Head Injury and Increased Intracranial Pressure. As in the case of other potent analgesics, the potential of pentazocine for elevating cerebrospinal fluid pressure may be attributed to CO2 retention due to the respiratory depressant effects of the drug. These effects may be markedly exaggerated in the presence of head injury, other intracranial lesions, or a pre-existing increase in intracranial pressure. Furthermore, pentazocine can produce effects which may obscure the clinical course of patients with head injuries. In such patients, pentazocine hydrochloride and acetaminophen tablets must be used with extreme caution and only if its use is deemed essential.
Acute CNS Manifestations. Patients receiving therapeutic doses of pentazocine have experienced hallucinations (usually visual), disorientation, and confusion which have cleared spontaneously within a period of hours. The mechanism of this reaction is not known. Such patients should be closely observed and vital signs checked. If the drug is reinstituted, it should be done with caution since these acute CNS manifestations may recur.
There have been instances of psychological and physical dependence on parenteral pentazocine in patients with a history of drug abuse, and rarely, in patients without such a history. (SeeDRUG ABUSE AND DEPENDENCE.)
Due to the potential for increased CNS depressant effects, alcohol should be used with caution in patients who are currently receiving pentazocine.
Pentazocine may precipitate opioid abstinence symptoms in patients receiving courses of opiates for pain relief.
There is currently no manufacturer warning information available for this drug.
Pentazocine hydrochloride and acetaminophen tablets are indicated for the relief of mild to moderate pain.
Pentazocine hydrochloride and acetaminophen tablets are a combination of pentazocine hydrochloride USP, equivalent to 25 mg base and acetaminophen USP, 650 mg.
Pentazocine is a member of the benzazocine series (also known as the benzomorphan series). Chemically, pentazocine hydrochloride is (2R*,6R*,11R* )-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(3-methyl-2-butenyl)-2,6-methano-3-benzazocin-8-ol hydrochloride, a white, crystalline substance soluble in acidic aqueous solutions. It has the following structural formula:
C19H27NO•HCl Molecular Weight: 321.88
Chemically, acetaminophen is 4’-hydroxyacetanilide-. It has the following structural formula:
C8H9NO2 Molecular Weight: 151.16
Pentazocine is an analgesic and acetaminophen is an analgesic and antipyretic.
Each tablet for oral administration contains 25 mg of pentazocine as the hydrochloride and 650 mg of acetaminophen. In addition, each tablet contains the following inactive ingredients: colloidal silicon dioxide, crospovidone, D&C Yellow No. 10 Aluminum Lake, FD&C Blue No. 1 Aluminum Lake, microcrystalline cellulose, povidone, pregelatinized starch, sodium starch glycolate, and stearic acid.
