Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OMTRYG vs ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
OMTRYG is a combination of ombitasvir, paritaprevir, and ritonavir. Ombitasvir is an NS5A inhibitor that blocks viral RNA replication and assembly. Paritaprevir is an NS3/4A protease inhibitor that prevents viral polyprotein cleavage. Ritonavir is a CYP3A4 inhibitor used to boost paritaprevir levels.
Pentazocine is a mixed agonist-antagonist opioid analgesic that binds to mu, kappa, and sigma opioid receptors, primarily acting as an agonist at kappa receptors and partial agonist at mu receptors, resulting in analgesic and sedative effects. Acetaminophen (paracetamol) is an analgesic and antipyretic whose mechanism involves inhibition of cyclooxygenase (COX) enzymes, primarily COX-2, in the central nervous system, and possibly activation of descending serotonergic pathways.
Treatment of chronic hepatitis C virus (HCV) genotype 4 infection without cirrhosis or with compensated cirrhosis,Treatment of chronic HCV genotype 1 infection (with ribavirin or as part of combination therapy)
Moderate to severe pain where an opioid analgesic is appropriate
2 mg orally twice daily; if taste disturbance occurs, reduce to 1 mg twice daily.
One tablet (acetaminophen 500 mg / pentazocine hydrochloride 25 mg) orally every 4 hours as needed for pain; maximum daily dose: acetaminophen 4000 mg (8 tablets) and pentazocine hydrochloride 200 mg (8 tablets).
Terminal elimination half-life is 12-14 hours in healthy adults, allowing once-daily dosing. In renal impairment (Cr Cl <30 m L/min), half-life prolongs to 24-36 hours requiring dose adjustment.
Acetaminophen: 2-3 hours (prolonged in hepatic impairment). Pentazocine: 2-3 hours (terminal), with clinical analgesic effect lasting 3-4 hours.
Ombitasvir: primarily metabolized by CYP3A4; Paritaprevir: primarily metabolized by CYP3A4; Ritonavir: primarily metabolized by CYP3A4 and to a lesser extent by CYP2D6.
Pentazocine is extensively metabolized in the liver via oxidation and glucuronidation; significant first-pass metabolism. Acetaminophen is metabolized primarily in the liver via conjugation with glucuronide and sulfate, and oxidation via CYP2E1, CYP1A2, and CYP3A4 to a toxic metabolite (NAPQI).
Primarily renal excretion unchanged (approximately 70%), with 30% metabolized hepatically and excreted in feces via bile. Renal clearance accounts for ~60% of total clearance.
Acetaminophen: renal (2-4% unchanged, ~85% as glucuronide and sulfate conjugates). Pentazocine: renal (~60% as unchanged and conjugates), biliary/fecal (~20%).
Approximately 95% bound to serum albumin.
Acetaminophen: 10-25% (albumin). Pentazocine: 60-70% (albumin and alpha-1 acid glycoprotein).
0.3-0.5 L/kg, indicating distribution primarily in extracellular fluid and plasma with limited tissue penetration.
Acetaminophen: 0.9 L/kg. Pentazocine: 5-7 L/kg (extensive tissue distribution).
Oral: 60-80% (first-pass effect); Subcutaneous: 90-100%.
Acetaminophen oral: 60-90%. Pentazocine oral: ~20% (extensive first-pass metabolism). Intramuscular: pentazocine 100%.
No dose adjustment required for GFR ≥30 m L/min; avoid use if GFR <30 m L/min.
Cr Cl 30-50 m L/min: use with caution; decrease dose interval to every 6 hours if needed. Cr Cl <30 m L/min: restrict pentazocine; consider alternative. Not recommended for patients on dialysis.
No dose adjustment required for Child-Pugh A or B; not recommended in Child-Pugh C due to lack of data.
Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce pentazocine dose by 50%; avoid acetaminophen >2 g/day. Child-Pugh Class C: contraindicated due to acetaminophen hepatotoxicity and pentazocine accumulation.
Not approved for pediatric patients <18 years; safety and efficacy not established.
Not recommended in children <12 years due to lack of safety data. For adolescents ≥12 years, adult dosing may be considered based on weight (≥50 kg).
No dose adjustment required based on age; monitor for taste disturbance and renal function.
Reduce pentazocine dose by 50% (e.g., one tablet every 6 hours) due to increased risk of CNS depression, confusion, and constipation. Monitor renal function; avoid exceeding 4 g/day acetaminophen.
WARNING: HEPATITIS B VIRUS REACTIVATION — Test all patients for evidence of current or prior HBV infection before initiating treatment. HBV reactivation has been reported in patients coinfected with HCV and HBV, which can result in fulminant hepatitis, hepatic failure, and death.
