Effects of L-tryptophan on the development of tolerance to the antitussive effects of dihydrocodeine.
The effects of L-tryptophan on the development of tolerance to the antitussive effects of dihydrocodeine were examined in rats. Chronic co-administration of L-tryptophan with dihydrocodeine prevented the development of tolerance to the antitussive effects of dihydrocodeine. Furthermore, the antitussive effects of dihydrocodeine in dihydrocodeine-tolerant rats were fully restored by acute co-administration of L-tryptophan, as evidenced by a decrease of about 50% in the ED50 value of dihydrocodeine. Thus, it is concluded that L-tryptophan may antagonized the development of tolerance to the antitussive effects of dihydrocodeine.
Kamei
J
J
Department of Pharmacology, School of Pharmacy, Hoshi University, Tokyo, Japan.
Mori
T
T
Kasuya
Y
Y
D000818:Animals; D000996:Antitussive Agents; D003061:Codeine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003371:Cough / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D004558:Electric Stimulation; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects; D014132:Trachea / Q000502:physiology; D014364:Tryptophan / Q000494:pharmacology*
D000996:Antitussive Agents; D014364:Tryptophan; C014481:dihydrocodeine; D003061:Codeine