**Off Market Drug**
This medication is no longer available in the United States. Information provided here is for reference purposes only.
- 642 Tab
- Darvon N
- Darvocet A500
- Darvocet-N 50
- Darvocet-N 100
opioid agonists nonopioid analgesic combinations
Mild to moderate pain.
- Binds to opiate receptors in the CNS.
- Alters the perception of and response to painful stimuli, while producing generalized CNS depression.
Decrease in mild to moderate pain.
Absorption: Well absorbed following oral administration. Napsylate salt is more slowly absorbed.
Distribution: Widely distributed. Probably crosses the placenta. Enters breast milk in small amounts.
Metabolism and Excretion: Mostly metabolized by the liver. Some conversion to norpropoxyphene, a toxic metabolite. This metabolite accumulates in elderly patients and patients with decreased renal function.
Half-life: 6–12 hr.
TIME/ACTION PROFILE (analgesic effect)
|PO||15–60 min||2–3 hr||4–6 hr|
- History of suicidal ideation
- OB: Lactation: Pedi: Safety not established.
Use Cautiously in:
- Head trauma
- ↑ intracranial pressure
- Severe renal, hepatic, or pulmonary disease
- Adrenal insufficiency
- Geri: Appears on Beers list. Elderly or debilitated patients require reduced doses
- Undiagnosed abdominal pain
- Prostatic hyperplasia.
Adverse Reactions/Side Effects
CNS: dizziness, weakness, dysphoria, euphoria, headache, insomnia, paradoxical excitement, sedation
EENT: blurred vision
GI: nausea, abdominal pain, constipation, vomiting
Misc: physical dependence, psychological dependence, tolerance
* CAPITALS indicate life-threatening.
Underline indicate most frequent.
- Use with extreme caution in patients receiving MAO inhibitors (may result in unpredictable, severe, and potentially fatal reactions–decrease initial dose to 25% of usual dose).
- Use with extreme caution with alcohol, antidepressants, sedative/hypnotics, or muscle relaxants (may result in severe CNS depression and possibly death).
- CYP3A4 inhibitors, including ritonavir, ketoconazole, itraconazole, clarithromycin, nelfinavir, nefazodone, amiodarone, aprepitant, diltiazem, erythromycin, fluconazole, fosamprenavir, or verapamil may ↑ propoxyphene levels.
- CYP3A4 inducers, including rifampin, carbamazepine, or phenytoin may ↑ levels of norpropoxyphene.
- Smoking ↑ metabolism and may ↓ analgesic effectiveness.
- Administration of partial-antagonist opioid analgesics may precipitate withdrawal in physically dependent patients.
- Nalbuphine or buprenorphine may ↓ analgesia.
- Concomitant use of kava-kava, valerian, or chamomile can ↑ CNS depression.
- St. John's wort may ↓ levels of norpropoxyphene.
Grapefruit juice may ↑ propoxyphene levels.
Consider cumulative effects of additional acetaminophen (should not exceed 4 g acetaminophen/day); if toxic levels are exceeded, change to pure propoxyphene product
PO (Adults): 65 mg q 4 hr (hydrochloride–Darvon) or 100 mg q 4 hr (napsylate–Darvon-N) as needed (not to exceed 390 mg/day as hydrochloride or 600 mg/day as napsylate). 100 mg propoxyphene napsylate = 65 mg propoxyphene hydrochloride.
Availability (generic available)
Capsules: 65 mg
Tablets: 65 mg
Capsules: 100 mg
Tablets: 100 mg
Tablets: propoxyphene 65 mg/acetaminophen 650 mg
Tablets: propoxyphene 50 mg/acetaminophen 325 mg, propoxyphene 100 mg/acetaminophen 650 mg, propoxyphene 100 mg/acetaminophen 500 mg
- Assess type, location, and intensity of pain prior to and 2 hr (peak) following administration. When titrating opioid doses, increases of 25–50% should be administered until there is either a 50% reduction in the patient's pain rating on a numeric or visual analogue scale or the patient reports satisfactory pain relief. A repeat dose can be safely administered at the time of the peak if previous dose is ineffective and side effects are minimal.
- Use an equianalgesic chart (see equianalgesic dosing guidelines) when changing routes or when changing from one opioid to another.
- Prolonged, high-dose therapy may lead to physical and psychological dependence and tolerance. This should not prevent patient from receiving adequate analgesia. Most patients who receive propoxyphene for pain do not develop psychological dependence. Progressively higher doses or change to a stronger opioid may be required to relieve pain with long-term therapy.
- Assess BP, pulse, and respirations before and periodically during administration. If respiratory rate is <10/min, assess level of sedation. Physical stimulation may be sufficient to prevent significant hypoventilation. Dose may need to be decreased by 25–50%. Initial drowsiness will diminish with continued use.
- Assess bowel function routinely. Prevention of constipation should be instituted with increased intake of fluids and bulk, and laxatives to minimize constipating effects. Stimulant laxatives should be administered routinely if opioid use exceeds 2–3 days, unless contraindicated.
- Geri: Geriatric patients may be more sensitive to CNS effects; monitor closely and assess falls risk.
Lab Test Considerations:
May cause ↑ serum amylase and lipase levels.
- May cause ↑ AST, ALT, serum alkaline phosphatase, LDH, and bilirubin concentrations.
If an opioid antagonist is required to reverse respiratory depression or coma, naloxone (Narcan) is the antidote. Dilute the 0.4-mg ampule of naloxone in 10 mL of 0.9% NaCl and administer 0.5 mL (0.02 mg) by IV push every 2 min. For patients weighing <40 kg, dilute 0.1 mg of naloxone in 10 mL of 0.9% NaCl for a concentration of 10 mcg/mL and administer 0.5 mcg/kg every 2 min. Titrate dose to avoid withdrawal, seizures, and severe pain.
Explain therapeutic value of medication prior to administration, to enhance the analgesic effect.
- Regularly administered doses may be more effective than prn administration. Analgesic is more effective if given before pain becomes severe.
- Coadministration with nonopioid analgesics may have additive analgesic effects and may permit lower opioid doses.
- Medication should be discontinued gradually after long-term use to prevent withdrawal symptoms.
- PO Doses may be administered with food or milk to minimize GI irritation.
- Advise patient to take medication as directed and not to take more than the recommended amount. Severe and permanent liver damage may result from prolonged use or high doses of acetaminophen. Renal damage may occur with prolonged use of acetaminophen or aspirin. Doses of nonopioid agents should not exceed the maximum recommended daily dose. Instruct patient to read Medication Guide before taking and with each Rx refill; new information may be available.
- Instruct patient on how and when to ask for pain medication.
- Caution patient to avoid drinking grapefruit juice during propoxyphene therapy.
- May cause drowsiness or dizziness. Caution patient to avoid driving and other activities requiring alertness until response to the drug is known.
- Geri: Advise geriatric patients of increased risk for CNS effects and potential for falls.
- Advise patient to change positions slowly to minimize orthostatic hypotension.
- Caution patient to avoid concurrent use of alcohol or other CNS depressants with this medication and to notify health care professional before taking other Rx, OTC, or herbal products.
- Encourage patient to turn, cough, and breathe deeply every 2 hr to prevent atelectasis.
- Advise patient that good oral hygiene, frequent mouth rinses, and sugarless gum or candy may decrease dry mouth.
Decrease in severity of pain without a significant alteration in level of consciousness.
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