WARNINGS
Drug Dependence
Special care should be exercised in prescribing pentazocine for emotionally unstable patients and for those with a history of drug misuse. Such patients should be closely supervised when greater than 4 or 5 days of therapy is contemplated. There have been instances of psychological and physical dependence on TALWIN in patients with such a history and, rarely, in patients without such a history. Extended use of parenteral TALWIN may lead to physical or psychological dependence in some patients. When TALWIN is abruptly discontinued, withdrawal symptoms such as abdominal cramps, elevated temperature, rhinorrhea, restlessness, anxiety, and lacrimation may occur. However, even when these have occurred, discontinuance has been accomplished with minimal difficulty. In the rare patient in whom more than minor difficulty has been encountered, reinstitution of parenteral TALWIN with gradual withdrawal has ameliorated the patient's symptoms. Substituting methadone or other narcotics for TALWIN in the treatment of the pentazocine abstinence syndrome should be avoided. There have been rare reports of possible abstinence syndromes in newborns after prolonged use of TALWIN during pregnancy.
In prescribing parenteral TALWIN for chronic use, particularly if the drug is to be self-administered, the physician should take precautions to avoid increases in dose and frequency of injection by the patient.
Just as with all medication, the oral form of TALWIN is preferable for chronic administration.
Tissue Damage at Injection Sites
Severe sclerosis of the skin, subcutaneous tissues, and underlying muscle have occurred at the injection sites of patients who have received multiple doses of pentazocine lactate. Constant rotation of injection sites is, therefore, essential. In addition, animal studies have demonstrated that TALWIN is tolerated less well subcutaneously than intramuscularly. (See DOSAGE AND ADMINISTRATION.)
Head Injury and Increased Intracranial Pressure
As in the case of other potent analgesics, the potential of TALWIN injection 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 preexisting increase in intracranial pressure. Furthermore, TALWIN can produce effects which may obscure the clinical course of patients with head injuries. In such patients, TALWIN 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.
Due to the potential for increased CNS depressant effects, alcohol should be used with caution in patients who are currently receiving pentazocine.
Ambulatory Patients
Since sedation, dizziness, and occasional euphoria have been noted, ambulatory patients should be warned not to operate machinery, drive cars, or unnecessarily expose themselves to hazards.
Myocardial Infarction
Caution should be exercised in the intravenous use of pentazocine for patients with acute myocardial infarction accompanied by hypertension or left ventricular failure. Data suggest that intravenous administration of pentazocine increases systemic and pulmonary arterial pressure and systemic vascular resistance in patients with acute myocardial infarction.
NOTE: Acetone sodium bisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people, is contained in multiple-dose vials. The overall prevalence of sulfite sensitivity in the general population is unknown and probably low. Sulfite sensitivity is seen more frequently in asthmatic than in nonasthmatic people. The ampuls in the Uni-Amp™ Pak do not contain acetone sodium bisulfite.