Balacet 325 (propoxyphene napsylate 100 mg and acetaminophen 325 mg)

NOVEMBER 01, 2005

Balacet 325 (propoxyphene napsylate 100 mg and acetaminophen 325 mg) has received FDA approval for mild-to-moderate pain management in patients 18 years and older. Balacet 325 is manufactured and marketed by Cornerstone Bio- Pharma.1


Propoxyphene and acetaminophen are familiar drugs to the medical community, and their use—both together and alone—has been tested and marketed by various manufacturers for years. A mild, centrally acting narcotic analgesic, the structure of propoxyphene is similar to that of methadone. It displays approximately two thirds the potency of codeine. Propoxyphene is available in 2 forms: propoxyphene hydrochloride and propoxyphene napsylate. The bioavailability of 65 mg of propoxyphene hydrochloride is approximately equivalent to 100 mg of propoxyphene napsylate. A myriad of propoxyphene preparations are currently available in the United States; it is marketed both alone and in combination with acetaminophen.

Unintentional Acetaminophen Overdose

Balacet 325 is promoted to reduce acetaminophen overuse. According to the United States Pharmacopeia, maximum daily intake of acetaminophen for short-term (< 10 days) pain control should be <4000 mg; maximum daily intake for long-term (> 10 days) should be <2600 mg. At its maximum dose, Balacet 325 contributes 1950 mg of acetaminophen daily. Cornerstone BioPharma, the manufacturer of Balacet 325, claims that less than one third of patients are aware of the potential for acetaminophen-related liver damage. Given acetaminophen's wide availability in both OTC and prescription products, unintentional overdose by patients using acetaminophen for mild-to-moderate pain control is a realistic concern. Cornerstone BioPharma hopes to offer a safer means to decrease pain with Balacet 325.1 Balacet 325 can be given as 1 tablet up to every 4 hours as needed, with a maximum daily dose of 6 tablets.2


Balacet 325 is contraindicated in patients with a history of hypersensitivity to propoxyphene or acetaminophen. Its use is also discouraged in patients with addictive or suicidal tendencies and in patients currently using antidepressants, tranquilizers, or excessive amounts of alcohol. Patients and providers should be aware that overuse of Balacet 325 may lead to dependence and/or tolerance. Balacet 325 should be avoided in patients with renal or hepatic impairment and in women who are pregnant. Geriatric patients may require a longer dosing interval. The use of Balacet 325 is not approved for use in pediatric patients. Caution should be used in patients concomitantly receiving other medications such as antidepressants, anticonvulsants, or anticoagulants, as propoxyphene is likely to affect the metabolism of these drugs and alter their levels. Balacet 325 is a Schedule IV medication; appropriate measures should be taken in the dispensing of this medication.2

In clinical trials, the most common adverse reactions to Balacet 325 included dizziness, sedation, nausea, and vomiting. Other less commonly reported adverse reactions included constipation, abdominal pain, skin rashes, lightheadedness, headache, weakness, euphoria, dysphoria, hallucinations, and visual disturbances.2

Dr. Holmberg is a pharmacist with Phoenix Children's Hospital, Phoenix, Ariz.

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