Pharmacology Update

Editor’s Note:

Beginning this issue, The Pharmacology Update column will bring you the latest breaking news from the pharmaceutical industry and clinical pharmacy issues. These updates will include reports of new medications, new indications for medications, reports of adverse drug reactions, and updates on prescribing guidelines. Many of these issues will be expanded upon in future issues of PTDA, but the intent of this column is to report new developments as they are happening.

By William T. Elliott, MD

Oxybutynin (ditropan), commonly used for incontinence in the elderly, has been associated with memory and cognitive problems, according to a recent paper in the Journal of the American Geriatric Society. The small study used doses that were somewhat higher than the standard dose given to the elderly, but the findings should alert clinicians to the potential for cognitive problems in the elderly.

Raloxiphen (Evista-Eli Lilly) is the first of a new class of drugs called selective estrogen receptor modulators. Raloxiphen, sometimes called a designer estrogen, is selective for certain estrogen receptors but does not seem to stimulate breast or endometrial tissue. The drug is approved for the treatment of osteoporosis and seems to have a beneficial effect on serum lipids, but it does not help hot flashes, and it may increase the risk for thromboembolic events.

Just as terfenadine was about to go off patent, Hoechst has pulled Seldane off the market for safety concerns. Hoechst’s replacement, which still has years of patent protection, is fexofenadine (Allegra). Generic terfenadine is still available.

Troglitazone (Rezulin) has been the subject of intense concern over hepatotoxicity. Reports of severe liver toxicity resulting in liver failure and death have prompted the drug’s removal from England’s market.

Troglitazone remains available in the United States for the treatment of diabetes, but the FDA is recommending frequent liver function tests if the drug is to be prescribed—once a month for the first six months of therapy, every other month for the next six months, and periodically thereafter. Despite these concerns, the NIH has decided to keep troglitazone as one treatment arm in the ongoing diabetes prevention trial.

Several new antibiotics are about to be launched. Warner-Lambert is introducing a new third-generation cephalosporin. Cefdinir (Omnicef) is a once-daily capsule and pediatric solution for the treatment of upper- and lower-tract respiratory infections, ENT infections, and skin infections. Pfizer has received permission to market trovafloxacin (Trovan), a new quinolone, in both an oral and intravenous preparation. The drug was approved for 14 indications—the largest number of indications ever received by a new drug. These indications include respiratory infections, surgical prophylaxis (the first ever oral drug for this indication), abdominal infections, and gonorrhea. It is effective against a wide range of organisms including gram-positive, gram-negative, anaerobic, and atypical bacteria. Searle is about to market a once-a-day metronidazole preparation (Flagyl ER). The 750 mg tablet is approved for the treatment of bacterial vaginosis.

Merck has reformulated finasteride (Proscar), its moderately effective benign prostatic hypertrophy (BPH) drug, and has received approval from the FDA to market the drug for male pattern baldness. Propecia, the new product, should be available this month. It is only for male use and is associated with minimal side effects. The drug has to be taken continuously for any benefit to be maintained.

Bristol-Myers Squibb, the makers of Excedrin, have received FDA approval to market the first over-the-counter preparation designed to treat migraine headache. Excedrin Migraine contains aspirin, acetaminophen, and caffeine. Its packaging will be unique from other Excedrin products and will include patient information, such as recommendations on when to consult a physician.

The fen-phen debacle seems to be getting worse. The incidence of valvular abnormalities may be higher than originally believed. Joint guidelines from the NIH, FDA, and CDC recommend any patient who took fenfluramine or dexfenfluramine should have a echocardiogram prior to undergoing any dental or surgical procedure. These patients are felt to be at a high risk for endocarditis and should be prioritized to be assessed until more definitive guidelines can be developed.

The incidence of sexual dysfunction associated with SSRI antidepressants (Prozac, Paxil, Zoloft, Luvox) has been widely underreported, so the FDA is considering a change in labeling of the drugs. According to members of the Psychopharmacologic Drugs Advisory Committee, sexual dysfunction may occur in the majority of patients who are on these medications.