Do you take more than one medication? If so, have you checked to see whether they are safe together? One reader discovered that a blood pressure pill raises the danger of simvastatin.
How Does Diltiazem Boost the Danger of Simvastatin?
Q. I have a warning for anyone taking both simvastatin (Zocor) and diltiazem (Cardizem). The very week my cardiologist started me on simvastatin, the FDA and Merck both came out with a warning about the interaction of these two drugs.
Apparently, diltiazem raises the plasma concentration levels of simvastatin. In my case, it must have been a huge increase. My cholesterol dropped from 231 to 143 in just three weeks.
Then my doctor lowered the dose, but it was too late. I had developed multiple problems, including severe balance problems, digestive upset and a deep itchy rash on both legs and feet as well as a wobbly walk.
I am taking other medications as well, including Pradaxa, so there may be other interactions, but the rash completely disappeared after stopping the simvastatin. Unfortunately, the balance and vertigo problems remain.
Watching Out for Risky Interactions:
A. When simvastatin (to lower cholesterol) and diltiazem (to control blood pressure) are given together, the blood level of simvastatin rises and the concentration of diltiazem decreases (Life Sciences, Dec. 3, 2004). This can lower cholesterol more rapidly, but it can raise the danger of simvastatin and result in adverse effects as well.
We are also concerned about the potential interaction of simvastatin with dabigatran (Pradaxa). This combination can cause major bleeding (CMAJ, online Nov. 21, 2016).
What Should You Do?
Ask your doctor whether a different statin (not lovastatin) would work for you. Lovastatin is metabolized through the same enzymes as simvastatin and is also affected by diltiazem. Other statins are exempt from this interaction.
Any time you are given a prescription, check with both the prescriber and the pharmacist. Ask specifically about each of the other drugs you are taking. You can use our free Drug Safety Questionnaire as a way to organize this discussion.
We have written about the dangers of incompatible prescriptions and the need to remain vigilant in our book, Top Screwups Doctors Make and How to Avoid Them. If you must take multiple prescription drugs, it could be worth a read.