The minimum effective analgesic concentration will vary widely among patients, especially among patients who have been previously treated with potent agonist opioids. The minimum effective analgesic concentration of pentazocine for any individual patient may increase over time due to an increase in pain, the development of a new pain syndrome, and/or the development of analgesic tolerance [see Dosage and Administration ].
There is a relationship between increasing pentazocine plasma concentration and increasing frequency of dose-related opioid adverse reactions such as nausea, vomiting, CNS effects, and respiratory depression. In opioid-tolerant patients, the situation may be altered by the development of tolerance to opioid-related adverse reactions see Dosage and Administration ].
Pentazocine weakly antagonizes the analgesic effects of morphine, meperidine, and phenazocine; in addition, it produces incomplete reversal of cardiovascular, respiratory, and behavioral depression induced by morphine and meperidine. Pentazocine has about 1/50 the antagonistic activity of nalorphine. It also has sedative activity.
Naloxone when administered orally at 0.5 mg has no pharmacologic activity. Naloxone hydrochloride administered parenterally at the same dose is an antagonist to pentazocine and a pure antagonist to narcotic analgesics.
Pentazocine and Naloxone Tablets are a potent analgesic when administered orally. However, the presence of naloxone in Pentazocine and Naloxone Tablets is intended to prevent the effect of pentazocine if the product is misused by injection.
Studies in animals indicate that the presence of naloxone does not affect pentazocine analgesia when the combination is given orally. If the combination is given by injection the action of pentazocine is neutralized.
Onset of significant analgesia usually occurs between 15 and 30 minutes after oral administration, and duration of action is usually three hours or longer.
Pentazocine is well absorbed from the gastrointestinal tract. Concentrations in plasma coincide closely with the onset, duration, and intensity of analgesia. The time to mean peak concentration in 24 normal volunteers was 1.7 hours (range 0.5 to 4 hours) after oral administration and the mean plasma elimination half-life was 3.6 hours (range 1.5 to 10 hours).
Pentazocine is metabolized in the liver and excreted primarily in the urine. The products of the oxidation of the terminal methyl groups and glucuronide conjugates are excreted by the kidney. Elimination of approximately 60% of the total dose occurs within 24 hours. Pentazocine passes into the fetal circulation.
Pentazocine and Naloxone Hydrochloride Tablets are indicated for the management of pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate.
Limitations of Use
Because of the risks of addiction, abuse, and misuse, with opioids, even at recommended doses, reserve Pentazocine and Naloxone Tablets for use in patients for whom alternative treatment options [e.g., non-opioid analgesics]
- Have not been tolerated, or are not expected to be tolerated,
- Have not provided adequate analgesia, or are not expected to provide adequate analgesia
Pentazocine and Naloxone Hydrochloride Tablets, are contraindicated in patients with:
- Significant respiratory depression [see WARNINGS ]
- Acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment [see WARNINGS ]. Patients with known or suspected gastrointestinal obstruction, including paralytic ileus [see WARNINGS]
- Patients with hypersensitivity to either pentazocine, naloxone, or any of the formulation excipients (e.g., anaphylaxis) [see WARNINGS ].
Pentazocine and Naloxone Tablets contain pentazocine, a Schedule IV controlled substance. As an opioid, Pentazocine and Naloxone Tablets expose users to the risks of addiction, abuse, and misuse [see DRUG ABUSE AND DEPENDENCE ].
Although the risk of addiction in any individual is unknown, it can occur in patients appropriately prescribed Pentazocine and Naloxone Tablets. Addiction can occur at recommended dosages and if the drug is misused or abused.
