Pentazocine HCl and Acetaminophen (pentazocine hydrochloride 25 mg acetaminophen 650 mg) Dailymed

Pentazocine and acetaminophen tablets are a Schedule IV controlled substance. Abuse and addiction are separate and distinct from physical dependence and tolerance. Abuse is characterized by misuse of a drug for non-medical purposes, often in combination with other psychoactive substances. Addiction is a disease of repeated drug abuse. Addiction is a primary, chronic, neurobiologic disease, with genetic, psychosocial, and environmental factors influencing its development and manifestations. Addiction is characterized by behaviors that include one or more of the following: impaired control over drug use, compulsive use, continued use despite harm, and craving. Drug addiction is a treatable disease, utilizing a multidisciplinary approach, but relapse is common. Physical dependence is a state of adaptation that is manifested by a specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the drug, and/or administration of an antagonist. Tolerance is a state of adaptation in which exposure to a drug induces changes that result in a diminution of one or more of the drug’s effects over time. Tolerance may occur to both the desired and undesired effects of drugs, and may develop at different rates for different effects. Physicians should be aware that addiction may not be accompanied by concurrent tolerance and symptoms of physical dependence in all addicts.  In addition, abuse of opioids can occur in the absence of addiction and is characterized by misuse of the drug for non-medical purposes, and often in combination with other psychoactive substances. There have been some reports of dependence and of withdrawal symptoms with pentazocine and acetaminophen tablets. Patients with a history of drug dependence should be under close supervision while receiving pentazocine orally. There have been rare reports of possible abstinence syndromes in newborns after prolonged use of pentazocine during pregnancy. There have been reports of development of addiction and physical dependence in patients receiving parenteral pentazocine. People with a history of drug abuse or alcohol abuse may have a higher chance of becoming addicted to opioid medicines. Abrupt dose cessation or rapid dose reduction following the extended use of parenteral pentazocine has resulted in withdrawal symptoms such as abdominal cramps, nausea, vomiting, elevated temperature, chills, rhinorrhea, restlessness, anxiety, or lacrimation.  In general opioid therapy should not be abruptly discontinued. When the patient no longer requires treatment with pentazocine and acetaminophen, the drug should be tapered gradually to prevent signs and symptoms of withdrawal in patients who have been receiving opioids for an extended period of time and might have become physically dependent. In prescribing pentazocine and acetaminophen tablets for chronic use, the physician should take under consideration that proper assessment of the patient, proper prescribing practices, periodic re-evaluation of therapy, and proper dispensing and storage are appropriate measures that help to identify and decrease misuse and abuse of opioid drugs. Severe, even lethal, consequences may result from misuse of tablets by injection either alone or in combination with other substances, such as pulmonary emboli, vascular occlusion, ulceration and abscesses, and withdrawal symptoms in narcotic dependent individuals.

