From Dog

Dextromethorphan is an NMDA receptor antagonist that works similar in action to ketamine and codeine, exerting its effects through central sites of action[1].

This drug has antiemetic, anti-seizure, analgesic and antitussive properties and has been used to control motion sickness-associated vomiting and chronic coughing associated with bronchitis in dogs. It has also been used to treat repetitive self-directed scratching, biting, or chewing in dogs with atopy[2].

In humans, it is used to reduce opioid and alcohol dependence[3].

A metabolite of dextromethorphan, dextrorphan, has been shown to behave pharmacodynamically in a similar manner to dextromethorphan[4].

Due to its half-life, rapid clearance and poor bioavailability, dextromethorphan has limited potential as a chronically administered therapeutic drug in dogs.

Recommended dose rate in dogs is 0.5 - 2.0 mg/kg given orally every 12 - 24 hours.


  1. Bolser DC (2009) Central mechanisms II: pharmacology of brainstem pathways. Handb Exp Pharmacol 187:203–217
  2. Dodman NH et al (2004) The use of dextromethorphan to treat repetitive self-directed scratching, biting, or chewing in dogs with allergic dermatitis. J Vet Pharmacol Ther 27(2):99-104
  3. Manning BH et al (1996) Continuous co-administration of dextromethorphan or MK-801 with morphine: attenuation of morphine dependence and naloxone-reversible attenuation of morphine tolerance. Pain 67(1):79-88
  4. Kukanich B & Papich MG (2004) Plasma profile and pharmacokinetics of dextromethorphan after intravenous and oral administration in healthy dogs. J Vet Pharmacol Ther 27(5):337-341