Generics not as good for thyroid drugs

Q: I’ve been taking the thyroid medication Synthroid 100 micrograms/day for over two years. Recently, when I picked up my prescription, the pharmacy gave me the generic for Synthroid (levothyroxine). The pharmacist says they’re equivalent, but my doctor disagrees. Who’s right?

T.C.

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Mitchell Hecht

Ask Doctor H

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Allentown, Pa.

A: I’d have to side with your doctor. Thyroid drugs like Synthroid have a very narrow window within which they’ll work as intended. Thyroid medication is adjusted in micrograms (one one-thousandth of a gram). In order for a drug to gain FDA approval, each pill must differ from one another in its said dose and effects by plus or minus 5 percent.

For generic drugs, the FDA has what it calls “bioequivalence” (sameness). Assume that 100 percent represents your 100-microgram daily dose of Synthroid. The FDA considers a generic drug (or comparable brand drug) to be bioequivalent if it resembles the reference drug in question within the range of 80 to 125 percent. That means that a purported 100 micrograms of generic thyroid medication may have as little as 80 micrograms or as much as 125 micrograms and still be called “equivalent.” Whatever brand name thyroid medication you may be taking, don’t switch to generic.

Q: A friend of mine explained to me that she has a rare blistering skin condition called epidermolysis bullosa. Her son and father also have it. Can you tell me something about it?

T.L.

Orlando

A: Epidermolysis bullosa (EB) is a rare inherited skin condition that is estimated to occur with varying degrees of severity in 1 out of every 200,000 live births in the United States.

A defect in the anchors that hold together the outer layer (epidermis) and the middle layer of the skin (dermis) allows the two layers to move independently. That movement creates friction from rubbing and subsequent blister formation. These blisters can occur anywhere on the body and can lead to painful sores, skin breakdown and wound infections. Here’s a helpful Web site for those affected by EB and those interested in learning more about EB: www.ebinfoworld.com.

Dr. Mitchell Hecht is a Roswell physician specializing in internal medicine. Send questions to “Ask Dr. H,” P.O. Box 767787, Roswell, GA 30076.