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(Generic versions may still be available.)
DARVOCET-N® 50 and DARVOCET-N® 100
(propoxyphene napsylate and acetaminophen) Tablets, USP
- There have been numerous cases of accidental and intentional overdose with propoxyphene products either alone or in combination with other CNS depressants, including alcohol. Fatalities within the first hour of overdosage are not uncommon. Many of the propoxyphene related deaths have occurred in patients with previous histories of emotional disturbances or suicidal ideation/attempts and/or concomitant administration of sedatives, tranquilizers, muscle relaxants, antidepressants, or other CNS-depressant drugs. Do not prescribe propoxyphene for patients who are suicidal or have a history of suicidal ideation.
- The metabolism of propoxyphene may be altered by strong CYP3A4 inhibitors (such as ritonavir, ketoconazole, itraconazole, troleandomycin, clarithromycin, nelfinavir, nefazadone, amiodarone, amprenavir, aprepitant, diltiazem, erythromycin, fluconazole, fosamprenavir, grapefruit juice, and verapamil) leading to enhanced propoxyphene plasma levels. Patients receiving propoxyphene and any CYP3A4 inhibitor should be carefully monitored for an extended period of time and dosage adjustments should be made if warranted (see CLINICAL PHARMACOLOGY - Drug Interactions, and WARNINGS, PRECAUTIONS and DOSAGE AND ADMINISTRATION for further information).
Darvocet-N contains propoxyphene napsylate and acetaminophen.
Propoxyphene Napsylate, USP is an odorless, white crystalline powder with a bitter taste. It is very slightly soluble in water and soluble in methanol, ethanol, chloroform, and acetone. Chemically, it is (αS,1R)-α-[2-(Dimethylamino)-1-methylethyl]-α phenylphenethyl propionate compound with 2-naphthalenesulfonic acid (1:1) monohydrate, which can be represented by the accompanying structural formula. Its molecular weight is 565.72.
Propoxyphene napsylate differs from propoxyphene hydrochloride in that it allows more stable liquid dosage forms and tablet formulations. Because of differences in molecular weight, a dose of 100 mg (176.8 µmol) of propoxyphene napsylate is required to supply an amount of propoxyphene equivalent to that present in 65 mg (172.9 µmol) of propoxyphene hydrochloride.
Acetaminophen, 4'-hydroxyacetanilide, is a non-opiate, non-salicylate analgesic and antipyretic which occurs as a white, odorless, crystalline powder, possessing a slightly bitter taste. The molecular formula for acetaminophen is C8H9NO2 and the molecular weight is 151.17. It may be represented by the following structural formula:
Each tablet of Darvocet-N (propoxyphene napsylate and acetaminophen) 50 contains 50 mg (88.4 µmol) propoxyphene napsylate and 325 mg (2,150 µmol) acetaminophen.
Each tablet of Darvocet-N (propoxyphene napsylate and acetaminophen) 100 contains 100 mg (176.8 µmol) propoxyphene napsylate and 650 mg (4,300 µmol) acetaminophen.
Each tablet also contains amberlite, cellulose, F D & C Yellow No. 6, magnesium stearate, stearic acid, titanium dioxide, and other inactive ingredients.
What are the possible side effects of acetaminophen and propoxyphene (Balacet, Darvocet A500, Darvocet-N 100, Darvocet-N 50, Propacet 100)?
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have a serious side effect such as:
- shallow breathing, slow heartbeat, feeling like you might pass out;
- chest pain, feeling short of breath;
- confusion, unusual thoughts or behavior;
- seizure (convulsions); or
- nausea, stomach pain, loss of appetite, itching, dark urine,...
What are the precautions when taking propoxyphene napsylate and acetaminophen (Darvocet-N)?
Last reviewed on RxList: 12/20/2010
This monograph has been modified to include the generic and brand name in many instances.
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