Statin Drug-Drug Interactions in CV Patients Underappreciated, Says AHA

DALLAS, TX — The American Heart Association has issued a new scientific statement on how to manage drug-drug interactions in patients receiving statins and other heart-disease medications^[1].

"The general purpose of this document was to be able to provide a clinically useful tool so that when these drugs do have to be combined, you have something you can utilize to know where your limits are, and if you have to combine them you know what you're dealing with," first author Dr Barbara S Wiggins (Medical University of South Carolina, Charleston) told heartwire from Medscape.

Cardiologists should be aware that these interactions exist and understand the magnitude and what their limitations are when they do have to use them in combination, she said.

"Most of these drug interactions were known before, but not necessarily in terms of the magnitude of the interactions," she added.

The statement was published online October 17, 2016 in Circulation.

The two most common drug-drug interactions involving statins are the ones mediated by the cytochrome P-450 enzyme system and permeability glycoprotein, the researchers write.

 For example:

• For conivaptan, they say combination with lovastatin or simvastation may be harmful for muscle-related toxicity.
• For amiodarone, they say to limit the dose of lovastatin to 40 mg daily and the dose of simvastatin to 20 mg daily.
• For digoxin, they say combination with atorvastatin is reasonable.

With differences in pharmacokinetic profiles of statin agents, including absorption, distribution, metabolism, and excretion, drug-drug interactions commonly stem from a direct effect on one or more of these parameters, the researchers wrote.

For cardiovascular patients, statin drug-drug interactions are commonly unavoidable and need to be clinically managed, they write, and clinicians should know the dose limits, adverse effects, and monitoring parameters. They recommend that clinicians and statin-treated patients review all medications at each clinical encounter and during transitions of care.

The statement lists doses for certain heart-disease medications for safely using with statins, as well as the combinations of statins and heart-disease drugs that may be harmful.

http://www.medscape.com/

Graham