Talwin (Sanofi-Aventis Canada) Product Monograph

SUMMARY PRODUCT INFORMATION

INDICATIONS AND CLINICAL USE

Adults

TALWIN is indicated for the relief of chronic or acute pain of moderate to severe degree.

TALWIN is not indicated as an as-needed (prn) analgesic.

Geriatrics (> 65 years of age)

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, concomitant disease or other drug therapy.

Pediatrics (< 18 years of age)

The safety and efficacy of TALWIN has not been studied in the pediatric population. Therefore the use of TALWIN is not recommended in patients under 18 years of age.

CONTRAINDICATIONS

• Patients who are hypersensitive to the active substance pentazocine hydrochloride or other opioid analgesics or to any ingredient in the formulation. For a complete listing, see the DOSAGE FORMS, COMPOSITION AND PACKAGING section of the Prescribing Information.
• In patients with known or suspected mechanical gastrointestinal obstruction (e.g., bowel obstruction or strictures) or any diseases/conditions that affect bowel transit (e.g., ileus of any type).
• Patients with suspected surgical abdomen (e.g., acute appendicitis or pancreatitis).
• Patients with mild pain that can be managed with other pain medications.
• Patients with acute or severe bronchial asthma, chronic obstructive airway, or status asthmaticus.
• Patients with acute respiratory depression, elevated carbon dioxide levels in the blood and cor pulmonale.
• Patients with acute alcoholism, delirium tremens, and convulsive disorders.
• Patients with severe CNS depression, increased cerebrospinal or intracranial pressure, and head injury.
• Patients taking monoamine oxidase (MAO) inhibitors (or within 14 days of such therapy).
• Women who are breast-feeding or pregnant (see SERIOUS WARNINGS AND PRECAUTIONS, and WARNINGS AND PRECAUTIONS).

WARNINGS AND PRECAUTIONS

SERIOUS WARNINGS AND PRECAUTIONS

General

Patients should be instructed not to give TALWIN (pentazocine hydrochloride) tablets to anyone other than the patient for whom it was prescribed, as such inappropriate use may have severe medical consequences, including death. TALWIN should be stored securely to avoid theft or misuse.

TALWIN should only be prescribed by persons knowledgeable in the continuous administration of potent opioids, in the management of patients receiving potent opioids for the treatment of pain, and in the detection and management of respiratory depression, including the use of opioid antagonists.

Patients should be cautioned not to consume alcohol while taking TALWIN as it may increase the chance of experiencing serious adverse events, including death.

Hyperalgesia that will not respond to a further dose increase of pentazocine hydrochloride can occur at particularly high doses. A pentazocine hydrochloride dose reduction or change in opioid may be required.

Abuse and Misuse

Like all opioids, TALWIN is a potential drug of abuse and misuse, which can lead to overdose and death. Therefore, TALWIN should be prescribed and handled with caution.

Patients should be assessed for their clinical risks for opioid abuse or addiction prior to being prescribed opioids. All patients receiving opioids should be routinely monitored for signs of misuse and abuse.

Opioids, such as TALWIN, should be used with particular care in patients with a history of alcohol and illicit/prescription drug abuse. However, concerns about abuse, addiction, and diversion should not prevent the proper management of pain.

TALWIN is intended for oral use only. The tablets should be swallowed whole, and not chewed or crushed. Abuse of oral dosage forms can be expected to result in serious adverse events, including death.

Cardiovascular

Pentazocine hydrochloride administration may result in severe hypotension in patients whose ability to maintain adequate blood pressure is compromised by reduced blood volume, or concurrent administration of drugs such as phenothiazines and other tranquilizers, sedative/hypnotics, tricyclic antidepressants or general anesthetics. These patients should be monitored for signs of hypotension after initiating or titrating the dose of TALWIN.

The use of TALWIN in patients with circulatory shock should be avoided as it may cause vasodilation that can further reduce cardiac output and blood pressure.

Patients with Cardiovascular disease: TALWIN can elevate blood pressure, possibly through the release of endogenous catecholamines. Particular caution should be observed in conditions where alterations in vascular resistance and blood pressure might be particularly undesirable such as in the acute phase of myocardial infarction.

Dependence/Tolerance

As with other opioids, tolerance and physical dependence may develop upon repeated administration of TALWIN and there is a potential for development of psychological dependence.

Physical dependence and tolerance reflect the neuroadaptation of the opioid receptors to chronic exposure to an opioid, and are separate and distinct from abuse and addiction. Tolerance, as well as physical dependence, may develop upon repeated administration of opioids, and are not by themselves evidence of an addictive disorder or abuse.

In chronic usage, care should be exercised to avoid any unnecessary increase in dosage since prolonged use of high doses of TALWIN may produce dependence. Patients with a history of drug abuse should be under close supervision when receiving TALWIN.

