Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DUTASTERIDE vs ACETAMINOPHEN AND CODEINE PHOSPHATE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Competitive inhibitor of type II and type I 5α-reductase isoenzymes, blocking conversion of testosterone to dihydrotestosterone (DHT) in prostate, hair follicles, and other tissues.
Acetaminophen: centrally acting analgesic and antipyretic, possibly via inhibition of cyclooxygenase (COX) and modulation of cannabinoid receptors. Codeine: prodrug converted to morphine; mu-opioid receptor agonist.
FDA: Treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate,FDA: Reduce risk of acute urinary retention,FDA: Reduce need for BPH-related surgery,Off-label: Male androgenetic alopecia
Mild to moderate pain,Pain accompanied by fever
0.5 mg orally once daily.
One or two tablets (acetaminophen 300 mg/codeine 30 mg per tablet) orally every 4-6 hours as needed for pain; maximum 12 tablets daily.
Terminal half-life approximately 3-4 weeks (21-35 days) in young adults; 5-6 weeks in elderly; supports once-daily dosing due to slow elimination.
Acetaminophen: 2–3 hours (prolonged in hepatic impairment). Codeine: 2.5–3.5 hours; metabolites: morphine 1.5–2.5 hours, codeine-6-glucuronide 3–4 hours. Clinical context: dosing interval every 4–6 hours.
Extensively metabolized in liver via CYP3A4 and CYP1A2; minor metabolism by CYP2C8, CYP2C9, CYP2C19, and CYP2D6.
Acetaminophen: primarily glucuronidation and sulfation in liver; minor CYP450 (CYP2E1) to toxic NAPQI. Codeine: CYP2D6 to morphine; CYP3A4 to norcodeine; glucuronidation.
Primarily fecal (70%) as metabolites; renal excretion accounts for <5% unchanged drug.
Acetaminophen: renal elimination of conjugated metabolites (glucuronide 60%, sulfate 30%, cysteine/mercapturate <5%), less than 5% unchanged. Codeine: renal elimination of codeine (5–15%), morphine (5–10%), norcodeine (10–20%), and conjugates; 90% excreted in urine within 24 hours.
>99% bound to albumin and alpha-1 acid glycoprotein; high affinity.
Acetaminophen: 10–25% (albumin). Codeine: 7–25% (primarily albumin).
Approximately 300-500 L (3-5 L/kg), indicating extensive tissue distribution, particularly to prostate and seminal vesicles.
Acetaminophen: 0.9 L/kg. Codeine: 3–6 L/kg (extensive tissue distribution).
Oral: Approximately 60% (range 40-80%) with food; not administered parenterally.
Oral: acetaminophen 88% (variable first-pass); codeine 50–60% (first-pass metabolism to morphine, norcodeine, and conjugates).
No dose adjustment required for renal impairment (including dialysis).
GFR 30-50 m L/min: administer every 6 hours; GFR 10-29 m L/min: administer every 8 hours; GFR <10 m L/min: administer every 12 hours; hemodialysis: not recommended.
Contraindicated in Child-Pugh Class C; use with caution in mild to moderate impairment (Child-Pugh A/B) with no specific dose adjustment established.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50% and extend interval to every 8 hours; Child-Pugh C: contraindicated.
Not indicated in pediatric patients; safety and efficacy not established.
For children ≥12 years: acetaminophen 10-15 mg/kg/dose and codeine 0.5-1 mg/kg/dose orally every 4-6 hours; maximum acetaminophen 75 mg/kg/day, codeine 6 mg/kg/day. For children <12 years: not recommended due to codeine safety concerns.
No specific dose adjustment required; monitor for adverse effects (e.g., dizziness, orthostatic hypotension) due to age-related comorbidities.
Start with lowest effective dose; acetaminophen component maximum 3 g/day; consider reduced codeine dose (e.g., 15 mg) due to increased sensitivity and risk of respiratory depression; extend dosing interval to every 6-8 hours.
No FDA black box warning.
Risk of medication errors: confusion between milligram and milliliter doses, and between codeine and acetaminophen components. Contraindicated for postoperative pain management in children following tonsillectomy/adenoidectomy due to risk of respiratory depression and death.
Risk of high-grade prostate cancer in men aged 50-79 with elevated PSA and previous negative biopsy (see PLCO trial),Increased risk of sexual adverse events (impotence, decreased libido, ejaculation disorders) that may persist after discontinuation,Elevated PSA levels: use caution when interpreting PSA values; establish new baseline after 6 months of treatment
Hepatotoxicity (acetaminophen overdose); respiratory depression; drug dependence; ultra-rapid metabolizers of codeine (CYP2D6) leading to morphine toxicity; concomitant CNS depressants; use in pediatric patients; avoid alcohol.
