The Pharmaceutical Journal
Vol 270 No 7244 p502
12 April 2003

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Congress summary  April 12    April 5

Related websites
American College of Cardiology congress (more)
Journal of the American College of Cardiology (www.cardiosource.com)

Switching statins leads to theoretical drug interactions

Deliberately switching hospital patients to simvastatin (Zocor) from other statins raises theoretical problems of drug interactions that are not seen in practice, hospital pharmacists told participants at the American College of Cardiology meeting in Chicago last week.

The number of patients with theoretical recorded drug interactions rose from 6.1 per cent to 16.4 per cent when most patients admitted to five hospitals had their statin therapy switched to equivalent doses of simvastatin. However, no increase in side effects was noted. Most of the increase was related to a potential interaction between simvastatin and diltiazem that is not included in either the American or United Kingdom summary of product characteristics for Zocor.

Peter Dumo, PharmD, of Harper University Hospital, Detroit, and Wayne State University presented data on a therapeutic intervention policy (Journal of the American College of Cardiology 2003;41[Suppl A]:525A). He explained to The Journal during the meeting that the intervention policy had been agreed by the hospital group pharmacy and therapeutics committee. The proportion of patients taking simvastatin rose from around one-third to nine-tenths after the policy started in March 2002. Only patients on the highest dose of atorvastatin (Lipitor) or those where the prescriber specifies "dispense as written" are not switched. Prescriptions for other products received in the pharmacy are changed automatically. A note is sent to the prescriber and a sticker placed in the patient's notes.

Professor Dumo said that the most important thing about the therapeutic intervention process, a common formulary management approach in the United States, is to evaluate the changes made afterwards. "A lot of people are making changes, but not many are looking at the effects," he said. "When doing therapeutic intervention with any drug there is a potential risk of reduced efficacy. Safe processes are the key and there must be a review to see that these are working."

The hospital group has carried out a similar intervention switching patients to amlodipine (Istin) from other dihydropyridine calcium channel blockers, again without any major adverse events being recorded. Professor Dumo was unable to give any figures for the savings made or costs incurred by the pharmacy department for either of the interventions.

The Pharmaceutical Journal attended the American College of Cardiology congress courtesy of Merck/Schering-Plough Pharmaceuticals