Pentazocine

A to Z Drug Facts

 Action Produces analgesia by an agonistic effect at the kappa opioid receptor. Weakly antagonizes effects of opiates at mu opioid receptor; does not appear to increase biliary tract pressure.

 Indications

Oral and parenteral forms: Management of moderate to severe pain. Parenteral form: Preoperative or preanesthetic medication; supplement to surgical anesthesia.

 Contraindications Hypersensitivity to naloxone (in Talwin NX) or sulfites.

 Route/Dosage

Moderate-to-Severe Pain

PENTAZOCINE

ADULTS: PO 50 mg q 3 to 4 hr; increase to 100 mg if necessary (max 600 mg/day). IM/SC/IV 30 mg q 3 to 4 hr prn (max 360 mg/day). Doses > 30 mg IV or 60 mg SC/IM are not recommended.

PENTAZOCINE 12.5 MG WITH ASPIRIN 325 MG (Talwin Compound):

ADULTS: PO 2 tablets tid to qid.

PENTAZOCINE 25 MG WITH ACETAMINOPHEN 650 MG (Talacen):

ADULTS: PO 1 tablet q 4 hr (max 6 tablets/day).

Labor

ADULTS: IM 30 mg as single dose; alternatively, when contractions are regular, IV 20 mg for 2 to 3 doses given q 2 to 3 hr.

 Interactions

Alcohol: Causes additive CNS depression. Barbiturate anesthetics and any other CNS depressants (eg, benzodiazepines, antidepressants): Causes increased CNS and respiratory depression. INCOMPATIBILITIES: Barbiturates: Do not mix in the same syringe with pentazocine; precipitation will occur.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Hypotension; hypertension; tachycardia; circulatory depression; shock. CNS: Lightheadedness; dizziness; euphoria; hallucinations; disorientation; confusion; seizures. DERM: Nodules, soft tissue induration, depressions, sclerosis and ulceration at injection sites. EENT: Visual disturbances. GI: Nausea. GU: Urinary retention. HEMA: Granulocytopenia. RESP: Respiratory depression; transient apnea in newborns whose mothers received parenteral pentazocine during labor. OTHER: Anaphylaxis; tolerance; psychological and physical dependence in long-term use.

 Precautions

Pregnancy: Category C. Neonatal abstinence syndrome may develop. Labor: Pentazocine rapidly crosses placenta with cord blood levels 40% to 70% of maternal serum levels. Use drug with caution in women delivered of premature infants. Children: Not recommended for children < 12 yr old. Special-risk patients: Use with caution in patients with MI, decreased respiratory reserve, asthma, respiratory depression, head injury or increased intracranial pressure. Abuse/Dependence/Withdrawal: Abuse potential exists. Abrupt discontinuation after long-term use may cause withdrawal symptoms. Do not substitute other opiates in pentazocine withdrawal syndrome. Pentazocine may induce withdrawal symptoms in narcotic-dependent patients. Acute CNS manifestations: Hallucinations, disorientation, confusion, and seizures. Renal or hepatic impairment: Duration of action may be prolonged; dosage reduction may be required. Sulfite sensitivity: Drug may cause allergic-type reactions (eg, hives, itching, wheezing, anaphylaxis) in susceptible persons. “Ts and Blues”: Refers to drug abuse by IV injection of oral pentazocine and tripelennamine (antihistamine) as substitute for heroin. Complications of injecting oral pentazocine include pulmonary emboli, vascular occlusion, ulceration, seizures, strokes, and CNS infections. Addition of naloxone to pentazocine tablets (Talwin NX) prevents this drug abuse; it may cause withdrawal in narcotic-dependent individuals. Tissue damage: Severe sclerosis of skin, SC tissues, and underlying muscle have occurred at injection sites.

 Administration/Storage

• Pentazocine is a schedule IV drug; keep it locked according to hospital policy.
• When anti-inflammatory or antipyretic effects are desired in addition to analgesia, aspirin or acetaminophen can be administered concomitantly with oral form of pentazocine.
• Do not mix barbiturate in same syringe with pentazocine; precipitation will occur.
• If frequent injections are needed, rotate sites.
• For IM administration; inject deep into well-developed tissue.
• For IV administration; inject undiluted by slow bolus. Do not exceed a 30 mg dose.
• Administer SC only when necessary; severe tissue damage is possible at injection sites.
• Store in tightly-closed, light-resistant containers.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Assess for signs of physical and psychological dependence throughout course of therapy.
• Assess respiratory rate and quality, BP, and pulse before administering drug and periodically during therapy.
• Assess for adverse reactions (eg, hypotension, shock, dizziness, hallucinations, seizures, urinary retention, tissue changes from injections).
• Assess newborns whose mothers received parenteral pentazocine for apnea.
• Rate patient's pain before and after each dose. Determine and record onset, durations, location, intensity, and quality of pain.
• Notify physician if medication does not relieve patient's pain.
• If anaphylaxis occurs, prepare to institute emergency oxygen, mechanical ventilation, IV fluids, and vasopressors.
• If constipation occurs, give stool softeners or laxative, teach high-fiber diet and increase fluid consumption to 2 to 3 L/day if tolerated.

 Patient/Family Education

• For maximum effectiveness, instruct patient to take medication before intolerable pain develops.
• Tell patient to take medication exactly as prescribed, to minimize dependence.
• Teach patient to consume 2 to 3 L of fluids each day, if tolerated, to prevent constipation.
• Inform patient that aspirin or acetaminophen may be taken concurrently for additive analgesia as well as its anti-inflammatory and antipyretic effects.
• Explain therapeutic value of pentazocine prior to administration to enhance the analgesic effect.
• Caution patient not to stop taking drug abruptly without consulting physician.
• Advise patient to avoid sudden position changes to prevent orthostatic hypotension.
• Instruct patient to avoid intake of alcoholic beverages or other CNS depressants.
• Advise patient that drug may cause dizziness and to use caution while driving or performing other tasks requiring mental alertness.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts