Studies on the epidemiology of common adverse cutaneous drug reactions have rarely been reported, since they can only be successfully conducted in clinics of internal medicine employing consultant dermatologists and having a comprehensive or intensive system of monitoring. Between 1974 and 1993, the adverse skin reactions occurring in divisions of general internal medicine of three different hospitals were monitored by a computerized comprehensive system. The "drug-monitoring patient" was defined as the recipient of at least one drug during hospitalization. The relationship of the skin reactions to drug causality in these patients had to be either definite (proven by re-exposure) or probable (drug relation greater than that of nondrug causality). The skin reactions were classified into four diagnostic groups. Maculopapular exanthema, urticaria, and vasculitis were the three main groups. The fourth group comprised cases of nonhomogeneous but clinically well-defined special exanthema. For selected drugs and years of observation, special emphasis was placed on the study of time patterns (reaction time, exposure time). A total of 1317 definite or probable drug-induced skin reactions occurred during the hospitalization of 48,005 consecutively admitted "drug-monitoring patients": 1201 cases of maculopapular exanthema, 78 cases of urticaria, 18 cases of cutaneous vasculitis, and 20 cases of special exanthema (five of erythema multiforme minor, six of fixed eruption, one of photosensitivity reaction, and eight of acneiform eruption). The main drugs involved did not differ for the three main types of skin reactions, penicillins ranking in the first place, followed by sulfonamides--most often combined with trimethoprim--and in the third place nonsteroidal anti-inflammatory drugs. The reaction time (time from last drug exposure to first skin manifestation) for urticaria showed a relevant proportion of the acute type (within 1 h) and most of the subacute type (1-24 h). For maculopapular exanthema, the subacute or, rarely, the latent type (1-8 days, exceptionally more than 8 days) predominated. For aminopenicillins, the rate of occurrence of skin reactions increased with increasing exposure time up to 12 days, and then markedly diminished. Possibly due to the tendency to withdraw suspected drugs even in the case of minor (e.g., maculopapular) skin reactions, no severe events such as erythema multiforme major/Stevens-Johnson syndrome or toxic epidermal necrolysis occurred.

Fifty-six patients with serologically confirmed bee sting hypersensitivity were treated for 1-3 years with either bee venom (BV) (31 patients) or wholebody extract (WBE) (25 per cent of re-exposed patients on BV-therapy showed a diminished reaction and 75% no reaction. Thirty-three per cent of re-exposed patients on WBE-therapy developed an unchanged or worse reaction, 42% a diminished reaction and 25% no reaction at all. An initial rise in BV-specific IgE was observed in BV-treated patients, whereas IgE levels after 1 year of treatment lay significantly below pretreatment values in both treatment groups. BV-specific IgG increased markedly in patients on BV-therapy and decreased slightly in those on WBE-therapy. The initial IgE increase induced by BV-therapy was insignificant in patients with high pretreatment levels of specific IgG-antibodies. Similarly, re-exposed patients with high BV-specific IgG showed no IgE increase, whereas a substantial rise in specific IgE was observed in those with low IgG. On the basis of clinical and serological results immunotherapy with BV is considered to be clearly superior to immunotherpy with WBE.

The patients with a lethal outcome were presented under the eight pharmacologic-therapeutic classes of drugs and the classification proposed by NS Irey. This is based on long histopathologic experience and helps to identify preventable risks.

42 patients with confirmed hypersensitivity to honey bee (HBV) and/or yellow jacket (YJV) were treated with the respective venoms (7 with HBV, 5 with VJV and 30 with both venoms). Treatment tolerance, skin tests (ST), specific IgE- and specific IgG-antibodies were monitored before, after 3, 6, 12, 24 and 36 months. 21 patients had a rush and 21 a conventional treatment schedule. Maintenance dose was 100 micrograms. Adverse effects occurred as large local (8 patients), slight systemic (12 patients) and moderate to severe systemic reactions (4 patients). Of 24 re-exposed patients 17 had no reaction at all, six a markedly decreased and one an unchanged reaction. After 3 years of treatment ST became negative in nine of 31 patients on HBV and in seven of 26 patients on YJV. RAST became negative in three of 30 patients on HBV and 17 of 29 patients on YJV treatment. Both ST and RAST became negative in five HBV- and 10 YJV-treated patients. Loss of venom hypersensitivity according to diagnostic tests may correspond to actual desensitization and enable discontinuation of immunotherapy.

Age by itself is not an important risk factor for ADRs. Age-related changes are the consequence of a number of individual factors, for example morbidity associated with polypharmacy, decline in renal or liver function in the elderly, hypoalbuminaemia, reduced body weight, etc. The relationship between gastrointestinal bleeding and non-steroidal anti-inflammatory drugs can be assessed globally in large cohort studies with access to computerized data, but complete accuracy requires access to the original patient records. The increase in the risk of GI bleeding in users of NSAIDs and aspirin was 50% above that in non-users. About a quarter of ADRs in hospitalized patients seem not to arise from purely pharmacological mechanisms. They are mainly due to allergic, anaphylactoid, or idiosyncratic reactions and to intolerance. In such non-pharmacological reactions, the time of exposure, reaction time, and even dosage may be important factors in identification of the causal drug. The use of benzodiazepines can be optimized by taking into account potency, time of action and the different syndromes encountered after withdrawal. Following long-term use problems of relapse and rebound are being increasingly recognized, in addition to organic withdrawal symptoms. In psychiatric patients extrapyramidal disorders due to neuroleptics are common. The rates of these ADRs differ markedly between various drugs, even after dosages and co-medications are taken into account. Epidemiological screening for potentially carcinogenic drugs can only be done in large cohorts of patients with pre-recorded full information sets as may be found in an HMO (Health Maintenance Organization). The findings of several such studies have been published in specialist cancer journals.(ABSTRACT TRUNCATED AT 250 WORDS)