Classification of ADRs: a proposal for harmonization and differentiation based on the experience of the Comprehensive Hospital Drug Monitoring Bern/St. Gallen, 1974–1993

Abstract

The present paper deals with the classification of adverse drug reactions (ADRs) according to today's largely accepted pathomechanisms. The classification system applied, relies primarily on the proposals of Rawlins and Thomson with type A ('augmented') and B ('bizarre') reactions. In the database of the Comprehensive Hospital Drug Monitoring (CHDM) Bern/St. Gallen on 48,005 consecutively hospitalized patients, ADRs had been attributed to 10 different pathomechanisms. These permit a versatile new system, easily adaptable to expanding knowledge. If we look at the 12,785 ADRs registered in the CHDM Bern/St. Gallen from 1974 to 1993, 76% were of type A, 13% of type B, and 11% of a pathomechanism not yet defined (type X). The main subgroups were A1 'not specified' in type A, Ba allergic/immunological and Bpa pseudoallergic/anaphylactoid in type B. Dose-related (A2) and drug-related reactions (A4, intolerance in a restricted sense), drug-to-drug interactions (A5), rebound/withdrawal effects (A6) and secondary reactions (A7) represented smaller subgroups. Patient-related reactions (A3, 'idiosyncrasy' in the strict sense) were not assessed. Today's algorithms for ADRs mainly rely on pharmacological, i.e. type A reactions. For most of the type B reactions adaptations including the experience of allergists, clinical immunologists and infectious disease specialists should be respected.

In vitro diagnosis of T cell‐mediated drug allergy

“…Type B reactions comprise idiosyncratic reactions due to some individual predisposition or hypersensitivity reactions [3]. Drug hypersensitivity reactions (DHRs) account for approximately 15% of ADRs [4] and can be subdivided into drug allergic and non-allergic hypersensitivities. Non-allergic hypersensitivity reactions may imitate an allergy by direct stimulation of effector cells, but without detectable response of the adaptive immune system.…”

Patients with drug reactions – is it worth testing?

“…Type A reactions make up more than 80% of all drug reactions (2) and are usually documented in common prescription manuals. According to Hunziker et al.…”

Pharmacovigilance in veterinary medicine in Chile: a pilot study

“…In the case of amoxicillin and vitamin K, most frequently described ADRs correspond to type B reactions, defined as dose‐independent, hypersensitivity reactions. ADRs corresponding to acepromazine are of type A reactions (explained by the drug pharmacological effect) and dose dependent (Hunziker et al. , 2002; EMEA, 2004; Aagaard & Hansen, 2009).…”