Finasteride (Proscar - Merck) has now been approved by the US Food and Drug Administration (FDA) for oral treatment of benign prostatic hyperplasia. A 4-aza-steroid, the drug is a specific inhibitor of steroid 5 -reductase, the enzyme that catalyzes conversion of testosterone to dihydrotestosterone. Dihydrotestosterone is required for development and maintenance of prostatic hypertrophy (JS Tenover, Endocrinol Metab Clin North Am, 20:893, 1991).

Zolpidem (Ambien - Searle), an imidazopyridine hypnotic available in Europe for several years, was recently approved by the US Food and Drug Administration for short-term treatment of insomnia.

Loratadine (Claritin - Schering), a new H 1 -receptor antagonist, has been approved by the U.S. Food and Drug Administration for treatment of seasonal allergic rhinitis in patients more than 12 years old. It will compete with older, relatively sedating drugs such as chlorpheniramine (Chlor-Trimeton, and others) and clemastine (Tavist - Medical Letter, 35:9, 1993) and with newer relatively non-sedating agents such as terfenadine (Seldane) and astemizole (Hismanal).

Isosorbide mononitrate, the major active metabolite of isosorbide dinitrate, was first approved in the USA for oral use in patients with chronic stable angina in 1992 (Medical Letter, 34:61, 1992). Now an extended-release formulation of isosorbide mononitrate (Imdur -Key) has been approved by the US Food and Drug Administration.

Fluvastatin (Lescol - Sandoz), an HMG-CoA reductase inhibitor, was recently marketed in the USA for treatment of hypercholesterolemia. A synthetic mevalonolactone derivative, it is chemically distinct from previously available drugs in this class.

An intravenous formulation of amiodarone (Cordarone IV -Wyeth-Ayerst) has been approved by the US Food and Drug Administration (FDA) for treatment and prophylaxis of recurrent ventricular fibrillation (VF) or hemodynamically unstable ventricular tachycardia (VT) in patients refractory to other therapy.

Nisoldipine (Sular -Zeneca), a dihydropyridine calcium-channel blocker structurally similar to nifedipine, has been approved for marketing by the US Food and Drug Administration. It is available in an oral extended-release formulation for treatment of hypertension.

Lantaoprost, a prostaglandin F2-alpha analog, has been approved by the FDA for topical treatment of elevated intraocular pressure in patients with open-angle glaucoma and ocular hypertension refractory to other drugs.

Olanzapine (Zyprexa - Lilly), a thienobenzodiazepine that structurally resembles and binds to many of the same receptors as clozapine (Clozaril), is now available in the USA for treatment of schizophrenia and other psychotic disorders.

Topical tretinoin (all-trans-retinoic acid) has been used for years to treat skin damaged by chronic exposure to the sun (Medical Letter, 34:28, 1992). First approved by the FDA only for treatment of acne in concentrations ranging from 0.025% to 0.1% (Retin-A, and others), it has now been approved as an 0.05% formulation in an emollient cream base (Renova) for topical treatment of photodamaged skin. In recent years, alpha-hydroxy acids incorporated in some cosmetics have also been promoted as effective in improving the appearance of aging skin.