Butorphanol.

Butorphanol (Stadol) is a synthetic agonist-antagonist analgesic from the 14-hydroxymorphinan series. Animal studies display analgesia, antitussive effects, low gastrointestinal activity, limited respiratory depression, some cardiovascular and skeletal muscle actions, diuresis, slight miosis and opiate antagonism. Butorphanol is metabolized in the liver with renal excretion, yielding a half-life of 3-4 h.

Review and evaluation of the NCI/NTP carcinogenesis bioassays.

A comparison of the carcinogenesis bioassay results obtained by the National Cancer Institute (NCI) and the National Toxicology Program (NTP) indicates that approximately one-half of the bioassays directed by both institutions were positive for carcinogenicity. The more recent 85 bioassays completed by NTP reveal a higher proportion of studies interpreted as demonstrating no evidence of carcinogenicity than represented in the initial 198 bioassays conducted by NCI. Of the 100 NCI bioassays that were not positive for carcinogenicity 3 (3%) were classified in the category of "no evidence for carcinogenicity in two animal species.