Assess each patient’s risk for opioid addiction, abuse, or misuse prior to prescribing Pentazocine and Naloxone Tablets, and monitor all patients receiving Pentazocine and Naloxone Tablets for the development of these behaviors and conditions. Risks are increased in patients with a personal or family history of substance abuse (including drug or alcohol abuse or addiction) or mental illness (e.g., major depression). The potential for these risks should not, however, prevent the proper management of pain in any given patient. Patients at increased risk may be prescribed opioids such as Pentazocine and Naloxone Tablets, but use in such patients necessitates intensive counseling about the risks and proper use of Pentazocine and Naloxone Tablets along with intensive monitoring for signs of addiction, abuse, and misuse.
Opioids are sought by drug abusers and people with addiction disorders and are subject to criminal diversion. Consider these risks when prescribing or dispensing Pentazocine and Naloxone Tablets. Strategies to reduce these risks include prescribing the drug in the smallest appropriate quantity and advising the patient on the proper disposal of unused drug [see PRECAUTIONS; Information for Patients ]. Contact local state professional licensing board or state controlled substances authority for information on how to prevent and detect abuse or diversion of this product.
Opioid Analgesic Risk Evaluation and Mitigation Strategy (REMS)
To ensure that the benefits of opioid analgesics outweigh the risks of addiction, abuse, and misuse, the Food and Drug Administration (FDA) has required a Risk Evaluation and Mitigation Strategy (REMS) for these products. Under the requirements of the REMS, drug companies with approved opioid analgesic products must make REMS-compliant education programs available to healthcare providers. Healthcare providers are strongly encouraged to do all of the following:
- Complete a REMS-compliant education program offered by an accredited provider of continuing education (CE) or another education program that includes all the elements of the FDA Education Blueprint for Health Care Providers Involved in the Management or Support of Patients with Pain.
- Discuss the safe use, serious risks, and proper storage and disposal of opioid analgesics with patients and/or their caregivers every time these medicines are prescribed. The Patient Counseling Guide (PCG) can be obtained at this link: www.fda.gov/OpioidAnalgesicREMSPCG.
- Emphasize to patients and their caregivers the importance of reading the Medication Guide that they will receive from their pharmacist every time an opioid analgesic is dispensed to them.
- Consider using other tools to improve patient, household, and community safety, such as patient-prescriber agreements that reinforce patient-prescriber responsibilities.
To obtain further information on the opioid analgesic REMS and for a list of accredited REMS CME/CE, call 800-503-0784, or log on to www.opioidanalgesicrems.com. The FDA Blueprint can be found at www.fda.gov/OpioidAnalgesicREMSBlueprint.
Life-Threatening Respiratory Depression
Serious, life-threatening, or fatal respiratory depression has been reported with the use of opioids, even when used as recommended. Respiratory depression, if not immediately recognized and treated, may lead to respiratory arrest and death. Management of respiratory depression may include close observation, supportive measures, and use of opioid antagonists, depending on the patient’s clinical status [see OVERDOSAGE ]. Carbon dioxide (CO2 ) retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
While serious, life-threatening, or fatal respiratory depression can occur at any time during the use of Pentazocine and Naloxone Tablets, the risk is greatest during the initiation of therapy or following a dosage increase. Monitor patients closely for respiratory depression, especially within the first 24 to 72 hours of initiating therapy with and following dosage increases of Pentazocine and Naloxone Tablets.
To reduce the risk of respiratory depression, proper dosing and titration of Pentazocine and Naloxone Tablets are essential [see DOSAGE AND ADMINISTRATION ]. Overestimating the Pentazocine and Naloxone Tablets dosage when converting patients from another opioid product can result in a fatal overdose with the first dose.
Accidental ingestion of even one dose of Pentazocine and Naloxone Tablets, especially by children, can result in respiratory depression and death due to an overdose of pentazocine.
Neonatal Opioid Withdrawal Syndrome
Prolonged use of Pentazocine and Naloxone Tablets during pregnancy can result in withdrawal in the neonate. Neonatal opioid withdrawal syndrome, unlike opioid withdrawal syndrome in adults, may be life-threatening if not recognized and treated, and requires management according to protocols developed by neonatology experts. Observe newborns for signs of neonatal opioid withdrawal syndrome and manage accordingly. Advise pregnant women using opioids for a prolonged period of the risk of neonatal opioid withdrawal syndrome and ensure that appropriate treatment will be available [see PRECAUTIONS; Information for Patients, Pregnancy ].
