Health Canada has received more reports of a rare but potentially serious muscle reaction in people taking the anti-cholesterol pill Crestor a top-selling new drug in Canada that a U.S. drug official has named as one of five drugs that should be looked at more closely.
As of August 31, five more cases of rhabdomyolysis a breakdown in muscle tissue that can lead to kidney damage had been reported in Crestor users since Health Canada advised Canadians in June of a possible link between Crestor and the muscle-wasting condition.
At that time, eight cases of rhabdomyolysis had been reported in patients taking Crestor since the drug was approved in February 2003.
There is no proof the latest cases of muscle damage were caused by exposure to Crestor. Health Canada says “causality assessments” have not been completed and that adverse drug reaction reports are based on suspicion only.
As well, of the eight cases of rhabdomyolysis reported as of June, all patients had at least one underlying risk factor, such as kidney problems or an under-active thyroid gland.
AstraZeneca, maker of Crestor, says it is fully confident in the drug’s safety and efficacy and that the risk of muscle breakdown is in line with that for other statins less than 0.01 per cent.
Dr. Carley Vint-Reed, scientific director of cardiovascular research for AstraZeneca Canada, also said Health Canada has not alerted the company of any concerns about Crestor’s safety.
The department says it is reviewing kidney-, liver- and muscle-related adverse events for Crestor and is comparing the risk of rhabdomyolysis for all cholesterol drugs in the “statin” family.
The analysis comes amid concerns about aggressive use of statins in people with no evidence of heart disease, and treatment guidelines that keep lowering the threshold for what doctors consider “safe” cholesterol.
Statins have become the fastest growing drug class in Canada. More than 17 million prescriptions – totalling more than $1.5 billion – were dispensed by Canadian drug stores in the 12-month period ending in September, according to IMS Health Canada, which tracks prescription drug sales.
Nearly 1.6 million prescriptions were filled for Crestor.
Health Canada says patients taking Crestor or any cholesterol-lowering drug should immediately report any unexplained muscle pain, muscle weakness or cramps, or any brown or discolored urine to their doctor.