TALACEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for TALACEN (TALACEN).

How it works

Pentazocine is a mixed agonist-antagonist opioid analgesic that acts at mu, kappa, and delta opioid receptors; naloxone is an opioid antagonist that reduces abuse potential.

What the body does with it

Metabolism	Pentazocine is extensively metabolized in the liver, primarily via glucuronidation and oxidation pathways (CYP2D6 and CYP3A4); naloxone undergoes hepatic metabolism (glucuronidation).
Excretion	Renal: ~55-60% as pentazocine (unchanged and conjugated glucuronides), ~20% as naloxone (unchanged and metabolites); fecal: ~15-20% via bile; total renal elimination ~75-80%.
Half-life	Pentazocine: 4-5 hours (terminal); naloxone: 1-2 hours. Oral pentazocine half-life extended in hepatic impairment (up to 10-12 hours).
Protein binding	Pentazocine: ~60% (primarily albumin); naloxone: ~45% (albumin and other proteins).
Volume of Distribution	Pentazocine: 3-5 L/kg (extensive tissue distribution); naloxone: 2-3 L/kg.
Bioavailability	Oral: 20-30% (high first-pass metabolism for pentazocine; naloxone <2% oral due to extensive first-pass, but sufficient to antagonize pentazocine effects).
Onset of Action	Oral: 15-30 minutes; IM: 15-20 minutes; IV: 2-3 minutes.
Duration of Action	Oral: 2-4 hours; IM/IV: 3-4 hours. Duration may be shorter due to naloxone antagonism at higher doses.

Classification & Brands

Dosing & administration

1 tablet (pentazocine hydrochloride 25 mg and acetaminophen 650 mg) orally every 4 hours as needed, not to exceed 6 tablets per day.

Dosage form	TABLET
Renal impairment	CrCl < 30 mL/min: not recommended; CrCl 30-50 mL/min: increase dosing interval to every 6 hours; monitor for adverse effects.
Liver impairment	Child-Pugh Class C: contraindicated; Child-Pugh Class B: reduce dose by 50% and increase dosing interval to every 8 hours; Child-Pugh Class A: no adjustment necessary.
Pediatric use	Not recommended for pediatric use; safety and efficacy not established.
Geriatric use	Initiate at lowest effective dose (1 tablet every 6 hours); monitor for CNS depression, constipation, and acetaminophen toxicity; avoid in patients with renal or hepatic impairment.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for TALACEN (TALACEN).

Breastfeeding

Acetaminophen is excreted into breast milk in low amounts (M/P ratio approximately 1.0) and is considered compatible with breastfeeding. Pentazocine is excreted in low concentrations (M/P ratio unknown); limited data suggest minimal risk. However, monitor for infant sedation or withdrawal symptoms. The American Academy of Pediatrics considers pentazocine compatible with breastfeeding.

Teratogenic Risk

Talacen (acetaminophen and pentazocine) has a teratogenic risk profile: First trimester: Limited human data show no increased risk of major malformations from acetaminophen; pentazocine is not associated with congenital anomalies in humans. Second trimester: No specific risks documented. Third trimester: Chronic use may lead to neonatal opioid withdrawal syndrome with pentazocine; acetaminophen is considered low risk. Overall, Talacen is classified as FDA Pregnancy Category C due to pentazocine.

Warnings & precautions

■ FDA Black Box Warning

Risk of medication errors: Talacen tablets contain pentazocine hydrochloride and naloxone hydrochloride. Naloxone is present to reduce abuse liability, but does not protect against overdose if tablets are taken orally. Concomitant use with benzodiazepines or other CNS depressants may result in profound sedation, respiratory depression, coma, and death.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Significant respiratory depression","Acute or severe bronchial asthma","Known or suspected gastrointestinal obstruction","Hypersensitivity to pentazocine or naloxone"]

Clinical Precautions

Precautions

["Addiction, abuse, and misuse","Life-threatening respiratory depression","Neonatal opioid withdrawal syndrome","Risks from concomitant use with benzodiazepines or other CNS depressants","Adrenal insufficiency","Severe hypotension","Seizures in patients with seizure disorders","Withdrawal after rapid dose reduction"]

Clinical Tips & Counseling

Drug interactions

Loading safety data…

TALACEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for TALACEN (TALACEN).

How it works

Pentazocine is a mixed agonist-antagonist opioid analgesic that acts at mu, kappa, and delta opioid receptors; naloxone is an opioid antagonist that reduces abuse potential.

What the body does with it

Metabolism	Pentazocine is extensively metabolized in the liver, primarily via glucuronidation and oxidation pathways (CYP2D6 and CYP3A4); naloxone undergoes hepatic metabolism (glucuronidation).
Excretion	Renal: ~55-60% as pentazocine (unchanged and conjugated glucuronides), ~20% as naloxone (unchanged and metabolites); fecal: ~15-20% via bile; total renal elimination ~75-80%.
Half-life	Pentazocine: 4-5 hours (terminal); naloxone: 1-2 hours. Oral pentazocine half-life extended in hepatic impairment (up to 10-12 hours).
Protein binding	Pentazocine: ~60% (primarily albumin); naloxone: ~45% (albumin and other proteins).
Volume of Distribution	Pentazocine: 3-5 L/kg (extensive tissue distribution); naloxone: 2-3 L/kg.
Bioavailability	Oral: 20-30% (high first-pass metabolism for pentazocine; naloxone <2% oral due to extensive first-pass, but sufficient to antagonize pentazocine effects).
Onset of Action	Oral: 15-30 minutes; IM: 15-20 minutes; IV: 2-3 minutes.
Duration of Action	Oral: 2-4 hours; IM/IV: 3-4 hours. Duration may be shorter due to naloxone antagonism at higher doses.

Classification & Brands

Dosing & administration

1 tablet (pentazocine hydrochloride 25 mg and acetaminophen 650 mg) orally every 4 hours as needed, not to exceed 6 tablets per day.

Dosage form	TABLET
Renal impairment	CrCl < 30 mL/min: not recommended; CrCl 30-50 mL/min: increase dosing interval to every 6 hours; monitor for adverse effects.
Liver impairment	Child-Pugh Class C: contraindicated; Child-Pugh Class B: reduce dose by 50% and increase dosing interval to every 8 hours; Child-Pugh Class A: no adjustment necessary.
Pediatric use	Not recommended for pediatric use; safety and efficacy not established.
Geriatric use	Initiate at lowest effective dose (1 tablet every 6 hours); monitor for CNS depression, constipation, and acetaminophen toxicity; avoid in patients with renal or hepatic impairment.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for TALACEN (TALACEN).

Breastfeeding

Teratogenic Risk

Warnings & precautions

■ FDA Black Box Warning

Side Effect Profile

Serious Effects

Absolute Contraindications

["Significant respiratory depression","Acute or severe bronchial asthma","Known or suspected gastrointestinal obstruction","Hypersensitivity to pentazocine or naloxone"]