Propoxyphene/Acetaminophen

A to Z Drug Facts

 Action Propoxyphene relieves pain by stimulating opiate receptors in CNS; also causes respiratory depression; peripheral vasodilation, inhibition of intestinal peristalsis, sphincter of Oddi spasm, stimulation of receptors that cause vomiting, increased bladder tone. Acetaminophen inhibits synthesis of prostaglandins; does not have significant anti-inflammatory effects or antiplatelet effects; produces antipyresis by direct action on the hypothalamic heat-regulating center.

 Indications Relief of mild-to-moderate pain; as analgesic-antipyretic in presence of aspirin allergy, hemostatic disturbances, bleeding diatheses, upper GI disease and gouty arthritis.

 Contraindications Standard considerations.

 Route/Dosage

PROPOXYPHENE NAPSYLATE

ADULTS: PO 100 mg (with 650 mg acetaminophen) q 4 hr prn; not to exceed 600 mg/day.

PROPOXYPHENE HYDROCHLORIDE

ADULTS: PO 65 mg (with 650 mg acetaminophen) q 4 hr; not to exceed 390 mg/day.

 Interactions

Carbamazepine: Increased carbamazepine serum levels; increased risk of acetaminophen hepatotoxicity. Charcoal: Decreased propoxyphene absorption. Cigarette smoking: Decreased propoxyphene effect because of liver enzyme induction. CNS depressants (alcohol, antidepressants, barbiturates, muscle relaxants, sedatives, tranquilizers): Increased CNS and respiratory depression. Hydantoins: Increased risk of acetaminophen hepatotoxicity. Sulfinpyrazone: Increased risk of acetaminophen hepatotoxicity. Warfarin: Potentiation of hypoprothrombinemic effect.

 Lab Test Interferences Increased amylase and lipase for up to 24 hr after administration.

 Adverse Reactions

CV: Hypotension. CNS: Lightheadedness; weakness; fatigue; sedation; dizziness; disorientation; uncoordination; paradoxical excitement; euphoria; dysphoria; insomnia. GI: Nausea; vomiting; constipation; anorexia; stomach pain; biliary spasm. GU: Urinary retention or hesitancy. RESP: Dyspnea; depression of cough reflex. OTHER: Tolerance; psychological and physical dependence with long-term use; histamine release; pain at injection site.

 Precautions

Pregnancy: Category C (D if used for prolonged periods). Lactation: Excreted in breast milk. Children: Safety and efficacy not established. Special-risk patients: Use with caution in patients with myxedema, acute alcoholism, acute abdominal conditions, ulcerative colitis, decreased respiratory reserve, head injury or increased cranial pressure, hypoxia, supraventricular tachycardia, depleted blood volume or circulatory shock. Drug dependence: Has abuse potential. Fatalities: Excessive doses, either alone or in combination with other CNS depressants (including alcohol), are major cause of drug-induced death. Do not use in patients who are suicidal or addiction prone. Hepatic and renal impairment: Use drug with caution; reduce total daily dosage; advise chronic alcoholics to limit acetaminophen intake to < 2 g/day.

 Administration/Storage

• Give with food or milk if GI upset occurs.
• Be aware that 65 mg of HCl form is equivalent to 100 mg of napsylate form in delivering same amount of propoxyphene.
• Store in light-resistant container at room temperature.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note potential for suicide or drug dependence.
• Assess pain prior to and 30 to 60 min after administration.
• Observe for respiratory depression, dizziness, sedation, nausea, vomiting or constipation; notify physician if these symptoms occur.
• Provide safety measures (eg, accessible call bell, side rails, night light) and assist with ambulation.
• Monitor for prolonged duration of action in cases of hepatic or renal impairment and report to physician, since dose may need to be reduced.

 Patient/Family Education

• Advise patient to take drug with food if GI upset occurs.
• For long term therapy, explain that dosage will be tapered slowly before stopping to prevent withdrawal symptoms.
• Advise patient not to take any other medications (prescription or otc) containing acetaminophen except on advice of physician.
• Tell patient not to wait until pain level is high to self-medicate because drug will not be as effective.
• Advise patient to notify physician if drug does not provide pain relief.
• Explain that increasing fluid and fiber intake may help decrease constipation; stool softeners and laxatives may also be suggested.
• Instruct patient to report the following symptoms to physician: Shortness of breath, difficulty breathing, nausea, vomiting, constipation or other side effects.
• Caution patient to avoid sudden position changes to prevent orthostatic hypotension.
• Instruct patient to avoid intake of alcoholic beverages or other CNS depressants.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts