Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE vs CLOMID
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 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.
Competitive antagonist of estrogen receptors (ER) in hypothalamus and pituitary, leading to increased gonadotropin-releasing hormone (Gn RH) and subsequent LH and FSH release, stimulating ovulation.
Moderate to severe pain where an opioid analgesic is appropriate
Treatment of ovulatory dysfunction in women desiring pregnancy (FDA approved),Off-label: treatment of male infertility (oligospermia)
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).
50 mg orally once daily for 5 days, starting on day 5 of the menstrual cycle. May increase to 100 mg daily if no response.
Acetaminophen: 2-3 hours (prolonged in hepatic impairment). Pentazocine: 2-3 hours (terminal), with clinical analgesic effect lasting 3-4 hours.
Terminal half-life is 5–7 days for zuclomiphene (active isomer), with prolonged elimination due to enterohepatic recirculation.
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).
Hepatic via CYP3A4 and CYP2D6; undergoes enterohepatic circulation; terminal half-life ~5-7 days
Acetaminophen: renal (2-4% unchanged, ~85% as glucuronide and sulfate conjugates). Pentazocine: renal (~60% as unchanged and conjugates), biliary/fecal (~20%).
Primarily hepatic metabolism; metabolites excreted in feces (42%) and urine (8% unchanged).
Acetaminophen: 10-25% (albumin). Pentazocine: 60-70% (albumin and alpha-1 acid glycoprotein).
Highly protein bound (>99%), primarily to albumin.
Acetaminophen: 0.9 L/kg. Pentazocine: 5-7 L/kg (extensive tissue distribution).
Not well-characterized; limited data suggest a large Vd (>100 L) due to extensive tissue distribution.
Acetaminophen oral: 60-90%. Pentazocine oral: ~20% (extensive first-pass metabolism). Intramuscular: pentazocine 100%.
Oral bioavailability is approximately 50% due to first-pass metabolism.
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 specific adjustment required; use caution in severe impairment (Cr Cl <30 m L/min) as data limited.
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.
Contraindicated in severe hepatic impairment (Child-Pugh class C). For mild to moderate impairment, no adjustment recommended, but monitor liver function.
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).
Not indicated for use in children; safety and efficacy not established.
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.
Not indicated for postmenopausal women. Use not recommended in elderly due to lack of efficacy in anovulation.
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.
None
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
Ovarian hyperstimulation syndrome (OHSS),Ovarian enlargement,Visual disturbances (especially with prolonged use),Multiple pregnancy (increased risk),Ectopic pregnancy,Ovarian cancer risk (theoretical, based on prolonged use)
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)
Pregnancy (Category X),Liver disease or dysfunction,Undiagnosed abnormal vaginal bleeding,Ovarian cyst or enlargement not due to polycystic ovary syndrome,Hypersensitivity to clomiphene or components
Avoid alcohol consumption due to increased risk of hepatotoxicity from acetaminophen. No specific food interactions; take with food if gastrointestinal upset occurs.
No specific food interactions. Avoid grapefruit as it may alter metabolism (theoretical due to CYP3A4 involvement).
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.
Clomiphene citrate is contraindicated in pregnancy. It is associated with an increased risk of fetal malformations, including neural tube defects, specifically when exposure occurs during the first trimester. Second and third trimester risks are not well studied due to contraindication, but theoretical risks include ovarian hyperstimulation syndrome (OHSS) effects on pregnancy.
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.
Safety in breastfeeding is not established. Clomiphene may reduce milk production. The M/P ratio is unknown. It is generally not recommended during breastfeeding.
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.
No dose adjustments are relevant as clomiphene is contraindicated in pregnancy. Pharmacokinetic changes in pregnancy are not applicable due to contraindication.
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.
Monitor ovarian size via ultrasound to reduce risk of ovarian hyperstimulation syndrome (OHSS). Limit course to 3-6 cycles due to increased risk of ovarian tumors. Check pregnancy test before each cycle. Use with caution in liver disease.
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.
Take exactly as prescribed, typically 50 mg daily for 5 days starting on day 5 of menstrual cycle.,Report abdominal pain, bloating, nausea, or weight gain (possible OHSS).,Avoid alcohol due to hepatotoxicity risk.,Most pregnancies occur within first 3 cycles; consider alternative after 6 cycles.,May cause visual disturbances; report blurred vision or spots.
"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."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE vs CLOMID, answered by our medical review team.
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.. CLOMID is a Selective Estrogen Receptor Modulator that works by Competitive antagonist of estrogen receptors (ER) in hypothalamus and pituitary, leading to increased gonadotropin-releasing hormone (Gn RH) and subsequent LH and FSH release, stimulating ovulation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE and CLOMID 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 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).. The standard adult dose of CLOMID is: 50 mg orally once daily for 5 days, starting on day 5 of the menstrual cycle. May increase to 100 mg daily if no response.. 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 ACETAMINOPHEN AND PENTAZOCINE HYDROCHLORIDE and CLOMID 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. 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. CLOMID is classified as Category C. Clomiphene citrate is contraindicated in pregnancy. It is associated with an increased risk of fetal malformations, including neural tube defects, specifically when exposure occurs. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.