Spontaneous reports of hypersensitivity adverse drug reactions in Portugal: a retrospective analysis

Hypersensitivity adverse drug reactions (ADRs) are usually serious, unpredictable, and associated with high morbidity and mortality. This study describes cases of hypersensitivity ADRs spontaneously reported in Central Portugal.

Spontaneous reports (SRs) of ADRs received between 2010 and 2017 were reviewed to identify cases of hypersensitivity reactions, using a Standardized MedDRA Query (SMQ). Seriousness, expectedness, and causality were assessed. Descriptive statistics were used to analyze data.

Among 2050 SRs, 598 (29.2%) contained 726 hypersensitivity ADRs: 657 (90.5%) serious, 569 (78.4%) unexpected, and 469 (64.6%) certainly related to drug exposure. Anaphylactic reactions (n = 93; 12.8%), rash maculopapular (n = 82; 11.3%), rash (n = 67; 9.2%) and DRESS (n = 54; 7.4%) were the most common reactions. Frequently implicated drug classes comprised antibiotics (n = 150; 23.0%), antineoplastic agents (n = 124; 19.0%), antigout preparations (n = 54; 8.3%), and anti-inflammatories (n = 44; 6.8%). Top-causative drugs were allopurinol (n = 54; 8.3%), docetaxel (n = 46; 7.1%), and trimethoprim/sulfamethoxazole (n = 26; 4.0%).

Most hypersensitivity ADRs were serious, unexpected, and with strong causal relationship with suspected drugs. Allopurinol was the top-causative drug. Besides antibiotics and anti-inflammatories, antineoplastic agents were frequently cited. These results deserve further investigation.