Pentazocine (Talwin) is an opioid pain medicine that is used to treat patients with moderate to severe pain.

Indications of Pentazocine:

• Injection:

  • Anesthesia:

    • It is used as a complement to surgical anaesthetic for sedation prior to surgery.

  • Pain management:

    • It works well to manage severe pain that cannot be treated with other methods and necessitates the use of an opioid analgesic.

• Oral [Canadian product]:

  • Pain management:

    • It is prescribed for moderate to severe chronic or acute pain.

  • Limitations of use:

    • Pentazocine should only be used on patients for whom existing treatment choices (such as nonopioid analgesics and opioid combination medications) are ineffective, poorly tolerated, or would otherwise fall short of providing acceptable pain control.

Pentazocine (Talwin) dose in adults:

Note: Injections of pentazocine have been banned in the US for more than a year.

Pentazocine (Talwin) Injection:

• Dose in the Anesthesia for pain management:

  • IM, SubQ:
    • 30 mg every three to four hours with a maximum dose of 60 mg
    • 360 mg  per day is maximum dose 
  • IV:
    • 30 mg every 3 to 4 hours, with a dosage cap of 30 mg.
    • 360 mg per day is maximum dose

• Dose in the Labor pain:

  • IM:
    • 30 mg one time
  • IV:
    • 20 mg as needed every two to three hours
    • 60 mg is maximum dose

Pentazocin Oral:

Dose in the management of Pain:

• Not receiving opioids at the time of initiation:

  • 50 mg every four hours at first; increasing the dose in accordance with response and tolerability to 50 to 100 mg every three to four hours.
  • The daily maximum is 600 mg.

• Receiving opioids at the time of initiation:

  • For a thorough dosage conversion, consult the information provided by the manufacturer.

• Discontinuation of therapy:

  • When stopping a long-term opioid medication regimen, the dose is decreased gradually.
  • There isn't yet a tapering schedule that is ideal for all patients.
  • The suggested timetables range from gradual (10% reductions weekly, for example) to abrupt (25–50% reductions every few days).
    Individualized tapering schedules should be used to reduce opioid withdrawal while taking into account the aims and issues unique to the patient as well as the pharmacokinetics of the opioid being reduced.
  • Slow tapering is required in patients receiving opioids for years, whereas more rapid tapers may be appropriate in patients experiencing severe adverse effects.
  • Signs/symptoms of withdrawal should be carefully monitored.
  • Slow tapering should be done in patients displaying withdrawal symptoms, alterations may include increasing the interval between dose reductions, decreasing amount of daily dose reduction, pausing the taper and restarting when the patient is ready, and/or coadministration of an alpha-2 agonist (eg, clonidine) to blunt withdrawal symptoms.
  • Nonopioid analgesics should be given for pain management during the taper; consider nonopioid adjunctive treatments for withdrawal symptoms (eg, GI complaints, muscle spasm) as required.

Pentazocine (Talwin) dose in children:

Talwin dose in the treatment of perioperative Analgesia: 

• Children 5 to 9 years:

  • Initial: 0.5 mg/kg intravenous given with an anaesthetic; if the process takes longer than expected, tiny incremental doses may be repeated as needed every 30 to 45 minutes.
  • 1.5 mg/kg maximum total dosage per operation.
  • Based on a study of 50 paediatric surgical patients (n=50), the recommended dosage.

Pentazocine dose in the treatment of postoperative Analgesia:

• Children 5 to 8 years:

  • 15 mg one IM dose

• Children ≥9 years and Adolescents <15 years:

  • 30 mg one IM dose

Pentazocine dose in the treatment of preoperative Sedation:

• Children and Adolescents ≤16 years:

  • 0.8 to 1.9 mg/kg/dose may offer a gentler induction, according to clinical research; 0.5 mg/kg intramuscular as a single dosage.
  • Note: The typical dose for adults is 30 mg.

Pentazocine pregnancy Risk Category: C

• Studies on animal reproduction showed that there were adverse events.
• Pentazocine can be used to relieve pain during labor. However, opioids can temporarily alter the heart rate of the foetus.
• [US Boxed Warning]
  • Neonatal withdrawal syndrome may happen if long-term opiate use is sustained while pregnant. This may pose a life-threatening situation. It's crucial to keep a watchful eye on the newborn.
  • The prescribing physician should only prescribe the lowest possible dosage of opioids if necessary.
  • Neonatal withdrawal syndrome is characterized by fever, temperature instability and vomiting, diarrhea, vomiting or poor nutrition/weight gain, high pitched crying, increased muscle tone, irritability and seizure.
  • Long-term therapy can help with secondary hypogonadism, which is a condition that causes sexual dysfunction.

