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 CODOXY
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.
Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, although it can bind to other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Like all full opioid agonists, there is no ceiling effect for analgesia. Oxycodone is combined with aspirin to provide additive analgesic effects.
Moderate to severe pain relief; combinations are used to reduce abuse potential.
Management of moderate to moderately severe pain where the use of an opioid analgesic is appropriate
Oral: One tablet (naloxone 0.5 mg / pentazocine 50 mg) every 3-4 hours as needed for pain; maximum 12 tablets daily.
1-2 capsules orally every 4-6 hours as needed for pain, not to exceed 8 capsules per day. Each capsule contains 5 mg hydrocodone bitartrate and 325 mg acetaminophen.
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 half-life is 3.5 hours in patients with normal renal function; extends to 5-8 hours in moderate renal impairment.
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).
Oxycodone is metabolized by CYP3A4 and CYP2D6. N-demethylation to noroxycodone (via CYP3A4) is the primary metabolic pathway. CYP2D6-mediated O-demethylation to oxymorphone is a minor pathway but produces a more potent metabolite.
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.
Renal excretion of unchanged drug accounts for approximately 70% of elimination; biliary/fecal excretion accounts for 30%.
Pentazocine: Approximately 35-65% bound to plasma proteins (mainly albumin). Naloxone: Approximately 32-45% bound to plasma proteins (mainly albumin).
Approximately 92% bound to albumin.
Pentazocine: Vd ~2-3 L/kg, indicating extensive tissue distribution. Naloxone: Vd ~2-3 L/kg, also indicating wide distribution.
2.4 L/kg; indicates extensive tissue distribution.
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: 60-70% due to first-pass metabolism.
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.
For GFR 30-50 m L/min: administer every 8 hours. For GFR 10-29 m L/min: administer every 12 hours. For GFR <10 m L/min: use not recommended.
Child-Pugh Class A: No adjustment; Child-Pugh Class B: Reduce dose by 50% or extend interval; Child-Pugh Class C: Avoid use.
Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce dose by 50% and extend interval to every 8 hours. Child-Pugh Class C: contraindicated.
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.
For children ≥2 years: 0.1-0.2 mg/kg hydrocodone component every 4-6 hours as needed, maximum 6 doses per day. Use weight-based dosing; do not exceed acetaminophen 75 mg/kg/day.
Initiate with half the usual adult dose (one-half tablet) and titrate carefully due to increased sensitivity and risk of respiratory depression.
Initiate at lowest effective dose (e.g., 1 capsule every 6 hours) due to increased risk of respiratory depression and falls. Titrate cautiously. Maximum 6 capsules per day.
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.
Addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal syndrome; risks from concomitant use with benzodiazepines or other CNS depressants; and interactions with drugs affecting cytochrome P450 isoenzymes.
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.
Addiction, abuse, and misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal syndrome; risks from concomitant use with benzodiazepines or other CNS depressants; severe hypotension; gastrointestinal obstruction; seizures; serotonin syndrome; adrenal insufficiency; and androgen deficiency.
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.
Significant respiratory depression; acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment; known or suspected gastrointestinal obstruction, including paralytic ileus; hypersensitivity to oxycodone, aspirin, or any component of the formulation.
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.
Avoid alcohol and grapefruit juice. Alcohol potentiates CNS depression. Grapefruit juice may increase codeine metabolism via CYP3A4, leading to variable effects. No significant food restrictions otherwise; take with food if GI upset occurs.
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.
No human data; animal studies not available. Avoid during pregnancy, especially first trimester, due to potential oxycodone-induced neural tube defects.
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.
Oxycodone is excreted into breast milk; M/P ratio ~3.6:1. Risk of infant sedation and respiratory depression. Contraindicated during breastfeeding.
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.
No established dose adjustments; increased clearance in pregnancy may require higher doses for analgesia, but use is contraindicated.
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.
CODOXY is a fixed-dose combination of codeine (opioid) and doxylamine (antihistamine). Use lowest effective dose for shortest duration due to opioid dependence and respiratory depression risk. Avoid in children <12 years for post-tonsillectomy pain and in those <18 with respiratory compromise. Monitor for CNS depression, especially with alcohol. Doxylamine adds anticholinergic effects (constipation, dry mouth, urinary retention). Caution in elderly, renal impairment, and breastfeeding.
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.
Take exactly as prescribed; do not increase dose or frequency without consulting your doctor.,This medication may cause drowsiness, dizziness, or blurred vision; avoid driving or operating machinery until you know how it affects you.,Avoid alcohol and other sedatives (e.g., benzodiazepines, sleep aids) as they increase risk of severe drowsiness and breathing problems.,Do not use with other products containing codeine or antihistamines (including cough/cold medicines).,Store securely away from children; misuse can cause addiction, overdose, or death.,If you are pregnant, plan to become pregnant, or are breastfeeding, inform your healthcare provider before use.,Common side effects: constipation, dry mouth, nausea. Increase fluid intake and fiber to prevent constipation.,Seek emergency help if you experience slow or shallow breathing, confusion, or fainting.
"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 CODOXY, 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.. CODOXY is a Antitussive Combination that works by Oxycodone is a full opioid agonist with relative selectivity for the mu-opioid receptor, although it can bind to other opioid receptors at higher doses. The principal therapeutic action of oxycodone is analgesia. Like all full opioid agonists, there is no ceiling effect for analgesia. Oxycodone is combined with aspirin to provide additive analgesic effects.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between NALOXONE HYDROCHLORIDE AND PENTAZOCINE HYDROCHLORIDE and CODOXY 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 CODOXY is: 1-2 capsules orally every 4-6 hours as needed for pain, not to exceed 8 capsules per day. Each capsule contains 5 mg hydrocodone bitartrate and 325 mg acetaminophen.. 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 CODOXY 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. CODOXY is classified as Category C. No human data; animal studies not available. Avoid during pregnancy, especially first trimester, due to potential oxycodone-induced neural tube defects.. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.