Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
NALOXONE HYDROCHLORIDE AND PENTAZOCINE HYDROCHLORIDE vs OMTRYG
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Pentazocine is a mixed agonist-antagonist opioid that binds to mu-opioid receptors (partial agonist) and kappa-opioid receptors (agonist), producing analgesia. Naloxone is a pure opioid antagonist that competitively blocks mu, kappa, and delta receptors; when administered orally, naloxone undergoes extensive first-pass metabolism, reducing systemic absorption and primarily blocking the effects of pentazocine if the combination is misused parenterally.
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.
Moderate to severe pain relief; combinations are used to reduce abuse potential.
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)
Oral: One tablet (naloxone 0.5 mg / pentazocine 50 mg) every 3-4 hours as needed for pain; maximum 12 tablets daily.
2 mg orally twice daily; if taste disturbance occurs, reduce to 1 mg twice daily.
Pentazocine has an elimination half-life of 2-3 hours in healthy adults, which may be prolonged in patients with hepatic impairment. Naloxone has a terminal half-life of 0.5-1.5 hours in adults, with a rapid decline in plasma levels; the short half-life limits its duration of opioid antagonism.
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.
Pentazocine is metabolized primarily by hepatic conjugation (glucuronidation) and oxidation via CYP2C19 and CYP2D6; naloxone is extensively metabolized by the liver, primarily via glucuronidation (UGT2B7).
Ombitasvir: primarily metabolized by CYP3A4; Paritaprevir: primarily metabolized by CYP3A4; Ritonavir: primarily metabolized by CYP3A4 and to a lesser extent by CYP2D6.
Pentazocine is primarily metabolized in the liver and excreted in urine as conjugates of glucuronide and sulfate, with about 60% of a dose excreted renally within 24 hours as metabolites and unchanged drug (less than 5% unchanged). Naloxone undergoes extensive hepatic metabolism to naloxone-3-glucuronide, which is excreted renally; approximately 50% of a dose is excreted as conjugates in urine within 6 hours.
Primarily renal excretion unchanged (approximately 70%), with 30% metabolized hepatically and excreted in feces via bile. Renal clearance accounts for ~60% of total clearance.
Pentazocine: Approximately 35-65% bound to plasma proteins (mainly albumin). Naloxone: Approximately 32-45% bound to plasma proteins (mainly albumin).
Approximately 95% bound to serum albumin.
Pentazocine: Vd ~2-3 L/kg, indicating extensive tissue distribution. Naloxone: Vd ~2-3 L/kg, also indicating wide distribution.
0.3-0.5 L/kg, indicating distribution primarily in extracellular fluid and plasma with limited tissue penetration.
Oral pentazocine: 20-30% due to first-pass metabolism. Intramuscular pentazocine: 100%. Subcutaneous pentazocine: 100%. Oral naloxone: <2% due to extensive first-pass metabolism. Intramuscular and subcutaneous naloxone: 100%. Intravenous: 100% for both.
Oral: 60-80% (first-pass effect); Subcutaneous: 90-100%.
GFR 30-50 m L/min: Administer every 6 hours; GFR 10-29 m L/min: Administer every 8-12 hours; GFR <10 m L/min: Administer every 12 hours or consider alternative.
No dose adjustment required for GFR ≥30 m L/min; avoid use if GFR <30 m L/min.
Child-Pugh Class A: No adjustment; Child-Pugh Class B: Reduce dose by 50% or extend interval; Child-Pugh Class C: Avoid use.
No dose adjustment required for Child-Pugh A or B; not recommended in Child-Pugh C due to lack of data.
Not recommended for children under 12 years. For older children (≥12 years): Pentazocine 50 mg (with naloxone 0.5 mg) orally every 3-4 hours as needed; maximum 6 tablets daily.
Not approved for pediatric patients <18 years; safety and efficacy not established.
Initiate with half the usual adult dose (one-half tablet) and titrate carefully due to increased sensitivity and risk of respiratory depression.
No dose adjustment required based on age; monitor for taste disturbance and renal function.
Risk of respiratory depression, particularly in elderly, cachectic, or debilitated patients; risk of addiction, abuse, and misuse; risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy; risk of life-threatening respiratory depression when used with benzodiazepines or other CNS depressants.
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.
Respiratory depression; hypotension; increased intracranial pressure; seizure risk (pentazocine); opioid-induced hyperalgesia; adrenal insufficiency; severe hypotension; interaction with MAOIs; risk of dependence and withdrawal; gastrointestinal obstruction; impaired renal or hepatic function; head injury.
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)
Hypersensitivity to pentazocine or naloxone; significant respiratory depression; acute or severe bronchial asthma; GI obstruction; known or suspected paralytic ileus; patients receiving MAOIs or within 14 days.
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)
No specific food interactions are reported for this combination. However, grapefruit juice may theoretically affect metabolism via CYP3A4 (pentazocine is metabolized by CYP3A4), but clinical significance is unknown. Advise patients to maintain a consistent diet.