Pentazocine: Risk of respiratory depression, particularly in elderly, cachectic, or debilitated patients. Concomitant use with benzodiazepines or other CNS depressants may result in profound sedation, respiratory depression, coma, and death. Patients should be monitored for respiratory depression and sedation.
Risk of hepatitis B virus reactivation,Hepatic decompensation/hepatic failure in patients with cirrhosis,ALT elevations and hepatic injury,Risk of drug interactions (significant CYP3A4 inhibition),Use with ribavirin: ribavirin-related adverse effects (e.g., anemia, teratogenicity)
Respiratory depression risk, especially in patients with compromised respiratory function,Potential for opioid dependence, abuse, and misuse,Risk of withdrawal if discontinued abruptly after prolonged use,Pentazocine may cause opioid withdrawal in patients dependent on pure mu agonists,Acetaminophen hepatotoxicity at high doses or with chronic use; risk increased with alcohol consumption or pre-existing liver disease,Central nervous system depression additive with other CNS depressants,Elderly or debilitated patients may have increased sensitivity to effects,May cause hypotension, especially in hypovolemic patients,Serotonin syndrome risk when used with serotonergic drugs,Pentazocine may cause hallucinations, confusion, or other psychotomimetic effects
Severe hepatic impairment (Child-Pugh C),Known hypersensitivity to ombitasvir, paritaprevir, ritonavir, or any component of the formulation,Coadministration with drugs highly dependent on CYP3A4 for clearance (e.g., alfuzosin, amiodarone, sildenafil when used for pulmonary arterial hypertension, ergot derivatives, lovastatin, simvastatin, midazolam, triazolam),Moderate to severe hepatic impairment in patients with cirrhosis (Child-Pugh B and C)
Hypersensitivity to either component,Severe respiratory depression (e.g., acute asthma, hypercapnia),Acute or severe bronchial asthma,Suspected surgical abdomen (may obscure diagnosis),Monoamine oxidase inhibitor (MAOI) use (current or within 14 days),Severe hepatic impairment or active liver disease (acetaminophen component),Known or suspected gastrointestinal obstruction (including paralytic ileus)
No clinically significant food interactions reported.
Avoid alcohol consumption due to increased risk of hepatotoxicity from acetaminophen. No specific food interactions; take with food if gastrointestinal upset occurs.
Pregnancy Category X: contraindicated in pregnancy. First trimester: major congenital malformations (e.g., neural tube defects, cardiac anomalies). Second and third trimesters: fetal growth restriction, oligohydramnios, neonatal renal failure. Risk is dose-dependent.
Acetaminophen: Generally considered low risk; no consistent evidence of teratogenicity in any trimester. Pentazocine: Limited human data; animal studies show no teratogenicity at clinically relevant doses. However, use in third trimester may cause neonatal respiratory depression and withdrawal syndrome. Overall, risk is low but pentazocine should be avoided near term.
Contraindicated during breastfeeding. M/P ratio not established; drug excreted into breast milk. Potential for serious adverse effects in nursing infant (renal toxicity).
Acetaminophen: Excreted in low amounts (M/P ratio ~0.2-0.9); compatible with breastfeeding. Pentazocine: Excreted in breast milk; M/P ratio unknown; may cause CNS effects in infants. Use with caution, especially in neonates or premature infants. Monitor infant for sedation and respiratory depression.
Not applicable; contraindicated in pregnancy. No dose adjustment recommended due to contraindication.
Acetaminophen: No significant pharmacokinetic changes in pregnancy; standard dosing (max 3-4 g/day) applies. Pentazocine: Clearance may increase due to enhanced hepatic metabolism; dose adjustments not routinely recommended but monitor response. Avoid high doses near term due to risk of neonatal depression.
OMTRYG (triptorelin pamoate) is a Gn RH agonist used for advanced prostate cancer. Monitor for tumor flare at therapy initiation; consider antiandrogen coadministration for first month. Baseline and periodic serum testosterone and PSA levels are essential. Caution in patients with spinal cord compression or urinary tract obstruction. Risk of QT prolongation; assess electrolytes and ECG in at-risk patients. Depot formulation provides 6-month coverage.
Pentazocine is a mixed agonist-antagonist opioid; avoid in opioid-dependent patients due to risk of precipitated withdrawal. Acetaminophen component limits total daily dose to 4 g (or less in hepatic impairment) to prevent hepatotoxicity. Monitor for respiratory depression, especially in elderly or those with COPD. Injection site reactions (e.g., sterile abscesses, fibrosis) common with repeated intramuscular use. May cause dysphoria, hallucinations, or CNS stimulation (unlike typical opioids). Contraindicated in acute porphyria due to porphyrinogenic potential.
