title: Oral administration of dextromethorphan prevents the development of morphine tolerance and dependence in rats.
abstract: Combined oral administration of morphine sulfate (MS) and the over-the-counter antitussive drug and N-methyl-D-aspartate receptor antagonist dextromethorphan (DM) prevented the development of tolerance to the antinociceptive effects of MS (15, 24, or 32 mg/kg) in rats. This combined oral treatment regimen also attenuated signs of naloxone-precipitated physical dependence on morphine in the same rats. A wide range of ratios of MS to DM (2:1, 1:1, and 1:2) were effective for preventing the development of morphine tolerance and dependence. In addition, we provide evidence that under certain circumstances DM increases the acute antinociceptive effects of MS. All of these results indicate that oral treatment that combines DM with opiate analgesics may be a powerful approach for simultaneously preventing opiate tolerance and dependence and enhancing analgesia in humans.
authors.affiliation: Department of Anesthesiology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298, USA.
authors.forename: J
authors.initials: J
authors.lastname: Mao
authors.forename: D D
authors.initials: DD
authors.lastname: Price
authors.forename: F S
authors.initials: FS
authors.lastname: Caruso
authors.forename: D J
authors.initials: DJ
authors.lastname: Mayer
mesh_terms: D000284:Administration, Oral; D000818:Animals; D003915:Dextromethorphan / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004361:Drug Tolerance; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D019966:Substance-Related Disorders / Q000517:prevention & control*; D013997:Time Factors
chemical_list: D004338:Drug Combinations; D003915:Dextromethorphan; D009020:Morphine