Risk of Overdose
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.
Respiratory Depression
Respiratory depression is the chief hazard from all opioid agonist preparations. Respiratory depression occurs most frequently in elderly or debilitated patients, usually following large initial doses in non-tolerant patients, or when opioids are given in conjunction with other agents that depress respiration. Propoxyphene napsylate and acetaminophen tablets should be used with extreme caution in patients with significant chronic obstructive pulmonary disease or cor pulmonale, and in patients having substantially decreased respiratory reserve, hypoxia, hypercapnia, or preexisting respiratory depression. In such patients, even usual therapeutic doses of propoxyphene napsylate and acetaminophen tablets may decrease respiratory drive to the point of apnea. In these patients alternative non-opioid analgesics should be considered, and opioids should be employed only under careful medical supervision at the lowest effective dose.
Hypotensive Effect
Propoxyphene napsylate and acetaminophen tablets, like all opioid analgesics, may cause severe hypotension in an individual whose ability to maintain blood pressure has been compromised by a depleted blood volume, or after concurrent administration with drugs such as phenothiazines or other agents which compromise vasomotor tone. Propoxyphene napsylate and acetaminophen tablets may produce orthostatic hypotension in ambulatory patients. Propoxyphene napsylate and acetaminophen tablets, like all opioid analgesics, should be administered with caution to patients in circulatory shock, since vasodilatation produced by the drug may further reduce cardiac output and blood pressure.
Head Injury and Increased Intracranial Pressure
The respiratory depressant effects of narcotics and their capacity to elevate cerebrospinal fluid pressure may be markedly exaggerated in the presence of head injury, other intracranial lesions or a preexisting increase in intracranial pressure. Furthermore, narcotics produce adverse reactions which may obscure the clinical course of patients with head injuries.
Drug Interactions
The concomitant use of propoxyphene and CNS depressants, including alcohol, can result in potentially serious adverse events including death. Because of its added depressant effects, propoxyphene should be prescribed with caution for those patients whose medical condition requires the concomitant administration of sedatives, tranquilizers, muscle relaxants, antidepressants, or other CNS-depressant drugs.
Usage in Ambulatory Patients
Propoxyphene may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks, such as driving a car or operating machinery. The patient should be cautioned accordingly.
Use With Other Acetaminophen-Containing Agents
Due to the potential for acetaminophen hepatotoxicity at doses higher than the recommended dose, propoxyphene napsylate and acetaminophen tablets should not be used concomitantly with other acetaminophen-containing products.
Use With Alcohol
Hepatotoxicity and severe hepatic failure occurred in chronic alcoholics following therapeutic doses of acetaminophen. Patients should be cautioned about the concomitant use of propoxyphene products and alcohol because of potentially serious CNS-additive effects of these agents that can lead to death.
There is currently no manufacturer warning information available for this drug.
Propoxyphene napsylate and acetaminophen tablets are indicated for the relief of mild to moderate pain.
Propoxyphene napsylate and acetaminophen tablets USP contain propoxyphene napsylate and acetaminophen.
Propoxyphene napsylate is an odorless, white crystalline powder with a bitter taste. It is very slightly soluble in water, soluble in methanol, in ethanol, in chloroform, and in acetone. Chemically it is (αS,1R)-α-[2-(dimethylamino)-1-methylethyl]-α-phenylphenethyl propionate compound with 2-naphthalenesulfonic acid (1:1) monohydrate and can be represented by the following structural formula:
C22H29NO2•C10H8O3S•H2O M.W. 565.74
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. Chemically, it is acetamide, N-(4-hydroxyphenyl)- and can structurally be represented by the following:
C8H9NO2 M.W. 151.16
Each pink or white tablet of propoxyphene napsylate and acetaminophen tablets contains 100 mg propoxyphene napsylate and 650 mg acetaminophen.
Propoxyphene napsylate and acetaminophen tablets, USP 100 mg/650 mg (PINK) contain the following inactive ingredients: colloidal silicon dioxide, D&C red No. 27 aluminum lake, D&C yellow No. 10 aluminum lake, hydroxypropyl cellulose, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, povidone, pregelatinized starch, stearic acid, titanium dioxide, and crospovidone.
Propoxyphene napsylate and acetaminophen tablets, USP 100 mg/650 mg (WHITE) contain the following inactive ingredients: castor oil, colloidal silicon dioxide, hypromellose, magnesium stearate, microcrystalline cellulose, povidone, pregelatinized starch, stearic acid, and crospovidone.
