A comparative randomized double-blind clinical trial of isoaminile citrate and chlophedianol hydrochloride as antitussive agents.

The efficacy and safety of a new centrally acting antitussive agent, isoaminile citrate, was compared with that of chlophedianol hydrochloride in a double-blind, randomized interpatient study. A total of 66 patients participated, two and four patients were lost to follow-up with isoaminile and chlophedianol, respectively. In the experimentally induced cough in 12 normal human subjects, isoaminile (40 mg) was as effective as chlophedianol (20 mg), but its duration of action was somewhat longer. One subject developed allergic skin rash with chlophedianol and was withdrawn from the study. In 60 patients with cough associated with chest diseases, isoaminile (40 mg, 3 x daily) was as effective as chlophedianol (20 mg, 3 x daily) in suppressing cough as judged from the 3-h and 24-h cough counts. The increase in PEFR at day 7 of treatment was somewhat more marked with chlophedianol as compared with isoaminile. None of the drugs interfered with the expectoration process. The side effects observed were few, mild in nature, and did not require a decrease in dose or withdrawal of treatment in any of the patients. Isoaminile citrate was concluded to be an effective and relatively safe antitussive agent. Isoaminile citrate, alpha(isopropyl)-alpha-(beta-dimethylaminoproyl) phenylacetonitrile citrate, is a centrally acting antitussive agent. In animal experiments this drug was as efficacious as codeine but was devoid of any respiratory depressant effect [Krause 1958, Kuroda et al. 1971]. This controlled double-randomized interpatient study was designed to test the comparative efficacy and safety of isoaminile and chlophedianol, another centrally acting antitussive, in humans.