Home Drug Guide Propoxyphene Hydrochloride and Acetaminophen

Drug Guide

Generic Name

Propoxyphene Hydrochloride and Acetaminophen

Brand Names Darvocet, Wygesic, Dolene Ap-65

Classification

Therapeutic: Analgesic, Centrally Acting

Pharmacological: Opioid analgesic combination

FDA Approved Indications

Mild to moderate pain

Mechanism of Action

Propoxyphene hydrochloride acts as a centrally acting analgesic that interacts with opioid receptors, producing analgesia. Acetaminophen inhibits prostaglandin synthesis in the CNS and works peripherally to block pain impulse generation.

Dosage and Administration

Adult: Typically 65 mg propoxyphene/650 mg acetaminophen every 4 hours as needed, not to exceed 12 pills in 24 hours.

Pediatric: Not recommended for children under 18 years due to safety concerns.

Geriatric: Dose reduction may be necessary due to increased sensitivity and risk of adverse effects.

Renal Impairment: Use with caution; dose adjustment may be necessary.

Hepatic Impairment: Use with caution, especially with chronic liver disease; dose adjustment recommended.

Pharmacokinetics

Absorption: Rapidly absorbed from gastrointestinal tract.

Distribution: Widely distributed, crosses the blood-brain barrier.

Metabolism: Metabolized mainly in the liver via conjugation; active metabolites are minimal.

Excretion: Excreted primarily in urine.

Half Life: Approximately 3-4 hours for propoxyphene; approximately 2-3 hours for acetaminophen.

Contraindications

Hypersensitivity to propoxyphene, acetaminophen, or excipients.
Use caution in patients with respiratory depression, hepatic impairment, or history of substance abuse.

Precautions

Potential for dependence and abuse.
Use cautiously in the elderly, with respiratory diseases, or those with pre-existing hepatic conditions.

Adverse Reactions - Common

Dizziness (Common)
Nausea (Common)
Somnolence (Common)

Adverse Reactions - Serious

Respiratory depression (Rare)
Hepatotoxicity with overdose (Rare)
Cardiac arrhythmias (Rare)

Drug-Drug Interactions

Alcohol, CNS depressants, other opioids, CYP3A4 inhibitors, hepatotoxic drugs

Drug-Food Interactions

N/A

Drug-Herb Interactions

St. John's Wort, ginseng (may increase metabolism or toxicity)

Nursing Implications

Assessment: Monitor pain relief, respiratory status, liver function, and signs of misuse or abuse.

Diagnoses:

Pain, acute
Risk for respiratory depression
Risk for liver injury

Implementation: Administer with food or milk to reduce gastrointestinal irritation. Monitor liver enzymes during prolonged therapy.

Evaluation: Assess relief of pain, respiratory status, and liver function tests.

Patient/Family Teaching

Advise about the risk of dependence and addiction.
Instruct to avoid alcohol and CNS depressants.
Report signs of allergic reaction, overdose, or liver toxicity.

Special Considerations

Black Box Warnings:

Potential for cardiac arrhythmias and serious cardiac conduction disturbances with overdose or in susceptible individuals.

Genetic Factors: Genetic variations may influence metabolism, especially CYP2D6-related pathways.

Lab Test Interference: May affect certain liver function tests.

Overdose Management

Signs/Symptoms: Respiratory depression, somnolence, confusion, hepatic failure, coma.

Treatment: Administer naloxone for respiratory depression; provide supportive care; consider activated charcoal if ingestion is recent; monitor hepatic function.

Storage and Handling

Storage: Store at room temperature, away from moisture and light.

Stability: Stable under proper storage conditions.