Pentazocine use during breastfeeding:

• Whether pentazocine is secreted in breast milk is unknown.
• Opioids given during labor can disrupt a newborn's natural instinct to breastfeed.
• Pentazocine therapy for breast-feeding mothers should be monitored for psychotomimetic reactions.
• Monitoring is important because large doses of opioids can cause sedation and apnea.
• According to the manufacturer's instructions, breast-feeding is a decision that depends on the risks and benefits to the infant and the benefits to the mother.

Pentazocine Dose adjustment in renal disease:

• The manufacturer's labelling does not mention dosage modifications.
• Take care when using.
• Some therapists have utilised the suggestions below..

  • GFR ≥50 mL/minute:

    • Dosage adjustment is not required

  • GFR 10 to 50 mL/minute:

    • Administer 75% of the normal dose.

  • GFR <10 mL/minute:

    • Administer 50% of normal dose.

Pentazocine Dose adjustment in liver disease:

There are no dosage adjustments provided in the manufacturer’s labeling. However decreased metabolism and predisposition to adverse effect might need dose reduction.

Side effects of Pentazocine (Talwin):

• Cardiovascular:

  • Circulatory Depression
  • Facial Edema
  • Flushing
  • Hypertension
  • Hypotension
  • Increased Peripheral Vascular Resistance
  • Shock
  • Syncope
  • Tachycardia

• Central Nervous System:

  • Central Nervous System Depression
  • Chills
  • Confusion
  • Disorientation
  • Dizziness
  • Drowsiness
  • Drug Dependence (Physical And Psychological)
  • Euphoria
  • Excitement
  • Hallucination
  • Headache
  • Insomnia
  • Irritability
  • Malaise
  • Nightmares
  • Paresthesia
  • Sedation

• Dermatologic:

  • Dermatitis
  • Diaphoresis
  • Erythema Multiforme
  • Pruritus
  • Skin Rash
  • Stevens-Johnson Syndrome
  • Toxic Epidermal Necrolysis
  • Urticaria

• Gastrointestinal:

  • Abdominal Distress
  • Anorexia
  • Constipation
  • Diarrhea
  • Dysgeusia
  • Nausea
  • Vomiting
  • Xerostomia

• Genitourinary:

  • Urinary Retention

• Hematologic & Oncologic:

  • Agranulocytosis (Rare)
  • Decreased White Blood Cell Count
  • Eosinophilia

• Hypersensitivity:

  • Anaphylaxis

• Local:

  • Injection Site Reaction (Tissue Damage And Irritation)

• Neuromuscular & Skeletal:

  • Tremor
  • Weakness

• Ophthalmic:

  • Blurred Vision
  • Diplopia
  • Miosis
  • Nystagmus

• Otic:

  • Tinnitus

• Respiratory:

  • Dyspnea
  • Respiratory Depression (Rare)

Contraindication to Pentazocine (Talwin):

• Hypersensitivity to pentazocine and any component of the formulation (eg, anaphylaxis).
• GI obstruction/ paralytic ileus
• In a setting that does not have resuscitative equipment, severe bronchial asthma
• Grave respiratory depression

Canadian labeling: Additional contraindications not in US labeling

• Hypersensitivity to other opioids
• Alcoholism
• Delirium tremens
• Acute appendicitis/pancreatitis
• Hypercapnia and COPD are symptoms of status asthmaticus.
• Convulsive disorders, severe CNS depression, head injury, and increased ICP
• Breastfeeding/pregnancy
• Combine within 14 days of monoamine-oxidase inhibitors.

Warnings and precautions

• Cardiovascular effects

  • It is important to avoid it in MI because of its potential for increasing systemic and pulmonary arterial pressures and systemic resistance.

• CNS depression:

  • CNS depression can cause impairments in mental or physical abilities. Patients should be cautious about driving or operating machinery.

• Hypotension

  • Patients with hypovolemia, heart disease, or medications that can exaggerate hypotensive effects (e.g. phenothiazines and general anesthetics), should not take pentazocine.
  • It may cause severe hypotension. Avoid it if you have circulatory shock.

