Docosanol

The exact mechanism of the antiviral activity of docosanol is unknown. In vitro studies indicate that docosanol affects the fusion between the virus and the plasma membrane, which inhibits intracellular uptake and replication of virus. In vitro studies demonstrate that docosanol-treated cells resist infection by lipid-enveloped viruses such as HSV-1. Docosanol has no effect against non-enveloped viruses.

Under conditions reflecting normal clinical use, docosanol could not be quantified (limit of quantification, LOQ = 10 ng/ml) in the plasma of treated patients. Ten women with active labial herpes simplex were treated with docosanol cream. After a single dose on study day 1 and after multiple doses (five times daily, study days 2-3), blood samples were withdrawn up to 24 hours after treatment and analysed for docosanol. Of the 209 plasma samples analysed, the docosanol level was below the LOQ in 208 and exactly at the LOQ in one sample.

Docosanol is metabolized to docosanoic acid, its major metabolite. Both docosanol and docosanoic acid are endogenous components of cell membranes in man, particularly in erythrocytes, brain, nerve myelin sheath, lung, and kidney.

Preclinical data revealed no special hazard for humans based on conventional studies of safety, pharmacology, repeated dose toxicity, genotoxicity and toxicity to reproduction.