times, usually fully recovered in about 2 weeks.

3 Severe cases include severe erythema multiforme, bullous epidermal necrolysis and systemic exfoliative dermatitis-type drug eruption. The following measures should be taken immediately:

(1) Corticosteroids: 300 ~ 500mg of hydrocortisone, 3g of vitamin C, 20 ~ 30ml of 10% potassium chloride, and slowly infusion of 1000 ~ 2000ml of 5 ~ 10% glucose solution, once a day, should be maintained for 24 hours continuous infusion When the body temperature returns to normal, when the rash mostly subsides and the blood is normal, the hormone dosage can be gradually reduced until a considerable amount of prednisone or dexamethasone is taken orally. If the rash subsides, the general condition improves, and then gradually reduce the oral dose of hormones. The principle is that each reduction is 1/6 to 1/10 of the daily dose at that time. Each reduction requires observation for 3 to 5 days, and pay attention to the reduction at any time. The phenomenon of rebound. The problem in treating severe drug eruption is often the improper dosage or usage of hormones, such as the initial dose is too small or it is reduced too quickly in the future.

(2) Antihistamines: Two oral drugs are selected at the same time.

(3) Transfusion of fresh blood or plasma: 200 ~ 400m1 each time, 2 ~ 3 times per week, usually 4 ~ 5 times.

(4) Antibiotics: Appropriate antibiotics are used to prevent infections, but care must be taken. Patients with severe drug rashes are often in a highly allergic state. Not only are they prone to cross-allergy of drugs, but they may also be multi-sensitivity, that is, they are sensitive to the original allergen Structurally completely unrelated drugs create allergies and cause new drug rashes.

(5) Local treatment: In patients with severe drug eruption, local treatment and care of skin and mucous membrane damage are very important and often become the key to success or failure of treatment. In the early acute stage, a large amount of powder or calamine lotion can be used for skin lesions to protect the skin and reduce inflammation and swelling. If there is oozing, use saline or 3% boric acid solution for wet compress and change it 4-6 times daily. After drying, use 0.5% neomycin and 3% bran oil paste, 1 2 daily. Times. Eye conjunctiva and cornea are often affected and must be treated in time. Rinse with normal saline or 3% boric acid water to remove secretions, drip triamcinolone or hydrocortisone eye drops every 3 to 4 hours, and rub boric acid or Hydrocortisone eye ointment to prevent blindness and conjunctival adhesions due to corneal exfoliation. Oral and lip mucosal damage often prevents eating, and can be rinsed with compound borax, several times a day, pupa ulcer cream or pearl yellow powder, tin powder and so on. Nasal feeding can be used for those who cannot eat.

(6) If it is accompanied by damage to organs such as heart, lung, liver, kidney, and brain, and hematopoiesis, etc., it shall be dealt with in a timely manner.

(7) Pay close attention to the balance between water and electrolytes; and give drugs such as adenosine triphosphate, coenzyme A, inosine, and vitamin B6 as appropriate.

[Precautionary note]

Because the incidence of drug reactions is high, the harm is great, and severe cases can cause death. Therefore, it is of great significance to pay attention to prevention. For example, if doctors do not give drugs casually and patients do not abuse drugs, drug reactions can be greatly reduced.

1. Before taking the medicine, make a clear diagnosis first, and don't use multiple drugs to siege before the condition is cleared, thinking that there is always a drug that will have an effect, so it is prone to unnecessary drug reactions.

2. The ingredients, properties, indications, contraindications, side effects, and contraindications of the drugs used should be thoroughly familiarized, so as not to abuse, misuse, and multi-use drugs.

3 Patients should be asked in detail before medication if they have a history of drug allergy, especially for those with an allergic constitution. For those who have had allergic reactions to drugs, attention should be paid to the occurrence of cross-sensitivity or multi-source sensitive reactions.

4 The medication should be planned, the dosage should not be too large, the type should not be too much, the time should not be too long, and periodic observation, especially the application of certain toxic drugs, such as immunosuppressants, anticancer drugs, etc., should be closely observed, often Check for blood etc.

5. When some organs have dysfunction, they often cannot tolerate certain drugs. For example, patients with kidney disease should be careful to use heavy metal drugs.

6. During the medication, some warning symptoms or intolerance should be noted, such as skin itching, erythema, or fever, etc., and should be discontinued as soon as it appears.

7. All those who have had an allergic drug reaction should be issued a drug contraindication card, indicating the name of the sensitizing drug and the type of reaction for reference during follow-up. 8. The national pharmaceutical administration must strengthen pharmaceutical administration. Before the drugs are put on the market, they must undergo strict inspections to ensure the quality of the drugs.