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U.S. Department of Health and Human Services


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Talacen (pentazocine hydrochloride and acetaminophen) tablets

Detailed View: Safety Labeling Changes Approved By FDA Center for Drug Evaluation and Research (CDER) – March 2011


Summary View



Drug Dependence
  • Pentazocine can cause a physical and psychological dependence.
Usage with Alcohol
  • Due to the potential for increased CNS depressant effects, alcohol should be used with caution in patients who are currently receiving pentazocine.
Patients Receiving Narcotics
  • Pentazocine is a mild narcotic antagonist. Some patients previously given narcotics, including methadone for the daily treatment of narcotic dependence, have experienced withdrawal symptoms after receiving pentazocine.
Certain Respiratory Conditions
  • Although respiratory depression has rarely been reported after oral administration of pentazocine, the drug should be administered with caution to patients with respiratory depression from any cause, severely limited respiratory reserve, severe bronchial asthma, and other obstructive respiratory conditions, or cyanosis.


CNS Effect
  • Caution should be used when Talacen is administered to patients prone to seizures; seizures have occurred in a few such patients in association with the use of pentazocine although no cause and effect relationship has been established.
  • Particular caution should be exercised in administering pentazocine to patients with porphyria since it may provoke an acute attack in susceptible individuals
Cardiovascular Disease
  • Pentazocine can elevate blood pressure, possibly through the release of endogenous catecholamines. Particular caution should be exercised in conditions where alterations in vascular resistance and blood pressure might be particularly undesirable, such as in the acute phase of myocardial infarction.
  • Caution should also be observed when administering pentazocine in patients with hypothyroidism, adrenocortical insufficiency, prostate hypertrophy, inflammatory or obstructive bowel disease, acute abdominal syndromes of unknown etiology, cholecystitis, pancreatitis, or acute alcohol intoxication and delirium tremens
Drug Interactions
  • Concomitant use of monoamine oxidase inhibitors (MAOIs) with pentazocine may cause CNS excitation and hypertension through their respective effects on catecholamines. Caution should therefore be observed in administering pentazocine to patients who are currently receiving MAOIs or who have received them within the preceding 14 days.
  • Agents with CNS depressant properties including phenothiazine, tricyclic antidepressants, and ethyl alcohol can enhance the central nervous system depressant effects of pentazocine (See WARNINGS).
  • Tobacco smoking could enhance the metabolic clearance rate of pentazocine reducing the clinical effectiveness of a standard dose of pentazocine.
  • Pentazocine can antagonize the effects of opiate agonists such as diamorphine, morphine, and heroin and is itself antagonized by naloxone
Pregnancy Category C
  • In animal reproduction studies (rodents) with pentazocine, teratogenic effects were reported only at doses high enough to cause maternal toxicity
Nonteratogenic Effects
  • 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.
Labor and Delivery
  • 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.


  • hypertension, hypotension, circulatory depression, tachycardia.
  • rarely respiratory depression
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 very closely observed and vital signs checked. If the drug is reinstituted, it should be done with caution since these acute CNS manifestations may recur.
Other CNS effects:
  • grand mal convulsions, increase in intracranial pressure
  • nausea, vomiting, constipation; diarrhea, anorexia, dry mouth, Biliary tract spasm, and rarely abdominal distress.
  • edema of the face, anaphylactic shock, dermatitis including pruritus, flushed skin including plethora, infrequently rash; and rarely urticaria.
  • visual blurring and focusing difficulty, miosis.
  • alterations in rate or strength of uterine contractions during labor.