Allopurinol-induced severe cutaneous adverse drug reactions: Risk minimization measures in Malaysia

PURPOSE: To describe risk minimization measures (RMMs) implemented in Malaysia for allopurinol-induced severe cutaneous adverse drug reactions (SCARs) and examine their impact using real-world data on allopurinol usage and adverse drug reaction (ADR) reports associated with allopurinol.

METHODS: Data on allopurinol ADR reports (2000-2018) were extracted from the Malaysian ADR database. We identified RMMs implemented between 2000 and 2018 from the minutes of relevant meetings and the national pharmacovigilance newsletter. We obtained allopurinol utilization data (2004-2018) from the Pharmaceutical Services Programme. To determine the impact of RMMs on ADR reporting, we considered ADR reports received within 1 year of RMM implementation. We used the Pearson χ2 test to examine the relation between the implementation of RMMs and allopurinol ADR reports.

RESULTS: The 16 RMMs for allopurinol-related SCARs implemented in Malaysia involved nine risk communications, four prescriber or patient educational material, and three health system innovations. Allopurinol utilization decreased by 21.5% from 2004 to 2018. ADR reporting rates for all drugs (n = 144 507) and allopurinol (n = 1747) increased. ADR reports involving off-label use decreased by 6% from 2011. SCARs cases remained between 20% and 50%. RMMs implemented showed statistically significant reduction in ADR reports involving off-label use for August 2014 [χ2(1, N = 258) = 5.32, P = .021] and October 2016 [χ2(1, N = 349) = 3.85, P = .0499].

CONCLUSIONS: RMMs to promote the appropriate use of allopurinol and prescriber education have a positive impact. We need further measures to reduce the incidence and severity of allopurinol-induced SCARs, such as patient education and more research into pharmacogenetic screening.