In a study of the interaction between alcohol and the calcium-channel blocker felodipine (Plendil), the grapefruit juice vehicle for the alcohol appeared to increase felodipine plasma concentrations. Subsequent studies have found that grapefruit juice increases plasma concentrations of several calcium-channel blockers and of some other drugs as well (DG Bailey et al, Clin Pharmacokinet, 26:91, 1994).

(Kodak) perform clinical chemistry tests using desk-top instruments, microliter samples and postage-stamp-sized analytical slides containing dry reagents layered on clear polyester and mounted in plastic. The system requires no wet reagents, except for electrolyte determinations, and is designed to require a minimum amount of training to operate. A single analysis takes about five minutes.

Tacrine hydrochloride (Cognex - Parke-Davis), an acridinamine derivative, will soon be available for treatment of cognitive deficits associated with Alzheimer's disease.

Four different desk-top systems are now widely used in physicians'; offices to measure blood chemistries. The Ektachem DT (Kodak) and Reflotron (Boehringer Mannheim), reviewed previously in The Medical Letter (volume 30, page 119, 1988; volume 31, page 90, 1989), resemble the Seralyzer (Miles Diagnostics) in cost; the Vision (Abbott), which is fully automated, is much more expensive.

Zafirlukast (za fir loo kast; Accolate - Zeneca), the first leukotriene receptor anta-gonist approved by the US Food and Drug Administration, is now being heavily promoted for oral maintenance treatment of chronic asthma in patients more than 12 years old. It is not recommended for treatment of acute asthma.

Healthcare providers are often asked if drugs can be used past their expiration date. Because of legal restrictions and liability concerns, manufacturers do not sanction such use and usually do not comment on the safety or effectiveness of their products beyond the date on the label. Since our last article on this subject, more data have become available.

Donepezil hydrochloride (Aricept - Eisai), a piperidine-based acetylcholinesterase inhibitor, is now being marketed for oral treatment of cognitive symptoms in patients with mild to moderate dementia due to Alzheimer's disease. Donepezil is the second drug approved for this indication; tacrine hydrochloride (Cognex), also an acetylcholinesterase inhibitor, has been available in the USA for four years (Medical Letter, 35:87, 1993).

Ciprofloxacin hydrochloride (Cipro - Miles), a synthetic antibacterial agent, was recently marketed in the USA for oral treatment of a wide variety of infections. Ciprofloxacin is the second fluoroquinolone to become available in this country; norfloxacin (Noroxin - Medical Letter, 29:25, 1987) is marketed only for treatment of urinary tract infections. Fluoroquinolones are more potent and have a much broader spectrum of activity than older quinolones such as nalidixic acid (NegGram).

Patients may be asking their physicians about use of histamine H2-receptor antagonists for treatment and prevention of heartburn. Cimetidine and famotidine have recently been released for over-the-counter sale and are being heavily advertised on television and in the print media.

Myocardial images produced by injections of radioactive thallium chloride (201Tl), usually during exercise, have been used for many years for diagnosis of coronary artery disease (Medical Letter, 21:49, 1979). Recently, some new techniques and radiopharmaceuticals have become available for myocardial imaging.