Pentazocin

Uses

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

Pentazocin is also used to associated treatment for these conditions: Mild pain, Severe Pain, Moderate Pain, Preanesthetic medication therapy

How Pentazocin works

The preponderance of evidence suggests that pentazocine antagonizes the opioid effects by competing for the same receptor sites, especially the opioid mu receptor.

Dosage

Pentazocin dosage

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 singleparenteraldose is 30 mg byintramuscular, 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 theanalgesiceffects of Pentazocin than younger patients. Elderly patients generally should be started on low doses of Pentazocin 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-lateralaspects of the thighs, and thedeltoidareas) isessential.

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.

Side Effects

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).

Precaution

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.

Interaction

Depressant affects potentiated by alcohol, CNS depressants; concurrent use with fluoxetine may lead to diaphoresis, ataxia flushing and tremor associated with serotonin syndrome.

Food Interaction

• Avoid alcohol.
• Take with or without food. Food does not significantly affect absorption.

[Moderate] MONITOR: Smoking tobacco may decrease the plasma concentrations and effects of pentazocine by enhancing its metabolic clearance.

MANAGEMENT: The possibility of reduced therapeutic effects of pentazocine should be considered in smokers.

Pentazocin Alcohol interaction

[Moderate] GENERALLY AVOID:

Ethanol may potentiate the central nervous system (CNS) depressant effects of opioid analgesics.

Concomitant use may result in additive CNS depression and impairment of judgment, thinking, and psychomotor skills.

In more severe cases, hypotension, respiratory depression, profound sedation, coma, or even death may occur.

Concomitant use of opioid analgesics with ethanol should be avoided.

Pentazocin Drug Interaction

Major: duloxetine, meperidine, fentanyl, acetaminophen / hydrocodoneModerate: furosemide, metoprolol, promethazineUnknown: naproxen, thyroid desiccated, aspirin, multivitamin with minerals, sulfamethoxazole / trimethoprim, glucose, heparin, sodium iodide, atorvastatin, acetaminophen, montelukast, cyanocobalamin, cholecalciferol

Pentazocin Disease Interaction

Major: impaired GI motility, infectious diarrhea, liver disease, prematurity, gastrointestinal obstruction, acute MI, drug dependence, intracranial pressure, respiratory depressionModerate: adrenal insufficiency, biliary spasm, hypothyroidism, renal dysfunction, seizure disorders, urinary retention

Elimination Route

Well absorbed from the gastro-intestinal tract.

Half Life

2 to 3 hours

Pregnancy & Breastfeeding use

Safe use of Pentazocin during pregnancy (other than labor) has not been established. Animal reproduction studies have not demonstrated teratogenic or embryotoxic effects. However, Pentazocin 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 Pentazocin during labor have experienced no adverse effects other than those that occur with commonly used analgesics. Pentazocin should be used with caution in women delivering premature infants.

Contraindication

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

Special Warning

Pediatric Use: The safety and efficacy of Pentazocin as preoperative or preanesthetic medication have been established in pediatric patients 1 to 16 years of age. Use of Pentazocin 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 Pentazocin as a premedication for sedation have not been established in pediatric patients less than one year old. Information on the safety profile of Pentazocin 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 Pentazocin than younger patients. Clinical data indicate that differences in various pharmacokinetic parameters of Pentazocin 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 Pentazocin 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.

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