Switch Medications Only for Good Reason

Question 1: My family physician asked me to switch to Crestor (rosuvastatin) to control my cholesterol. Until now I was on Zocor (simvastatin). I have read reports that there have been cases of serious side effects with Crestor, including seven cases of potentially fatal, muscle-destroying rhabdomyolosis when taking the 80 mg dose. Does it make sense to change medications?

Dr. Mitchell answers:
Both Crestor and Zocor are cholesterol-lowering medications in the same class, called HMG-CoA reductase inhibitors, or "statins." There are two main medical reasons to switch to a medication within the same class: possibly different side effects (e.g., one may cause muscle aches, one may not) or possibly different therapeutic effects (e.g., one may lower cholesterol more than another). Crestor has been touted as superior to many of the other statins, including Zocor.

Doctors may also switch drugs because of cost. For example, Lescol (fluvastatin) is probably the cheapest statin, but it also is probably the least effective. Certain insurance plans make deals with certain drug companies, so doctors may switch to lower a patient's co-pay.

Any newer medication, such as Crestor, is usually introduced with fanfare from the pharmaceutical company. This fanfare includes personal visits to physicians with treats (such as pens, paper, meals and snacks) while encouraging prescription of the new drug. Doctors say their prescribing patterns are not affected by those gifts.

Although all drugs are rigorously tested before being approved by the FDA, we learn much more about a drug once on the market, when it is widely prescribed and for a longer time period.

The FDA closely monitors any reports of adverse effects and it will pull a drug if the agency thinks it is unsafe. Personally, I shy away a bit from drugs until they're out a year or two unless there's a compelling reason to use them.

All in all, at the 10 mg to 40 mg doses, Crestor appears to be as safe as the other statins and possibly more efficacious. It may be the right choice for you.

Question 2: For years, I had been on enalapril for my blood pressure. Recently, I needed a second medication, so my doctor instead prescribed the combination medication Benicar HCT 40/25mg. This medication seemed to give me leg cramps, so my doctor changed it to two tablets of Diovan HCT 160/12.5mg. I still had leg cramps.

On studying these medications, I noted they have the same amount of hydrochlorothiazide, so I tried taking one tablet of the Diovan HCT. But still I am troubled with leg cramps.

Any suggestions?

Dr. Mitchell answers:
Hydrochlorothiazide, often abbreviated HCTZ, can cause leg cramps by depleting potassium stores.

The first thing to do would be to check your potassium and look for other (non-drug-related) causes of leg cramps. If the HCTZ is the culprit, you can either supplement your diet with potassium-rich foods such as tomato or orange juice, take a potassium tablet, or switch to another kind of blood pressure medication.

It's easier to sort out whether a medication is causing an adverse effect, such as leg cramps, if only one new medication is started at a time.

I'm not sure why your doctor substituted your enalapril, which is a generic medication, for the more expensive brand names of Benicar and Diovan, which are not in the same medication class as enalapril but are close cousins.

Sometimes it's more convenient to take a combination medication, instead of two different pills. In that case, a logical choice for a new prescription for you would have been enalapril-HCTZ.

There are literally dozens of blood pressure medications. I'm sure you can work with your doctor to find the right prescription for you.

Julie L. Mitchell, MD, MS, is an Assistant Professor of Medicine at the Medical College of Wisconsin. She practices internal medicine at the Froedtert & Medical College General Internal Medicine Clinic - East. Her column appears in the Milwaukee Journal-Sentinel.