Rapid exposure to altitudes more than 8,000 feet above sea level can cause serious medical problems. Since the last Medical Letter article on this subject (Vol. 30, page 89, 1988), some new information on prevention and treatment of these disorders has been reported.

Acrivastine/Pseudoephedrine (Semprex-D) for Seasonal Allergic Rhinitis (Burroughs-Wellcome), a combination of acrivastine with pseudoephedrine hydrochloride, has been approved by the US Food and Drug Administration for treatment of seasonal allergic rhinitis. Acrivastine is a new H 1 -receptor antagonist with a chemical structure similar to that of triprolidine (Actidil, and others) (RN Brogden and D McTavish, Drugs, 41:927, 1991). Pseudoephedrine is an α -adrenergic agonist. The combination is available only by prescription.

Cetirizine (Zyrtec - Pfizer), a histamine H 1 -receptor antagonist, has been approved by the US Food and Drug Administration for treatment of seasonal allergic rhinitis, perennial allergic rhinitis and chronic idiopathic urticaria in adults and children more than 12 years old.

Azelastine hydrochloride, a histamine-H1 receptor antagonist, has been marketed as a 0.1% nasal spray (Astelin - Wallace) for treatment of seasonal allergic rhinitis. Corticosteroid and cromolyn sodium nasal sprays are also available for this indication (Medical Letter, 37:5, 1995). Cromolyn sodium (Nasalcrom) has now been approved for over-the-counter use.

Carvedilol (Coreg - SmithKline Beecham and Boehringer-Mannheim), a betaadrenergic and alpha-adrenergic blocker approved by the FDA for treatment of hypertension in 1995, but not marketed at that time, has now been approved and marketed for treatment of mild or moderate (NYHA class II or III) heart failure stabilized on other drugs. It is being promoted as an add-on drug that reduces the morbidity and mortality of the disease.

Linezolid, the first of a new class of antibiotics, the oxazolidinones, has been marketed for treatment of infection due to vancomycin-resistant Enterococcus faecium, nosocomial and community-acquired pueumonia due to Staphylococcus aureus or penicillin-sucsceptible Streptococcus pneumoniae, and skin and skin structure infections, including those due to methicillin-resistant S. aureus (MRSA).

Zonisamide (Zonegran - Elan Pharma), a sulfonamide chemically unrelated to other antiepileptic drugs, has been approved by the FDA for adjunctive use in adults with partial seizures. Zonisamide has been available in Japan for more than 10 years.

Tenecteplase, a recombinant variant of human tissue plasminogen activator, is now available for thrombolysis in patients with acute myocardial infarction.

Nateglinide (Starlix), a new meglitinide oral glucose-lowering agent, has been approved by the FDA.

Ertapenem (er ta pen' em; Invanz - Merck), a carbapenem antibacterial with a narrower spectrum of activity than imipenem (Primaxin) or meropenem (Merrem), has been approved by the FDA for once-daily IV treatment of complicated intra-abdominal, urinary tract and skin and skin structure infections, acute pelvic infections, and community-acquired pneumonia.