Paracetamol + Pentazocine

Oral
Mild to moderate pain

Hypersensitivity to either component; raised intercranial pressure or head injury.

Head injury, other intracranial lesions or preexisting increase in intracranial pressure (impedes pupillary response required for neurological assessment); patients on opiate analgesics; opioid dependence; acute alcoholism; compromised respiratory, cardiac, renal or hepatic functions; epileptic patients; pregnancy & lactation, children. Caution when used in patients with MI who have accompanying nausea or vomiting. May experience withdrawal symptoms after receiving pentazocine.

Nausea, vomiting, constipation, anorexia, diarrhea, dizziness, sedation, disorientation, euphoria, headache, visual blurring, rarely dysphoria, sweating, flushing, rashes & urticaria; urinary retention, anaphylactoid reaction & drug abuse & dependence.
Potentially Fatal: Hepatic necrosis (especially in chronic alcoholics).

PO: C

Symptoms of overdose would be a combination of those observed with pentazocine overdose and paracetamol overdose. Pentazocine overdose may lead to anxiety, nightmares, strange thoughts and hallucinations. Marked respiratory depression associated with increased BP and tachycardia may also occur. Acute paracetamol overdose may cause nausea, vomiting, anorexia and abdominal pain. Severe overdosage may lead to potentially fatal hepatic necrosis. Treatment involves oxygen, IV fluids, vasopressors and other supportive measures.

Paracetamol may also enhance anticoagulant activity. Naloxone reverses effects of pentazocine.
Potentially Fatal: Alcohol & other CNS depressants potentiate depressant action of pentazocine.

Description: Pentazocine is an opioid analgesic with agonist/antagonist action. Paracetamol is a centrally and peripherally acting analgesic and antipyretic. The combination gives additive analgesic effects.
Pharmacokinetics:
Absorption: Pentazocine: Well absorbed from the GI tract. Paracetamol: Rapidly and almost completely absorbed from the GI tract.
Distribution: Pentazocine: Passes the placental barrier.
Metabolism: Pentazocine: Metabolised mainly by hepatic biotransformation. Paracetamol: Conjugated in the liver with glucuronic acid and to a smaller extent with sulfuric acid.
Excretion: Pentazocine: Elimination half-life ranges from 1.5-10 hr. Paracetamol: Elimination half-life ranges from 2-4 hr.

Analgesics (Non-Opioid) & Antipyretics / Analgesics (Opioid)