Detailed Drug Information:

DRUG CLASS AND MECHANISM: Propoxyphene is a medication fortreating pain. It is an opioid analgesic (related to opium) chemicallysimilar to methadone. The use of opium is at least 2300 years old. In1806, the first alkaloid of opium was isolated by Serturner. He called itmorphine, after the Greek god of dreams, Morpheus. Codeine, another opioidanalgesic was identified in 1832. Propoxyphene is half to two-thirds aspotent as codeine, meaning that 90 to 120mg of propoxyphene provides asmuch pain relief as 60mg of codeine. This is comparable to the pain reliefachieved by 600mg of aspirin. Opioid analgesics, including propoxyphene,reduce pain by blocking the receptors in the brain that are involved inthe perception (sensing) of pain.

Acetaminophen is a non-narcotic analgesic (pain reliever) andantipyretic (fever reducer). Acetaminophen relieves pain by elevating thethreshold for pain. It reduces fever through its action on theheat-regulating center of the brain. The combination of propoxyphene andacetaminophen achieves greater pain relief than either drug taken alone.For more information please see acetaminophen.

PRESCRIPTION: yes

PREPARATIONS: Capsules: 65 mg propoxyphene and 325 mgacetaminophen; 32 mg propoxyphene and 325 mg acetaminophen; Darvocet A500 capsules: 100 mg propoxyphene and 500 mg acetaminophen.

STORAGE: Capsules should be stored at room temperature, between15° (59°F) and 30°C (86°F).

PRESCRIBED FOR: Propoxyphene and acetaminophen is used for thetreatment of mild to moderate pain.

DOSING: Propoxyphene and acetaminophen usually are given every 4hours as needed for the relief of pain.

DRUG INTERACTIONS: Opioids such as propoxyphene can reduce theactivity of intestinal muscles. When combined with medications thatpossess anticholinergic activity, this effect on intestinal muscles may beaccentuated leading to constipation. Such drugs include dicyclomine (Bentyl), some antihistamines [carbinoxamine (Rondec), clemastine(Tavist), diphenhydramine (Benadryl), promethazine (Phenergan)], somephenothiazines [e.g. thioridazine (Mellaril), triflupromazine(Stelazine)], some tricyclic antidepressants [e.g. amitriptyline (Elavil),amoxapine (Asendin), clomipramine (Anafranil), protriptyline (Vivactil)],clozapine (Clozaril), cyclobenzaprine (Flexeril), and disopyramide(Norpace).

Propoxyphene adds to the sedating effects of alcohol and other drugsthat can cause sedation such as the benzodiazepine class of anti-anxietydrugs (e.g., Valium, Ativan, Klonopin, Xanax), the tricyclic class ofantidepressants (e.g., Elavil, Tofranil, Norpramin), dicyclomine (Bentyl),certain antihistamines (Benadryl, Vistaril, Atarax, Tavist), and certainantihypertensive medications (e.g., Catapres, Inderal).

For drug interactions of acetaminophen, please see acetaminophen.

PREGNANCY: There is very little information about the effects onthe fetus of propoxyphene given to pregnant women. Physicians may use itif they consider its benefits to outweigh potential (and unknown) risks.

NURSING MOTHERS: Low concentrations of propoxyphene have been measured in the breast milk of mothers taking propoxyphene. It is notknown whether these small amounts can cause side effects in nursinginfants.

SIDE EFFECTS: The most frequent adverse reactions ofpropoxyphene include lightheadedness, dizziness, sedation, nausea, andvomiting. Other side effects include drowsiness, constipation, and spasmof the ureter, which can lead to difficulty in urinating.

Propoxyphene can depress breathing and, therefore, is used with cautionin elderly, debilitated patients and in patients with serious lungdisease. Propoxyphene can impair thinking and the physical abilitiesrequired for driving or operating machinery. Propoxyphene may be habitforming. Mental and physical dependence can occur but are unlikely when itis used short-term.

For more information on acetaminophen, please see acetaminophen.