Drug rash with eosinophilia and systemic symptoms (DRESS) in patients receiving strontium ranelate

We have reviewed 47 drug rash with eosinophilia and systemic symptoms (DRESS) cases associated to strontium ranelate reported up to March 2011 to the Marketing Holder. The main signs were skin rash, fever, face oedema hypereosinophilia and liver involvement. For ten patients, persistence of DRESS symptoms was reported at the latest news obtained, and DRESS was identified as the direct cause of death in one case. The maximum incidence of DRESS associated with strontium ranelate was 1/24,112 [95 % CI (1/14,859; 1/42,194)] newly treated patients in France. Because DRESS is a severe drug reaction, the occurrence of a rash in a patient treated with strontium ranelate should lead to prompt and permanent treatment discontinuation. This study aims to describe cases of DRESS reported to the Marketing Authorisation Holder worldwide for patients receiving strontium ranelate by practitioner or by regulatory authorities. Spontaneously reported hypersensitivity events from the strontium ranelate pharmacovigilance database since marketing authorisation (2004) to March 2011 were reviewed by an expert committee. Cases of DRESS were classified as established, probable, possible or no DRESS according to expert judgement. National incidences of DRESS were estimated in relation to the number of newly treated patients. Up to March 2011, 325 cases of strontium ranelate-induced hypersensitivity events were assessed from which 47 DRESS cases were confirmed. Mean age was 68.7 years and besides skin rash, the main signs and symptoms were hypereosinophilia, liver involvement, fever and face oedema. Median time to skin reaction was 33.5 days after treatment start. Most patients (62 %) recovered at the time of reporting or were recovering. For ten patients, persistence of DRESS symptoms was reported at the latest news obtained. Relapses were observed in a single case. The mortality rate was 8.5 %. The maximum incidence of DRESS associated with strontium ranelate was 1/24,112 [95 % CI (1/14,859; 1/42,194)] newly treated patients in France. DRESS is a well-identified and characterised adverse reaction to strontium ranelate. This risk should be integrated in the risk-benefit balance evaluation of patient treatment, and the occurrence of a rash should lead to prompt and permanent treatment discontinuation with careful follow-up.