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pen-TAZ-oh-seen - Pronunciation guide

Brand Names

  • Talwin


Rx symbolPentazocine is a synthetic partial opiate agonist available as two separate salts. The hydrochloric salt found in oral dosage forms is a white, crystalline powder that is soluble in water and also in alcohol. The commercial injection is prepared from a pentazocine base with the assistance of lactic acid. Pentazocine exhibits many of the same characteristics as the true opiate agonists. After absorption, the drug is distributed widely into tissues. In horses, it has been shown to be 80% bound to plasma proteins.


In addition to symptomatic relief of pain in horses with colic, pentazocine is used in the amelioration of pain during postoperative recovery from fractures, trauma, and spinal disorders.

Dosage and Administration

Prescription medicationPentazocine
Method Dosage
(click row for calculator)
Concentration Period Duration
Intravenous or Intramuscular injection 0.33-1.1 mg/kg 30 mg/ml Treatment NA


  • Federal law restricts this drug to use by or on the order of a licensed veterinarian.
  • Extra-label use of drugs in treating animals is allowable only by licensed veterinarians within the context of a valid veterinarian-client-patient relationship, and does not include drug use in treating animals by the layman (except under the supervision of a licensed veterinarian).
  • The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your equine appears to feel better, the entire treatment plan should be completed to prevent relapse.
  • This medication may be available in forms and concentrations not noted in the above table. Always check the label and literature provided with the medication about the form and concentration and DO NOT USE the calculator if the information differs.
  • Calculator is for educational purposes only. Follow your veterinarian's instructions regarding use of this, or any medication.

Side Effects

Horses may develop transient ataxia and symptoms of central nervous system excitement. Pulse and respiratory rates may become elevated.


Pentazocine should only be used in combination with a sedative, such as xylazine or detomidine.

Pentazocine should not be used in place of appropriate treatment for colic in horses.

Pentazocine should not be used in debilitated horses.

Pentazocine is FDA approved for use in horses and is a prescription drug to be used or prescribed by a licensed veterinarian.

Pentazocine is a prohibited substance in most sanctioned competitions. Check with the individual regulatory group.


When used with pentazocine, other central nervous system depressants/anesthetic agents may cause increased CNS or respiratory depression. Dosage may need to be decreased. Always consult with a veterinarian.


Little information regarding acute overdose with pentazocine is available. For oral ingestion, the gut should be emptied, if indicated and safe to do so. Naloxone may help relieve overdose effects.


Talwin (Pantazocine Lactate Injection)Talwin (Pantazocine Lactate Injection)



About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.