A comparative study of the effects of chronic administration of propoxyphene salts to normal volunteers

Two salts of the oral analgesic agent propoxyphene, the hydrochloride salt and the 2-naphthylene sulfonic acid salt, were evaluated for safety in a 6-month study in normal male inmates of a penal institution. Parameters measured included subjective side effects, hematologic response, blood chemistry, and urine analysis as well as routine physical examination. There were 40 subjects in each drug group initially, and a concomitant control group of 40 subjects received placebo capsules for the duration of the study. There were no changes in any of the parameters measured which could be attributed to the drugs. An epidemic of mild, anicteric hepatitis did produce changes in liver function as measured by serum transaminases and alkaline phosphatase levels; however, these occurred with equal frequency in all 3 groups and were also observed in subjects not participating in the study. The results indicate the value of concomittant placebo controls in a study of this type.