"The the European Medicines Agency's (EMA's) Pharmacovigilance Risk Assessment Committee (PRAC) will review the risks and benefits of modified- and prolonged-release paracetamol (acetaminophen) tablets, the agency said today.
Pentazocine can cause a physical and psychological dependence. (See Drug Abuse and Dependence.)
Use In Head Injury and Increased Intracranial Pressure
In the presence of head injury, intracranial lesions or a preexisting increase in intracranial pressure, the possible respiratory depressant effects of pentazocine and its potential to elevate cerebrospinal fluid pressure (resulting from vasodilation following CO2 retention) may be markedly increased. Furthermore, pentazocine can produce effects on pupillary response and consciousness, which may obscure neurologic signs of further increases in intracranial pressure in patients with head injuries. In such patients, pentazocine must be used with extreme caution and only if its use is deemed essential.
Interactions with Alcohol and Drugs of Abuse
Pentazocine may be expected to have additive effects when used in conjunction with alcohol, other opioids, or illicit drugs that cause central nervous system depression because respiratory depression, hypotension, profound sedation, coma or death may result.
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.
Respiratory depression occurs more frequently in elderly or debilitated patients and in those suffering from conditions accompanied by hypoxia, hypercapnia, or upper airway obstruction, in whom even moderate therapeutic doses may significantly decrease pulmonary ventilation. Use TALWIN NX (pentazocine and naloxone) with extreme caution in patients with chronic obstructive pulmonary disease or cor pulmonale and in patients having a substantially decreased respiratory reserve (e.g., severe kyphoscoliosis), hypoxia, hypercapnia, or pre-existing respiratory depression. Alternative non-opioid analgesics should be considered, and TALWIN NX (pentazocine and naloxone) should be employed only under careful medical supervision at the lowest effective dose in such patients.
Acute CNS Manifestations
Patients receiving therapeutic doses of TALWIN NX (pentazocine and naloxone) 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.
Drug Abuse And Dependence
TALWIN NX (pentazocine and naloxone) is 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 TALWIN NX (pentazocine and naloxone) . Patients with a history of drug dependence should be under close supervision while receiving TALWIN NX (pentazocine and naloxone) . There have been rare reports of possible abstinence syndromes in newborns after prolonged use of TALWIN NX (pentazocine and naloxone) 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 TALWIN NX (pentazocine and naloxone) , 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 TALWIN NX (pentazocine and naloxone) 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.
The amount of naloxone present in TALWIN NX (pentazocine and naloxone) (0.5 mg per tablet) has no action when taken orally and will not interfere with the pharmacologic action of pentazocine. However, this amount of naloxone given by injection has profound antagonistic action to narcotic analgesics.
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.
Caution should be used when TALWIN NX (pentazocine and naloxone) is administered to patients prone to seizures; seizures have occurred in a few such patients in association with the use of pentazocine though 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.
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.
TALWIN NX (pentazocine and naloxone) should be used with caution in patients with myocardial infarction who have nausea or vomiting.
Impaired Renal or Hepatic Function
Decreased metabolism of pentazocine by the liver in extensive liver disease may predispose to accentuation of side effects. Although laboratory tests have not indicated that pentazocine causes or increases renal or hepatic impairment, the drug should be administered with caution to patients with such impairment.
Caution should also be observed when administering TALWIN NX (pentazocine and naloxone) 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.
Narcotic drug products are generally considered to elevate biliary tract pressure for varying periods following their administration. Some evidence suggests that pentazocine may differ from other marketed narcotics in this respect (i.e., it causes little or no elevation in biliary tract pressures). The clinical significance of these findings, however, is not yet known.
Carcinogenesis, Mutagenesis, Impairment of Fertility
No long-term studies in animals to test for carcinogenesis have been performed with the components of TALWIN NX (pentazocine and naloxone) .
Studies to evaluate the mutagenic potential of the components of TALWIN NX (pentazocine and naloxone) 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.
Pregnancy Category C
There are no adequate and well-controlled studies in pregnant women. TALWIN NX (pentazocine and naloxone) should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
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 (0.4-times the maximum daily human dose of pentazocine via 12 tablets on a mg/m2 basis).
Animal reproduction studies testing the combination of pentazocine and naloxone during organogenesis have been completed in rats and rabbits. In rats, a pentazocine:naloxone dose of 64 mg/kg:0.64 mg/kg via oral gavage increased the incidences of resorptions and extra ribs (0.2-times the maximum daily human dose of pentazocine via 12 tablets on a mg/m2 basis). There were no clear treatment related effects in rabbits treated with a pentazocine:naloxone dose of up to 64 mg/kg:0.64 mg/kg via oral gavage (0.3-times the maximum daily human dose of pentazocine via 12 tablets on a mg/m2 basis).
There has been no experience in this regard with TALWIN NX (pentazocine and naloxone) . However, there have been rare reports of possible abstinence syndromes in newborns after prolonged use of pentazocine during pregnancy.
Labor and Delivery
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. TALWIN NX (pentazocine and naloxone) should be used with caution in women delivering premature infants. The effect of TALWIN NX (pentazocine and naloxone) 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 TALWIN NX (pentazocine and naloxone) on the later growth, development, and functional maturation of the child are unknown at the present time.
Pentazocine is excreted in human milk. Caution should be exercised when TALWIN NX (pentazocine and naloxone) is administered to a nursing woman.
Safety and effectiveness in pediatric patients below the age of 12 years have not been established.
Controlled clinical studies of TALWIN NX (pentazocine and naloxone) did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses or effectiveness in analgesic activity between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 4/13/2011
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