The effectiveness and toxicity of many drugs can be radically affected by the time of day at which they are administered. This is because the body's clock-the suprachiasmatic nucleus, which takes its main cue from environmental light-regulates the peaks and troughs in hormone output, body temperature and other physiological activities throughout a 24 hour period. For example, administering some anticancer drugs during the night can substantially increase their activity compared with a daytime administration.
Based on this premise, Shigehiro Ohdo and colleagues at Kyushu University in Japan have investigated the effects of the antitumor cytokine drug, interferon-a, on circadian rhythms in mice (Nature Medicine, Vol. 7, No. 3, 01 Mar 2001). Repetitive administration of the cytokine disturbs the ability of the body clock to be cued by light and also alters the rhythm of clock-gene expression in the periphery and in the suprachiasmatic nucleus. These effects may explain some of the toxicity that is associated with this drug, which could be avoided by altering the dosage schedule.
Dr. Shigehiro Ohdo
Department of Clinical Pharmacokinetics
Division of Pharmaceutical Sciences Graduate School
Tel: 81 092 642 6658
Fax: 81 092 642 6660
(C) Nature Medicine press release.
Message posted by: Trevor M. D'Souza