OMTRYG is injected every 6 months by a healthcare provider.,You may experience a temporary increase in bone pain or urinary symptoms during the first few weeks.,Report new or worsening pain, difficulty urinating, or leg weakness immediately.,Hot flashes, decreased libido, and erectile dysfunction are common.,Do not stop treatment without consulting your doctor.,Keep all scheduled injections; missed doses can reduce effectiveness.
Do not exceed 4 grams of acetaminophen per day from all sources (including OTC medications).,Avoid alcohol while taking this medication; risk of liver damage increases.,This medication may cause dizziness, drowsiness, or hallucinations; avoid driving or operating machinery until effects are known.,Report any signs of allergic reaction (rash, difficulty breathing) or liver issues (yellow skin/eyes, dark urine).,Do not suddenly stop if used long-term; withdrawal symptoms may occur.,If you have opioid dependence, this medication may precipitate withdrawal symptoms.,This medication may cause constipation; maintain fluid and fiber intake.
No interactions on record
"Pentazocine, a mixed opioid agonist-antagonist, may attenuate the central nervous system (CNS) stimulant effects of dextroamphetamine by competitively blocking mu-opioid receptors and potentially altering dopamine release, leading to reduced analgesic efficacy of pentazocine and diminished therapeutic response to dextroamphetamine in treating attention deficit hyperactivity disorder (ADHD) or narcolepsy. This interaction can result in suboptimal pain control and exacerbation of ADHD symptoms, requiring dose adjustments or alternative therapies."
"The concurrent use of ipratropium, an anticholinergic agent, and pentazocine, a mixed opioid agonist-antagonist, may lead to an increased risk of central nervous system (CNS) depression and anticholinergic adverse effects. Pentazocine can enhance the sedative and respiratory depressant effects of ipratropium, while ipratropium may potentiate pentazocine's anticholinergic actions, such as dry mouth, blurred vision, constipation, and urinary retention. Clinically, this interaction can result in excessive sedation, confusion, and impaired cognitive and motor function, particularly in elderly or debilitated patients."
"The combination of pentazocine, a mixed agonist-antagonist opioid, with triazolam, a benzodiazepine, can lead to additive central nervous system (CNS) depression, including increased sedation, respiratory depression, and psychomotor impairment. This is due to the synergistic effects of both drugs on GABAergic and opioid receptors in the brainstem and cortex. Clinically, this may result in excessive drowsiness, confusion, ataxia, and an elevated risk of falls or respiratory compromise, particularly in elderly or debilitated patients."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about OMTRYG vs ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE, answered by our medical review team.
OMTRYG is a HMG-CoA Reductase Inhibitor (Statin) that works by OMTRYG is a combination of ombitasvir, paritaprevir, and ritonavir. Ombitasvir is an NS5A inhibitor that blocks viral RNA replication and assembly. Paritaprevir is an NS3/4A protease inhibitor that prevents viral polyprotein cleavage. Ritonavir is a CYP3A4 inhibitor used to boost paritaprevir levels.. ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE is a Opioid Agonist-Antagonist that works by Pentazocine is a mixed agonist-antagonist opioid analgesic that binds to mu, kappa, and sigma opioid receptors, primarily acting as an agonist at kappa receptors and partial agonist at mu receptors, resulting in analgesic and sedative effects. Acetaminophen (paracetamol) is an analgesic and antipyretic whose mechanism involves inhibition of cyclooxygenase (COX) enzymes, primarily COX-2, in the central nervous system, and possibly activation of descending serotonergic pathways.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between OMTRYG and ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of OMTRYG is: 2 mg orally twice daily; if taste disturbance occurs, reduce to 1 mg twice daily.. The standard adult dose of ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE is: One tablet (acetaminophen 500 mg / pentazocine hydrochloride 25 mg) orally every 4 hours as needed for pain; maximum daily dose: acetaminophen 4000 mg (8 tablets) and pentazocine hydrochloride 200 mg (8 tablets).. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between OMTRYG and ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. OMTRYG is classified as Category C. Pregnancy Category X: contraindicated in pregnancy. First trimester: major congenital malformations (e.g., neural tube defects, cardiac anomalies). Second and third trimesters: fet. ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE is classified as Category A/B. Acetaminophen: Generally considered low risk; no consistent evidence of teratogenicity in any trimester. Pentazocine: Limited human data; animal studies show no teratogenicity at c. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.