When you take more than one medication at a time, it’s a little like rolling dice. You never know when a particular combination will put you out of the game.
Take statins, for example. These cholesterol-lowering medications are taken by millions of Americans every day. We’re talking about drugs such as Crestor, Lescol and Lipitor or generics like lovastatin, pravastatin or simvastatin.
Insurance companies may consider them interchangeable, but not all these drugs are equally compatible with foods or other medicines. Grapefruit can raise blood levels and increase the potential for side effects of Lipitor, lovastatin and simvastatin. Grapefruit has little or no effect on Crestor, Lescol or pravastatin.
Then there is the case of the 82-year-old Norwegian lady who had been taking the blood thinner warfarin (Coumadin) for almost 30 years. It was prescribed because she had several blood clots deep in her legs (deep vein thrombosis) and one in her lungs (pulmonary embolism). She had been taking Lipitor together with Coumadin with no problems.
When the Norwegian government decided in 2005 to save money by switching people to generic simvastatin, her doctor changed her prescription. Within a month she showed up for a routine check of her anticoagulant. The doctors were alarmed to discover that her INR value (a measure of blood clotting) was almost four times higher than it had been for two years and in the danger zone (over 8).
Even though this woman was immediately hospitalized and given vitamin K to reverse the excessive blood-thinning effect of warfarin, the treatment didn’t work. Several hours later she died of a hemorrhagic stroke.
Her story was written up in the medical literature to alert physicians to the possibility of a dangerous interaction between simvastatin and warfarin (Annals of Pharmacotherapy, July, 2007). How many American doctors are aware of this potentially lethal interaction?
Keeping track of drug interactions is very complicated. Most insurance companies are more concerned about costs than potential incompatibility. Patients are frequently switched from a brand name drug to a different but related generic without a lot of consideration for the other medications they may be taking.
The FDA frequently doesn’t know about all dangerous interactions when it approves a new medicine. Consider the widely prescribed blood thinner Plavix. People with stents in their coronary arteries are often prescribed this medication to keep these tiny mesh tubes open.
A new report shows that people on Plavix who also take acid-suppressing drugs such as Nexium, Prevacid, Prilosec or Protonix are more likely to suffer a heart attack than those who take Plavix alone.
Nearly half the people who take Plavix are prescribed one of these stomach medicines, called a proton-pump inhibitor (PPI). That’s because Plavix can cause heartburn, nausea, stomachache and other digestive distress.
There are thousands of dangerous drug combinations. That’s why it is crucial for doctors and pharmacists to double-check compatibility before any new medicine is added. Readers can check for themselves by entering their medicines on the Web site www.iguard.org.