Patients Dependent on Narcotics: Because TALWIN is a weak narcotic antagonist, patients who are addicted to narcotics may experience withdrawal symptoms and therefore it should be given with special caution to such persons. In non-addicted patients receiving narcotics for a short period, symptoms believed to be related to antagonism may be observed. Intolerance or untoward reactions are usually not observed following administration of TALWIN to patients who have received single doses of or who have had limited exposure to narcotics.

Patients on prolonged therapy should be tapered gradually from the drug if it is no longer required for pain control. Withdrawal symptoms may occur following abrupt discontinuation of therapy or upon administration of an opioid antagonist. Some of the symptoms that may be associated with abrupt withdrawal of an opioid analgesic include body aches, diarrhea, gooseflesh, loss of appetite, nausea, vomiting, nervousness or restlessness, anxiety, runny nose, sneezing, lacrimation, tremors or shivering, stomach cramps, tachycardia, trouble with sleeping, unusual increase in sweating, palpitations, unexplained fever, weakness and yawning (see ADVERSE REACTIONS, DOSAGE AND ADMINISTRATION, Adjustment or Reduction of Dosage).

However, even when these symptoms have occurred, discontinuance has been accomplished with minimal difficulty. In the rare patient in whom more than minor difficulty has been encountered, reinstitution of TALWIN with gradual withdrawal has ameliorated the patient’s symptoms.

Use in Drug and Alcohol Addiction

TALWIN is an opioid with no approved use in the management of addictive disorders. Its proper usage in individuals with drug or alcohol dependence, either active or in remission is for the management of pain requiring opioid analgesia. Patients with a history of addiction to drugs or alcohol may be at higher risk of becoming addicted to TALWIN; extreme caution and awareness is warranted to mitigate the risk.

Endocrine and Metabolism

Patients with Porphyria: Particular caution should be exercised in administering TALWIN to patients with porphyria, since it may provoke an acute attack in susceptible individuals.

Caution should also be observed when administering TALWIN in patients with adrenocortical insufficiency.

Adrenal Insufficiency: Cases of adrenal insufficiency have been reported with opioid use, more often following greater than one 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.

Gastrointestinal Effects

Pentazocine hydrochloride and other morphine-like opioids have been shown to decrease bowel motility. Pentazocine hydrochloride may obscure the diagnosis or clinical course of patients with acute abdominal conditions (see CONTRAINDICATIONS and ADVERSE REACTIONS).

Genitourinary

Obstructive Uropathy: Because urinary retention has been observed in a few patients receiving TALWIN, caution is advised in administration of the drug to patients with obstructive uropathy.

Caution should also be observed when administering TALWIN in patients with prostate hypertrophy.

Neonatal Opioid Withdrawal Syndrome (NOWS)

Prolonged maternal use of opioids during pregnancy can result in withdrawal signs in the neonate. Neonatal opioid withdrawal syndrome, unlike opioid withdrawal syndrome in adults, may be life-threatening.

Neonatal opioid withdrawal syndrome presents as irritability, hyperactivity and abnormal sleep pattern, high pitched cry, tremor, vomiting, diarrhea and failure to gain weight. The onset, duration, and severity of neonatal opioid withdrawal syndrome vary based on the specific opioid used, duration of use, timing and amount of last maternal use, and rate of elimination of the drug by the newborn.

Use of TALWIN is contraindicated in pregnant women (see CONTRAINDICATIONS).

There have been rare reports of a withdrawal syndrome in newborns after prolonged use of TALWIN by the mother during pregnancy.

Neurologic

Interactions with Central Nervous System Depressants (including alcohol): Pentazocine hydrochloride should be used with caution and in a reduced dosage during concomitant administration of other opioid analgesics, general anesthetics, phenothiazines and other tranquilizers, sedative-hypnotics, tricyclic antidepressants, antipsychotics, antihistamines, benzodiazepines, centrally-active anti-emetics and other CNS depressants. Sedation, respiratory depression, hypotension, coma or death may result.

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 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 sedation and respiratory depression.

Advise both patients and caregivers about the risks of sedation and respiratory depression when TALWIN 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 DRUG INTERACTIONS).

TALWIN should not be consumed with alcohol as it may increase the chance of experiencing dangerous side effects, including death (see CONTRAINDICATIONS and ADVERSE REACTIONS, Sedation, and DRUG INTERACTIONS).

Severe pain antagonizes the subjective and respiratory depressant actions of opioid analgesics. Should pain suddenly subside, these effects may rapidly become manifest.