No clinically significant food interactions reported.
Pentazocine crosses the placenta; naloxone has limited placental transfer. No well-controlled human studies. First trimester: Risk cannot be excluded; avoid if possible. Second/Third trimester: Chronic use may cause fetal dependence; neonatal withdrawal syndrome reported. High doses near term may cause neonatal respiratory depression.
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.
Pentazocine is excreted in breast milk in small amounts (estimated relative infant dose <3%). Naloxone is poorly bioavailable orally. Generally considered compatible with breastfeeding; monitor infant for sedation or poor feeding. M/P ratio for pentazocine is approximately 1.0.
Contraindicated during breastfeeding. M/P ratio not established; drug excreted into breast milk. Potential for serious adverse effects in nursing infant (renal toxicity).
No established dose adjustments for pregnancy; however, pharmacokinetic changes (increased volume of distribution, enhanced clearance) may require higher or more frequent doses of pentazocine for adequate analgesia. Use lowest effective dose and shortest duration.
Not applicable; contraindicated in pregnancy. No dose adjustment recommended due to contraindication.
Naloxone in this fixed-dose combination is included to deter opioid abuse by reversing euphoria. The pentazocine component is a mixed agonist-antagonist opioid; naloxone has poor oral bioavailability but becomes active parenterally, precipitating withdrawal in opioid-dependent individuals. Use with caution in patients with impaired renal or hepatic function. Monitor for respiratory depression, especially in opioid-naive patients, as pentazocine alone can cause respiratory 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.
Take exactly as prescribed; do not crush or inject tablets, as injected naloxone can cause severe withdrawal in opioid-dependent individuals.,This medication contains naloxone to discourage misuse; injection will cause withdrawal symptoms.,Report any signs of withdrawal (e.g., nausea, vomiting, sweating, agitation) or breathing difficulty.,Avoid alcohol and other central nervous system depressants as they increase risk of respiratory depression.,Do not use with other opioids unless directed, as effects are unpredictable.,Keep out of reach of children; accidental ingestion may cause severe respiratory depression.
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.
"Cobicistat is a potent CYP3A4 inhibitor used to boost the pharmacokinetics of antiretroviral agents like atazanavir and darunavir. Naloxone primarily undergoes glucuronidation via UGT1A6 and UGT2B7, with minor CYP3A4 metabolism. Concomitant use with Cobicistat may modestly increase naloxone exposure due to CYP3A4 inhibition, but this is unlikely to be clinically significant given naloxone's wide therapeutic index and short half-life."
"Fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), is primarily metabolized by cytochrome P450 (CYP) 1A2 and 2D6. Naloxone, an opioid antagonist, is reported to inhibit CYP1A2, potentially decreasing the clearance of fluvoxamine. This interaction may lead to increased fluvoxamine plasma concentrations, elevating the risk of serotonin syndrome, QT prolongation, and other dose-dependent adverse effects, especially in patients receiving high doses or those with hepatic impairment."
"Naloxone, an opioid receptor antagonist, may inhibit the cytochrome P450 isoenzyme CYP3A4, which is responsible for the metabolism of ivacaftor. Concomitant administration can lead to reduced clearance of ivacaftor, resulting in elevated serum concentrations. This increase may potentiate the therapeutic effects and adverse reactions of ivacaftor, such as hepatotoxicity and QT prolongation."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about NALOXONE HYDROCHLORIDE AND PENTAZOCINE HYDROCHLORIDE vs OMTRYG, answered by our medical review team.
NALOXONE HYDROCHLORIDE AND PENTAZOCINE HYDROCHLORIDE is a Opioid Agonist-Antagonist that works by Pentazocine is a mixed agonist-antagonist opioid that binds to mu-opioid receptors (partial agonist) and kappa-opioid receptors (agonist), producing analgesia. Naloxone is a pure opioid antagonist that competitively blocks mu, kappa, and delta receptors; when administered orally, naloxone undergoes extensive first-pass metabolism, reducing systemic absorption and primarily blocking the effects of pentazocine if the combination is misused parenterally.. 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.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between NALOXONE HYDROCHLORIDE AND PENTAZOCINE HYDROCHLORIDE and OMTRYG 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 NALOXONE HYDROCHLORIDE AND PENTAZOCINE HYDROCHLORIDE is: Oral: One tablet (naloxone 0.5 mg / pentazocine 50 mg) every 3-4 hours as needed for pain; maximum 12 tablets daily.. The standard adult dose of OMTRYG is: 2 mg orally twice daily; if taste disturbance occurs, reduce to 1 mg twice daily.. 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 NALOXONE HYDROCHLORIDE AND PENTAZOCINE HYDROCHLORIDE and OMTRYG 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. NALOXONE HYDROCHLORIDE AND PENTAZOCINE HYDROCHLORIDE is classified as Category A/B. Pentazocine crosses the placenta; naloxone has limited placental transfer. No well-controlled human studies. First trimester: Risk cannot be excluded; avoid if possible. Second/Thi. 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. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.