Microx (Pennwalt), a new low-dosage formulation of the thiazide-type diuretic metolazone (Zaroxolyn; Diulo), was recently marketed in the USA. The manufacturer claims that the low dose of controls hypertension with less potassium loss, making it safer than other diuretics and as effective as combination drugs, such as Dyazide, that include both a thiazide and a potassium-sparing diuretic. Medical Letter consultants generally do not recommend Dyazide or other fixed-dose combinations for treatment of hypertension.

Astemizole (Hismanal - Janssen), a new antihistamine, was recently marketed in the USA for treatment of seasonal allergic rhinitis and chronic idiopathic urticaria. Like terfenadine (Seldane - Medical Letter, 27:65, 1985), astemizole is claimed to be no more sedating than placebo, but the new drug offers the advantage of a once-daily dosage schedule.

Alprazolam (Xanax - Upjohn), a triazolobenzodiazepine previously available in the USA for treatment of anxiety (Medical Letter 24:41, 1982), was recently approved by the US Food and Drug Administration (FDA) for treatment of panic disorder, with or without agoraphobia. According to one report, alprazolam was the fifth most widely prescribed drug in the USA last year (American Medical News, March 4, 1991, page 4).

Enoxaparin (Lovenox - Rh ne-Poulenc Rorer), the first low-molecular-weight heparin to become commercially available in the USA, was recently approved by the US Food and Drug Administration for prevention of deep vein thrombosis following hip replacement. Five other products have been marketed in Europe.

Implanted devices that monitor cardiac rhythm and can recognize and treat ventricular tachycardia or ventricular fibrillation are now widely used in the USA and other countries. Implantable cardioverter/defibrillators (ICDs) marketed here include the Ventak P and PRX (Cardiac Pacemakers, Inc., St. Paul, MN), the PCD (Medtronic, Minneapolis, MN), and the Cadence (Ventritex, Sunnyvale, CA) (JG Porterfield et al, Am J Cardiol, 72:301, 1993).

Valsartan (Diovan - Novartis), a non-peptide tetrazole, is the second angiotensin II receptor antagonist approved for oral treatment of hypertension by the US Food and Drug Administration. The first was losartan (Cozaar - Medical Letter, 37:57, 1995).

Celecoxib, a selective COX-2 inhibitor, has been approved by the FDA for treatment of osteoarthritis and rheumatoid arthritis.

Rabeprazole, a benzimidazole proton pump inhibitor similar to omeprazole and lansoprazole, has been approved by the FDA for treatment of duodenal ulcers, healing and maintenance treatment of erosive or ulcerative gastroesophageal reflux disease, and for long-term treatment of chronic hypersecretory conditions, including Zollinger-Ellison syndrome

Epirubicin, an analog of doxorubicin that has been available in Europe and Canada for 15 years, has now been approved by the FDA for adjuvant use after resection of the primary tumor in breast cancer patients with axillary node involvement.

Even though its effectiveness has not been established, many patients take St. John's Wort (Hypericum perforatum), an over-the-counter herbal extract, to treat symptoms of depression, often without the knowledge of their physicians. Recent reports indicate that St. John's wort interacts adversely with a number of drugs.