Rifaximin (Xifaxan - Salix), a non-absorbed oral antibiotic derived from rifampin (Rifadin, and others), has been approved by the FDA for treatment of travelers' diarrhea caused by noninvasive strains of Escherichia coli in patients 12 years of age or older. It has been available in Europe since 1987.

Rofecoxib (Vioxx - Merck) has been withdrawn from the market due to an increased risk of cardiovascular complications associated with its long-term use. The question remains whether all selective COX-2 inhibitors carry the same risk. Full-page advertisements in newspapers for celecoxib (Celebrex - Pfizer), the most widely used COX-2 inhibitor, assure the public that it does not.

Pramlintide acetate (Symlin - Amylin Pharmaceuticals), a synthetic analog of human amylin, has been approved by the FDA as adjunctive treatment for patients with type 1 or type 2 diabetes who inject insulin at mealtimes and have failed to achieve glucose control. Pramlintide is injected subcutaneously before meals.

Many physicians believe that antimicrobial prophylaxis before procedures that may cause transient bacteremia can prevent endocarditis and prosthetic joint infection in patients at increased risk for these disorders. The effectiveness of this common practice has never been established by controlled trials in humans.

Duloxetine hydrochloride (Cymbalta - Lilly), a selective serotonin and norepinephrine reuptake inhibitor (SNRI) available for treatment of depression, has also been approved by the FDA for treatment of neuropathic pain associated with diabetic peripheral neuropathy (DPN). Duloxetine is one of two drugs approved specifically for management of neuropathic pain due to diabetes; the other, pregabalin (Lyrica - Pfizer), will be marketed soon and will be reviewed in the next issue of The Medical Letter.

BiDil (NitroMed), a fixed-dose combination of isosorbide dinitrate and hydralazine, was approved by the FDA for adjunctive use in the treatment of heart failure in black patients.Both drugs are oral vasodilators that have been used together off-label for many years to treat heart failure in patients not responding to other drugs.

Zolpidem (Ambien - Sanofi-Aventis), a nonbenzodiazepine benzodiazepine receptor agonist, is the most frequently prescribed hypnotic in the US. As its patent approaches expiration, its manufacturer has received FDA approval to market an extended-release formulation of the drug, Ambien CR. The pharmacological rationale for doing so is that short-acting hypnotics like zolpidem are more effective at inducing sleep than they are at maintaining it.

The FDA has approved marketing of the corticosteroid mometasone furoate in an orally inhaled dry powder formulation (Asmanex Twisthaler - Schering-Plough) for maintenance treatment of asthma in patients at least 12 years old. Mometasone is also available as a mid-potency topical corticosteroid cream (Elocon) and as an intranasal spray (Nasonex) for treatment of allergic rhinitis.

A fixed-dose combination of oxycodone 5 mg and ibuprofen 400 mg (Combunox - Forest Laboratories) is now available and is being heavily advertised for short-term treatment of moderate to severe acute pain.

Gamma hydroxybutyrate (GHB), a central-nervous-system depressant notorious for its use in "date rape", was approved by the FDA in 2002 as sodium oxybate (Xyrem - Jazz Pharmaceuticals) for oral treatment of cataplexy in patients with narcolepsy. Now it has also been approved for treatment of excessive daytime sleepiness (EDS) in these patients. Xyrem is a Schedule III controlled substance.