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Fortalin: Full Drug Profile

Medically reviewed by Min Clinic Staff | Updated: January 2026

Fortalin - General Information

The first mixed agonist-antagonist analgesic to be marketed. It is an agonist at the kappa and sigma opioid receptors and has a weak antagonist action at the mu receptor. (From AMA Drug Evaluations Annual, 1991, p97)

 

Pharmacology of Fortalin

Fortalin is a potent analgesic which when administered orally in a 50 mg dose appears equivalent in analgesic effect to 60 mg (1 grain) of codeine. Onset of significant analgesia usually occurs between 15 and 30 minutes after oral administration, and duration of action is usually three hours or longer. Onset and duration of action and the degree of pain relief are related both to dose and the severity of pretreatment pain. Fortalin weakly antagonizes the analgesic effects of morphine and meperidine; in addition, it produces incomplete reversal of cardiovascular, respiratory, and behavioral depression induced by morphine and meperidine. Fortalin has about 1/50 the antagonistic activity of nalorphine. It also has sedative activity.

 

Fortalin for patients

Since sedation, dizziness, and occasional euphoria have been noted, ambulatory patients should be warned not to operate machinery, drive cars, or unnecessanly expose themselves to hazards. Pentazocine may cause physical and psychological dependence when taken alone and may have additive CNS depressant properties when taken in combination with alcohol or other CNS depressants.

 

Fortalin Interactions

Usage with Alcohol: Due to the potential for increased CNS depressants effects, alcohol should be used with caution in patients who are currently receiving pentazocine.

 

Fortalin Contraindications

TALWIN Nx should not be administered to patients who are hypersensitive to either pentazocine or naloxone.

 

Additional information about Fortalin

Fortalin Indication: For the relief of moderate to severe pain. Mechanism Of Action: The preponderance of evidence suggests that pentazocine antagonizes the opioid effects by competing for the same receptor sites, especially the opioid mu receptor. Drug Interactions: Cimetidine Cimetidine increases the effect of the narcoticNaltrexone Naltrexone may precipitate a withdrawal syndrome in opioid dependent individuals Food Interactions: Not Available Generic Name: Pentazocine Synonyms: L-pentazocine; Pentazocaine; Pentazocin Drug Category: Adjuvants, Anesthesia; Analgesics, Opioid; Narcotic Antagonists; Narcotics Drug Type: Small Molecule; Approved Other Brand Names containing Pentazocine: Fortalgesic; Fortalin; Fortral; Liticon; Pentagin; Soseton; Sosigon; Talwan; Absorption: Well absorbed from the gastro-intestinal tract. Toxicity (Overdose): Not Available Protein Binding: Not Available Biotransformation: Hepatic Half Life: 2 to 3 hours Dosage Forms of Fortalin: Solution IntravenousTablet Oral Chemical IUPAC Name: (1S,9S,13S)-1,13-dimethyl-10-(3-methylbut-2-en-1-yl)-10-azatricyclo[7.3.1.02,7]trideca-2,4,6-trien-4-ol Chemical Formula: C19H27NO Pentazocine on Wikipedia: https://en.wikipedia.org/wiki/Pentazocine Organisms Affected: Humans and other mammals