Generic Name: propoxyphene

Brand Names: Darvon-N, Darvon, PP-Cap

Uses

Pending revision, the material in this section should be considered in light of more recently available information in the MEDWATCH notification at the beginning of this monograph.

Pain

Relief of mild to moderate pain. Therapy in combination with acetaminophen or aspirin or with aspirin and caffeine may result in greater analgesia; however, some studies have shown no difference in analgesia.

Dosage and Administration

Administration

Oral Administration

Administer orally.

Dosage

Pending revision, the material in this section should be considered in light of more recently available information in the MEDWATCH notification at the beginning of this monograph.

Available as propoxyphene hydrochloride and propoxyphene napsylate; dosage expressed in terms of the salt.

Propoxyphene napsylate 100 mg is equivalent to propoxyphene hydrochloride 65 mg.

Adults

Pain

Oral

Propoxyphene hydrochloride: Usual dosage is 65 mg every 4 hours as needed. Doses <65 mg have questionable efficacy.

Propoxyphene napsylate: Usual dosage is 100 mg every 4 hours as needed.

Prescribing Limits

Adults

Pain

Oral

Propoxyphene hydrochloride: Maximum 390 mg daily.

Propoxyphene napsylate: Maximum 600 mg daily.

Special Populations

Hepatic Impairment

Consider dosage reduction.

Renal Impairment

Consider dosage reduction.

Geriatric Patients

Consider increase in dosing interval.

Cautions

Contraindications

• Known hypersensitivity to propoxyphene or any ingredient in the formulation.
• Suicidal or addiction prone.

Warnings/Precautions

Warnings

Pending revision, the material in this section should be considered in light of more recently available information in the MEDWATCH notification at the beginning of this monograph.

Opiate Withdrawal

Caution in patients dependent on opiates. Will not support morphine dependence; sudden substitution of usual propoxyphene dosage for opiates may result in acute opiate withdrawal symptoms. Avoid withdrawal symptoms by gradually reducing dosage of prior opiate as propoxyphene is substituted.

Abuse Potential

Possible tolerance, psychologic dependence, and physical dependence. Dependence liability is qualitatively similar to that of codeine, but quantitatively less.

CNS Depression

Performance of activities requiring mental alertness and physical coordination may be impaired.

Concurrent use of other CNS depressants may potentiate CNS depression. (See Specific Drugs under Interactions.)

Acute Toxicity

Pending revision, the material in this section should be considered in light of more recently available information in the MEDWATCH notification at the beginning of this monograph.

Propoxyphene preparations alone or in combination with other CNS depressants (e.g., alcohol) are a major cause of drug-related deaths; usually related to intentional overdose, but may be accidental. (See Contraindications under Cautions.)

General Precautions

Fixed-Combination Products

When used in fixed combination with other drugs, consider the cautions, precautions, and contraindications associated with the other drug(s).

Specific Populations

Pregnancy

Category C (category D, if used for prolonged periods).

Manufacturer states that safe use during pregnancy has not been established. Cases of withdrawal symptoms in neonates reported following use during pregnancy. Use during pregnancy only when potential benefits outweigh possible risks to fetus.

Lactation

Distributed into milk in low concentrations. Use with caution; however, in postpartum studies involving nursing women who received propoxyphene, no adverse effects observed in breast-fed infants.

Pediatric Use

Safety and efficacy not established.

Geriatric Use

Potential for reduced rate of propoxyphene metabolism. (See Geriatric Patients under Dosage and Administration.)

Hepatic Impairment

Use with caution; serum concentrations of the drug may be increased or elimination may be delayed. (See Hepatic Impairment under Dosage and Administration.)

Renal Impairment

Use with caution; serum concentrations of the drug may be increased or elimination may be delayed. (See Renal Impairment under Dosage and Administration.)

Common Adverse Effects

Dizziness, sedation, nausea, vomiting.

Interactions

Specific Drugs

Pharmacokinetics

Absorption

Bioavailability

Absorbed principally in the upper small intestine following oral administration. Peak plasma concentrations usually achieved within 2–2.5 hours (propoxyphene hydrochloride) or 3 hours (propoxyphene napsylate).

In large doses, the napsylate salt appears to be absorbed more gradually than the hydrochloride salt.

Onset

Analgesic effect occurs within 0.25–1 hour.

Duration

Analgesic effect persists for 4–6 hours.

Plasma Concentrations

Equimolar doses of propoxyphene hydrochloride or napsylate provide similar plasma concentrations.

Distribution

Extent

Distributed into CSF. Assumed to cross the placenta; however, placental fluid and fetal blood concentrations have not been determined. Distributed into milk in low concentrations.

Elimination

Metabolism

Metabolized mainly in the liver.

Approximately 25% of a dose is metabolized to norpropoxyphene (which has less CNS depressant activity than propoxyphene but greater local anesthetic effect).

Elimination Route

Propoxyphene and norpropoxyphene are excreted unchanged in urine.

Half-life

Propoxyphene: 6–12 hours.

Norpropoxyphene: 30–36 hours.

Stability

Storage

Oral

Capsules and Tablets

Tight, light resistant container at 15–30 °C.

Actions

• Mild analgesic effects at usual dosages.

• No antipyretic action and little or no antitussive activity. Norpropoxyphene has a local anesthetic effect.

Advice to Patients

Pending revision, the material in this section should be considered in light of more recently available information in the MEDWATCH notification at the beginning of this monograph.

• Potential for drug to impair mental alertness or physical coordination; use caution when driving or operating machinery until effects on individual are known.
• Importance of taking exactly as prescribed; do not exceed recommended dosage.
• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, and alcohol consumption. Importance of limiting alcohol intake.
• Importance of women informing their clinicians if they are or plan to become pregnant or plan to breast-feed.
• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Subject to control under the Federal Controlled Substances Act of 1970 as schedule IV (C-IV) drugs.

Comparative Pricing

This pricing information is subject to change at the sole discretion of DS Pharmacy. This pricing information was updated 09/2009. For the most current and up-to-date pricing information, please visit www.drugstore.com. Actual costs to patients will vary depending on the use of specific retail or mail-order locations and health insurance copays.

AHFS Drug Information. © Copyright, 1959-2009, Selected Revisions August 2009. American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland 20814.

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.