Patients receiving pentazocine and acetaminophen tablets should be given the following instructions by the physician: Do not take pentazocine and acetaminophen tablets if you are allergic to any of its ingredients. If you develop signs/symptoms of allergy such as a rash, hives, itching, vomiting, swelling of the face or mouth, or difficulty breathing, stop taking pentazocine and acetaminophen tablets and contact your healthcare provider immediately. Do not take more than 4000 milligrams of acetaminophen (alone or in combination with other products containing acetaminophen). Seek medical attention immediately upon ingestion of more than 4000 milligrams of acetaminophen per day, even if you feel well. Look for acetaminophen or APAP on package labels. Do not use more than one product that contains acetaminophen. Contact your healthcare provider if you took more than the recommended dose. Patients should be advised that pentazocine and acetaminophen is a narcotic pain reliever, and should be taken only as directed. The dose of pentazocine and acetaminophen should not be adjusted without consulting with a physician or other healthcare professional. Patients should be advised that pentazocine and acetaminophen tablets may cause drowsiness, dizziness, or lightheadedness and may impair mental and/or physical ability required for the performance of potentially hazardous tasks (e.g., driving, operating machinery). Patients started on pentazocine and acetaminophen tablets or patients whose dose has been adjusted should refrain from any potentially dangerous activity until it is established that they are not adversely affected. pentazocine and acetaminophen will add to the effect of alcohol and other CNS depressants (such as antihistamines, sedatives, hypnotics, tranquilizers, general anesthetics, phenothiazines, other opioids, and monoamine oxidase [MAO]inhibitors). Patients should not combine pentazocine and acetaminophen tablets with alcohol or other central nervous system depressants (sleep aids, tranquilizers) except by the orders of the prescribing physician, because dangerous additive effects may occur, resulting in serious injury or death. Women of childbearing potential who become or are planning to become pregnant should consult a physician prior to initiating or continuing therapy with pentazocine and acetaminophen. Safe use in pregnancy has not been established. Prolonged use of opioid analgesics during pregnancy may cause neonatal physical dependence, and neonatal withdrawal may occur. If patients have been receiving treatment with pentazocine and acetaminophen tablets for more than a few weeks and cessation of therapy is indicated, they should be counseled on the importance of safely tapering the dose and that abruptly discontinuing the medication could precipitate withdrawal symptoms. The physician should provide a dose schedule to accomplish a gradual discontinuation of the medication. Patients should be advised that pentazocine and acetaminophen is a potential drug of abuse. They should protect it from theft. It should never be given to anyone other than the individual for whom it was prescribed. Patients should be instructed to keep pentazocine and acetaminophen tablets in a secure place out of the reach of children. When pentazocine and acetaminophen tablets are no longer needed, please consult your pharmacist for proper disposal instructions. As with other opioids, patients taking pentazocine and acetaminophen tablets should be advised of the potential for severe constipation; appropriate laxatives and/or stool softeners as well as other appropriate treatments should be initiated from the onset of opioid therapy. Patients should be advised of the most common adverse events that may occur while taking pentazocine and acetaminophen tablets: constipation, nausea, somnolence, lightheadedness, dizziness, sedation, vomiting, and sweating.

Carcinogenesis, mutagenesis, and impairment of fertility studies have not been done with this combination product. Studies to evaluate the mutagenic potential of the components of pentazocine and acetaminophen tablets have not been conducted. Pentazocine, when administered orally or parenterally, had no adverse effect on either the reproductive capabilities or the course of pregnancy in rabbits and rats.  Embryotoxic effects on the fetuses were not shown. The daily administration of 4 mg/kg to 20 mg/kg pentazocine subcutaneously to female rats during a 14 day pre-mating period and until the 13th day of pregnancy did not have any adverse effects on the fertility rate.



There are no adequate and well-controlled studies in pregnant women.  Pentazocine and acetaminophen tablets should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

There are no adequate and well-controlled studies in pregnant women.  Pentazocine and acetaminophen tablets should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Animal studies with the combination of pentazocine and acetaminophen have not been completed. In a published report, a single dose of pentazocine administered to pregnant hamsters on gestation day 8 increased the incidence of exencephaly and cranioschisis at a dose of 196 mg/kg, SC (0.2-times the maximum daily human dose of pentazocine via 6 tablets on a mg/m2 basis).

There has been no experience in this regard with the combination pentazocine and acetaminophen.  However, there have been rare reports of possible abstinence syndromes in newborns after prolonged use of pentazocine during pregnancy. Frequent use of acetaminophen (defined as most days or daily use) in late pregnancy may be associated with an increased risk of persistent wheezing in the infant which may persist into childhood.

Patients receiving pentazocine during labor have experienced no adverse effects other than those that occur with commonly used analgesics.  However, pentazocine can cross the placental barrier and cause central nervous system depression in the newborn and, if used regularly throughout pregnancy, may lead to symptoms of withdrawal in the newborn. Pentazocine and acetaminophen tablets should be used with caution in women delivering premature infants.  The effect of pentazocine and acetaminophen tablets on the mother and fetus, the duration of labor or delivery, the possibility that forceps delivery or other intervention or resuscitation of the newborn may be necessary, or the effect of pentazocine and acetaminophen tablets on the later growth, development, and functional maturation of the child are unknown at the present time.