Pholcodine.

Pholcodine has antitussive activity similar to, or somewhat greater than, that of codeine in animal test systems. The drug, which has been formulated in many combination medications (45)--some rational and some quite irrational pharmacologically--also appears to be active in man, although the clear-cut demonstrations, unfortunately, are in artificially-induced cough models. Additional efficacy studies are needed. Preclinical toxicity studies demonstrate a generally safer profile for pholcodine than codeine, although pholcodine appears to have greater depressant effects on the respiratory and cardiovascular systems in animals. These effects have not been observed in man after administration of therapeutic doses. Pholcodine appears to be devoid of addiction liability in man. In contrast to codeine, pholcodine is not metabolised to morphine in man, a fact which may contribute to its more favourable toxicity profile, and it is metabolised and eliminated much more slowly than codeine.