Drug information of Pentazocine


Drug group:

Pentazocine is the first mixed agonist-antagonist analgesics. It is a synthetic opioid which is used in oral and parenteral forms as an analgesics for moderate to severe pain.

Mechanism of effect

inhibits pain pathways, which causes alteration in response to pain; produces analgesia, respiratory depression, and sedation


Agonist of kappa opiate receptors and partial agonist of mu opiate receptors in the CNS.


  • Half-life: 2-3hr
  • Peak plasma time: IM 15-60 min; IV 15 min
  • Metabolism: liver (oxidation and glucuronide conjugation)
  • Excretion: urine (mainly), feces



Treatment of moderate to severe pain/ preoperative surgery anesthesia:

30mg IV/IM/SC q3-4hr ( not to exceed 30mg/dose IV or 60mg/dose IM/SC

Not to exceed 360 mg /day IV/IM/SC

Labor pain:

20 mg IV; may give q2-3hr PRN; not to exceed 60 mg


preoperative surgery anesthesia:

>1 year: 0.5mg/kg IM as a single dose


<5 years: safety and efficacy not established

5-8years:15mg IM

>8years: 30mg IM

Drug contraindications

Hypersensitivity to this drug


Risk of opioid addiction and abuse, which lead to overdose and death

Serious, life threatening respiratory depression

Co administration with CNS depressant may result to sedation, coma and death

May increase frequency of seizures in patients with seizers disorders

May cause severe hypotension

Caution use in patients with inflammatory bowel disease, acute abdominal pain, gall bladder disease, hypothyroidism, renal disease

Points of recommendation

Monitor patients for the development of addiction, abuse, worsened seizures and respiratory depression.

Instruct patients not to consume alcohol while taking opioid

Use caution when selecting dosage for an elderly patients.

Warn not to drive or operate dangerous machinery unless they are tolerant to effects of this drug

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