Risks from Concomitant Use with Benzodiazepines or Other CNS Depressants
Profound sedation, respiratory depression, coma, and death may result from the concomitant use of Pentazocine and Naloxone Tablets with benzodiazepines or other CNS depressants (e.g., non-benzodiazepine sedatives/hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, other opioids, alcohol). Because of these risks, reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate.
Observational studies have demonstrated that concomitant use of opioid analgesics and benzodiazepines increases the risk of drug-related mortality compared to use of opioid analgesics alone. Because of similar pharmacological properties, it is reasonable to expect similar risk with the concomitant use of other CNS depressant drugs with opioid analgesics [see PRECAUTIONS, Drug Interactions].
If the decision is made to prescribe a benzodiazepine or other CNS depressant concomitantly with an opioid analgesic, prescribe the lowest effective dosages and minimum durations of concomitant use. In patients already receiving an opioid analgesic, prescribe a lower initial dose of the benzodiazepine or other CNS depressant than indicated in the absence of an opioid, and titrate based on clinical response. If an opioid analgesic is initiated in a patient already taking a benzodiazepine or other CNS depressant, prescribe a lower initial dose of the opioid analgesic, and titrate based on clinical response. Follow patients closely for signs and symptoms of respiratory depression and sedation.
Advise both patients and caregivers about the risks of respiratory depression and sedation when Pentazocine and Naloxone Tablets is used with benzodiazepines or other CNS depressants (including alcohol and illicit drugs). Advise patients not to drive or operate heavy machinery until the effects of concomitant use of the benzodiazepine or other CNS depressant have been determined. Screen patients for risk of substance use disorders, including opioid abuse and misuse, and warn them of the risk for overdose and death associated with the use of additional CNS depressants including alcohol and illicit drugs [see PRECAUTIONS; Information for Patients, Drug Interactions ].
Life-Threatening Respiratory Depression in Patients with Chronic Pulmonary Disease or in Elderly, Cachectic, or Debilitated Patients
The use of Pentazocine and Naloxone Tablets in patients with acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment is contraindicated.
Patients with Chronic Pulmonary Disease: Pentazocine and naloxone-treated patients with significant chronic obstructive pulmonary disease or cor pulmonale, and those with a substantially decreased respiratory reserve, hypoxia, hypercapnia, or pre-existing respiratory depression are at increased risk of decreased respiratory drive including apnea, even at recommended dosages of Pentazocine and Naloxone Tablets [see WARNINGS ].
Elderly, Cachectic, or Debilitated Patients: Life-threatening respiratory depression is more likely to occur in elderly, cachectic, or debilitated patients because they may have altered pharmacokinetics or altered clearance compared to younger, healthier patients [see WARNINGS ].
Monitor such patients closely, particularly when initiating and titrating Pentazocine and Naloxone Tablets and when Pentazocine and Naloxone Tablets are given concomitantly with other drugs that depress respiration [see WARNINGS ]. Alternatively, consider the use of non-opioid analgesics in these patients.
Cases of adrenal insufficiency have been reported with opioid use, more often following greater than 1 month of use. Presentation of adrenal insufficiency may include non-specific symptoms and signs including nausea, vomiting, anorexia, fatigue, weakness, dizziness, and low blood pressure. If adrenal insufficiency is suspected, confirm the diagnosis with diagnostic testing as soon as possible. If adrenal insufficiency is diagnosed, treat with physiologic replacement doses of corticosteroids. Wean the patient off of the opioid to allow adrenal function to recover and continue corticosteroid treatment until adrenal function recovers. Other opioids may be tried as some cases reported use of a different opioid without recurrence of adrenal insufficiency. The information available does not identify any particular opioids as being more likely to be associated with adrenal insufficiency.
Pentazocine and Naloxone Tablets may cause severe hypotension including orthostatic hypotension and syncope in ambulatory patients. There is increased risk in patients whose ability to maintain blood pressure has already been compromised by a reduced blood volume or concurrent administration of certain CNS depressant drugs (e.g., phenothiazines or general anesthetics) [see PRECAUTIONS; Information for Patients ]. Monitor these patients for signs of hypotension after initiating or titrating the dosage of Pentazocine and Naloxone Tablets. In patients with circulatory shock, Pentazocine and Naloxone Tablets may cause vasodilation that can further reduce cardiac output and blood pressure. Avoid the use of Pentazocine and Naloxone Tablets in patients with circulatory shock.
Risks of Use in Patients with Increased Intracranial Pressure, Brain Tumors, Head Injury, or Impaired Consciousness
In patients who may be susceptible to the intracranial effects of CO2 retention (e.g., those with evidence of increased intracranial pressure or brain tumors), Pentazocine and Naloxone Tablets may reduce respiratory drive, and the resultant CO2 retention can further increase intracranial pressure. Monitor such patients for signs of sedation and respiratory depression, particularly when initiating therapy with Pentazocine and Naloxone Tablets.
Opioids may also obscure the clinical course in a patient with a head injury. Avoid the use of Pentazocine and Naloxone Tablets in patients with impaired consciousness or coma.
Risks of Use in Patients with Gastrointestinal Conditions
Pentazocine and Naloxone Tablets are contraindicated in patients with known or suspected gastrointestinal obstruction, including paralytic ileus.
The administration of Pentazocine and Naloxone Tablets or other opioids may obscure the diagnosis or clinical course in patients with acute abdominal conditions.
Pentazocine and Naloxone Tablets may cause spasm of the sphincter of Oddi. Opioids may cause increases in serum amylase. Monitor patients with biliary tract disease, including acute pancreatitis, for worsening symptoms.
The use of Pentazocine and Naloxone Tablets, a mixed agonist/antagonist opioid analgesic, in patients who are receiving a full opioid agonist analgesic may reduce the analgesic effect and/or precipitate withdrawal symptoms. Avoid concomitant use of Pentazocine and Naloxone Tablets with a full opioid agonist analgesic.
When discontinuing Pentazocine and Naloxone Tablets, gradually taper the dosage (see DOSAGE AND ADMINISTRATION). Do not abruptly discontinue Pentazocine and Naloxone Tablets (see DRUG ABUSE AND DEPENDENCE)
Risks of Driving and Operating Machinery
Pentazocine and Naloxone Tablets may impair the mental or physical abilities needed to perform potentially hazardous activities such as driving a car or operating machinery. Warn patients not to drive or operate dangerous machinery unless they are tolerant to the effects of Pentazocine and Naloxone Tablets and know how they will react to the medication.
Acute CNS Manifestations
Patients receiving therapeutic doses of Pentazocine and Naloxone Tablets 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.
The amount of naloxone present in Pentazocine and Naloxone Tablets (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.
Increased Risk of Seizures in Patients with Seizure Disorders
The pentazocine in Pentazocine and Naloxone Tablets may increase the frequency of seizures in patients with seizure disorders, and may increase the risk of seizures occurring in other clinical settings associated with seizures. Monitor patients with a history of seizure disorders for worsened seizure control during Pentazocine and Naloxone Tablets therapy.
Risks of Driving and Operating Machinery
Pentazocine and Naloxone Tablets may impair the mental or physical abilities needed to perform potentially hazardous activities such as driving a car or operating machinery. Warn patients not to drive or operate dangerous machinery unless they are tolerant to the effects of Pentazocine and Naloxone Tablets and know how they will react to the medication [see Patient Counseling Information].
Chronic use of opioids may cause reduced fertility in females and males of reproductive potential. It is not known whether these effects on fertility are reversible [see ADVERSE REACTIONS].
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