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|Pentazocine Pentazocine Acetaminophen

Pentazocine

Trade Names:
Talacen
- Tablets 25 mg pentazocine (as HCl)/650 mg acetaminophen

Trade Names:
Talwin
- Injection 30 mg/mL (as lactate)

Trade Names:
Talwin Compound
- Tablets 12.5 mg pentazocine (as HCl)/325 mg aspirin

Trade Names:
Talwin NX
- Tablets 50 mg pentazocine (as HCl)/0.5 naloxone

Mechanism of Action

Pharmacology

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.

Pharmacokinetics

Absorption

Well absorbed from GI tract and from SC and IM sites. Bioavailability is less than 20% (oral).

Distribution

Moderate protein binding. Passes into fetal circulation.

Metabolism

Hepatic, extensive first-pass; also in intestinal mucosa.

Elimination

Primarily kidney (less than 5% unchanged), small amount biliary. T _{1/ 2} is 2 to 3 hr.

Onset

IM/SC is 15 to 20 min; IV is 2 to 3 min; oral is 15 to 30 min.

Peak

For analgesic effect, IM/SC is 30 to 60 min; IV is 15 to 30 min; oral is 60 to 90 min.

Duration

IM is 2 to 3 hr; SC is 2 to 3 hr; IV is 2 to 3 hr; oral is 3 hr.

Special Populations

Oral bioavailability is increased by 3-fold in cirrhotic patients.

Indications and Usage

Management of moderate to severe pain.

Preoperative or preanesthetic medication; supplement to surgical anesthesia.

Contraindications

Hypersensitivity to naloxone (in Talwin NX ) or sulfites.

Dosage and Administration

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.

IM / SC / IV 30 mg q 3 to 4 hr prn (max, 360 mg/day). Doses greater than 30 mg IV or 60 mg SC / IM are not recommended.

PO 50 mg q 3 to 4 hr; increase to 100 mg if necessary (max, 600 mg/day).

PO 2 tablets tid to qid.

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

General Advice

• 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.

Storage/Stability

Store in tightly closed, light-resistant containers.

Drug Interactions

Causes additive CNS depression.

Causes increased CNS and respiratory depression.

Incompatibility

Do not mix in the same syringe with pentazocine; precipitation will occur.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Hypotension; hypertension; tachycardia; circulatory depression; shock.

CNS

Lightheadedness; dizziness; euphoria; hallucinations; disorientation; confusion; seizures.

Dermatologic

Nodules, soft tissue induration, depressions, sclerosis and ulceration at injection sites.

EENT

Visual disturbances.

GI

Nausea.

Genitourinary

Urinary retention.

Hematologic

Granulocytopenia.

Respiratory

Respiratory depression; transient apnea in newborns whose mothers received parenteral pentazocine during labor.

Miscellaneous

Anaphylaxis; tolerance; psychological and physical dependence in long-term use.

Precautions

Pregnancy

Category C . Neonatal abstinence syndrome may develop.

Children

Not recommended for children less than 12 yr.

Labor and Delivery

Pentazocine rapidly crosses placenta with cord blood levels 40% to 70% of maternal serum levels. Use drug with caution in women delivering premature infants.

Special Risk Patients

Use with caution in patients with MI, decreased respiratory reserve, asthma, respiratory depression, head injury or increased intracranial pressure.

Sulfite Sensitivity

Drug may cause allergic-type reactions (eg, hives, itching, wheezing, anaphylaxis) in susceptible persons.

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.

“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.

Overdosage

Symptoms

Respiratory depression, hypertension, tachycardia.

Patient Information

• 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 health care provider.
• 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.