Acute CNS Manifestations: There have been reported instances of the acute onset of hallucinations (usually visual), disorientation, and confusion in patients receiving therapeutic doses of TALWIN. These manifestations have cleared spontaneously within hours upon discontinuation of the drug. The mechanism responsible for this reaction is not known. Patients demonstrating this reaction should be closely observed and if therapy with TALWIN is to be restarted, administration should proceed cautiously since the acute CNS manifestations may recur.

Head Injury: The respiratory depressant effects of pentazocine hydrochloride, and the capacity to elevate cerebrospinal fluid pressure, may be greatly increased in the presence of an already elevated intracranial pressure produced by trauma. Also, pentazocine hydrochloride may produce confusion, miosis, vomiting and other side effects which obscure the clinical course of patients with head injury. In such patients, pentazocine hydrochloride must be used with extreme caution and only if it is judged essential (see CONTRAINDICATIONS).

Seizure-Prone Patients: Caution should be observed in patients who are prone to convulsions; convulsions have occurred in a few such patients in association with the use of TALWIN, although no cause and effect relationship has been established.

Serotonin Syndrome: TALWIN could cause a rare but potentially life-threatening condition resulting from concomitant administration of serotonergic drugs (e.g. anti-depressants, migraine medications). Treatment with the serotoninergic drug should be discontinued if such events (characterized by clusters of symptoms such as hyperthermia, rigidity, myoclonus, autonomic instability with possible rapid fluctuations of vital signs, mental status changes including confusion, irritability, extreme agitation progressing to delirium and coma) occur and supportive symptomatic treatment should be initiated. TALWIN should not be used in combination with MAO inhibitors or serotonin-precursors (such as L-tryptophan, oxitriptan) and should be used with caution in combination with other serotonergic drugs (triptans, certain tricyclic antidepressants, lithium, tramadol, St. John’s Wort) due to the risk of serotonergic syndrome (see DRUG INTERACTIONS).

Peri-Operative Considerations

TALWIN is not indicated for pre-emptive analgesia (administration pre-operatively for the management of post-operative pain).

In the case of planned chordotomy or other pain-relieving operations, patients should not be treated with TALWIN for at least 24 hours before the operation and TALWIN should not be used in the immediate post-operative period.

Physicians should individualize treatment, moving from parenteral to oral analgesics as appropriate. Thereafter, if TALWIN is to be continued after the patient recovers from the post-operative period, a new dosage should be administered in accordance with the changed need for pain relief. The risk of withdrawal in opioid-tolerant patients should be addressed as clinically indicated.

The administration of analgesics in the peri-operative period should be managed by healthcare providers with adequate training and experience (e.g., by an anesthesiologist).

Pentazocine hydrochloride and other morphine-like opioids have been shown to decrease bowel motility. Ileus is a common post-operative complication, especially after intra-abdominal surgery with opioid analgesia. Caution should be taken to monitor for decreased bowel motility in post-operative patients receiving opioids. Standard supportive therapy should be implemented.

TALWIN should not be used in the early post-operative period (12 to 24 hours post-surgery) unless the patient is ambulatory and gastrointestinal function is normal.

Psychomotor Impairment

TALWIN may impair the mental and/or physical abilities needed for certain potentially hazardous activities such as driving a car or operating machinery. Patients should be cautioned accordingly. Patients should also be cautioned about the combined effects of pentazocine hydrochloride with other CNS depressants, including other opioids, phenothiazine, sedative/hypnotics and alcohol.

Respiratory

Respiratory Depression: Serious, life-threatening, or fatal respiratory depression has been reported with the use of opioids, even when used as recommended. Respiratory depression from opioid use, 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. Pentazocine hydrochloride should be used with extreme caution in patients with substantially decreased respiratory reserve, bronchial asthma established respiratory depression, obstructive respiratory conditions, pre-existing respiratory depression, hypoxia or hypercapnia (see CONTRAINDICATIONS).

While serious, life-threatening, or fatal respiratory depression can occur at any time during the use of TALWIN, the risk is greatest during the initiation of therapy or following a dose increase. Patients should be closely monitored for respiratory depression when initiating therapy with TALWIN and following dose increases.

Life-threatening respiratory depression is more likely to occur in the elderly, cachectic, or debilitated patients because they may have altered pharmacokinetics or altered clearance compared to younger, healthier patients.

To reduce the risk of respiratory depression, proper dosing and titration of TALWIN are essential. Overestimating the TALWIN dose when converting patients from another opioid product can result in a fatal overdose with the first dose. In these patients, the use of non-opioid analgesics should be considered, if feasible (see WARNINGS AND PRECAUTIONS, Special Populations, Special Risk Groups, and DOSAGE AND ADMINISTRATION).

TALWIN tablets contain sodium metabisulfite, a sulfite that may cause allergic-type reactions including anaphylactic symptoms and life-threatening or less severe asthmatic episodes in certain susceptible people. 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.

Use in Patients with Chronic Pulmonary Disease: Monitor patients with significant chronic obstructive pulmonary disease or cor pulmonale, and patients having a substantially decreased respiratory reserve, hypoxia, hypercapnia, or preexisting respiratory depression for respiratory depression, particularly when initiating therapy and titrating with TALWIN, as in these patients, even usual therapeutic doses of TALWIN may decrease respiratory drive to the point of apnea. In these patients, use of alternative non-opioid analgesics should be considered, if possible. The use of TALWIN is contraindicated in Patients with acute or severe bronchial asthma, chronic obstructive airway, or status asthmaticus (see CONTRAINDICATIONS).

Sexual Function/Reproduction

Long-term use of opioids may be associated with decreased sex hormone levels and symptoms such as low libido, erectile dysfunction, or infertility (see ADVERSE REACTIONS).

Special Populations

Special Risk Groups: Pentazocine hydrochloride should be administered with caution to patients with a history of alcohol and drug abuse and in a reduced dosage to debilitated patients, and in patients with severely impaired pulmonary function, Addison’s disease, hypothyroidism, myxedema, toxic psychosis, prostatic hypertrophy or urethral stricture.

Pregnant Women: Studies in humans have not been conducted. TALWIN crosses the placental barrier and is contraindicated in pregnant women. Animal reproduction studies have revealed no evidence of harm to the fetus due to pentazocine hydrochloride, teratogenic effects were reported only at doses high enough to cause maternal toxicity.

Prolonged maternal use of opioids during pregnancy can result in withdrawal signs in the neonate. Neonatal opioid withdrawal syndrome (NOWS), unlike opioid withdrawal syndrome in adults, may be life-threatening (see WARNINGS AND PRECAUTIONS, Neonatal Opioid Withdrawal Syndrome (NOWS), ADVERSE REACTIONS).

Pregnant women using opioids should not discontinue their medication abruptly as this can cause pregnancy complication such as miscarriage or still-birth. Tapering should be slow and under medical supervision to avoid serious adverse events to the fetus.

There have been rare reports of a withdrawal syndrome in newborns after prolonged use of TALWIN by the mother during pregnancy.

The safe use of TALWIN in pregnant women (other than during labor) has not been established.

Patients receiving TALWIN during labor have experienced no adverse effects other than those that occur with commonly used narcotic analgesics. Pentazocine can cross the placental barrier and can cause central nervous system depression in the newborn and, if used regularly throughout pregnancy, may lead to symptoms of withdrawal in the newborn. TALWIN should be used with caution in women delivering premature infants.

In case of pentazocine abuse during pregnancy, there is a risk of intrauterine growth retardation.

Labour, Delivery and Nursing Women: Since opioids can cross the placental barrier and are excreted in breast milk, TALWIN is contraindicated in nursing women and during labor and delivery. Life-threatening respiratory depression can occur in the infant if opioids are administered to the mother. Naloxone, a drug that counters the effects of opioids, should be readily available if TALWIN is used in this population.

Pediatrics (< 18 years of age): The safety and efficacy of TALWIN have not been studied in the pediatric population. Therefore, use of TALWIN is not recommended in patients under 18 years of age.

Geriatrics (> 65 years of age): In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range and titrate slowly, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy (see DOSAGE AND ADMINISTRATION and ACTION AND CLINICAL PHARMACOLOGY, Special Populations and Conditions, Geriatrics).

Patients with Hepatic Impairment:

Although laboratory tests have not indicated that TALWIN causes or increases hepatic impairment, the drug should be administered with caution to patients with such impairment. Extensive liver disease appears to predispose to a higher incidence of side effects (e.g. marked apprehension, anxiety, dizziness, sleepiness) with the usual clinical dose, and may be the result of decreased metabolism of the drug by the liver (see DOSAGE AND ADMINISTRATION and ACTION AND CLINICAL PHARMACOLOGY).

Patients with Renal Impairment:

Although laboratory tests have not indicated that TALWIN causes or increases renal impairment, the drug should be administered with caution to patients with such impairment (see DOSAGE AND ADMINISTRATION).

ADVERSE REACTIONS

Adverse Drug Reaction Overview

Adverse effects of TALWIN (pentazocine hydrochloride) tablets are similar to those of other opioid analgesics, and represent an extension of pharmacological effects of the drug class. The major hazards of opioids include respiratory and central nervous system depression and to a lesser degree, circulatory depression, respiratory arrest, shock and cardiac arrest.

The most frequently observed adverse reactions of TALWIN are sedation or somnolence, vertigo, nausea, vomiting, dizziness, lightheadedness and sweating. Sedation may be more marked in the elderly.

The following adverse effects occur less frequently with opioid analgesics and include those reported in TALWIN clinical trials, whether related or not to pentazocine hydrochloride:

Cardiovascular: infrequently hypotension, tachycardia, hypertension, and circulatory depression.

Dermatologic/Allergic: allergic reactions sometimes severe have been reported including edema of the face or anaphylactic shock, flushed skin including plethora, dermatitis including pruritus.

Erythema multiforme, toxic epidermal necrolysis have been reported.

Gastrointestinal: constipation, abdominal distress, anorexia, diarrhoea, dry mouth, biliary tract spasm.

Central and Peripheral Nervous System: euphoria, lightheadedness, headache, dizziness, weakness, disturbed dreams, hallucinations, visual disturbances, insomnia, tinnitus, irritability, excitement, sweating, infrequently flushing or chills, disorientation, paresthesia, syncope, grand mal convulsions, increased intracranial pressure, confusion, tremor.

Hallucinations were noted to occur more frequently when doses exceeding that recommended were employed.

Genitourinary: urinary retention

Hematologic: depression of white blood cell count, with rare cases of agranulocytosis, which is usually reversible, moderate transient eosinophilia.

Hepatobiliary: Scattered reports of abnormal liver function of questionable significance were noted during the clinical trials.

Musculoskeletal and connective tissue: muscle tremor

Ophthalmic: miosis

Pregnancy, puerperium and perinatal conditions: alterations in rate of strength of uterine contractions during labor, alterations in maturation.

Respiratory: respiratory depression

Other: chills

Sedation: Sedation is a common side effect of opioid analgesics, especially in opioid naïve individuals. Sedation may also occur partly because patients often recuperate from prolonged fatigue after the relief of persistent pain. Most patients develop tolerance to the sedative effects of opioids within three to five days and, if the sedation is not severe, will not require any treatment except reassurance. If excessive sedation persists beyond a few days, the dose of the opioid should be reduced and alternate causes investigated. Some of these are: concurrent CNS depressant medication, hepatic or renal dysfunction, brain metastases, hypercalcemia and respiratory failure. If it is necessary to reduce the dose, it can be carefully increased again after three or four days if it is obvious that the pain is not being well controlled. Dizziness and unsteadiness may be caused by postural hypotension, particularly in elderly or debilitated patients, and may be alleviated if the patient lies down.

Nausea and Vomiting: Nausea is a common side effect on initiation of therapy with opioid analgesics and is thought to occur by activation of the chemoreceptor trigger zone, stimulation of the vestibular apparatus and through delayed gastric emptying. The prevalence of nausea declines following continued treatment with opioid analgesics. When instituting therapy with an opioid for chronic pain, the routine prescription of an antiemetic should be considered. In the cancer patient, investigation of nausea should include such causes as constipation, bowel obstruction, uremia, hypercalcemia, hepatomegaly, tumor invasion of celiac plexus and concurrent use of drugs with emetogenic properties. Persistent nausea which does not respond to dosage reduction may be caused by opioid-induced gastric stasis and may be accompanied by other symptoms including anorexia, early satiety, vomiting and abdominal fullness. These symptoms respond to chronic treatment with gastrointestinal prokinetic agents.

Constipation: Practically all patients become constipated while taking opioids, on a persistent basis. In some patients, particularly the elderly or bedridden, fecal impaction may result. It is essential to caution the patients in this regard and to institute an appropriate regimen of bowel management at the start of prolonged opioid therapy. Stimulant laxatives, stool softeners, and other appropriate measures should be used as required. As fecal impaction may present as overflow diarrhea, the presence of constipation should be excluded in patients on opioid therapy prior to initiating treatment for diarrhea.

Androgen deficiency: Chronic use of opioids may influence the hypothalamic-pituitary-gonadal axis, leading to androgen deficiency that may manifest as low libido, impotence, erectile dysfunction, amenorrhea, or infertility. The causal role of opioids in the clinical syndrome of hypogonadism is unknown because the various medical, physical, lifestyle, and psychological stressors that may influence gonadal hormone levels have not been adequately controlled for in studies conducted to date. Patients presenting with symptoms of androgen deficiency should undergo laboratory evaluation.

DRUG INTERACTIONS

Overview

Interaction with Benzodiazepines and Other Central Nervous System (CNS) Depressants: Due to additive pharmacologic effect, the concomitant use of benzodiazepines or other CNS depressants (e.g. other opioids, sedatives/hypnotics, tricyclic antidepressants, tranquilizers, general anesthetics, antipsychotics, phenothiazines, antihistamines, antiemetics, and alcohol) and beta-blockers, increases the risk of sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate. Limit dosages and durations to the minimum required. Follow patients closely for signs of sedation and respiratory depression (see WARNINGS AND PRECAUTIONS, Neurologic, Interactions with Central Nervous System Depressants (including benzodiazepines and alcohol) and Psychomotor Impairment). TALWIN should not be consumed with alcohol as it may increase the chance of experiencing dangerous side effects.

Drug-Drug Interactions

TALWIN can antagonize the effects of opiate agonists such as diamorphine, morphine, and heroin and is itself antagonized by naloxone.

Because pentazocine has narcotic antagonist activity, it may provoke withdrawal symptoms if given to narcotic addicts, and it should be given with caution to patients recently being treated with large doses of narcotics.

Concomitant use of monoamine oxidase inhibitors (MAOIs) with TALWIN may cause CNS excitation and hypertension through their respective effects on catecholamines. Caution should, therefore, be observed in administering TALWIN to patients who are currently receiving MAOIs or who have received them within the preceding 14 days.

Coadministration of pentazocine hydrochloride with a serotonergic agent, such as a Selective Serotonin Re-uptake Inhibitor or a Serotonin Norepinephrine Re-uptake Inhibitor, may increase the risk of serotonin syndrome, a potentially life-threatening condition (see WARNINGS AND PRECAUTIONS).

Drug-Lifestyle Interactions

Tobacco smoking could enhance the metabolic clearance rate of TALWIN reducing the clinical effectiveness of a standard dose of TALWIN.

The concomitant use of alcohol should be avoided (see WARNINGS AND PRECAUTIONS, General).

DOSAGE AND ADMINISTRATION

TALWIN should only be used in patients for whom alternative treatment options are ineffective or not tolerated (e.g., non-opioid analgesics).

For acute pain, it is recommended that TALWIN be used for a maximum of 7 days at the lowest dose that provides adequate pain relief.

All doses of opioids carry an inherent risk of fatal or non-fatal adverse events. This risk is increased with higher doses. For the management of chronic non-cancer, non-palliative pain, it is recommended that 243 mg (90 morphine milligram equivalent) daily of TALWIN not be exceeded. Each patient should be assessed for their risk prior to prescribing TALWIN, as the likelihood of experiencing serious adverse events can depend upon the type of opioid, duration of treatment, level of pain as well as the patient’s own level of tolerance. In addition, the level of pain should be assessed routinely to confirm the most appropriate dose and the need for further use of TALWIN (see DOSAGE AND ADMINISTRATION, Adjustment or Reduction of Dosage).

TALWIN must be swallowed whole. Cutting, breaking, crushing, chewing, or dissolving TALWIN can lead to dangerous adverse events including death (see WARNINGS AND PRECAUTIONS).

Dosing Considerations

TALWIN (pentazocine hydrochloride tablets) should be used with caution within 12 hours pre-operatively and within the first 12-24 hours post-operatively (see WARNINGS AND PRECAUTIONS, Peri-operative Considerations).

TALWIN is not indicated for rectal administration.

TALWIN should be taken after meals, with a glass of water.

Recommended Dose and Dosage Adjustment

Individual dosing requirements vary considerably based on each patient's age, weight, severity and cause of pain, and medical and analgesic history.

Adults:

Patients Not Receiving Opioids at the Time of Initiation of TALWIN Treatment:

The usual adult starting dose is 50 mg every 4 hours after meals. Dosage should be adjusted to individual requirements and tolerance within the range of 50-100 mg (1-2 tabs) every 3 to 4 hours. Total daily oral dose should not exceed 600 mg.

Patients Currently Receiving Opioids

For patients who are receiving an alternate opioid, the "oral pentazocine equivalent" of the analgesic presently being used, should be determined. Having determined the total daily dosage of the present analgesic, Table 1 can be used to calculate the approximate daily oral pentazocine dosage that should provide equivalent analgesia. It is usually appropriate to treat a patient with only one opioid at a time. Further dose reductions should be considered due to incomplete cross-tolerance between opioids.

Opioid switching / rotation:

Conversion ratios for opioids are subject to variations in kinetics governed by genetics and other factors. Therefore, when switching from one opioid to another, reduce calculated dose by 25-50% to minimize the risk of overdose. Subsequently, up-titrate the dose as required to reach appropriate maintenance dose.

*** The maximum recommended daily dose of tramadol is 300 mg - 400 mg depending on the formulation.

a. Adapted from the 2017 Canadian guideline for opioids for chronic non-cancer pain. McMaster University; 2017 b. MED: Morphine Equivalent Dose

Patients with Hepatic Impairment:

Although laboratory tests have not indicated that TALWIN causes or increases hepatic impairment, the drug should be administered with caution to patients with such impairment. (see WARNINGS AND PRECAUTIONS).

Patients with Renal Impairment:

Although laboratory tests have not indicated that TALWIN causes or increases renal impairment, the drug should be administered with caution to patients with such impairment. (see WARNINGS AND PRECAUTIONS)

Geriatrics:

Respiratory depression has occurred in the elderly following administration of large initial doses of opioids to patients who were not opioid-tolerant or when opioids were co-administered with other agents that can depress respiration. TALWIN should be initiated at a low dose and slowly titrated to effect (see WARNINGS AND PRECAUTIONS and ACTION AND CLINICAL PHARMACOLOGY).

Use with Non-Opioid Medications:

If a non-opioid analgesic is being provided, it may be continued. If the non-opioid is discontinued, consideration should be given to increasing the opioid dose to compensate for the non-opioid analgesic. When anti-inflammatory or antipyretic effects are desired in addition to analgesia, acetyl salicylic acid (A.S.A.) can be administered concomitantly with TALWIN.

Dose Titration:

Dose titration is the key to success with opioid analgesic therapy. Proper optimization of doses scaled to the relief of the individual's pain should aim at administration of the lowest dose which will achieve the overall treatment goal of satisfactory pain relief with acceptable side effects.

Dosage adjustments should be based on the patient's clinical response.

Adjustment or Reduction of Dosage:

Physical dependence with or without psychological dependence tends to occur with chronic administration of opioids, including TALWIN. Withdrawal (abstinence) symptoms may occur following abrupt discontinuation of therapy. These symptoms may include body aches, diarrhea, gooseflesh, loss of appetite, nausea, nervousness or restlessness, runny nose, sneezing, tremors or shivering, stomach cramps, tachycardia, trouble with sleeping, unusual increase in sweating, palpitations, unexplained fever, weakness and yawning.

Following successful relief of moderate to severe pain, periodic attempts to reduce the opioid dose should be made. Smaller doses or complete discontinuation may become feasible due to a change in the patient’s condition or mental state. Patients on prolonged therapy should be withdrawn gradually from the drug if it is no longer required for pain control. In patients who are appropriately treated with opioid analgesics and who undergo gradual withdrawal for the drug, these symptoms are usually mild (see WARNINGS AND PRECAUTIONS). Tapering should be individualised and carried out under medical supervision.

The patient should be informed that reducing and/or discontinuing opioids decreases their tolerance to these drugs. If treatment needs to be re-initiated, the patient must start at the lowest dose and titrate up to avoid overdose.

Opioid analgesics may only be partially effective in relieving dysesthetic pain, postherpetic neuralgia, stabbing pains, activity-related pain and some forms of headache. That is not to say that patients with advanced cancer suffering from some of these forms of pain should not be given an adequate trial of opioid analgesics, but it may be necessary to refer such patients at an early time to other forms of pain therapy.

Disposal

TALWIN should be kept in a safe place, out of the sight and reach of children before, during and after use. TALWIN should not be used in front of children, since they may copy these actions.

TALWIN should never be disposed of in household trash. Disposal via a pharmacy take back program is recommended. Unused or expired TALWIN should be properly disposed of as soon as it is no longer needed to prevent accidental exposure to others, including children or pets. If temporary storage is required before disposal, a sealed child-proof container, such as a biohazard waste container or a lockable medication box could be obtained from a pharmacy.

Missed Dose

If the patient forgets to take one or more doses, they should take their next dose at the next scheduled time and in the normal amount.

OVERDOSAGE

Symptoms: The symptoms and clinical signs of TALWIN overdosage may resemble those of morphine or other opioids. They may include somnolence, respiratory depression, hypotension, hypertension, tachycardia, hallucinations or seizures. Circulatory failure and deepening coma may occur in more severe cases, particularly in patients who have also ingested other CNS depressants such as alcohol, sedative/hypnotics or antihistamines.

Treatment: Adequate measures to maintain ventilation and general circulatory support should be employed and consideration given to gastric lavage and gastric aspiration. For respiratory depression due to overdosage or unusual sensitivity to TALWIN, parenteral naloxone is a specific and effective antagonist. Initial doses of 0.4 to 2.0 mg of naloxone are recommended, repeated at 2-3 minute intervals if needed, up to a total of 10 mg. Anticonvulsant therapy may be necessary.

ACTION AND CLINICAL PHARMACOLOGY

Mechanism of Action

TALWIN (pentazocine hydrochloride) is a member of the benzazocine series of synthetic benzomorphans. It produces both analgesic (agonist) and narcotic antagonist effects.

Opiate antagonism: Pentazocine weakly antagonizes the analgesic effects of morphine, meperidine and phenazocine. In addition, it produces incomplete reversal of cardiovascular, respiratory and behavioral depression produced by morphine and meperidine. Pentazocine has about 1/50 the antagonistic activity of nalorphine.

Pharmacodynamics

Central Nervous System:

Pentazocine hydrochloride produces respiratory depression by direct action on brain stem respiratory centres. The respiratory depression involves both a reduction in the responsiveness of the brain stem centres to increases in CO₂ tension and to electrical stimulation.

Pentazocine hydrochloride depresses the cough reflex by direct effect on the cough centre in the medulla. Antitussive effects may occur with doses lower than those usually required for analgesia.

Pentazocine hydrochloride causes miosis, even in total darkness. Pinpoint pupils are a sign of opioid overdose but are not pathognomonic (e.g., pontine lesions of hemorrhagic or ischemic origin may produce similar findings). Marked mydriasis rather than miosis may be seen with hypoxia in the setting of oxycodone overdose.

Gastrointestinal Tract and Other Smooth Muscle:

Pentazocine hydrochloride causes a reduction in motility associated with an increase in smooth muscle tone in the antrum of the stomach and duodenum. Digestion of food in the small intestine is delayed and propulsive contractions are decreased. Propulsive peristaltic waves in the colon are decreased, while tone may be increased to the point of spasm resulting in constipation. Other opioid-induced effects may include a reduction in gastric, biliary and pancreatic secretions, spasm of the sphincter of Oddi, and transient elevations in serum amylase.

Cardiovascular System:

Pentazocine hydrochloride may produce release of histamine with or without associated peripheral vasodilation. Manifestations of histamine release and/or peripheral vasodilatation may include pruritus, flushing, red eyes, hyperhidrosis, hypertension and/or orthostatic hypotension.

Endocrine System:

Opioids may influence the hypothalamic-pituitary-adrenal or -gonadal axes. Some changes that can be seen include an increase in serum prolactin, and decreases in plasma cortisol and testosterone. Clinical signs and symptoms may manifest from these hormonal changes.

Immune System:

In vitro and animal studies indicate that opioids have a variety of effects on immune functions, depending on the context in which they are used. The clinical significance of these findings is unknown.

Absorption:

TALWIN is well absorbed from the gastrointestinal tract. The onset of analgesia following oral administration of TALWIN can occur within 15 to 30 minutes and the duration of effect is usually 3 hours or longer. The onset and duration of analgesia are, in part, related to the dose and severity of pretreatment pain. Peak serum levels of TALWIN occur between 1 and 3 hours after oral administration and the elimination half-life in plasma ranges between 2 to 5 hours. There is considerable variability between individuals in terms of the rate of TALWIN metabolism which may also account for the variability in analgesic response.

Oral bioavailability is low and somewhat variable between patients.

Metabolism:

TALWIN is extensively metabolized in the liver.

Excretion:

The metabolites are excreted by the kidney with only a small amount of unchanged drug excreted in the urine. Approximately 60% of an oral dose is eliminated in the urine in 24 hours.

Special Populations and Conditions

Pediatrics: Individuals under 18 years of age should not take TALWIN.

Hepatic Impairment:

Although laboratory tests have not indicated that Talwin causes or increases renal or hepatic impairment, the drug should be administered with caution to patients with such impairment. Extensive liver disease appears to predispose to a higher incidence of side effects (e.g. marked apprehension, anxiety, dizziness, sleepiness) with the usual clinical dose, and may be the result of decreased metabolism of the drug by the liver.

Renal Impairment:

Although laboratory tests have not indicated that TALWIN causes or increases renal impairment, the drug should be administered with caution to patients with such impairment.

STORAGE AND STABILITY

Store between 15 and 30°C.

DOSAGE FORMS, COMPOSITION AND PACKAGING

Composition:

Round, flat, bevelled white tablets of 50 mg engraved with “FTL” on one side and “50” on the other side.

Medicinal ingredient: Each tablet contains pentazocine hydrochloride equivalent to 50 mg base.

TALWIN is included in the Schedule to the Narcotic Control Act.

Non-medicinal ingredients: Aerosil, avicel, cornstarch, dibasic calcium phosphate, magnesium stearate, kolliphor, sodium metabisulphite.

Packaging:

• Blisters of 100 (10 x 10) tablets.

PART II: SCIENTIFIC INFORMATION

PHARMACEUTICAL INFORMATION

Drug Substance

Proper name: pentazocine hydrochloride

Chemical name: 2R*,6R*,11R*)-1,2,3,4,5,6-Hexahydro-6,11-dimethyl-3-(3-methyl-2-butenyl)-2,6-methano-3-benzazocin-8-ol hydrochloride

Molecular formula and molecular mass:

C₁₉H₂₇NO·HCl M.W. 321.88

Structural formula:

Physicochemical Properties:

pentazocine hydrochloride is a white, crystalline substance soluble in acidic aqueous solutions.