Muscular Adverse Drug Reactions Associated with Proton Pump Inhibitors: A Disproportionality Analysis Using the Italian National Network of Pharmacovigilance Database

Proton pump inhibitors (PPIs) have been implicated in the occurrence of moderate to severe myopathies in several case reports. This study was performed to assess the reporting risk of muscular adverse drug reactions (ADRs) associated with PPIs in the Italian National Network of Pharmacovigilance database. A disproportionality analysis (case/non-case) was performed using spontaneous reports collected in the database between July 1983 and May 2016. Reporting odds ratio (ROR) and 95% confidence intervals (CIs) were calculated as a measure of disproportionality. In a secondary and tertiary analysis, we explored the association of PPIs with muscular ADRs after taking into account the masking effect of statins. Moreover, the possibility of an interaction between PPIs and statins, leading to the occurrence of muscular ADRs, was also tested. The study was carried out on 274,108 reports. The ROR of muscular ADRs for PPIs, adjusted for age and gender, was 1.484 (95% CI 1.204-1.829; p < 0.001), whereas the ROR for rhabdomyolysis was 0.621 (95% CI 0.258-1.499). Similar results were obtained in the secondary analysis. The tertiary analysis, where PPIs were considered regardless of whether their role was suspected or concomitant, showed a potential disproportionate reporting for the combination PPIs-rhabdomyolysis (ROR 1.667, 95% CI 1.173-2.369; p < 0.01). The PPIs-statins combination was not associated with an enhanced ROR of muscular ADRs/rhabdomyolysis compared with statins alone. This explorative study suggests that the class of PPIs could be involved in reports of muscular ADRs, rather than any other ADR, more frequently than any non-statin drug. Our results must be corroborated by further studies.