Propoxyphene

Pronunciation

Pronunciation: pro-POX-ee-feen
Class: Opioid analgesic Propoxyphene Hydrochloride

Trade Names:
Darvon-N
- Tablets 100 mg (as napsylate)

Trade Names:
Darvon Pulvules
- Capsules 65 mg (as hydrochloride)

642 (Canada)

Pharmacology

Relieves pain by stimulating opiate receptors in CNS; also causes respiratory depression, peripheral vasodilation, inhibition of intestinal peristalsis, sphincter of Oddi spasm, stimulation of chemoreceptor that cause vomiting and increased bladder tone.

Pharmacokinetics

Absorption

T max is 2 to 2.5 h. C max is 0.05 to 0.1 mcg/mL.

Distribution

Distributes into breast milk.

Metabolism

Propoxyphene metabolizes in the liver to norpropoxyphene metabolite.

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Elimination

Renal (less than 10% unchanged) and biliary. The t ½ is 6 to 12 h (parent drug) and 30 to 36 h (metabolite).

Onset

30 to 60 min.

Peak

120 min.

Duration

4 to 6 h.

Special Populations

Elderly

Half-life may be increased because of decreased clearance rate.

Indications and Usage

Relief of mild to moderate pain.

Contraindications

Upper airway obstruction; acute asthma; diarrhea caused by poisoning or toxins.

Dosage and Administration

Propoxyphene hydrochloride
Adults

PO 65 mg every 4 h as needed; not to exceed 390 mg/day.

Propoxyphene Napsylate
Adults

PO 100 mg every 4 h as needed; not to exceed 600 mg/day.

General Advice

  • 65 mg of hydrochloride form is equivalent to 100 mg of napsylate form in delivering same amount of propoxyphene.
  • Administer without regard to meals. Administer with food if GI upset occurs.

Storage/Stability

Store at controlled room temperature (59° to 86°F).

Drug Interactions

Carbamazepine

Increased carbamazepine serum concentrations.

Charcoal

Charcoal decreases the GI absorption of propoxyphene.

Cigarette smoking

Decreased propoxyphene effect caused by liver enzyme induction.

CNS depressants (eg, alcohol, barbiturate anesthetics, sedatives, tranquilizers)

Additive CNS depression.

Protease inhibitors

Avoid combination with propoxyphene.

Warfarin

Potentiation of hypoprothrombinemic effect.

Laboratory Test Interactions

Increased amylase and lipase for up to 24 h after administration.

Adverse Reactions

Cardiovascular

Hypotension.

CNS

Lightheadedness; dizziness; sedation; disorientation; incoordination; paradoxical excitement; hallucinations; euphoria; dysphoria; insomnia.

Dermatologic

Sweating; pruritus; urticaria.

GI

Nausea; vomiting; constipation; abdominal pain.

Genitourinary

Urinary retention or hesitancy.

Hepatic

Jaundice; abnormal LFTs.

Respiratory

Depression of cough reflex.

Miscellaneous

Tolerance; psychological and physical dependence with chronic use; weakness.

Precautions

Warnings

Not for use in patients who are suicidal or addiction prone. Do not exceed recommended dose. Propoxyphene products in excessive doses or in drug interactions with CNS depressants (including alcohol) are major causes of drug-related deaths.


Pregnancy

Category C . Category D if used for long periods.

Lactation

Excreted in breast milk.

Children

Not recommended for children.

Elderly

The rate of propoxyphene metabolism may be reduced in some patients. Consider increased dosing interval.

Renal Function

Duration of action may be prolonged; may need to reduce dose.

Hepatic Function

Duration of action may be prolonged; may need to reduce dose.

Special Risk Patients

Use with caution in patients with myxedema, acute alcoholism, acute abdominal conditions, ulcerative colitis, decreased respiratory reserve, head injury or increased intracranial pressure, hypoxia, supraventricular tachycardia, depleted blood volume or circulatory shock.

Drug dependence

Has abuse potential.

Overdosage

Symptoms

CNS depression (stupor to coma), respiratory depression, hypotension, seizures, pulmonary edema, cardiac arrhythmias, respiratory-metabolic acidosis.

Patient Information

  • Advise patient to take drug with food if GI upset occurs.
  • Explain that increasing fluid and fiber intake may help decrease constipation. Use of stool softeners and laxatives may also be suggested.
  • Advise patient not to wait until pain level is high to self-medicate because drug will not be as effective.
  • For long-term therapy, explain that dosage will be tapered gradually to prevent withdrawal symptoms.
  • Tell patient to notify health care provider if drug does not provide pain relief.
  • Instruct patient to report the following symptoms to health care provider: shortness of breath or difficulty breathing, nausea, vomiting, constipation, or other effects of drug.
  • 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 or dizziness and to use caution while driving or performing other tasks requiring mental alertness.

Copyright © 2009 Wolters Kluwer Health.

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