Annals of Internal Medicine is published by the American College of Physicians-American Society of Internal Medicine (ACP-ASIM), an organization of more than 115,000 physicians trained in internal medicine. The following highlights are not intended to substitute for articles as sources of information. For an embargoed fax of an article, call 1-800-523-1546, ext. 2656 or 215-351-2656. Full content of the issue is available on the Internet at http://www.annals.org on August 15, 2000.
In a randomized, double-blind, placebo-controlled trial, zinc acetate lozenges reduced the duration and symptoms of colds (Article, p. 245). Study participants in the zinc group received approximately 80 milligrams of elemental zinc per day for four to five days, five times the recommended daily dietary allowance of 15 milligrams. Researchers caution that zinc therapy for the common cold should be limited to about three days, because high doses and long-term ingestion of zinc can cause copper deficiency.
An editorial says the effect of zinc on the common cold is still questionable (Editorial, p. 302). Although this small study asked patients to guess whether they were taking the active drug or a placebo, a larger study would allow data to be analyzed in terms of patients who guessed they were taking zinc, did not know or guessed they were taking the placebo. This feature (asking patients to guess whether they are taking the active drug or placebo) enhances study design and should become a standard feature of all randomized, double-blind, placebo-controlled trials, the author says.
A new prospective cohort study on the effect of antiretroviral therapy on HIV viral load in semen found both positive and troubling findings (Brief Communication, p. 280). After six months of therapy, 40 of 69 samples had no detectable HIV RNA in semen (a 66 percent reduction). But HIV RNA was detected in the semen of 29 (33 percent) of patients. Researchers did not know if the remaining detectable virus was sexually infectious, but it could be. Findings indicate that antiretroviral therapy may reduce sexual transmission of HIV, but researchers also warn that the therapy "may contribute to the selection of and transmission of drug-resistant virus and may consequently attenuate any beneficial effects of such therapy on public health."