• Injection-site reactions:

  • The epidermis, subcutaneous tissues, and underlying muscles may have severe sclerosis as a result of subcutaneous injections.

• Respiratory depression [US Boxed Warning]

  • Respiratory depression should be closely monitored as carbon dioxide retention may exacerbate the sedating effects associated with opioids.

• Conditions abdominales:

  • Patients with acute abdominal conditions may not be diagnosed or treated appropriately.

• Adrenocortical Insufficiency

  • Patients with adrenal insufficiency (Addison disease) should be cautious.
  • Long-term therapy can lead to mood disorder, osteoporosis and sexual dysfunction caused by secondary hypogonadism.

• Insufficiency of the biliary tract:

  • Patients with acute pancreatitis or biliary dysfunction should be cautious. Opioids may cause constriction in the sphincter.

• CNS depression/coma:

  • Patients who are unconscious or comatose are more susceptible to the intracranial effects CO retention. It should therefore not be used.

• Delirium tremens:

  • Patients with delirium-tremens should be taken with caution

• Head trauma

  • If intracranial pressure is increased due to head injury or intracranial lesions, intracranial pressure can rise.

• Hepatic impairment

  • Patients with hepatic impairment should be cautious.

• Obesity:

  • Patients who are severely obese should be taken with caution

• Prostatic hyperplasia/Urinary stricture:

  • Patients with prostatic hyperplasia or urinary stricture should be cautious.

• Psychosis:

  • Patients with toxic psychosis should be treated with caution.

• Renal impairment

  • Patients with impaired renal function should be cautious.

• Respiratory disease

  • It should not be used in COPD, cor pulmonale hypercapnia or preexisting respiratory depression. It is recommended to use alternative non-opioid pain relievers.

• Seizures:

  • Preexisting seizures may be exacerbated or caused by it. Use caution.

• Thyroid dysfunction:

  • Patients with thyroid dysfunction should be cautious.

Pentazocine: Drug Interaction

Monitoring parameters:

• BP
• Respiratory and mental status,
• bowel function
• Pain relief
• signs/symptoms of misuse, abuse, and addiction
• signs or symptoms of hypogonadism or hypoadrenalism.

How to administer Pentazocine (Talwin)?

Injection:

• IM, IV, or SubQ usage only. IM injection locations should be alternated (eg, the upper outer quadrants of the buttocks, mid-lateral aspects of the thighs, and the deltoid areas).
• There should be no intraarterial injection. Only use subcutaneous injections if absolutely essential (may cause tissue damage).

Oral: Tablet [Canadian product]:

• Only for oral usage. After meals, give the entire dose without crushing, chewing, blending, or breaking.

Mechanism of action of Pentazocine (Talwin):

• In the central nervous system (CNS), pentazocine functions as a kappa agonist and a partial agonist for mu opiate.
• It modifies how pain is perceived, how the body reacts to pain, and it blocks the ascending pain pathways.
• Similar to opioids, this causes analgesia, respiratory depression, and drowsiness.

Absorption:

• Oral: [Canadian Product]: Well absorbed; low bioavailability due to the extensive first-pass effect

The onset of action:

• IM, SubQ: 15 to 20 minutes.
• IV: 2 to 3 minutes
• Oral [Canadian product]: 15 to 30 minutes

Duration:

• Injection: 2 to 3 hours
• Oral [Canadian product]: ≥3 hours

Protein binding:

• 60%

Time to peak (serum):

• Oral [Canadian product]: 1 to 3 hours

Metabolism: Hepatic via oxidative and glucuronide conjugation pathways; extensive first-pass effect

Half-life elimination: Prolonged with hepatic impairment

• Neonates: 8 to 12 hours
• Children 4 to 8 years (mean ± SD): 3 ± 1.5 hours
• Adults: 2 to 5 hours

Excretion:

• Urine (small amounts as unchanged drug)

International Brands of Pentazocin (Talwin):

• Talwin
• Dolapent
• Fortal
• Fortalgesic[inj.]
• Fortalgesic[Suppos.]
• Fortalgesic[Tab.]
• Fortral
• Fortralin
• Fortralin[inj./rect.]
• Fortralin[inj.]
• Fortwin
• Ospronim
• Pellpenta
• Peltazon
• Pentagin
• Pentajin
• Pental
• Pentawin
• Pentazocinum
• Sosegon
• Sosegon[inj./rect.]
• Stopain
• Talwin
• Talwin Lactate

Pentazocine Brands in Pakistan: