Pentazocine is a benzomorphan derivative with mixed opioid agonist and antagonist actions. It alters perception of and response to pain and produces generalised CNS depression by binding to opiate receptors in the CNS and acting as a partial agonist/antagonist.

For the relief of moderate to severe pain. Pentazocine may also be used for preoperativeor preanesthetic medication and as a supplement to surgical anesthesia.

Tablet:

Adults: The usual initial adult dose is 1 tablet every three or four hours. This may be increased to 2 tablets when needed. Total daily dosage should not exceed 12 tablets.

Injection:

Adults, Excluding Patients in Labor: The recommended single parenteral dose is 30 mg by intramuscular, subcutaneous, or intravenous route. This may be repeated every 3 to 4 hours. Doses in excess of 30 mg intravenously or 60 mg intramuscularly or subcutaneously are not recommended. Total daily dosage should not exceed 360 mg. Elderly patients may be more sensitive to the analgesic effects of Pentazocine than younger patients. Elderly patients generally should be started on low doses of Pentazocine and observed closely.

The subcutaneous route of administration should be used only when necessary because of possible severe tissue damage at injection sites. When frequent injections are needed, the drug should be administered intramuscularly. In addition, constant rotation of injection sites (e.g., the upper outer quadrants of the buttocks, mid-lateral aspects of the thighs, and the deltoid areas) is essential.

Patients in Labor: A single, intramuscular 30 mg dose has been most commonly administered. An intravenous 20 mg dose has given adequate pain relief to some patients in labor when contractions become regular, and this dose may be given two or three times at two- to three-hour intervals, as needed.

Pediatric Patients Excluding Patients Less Than One-Year-Old: The recommended single parenteral dose as premedication for sedation is 0.5 mg/kg by intramuscular route.

Pentazocine should not be administered to patients who are hypersensitive to it.

Physical dependence; sedation, dizziness, euphoria, lightheadedness, alterations of mood; respiratory depression; visual hallucinations, disorientation, confusion; hypertension, tachycardia, circulatory depression; shock; hypotension; nausea, vomiting, constipation; seizures, diaphoresis; rash; blood dyscrasias; local tissue damages (SC), muscle fibrosis (IM).

May precipitate withdrawal in narcotic addicts. Impaired respiratory, renal and hepatic function; morbidly obese patients; thyroid dysfunction; prostatic hyperplasia or urinary stricture; biliary tract impairment; adrenal insufficiency (including Addison's disease); abdominal conditions. Elderly or debilitated patients; seizure-prone patients; children and infants (safety and efficacy not established in less than 1 yr); lactation. May impair ability to drive or operate machinery. Administer IM rather than SC (when frequent inj are needed) and inj sites should be varied.

Use in Special Populations

Pediatric Use: The safety and efficacy of Pentazocine as preoperative or preanesthetic medication have been established in pediatric patients 1 to 16 years of age. Use of Pentazocine in these age groups is supported by evidence from adequate and controlled studies in adults with additional data from published controlled trials in pediatric patients. The safety and efficacy of Pentazocine as a premedication for sedation have not been established in pediatric patients less than one year old. Information on the safety profile of Pentazocine as a postoperative analgesic in children less than 16 years is limited.

Geriatric Use: Elderly patients may be more sensitive to the analgesic effects of Pentazocine than younger patients. Clinical data indicate that differences in various pharmacokinetic parameters of Pentazocine may exist between elderly and younger patients. Sedating drugs may cause confusion and oversedation in the elderly; elderly patients generally should be started on low doses of Pentazocine and observed closely.

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

Pregnancy & Lactation

Safe use of Pentazocine during pregnancy (other than labor) has not been established. Animal reproduction studies have not demonstrated teratogenic or embryotoxic effects. However, Pentazocine should be administered to pregnant patients (other than labor) only when, in the judgment of the physician, the potential benefits outweigh the possible hazards. Patients receiving Pentazocine during labor have experienced no adverse effects other than those that occur with commonly used analgesics. Pentazocine should be used with caution in women delivering premature infants.