Women of childbearing potential (pregnancy category X; risk of fetal harm due to inhibition of 5α-reductase),History of hypersensitivity to dutasteride or other 5α-reductase inhibitors,Pediatric patients
Hypersensitivity to acetaminophen or codeine; severe respiratory depression; acute or severe asthma; paralytic ileus; post-operative pain management in children after tonsillectomy/adenoidectomy; breastfeeding (in ultra-rapid metabolizers); concomitant MAOIs.
No clinically significant food interactions. May be taken with or without food. Grapefruit juice does not affect dutasteride levels to a clinically relevant extent.
Avoid alcohol; high-fat meals may delay absorption but not clinically significant.
Dutasteride is contraindicated in pregnancy. It is a 5α-reductase inhibitor that can inhibit the conversion of testosterone to dihydrotestosterone (DHT), potentially causing abnormal development of external genitalia in male fetuses. Risk extends throughout all trimesters due to potential disruption of androgen-mediated development in male fetuses during the first trimester and cumulative effects from drug accumulation in adipose tissue. No adequate human studies exist; animal studies show teratogenicity in male offspring at clinically relevant doses.
Acetaminophen is considered low risk in all trimesters at therapeutic doses; chronic high doses may be associated with adverse outcomes. Codeine is associated with risk of respiratory depression and neonatal withdrawal if used near term; may cause neural tube defects and other malformations with first-trimester exposure, but data are conflicting. Use lowest effective dose for shortest duration.
No data on dutasteride in human milk. M/P ratio unknown. Dutasteride is highly lipophilic and likely excreted in breast milk. Because of potential adverse effects on the nursing infant (e.g., interference with androgen-mediated development in male infants), breastfeeding is contraindicated during therapy and for at least 6 months after the last dose due to long half-life (approximately 5 weeks).
Acetaminophen is excreted into breast milk in low amounts (M/P ratio ~0.91-1.42) and is considered compatible with breastfeeding. Codeine is also excreted in breast milk; risk of infant opioid toxicity depends on maternal CYP2D6 phenotype. Ultra-rapid metabolizers may produce higher morphine levels. Use with caution, avoid in known CYP2D6 ultra-rapid metabolizers, and monitor infant for sedation and respiratory depression.
No dose adjustment studies in pregnancy because dutasteride is contraindicated. Pharmacokinetic changes in pregnancy (increased volume of distribution, altered metabolism) could affect dutasteride levels, but no adjustments are recommended as drug should not be used. If inadvertently used, discontinue immediately and monitor for adverse effects.
No routine dose adjustment needed for acetaminophen. Codeine pharmacokinetics are altered in pregnancy: increased clearance and volume of distribution may require dose adjustment; however, due to variability in CYP2D6 metabolism, individualize dosing and monitor for efficacy and toxicity. Avoid codeine in pregnancy unless alternative analgesics are ineffective.
Monitor PSA levels cautiously, as dutasteride reduces serum PSA by approximately 50% after 6 months; double the PSA value for comparison to untreated men. Do not handle crushed or broken capsules if pregnant or planning pregnancy, as absorption through skin may cause fetal harm. Assess for signs of high-grade prostate cancer before initiating therapy, as dutasteride may increase the risk of Gleason 8-10 tumors. Onset of symptom relief may take 3-6 months; do not discontinue prematurely. Avoid concomitant use with strong CYP3A4 inhibitors (e.g., ritonavir, ketoconazole) as they increase dutasteride exposure.
For acute pain, limit codeine to 3 days; avoid in children under 12 due to CYP2D6 ultra-rapid metabolizer risk of fatal respiratory depression; monitor for constipation; assess liver function for acetaminophen hepatotoxicity; use with caution in renal impairment.
Take exactly as prescribed; do not stop or change dose without consulting your doctor.,Swallow the capsule whole; do not chew or open it.,It may take 3 to 6 months to see improvement in symptoms.,Avoid handling leaking or crushed capsules if you are a woman who is or may become pregnant; wash area immediately with soap and water if skin contact occurs.,Do not donate blood for at least 6 months after your last dose to prevent exposure to a pregnant woman.,Report any breast lumps, pain, or nipple discharge promptly.,You will need regular blood tests for PSA level monitoring; inform your doctor that you are taking dutasteride.,Dutasteride can decrease sperm count and may affect fertility; discuss this with your doctor if planning to father a child.
Take exactly as prescribed; do not exceed 4000 mg acetaminophen per day.,Avoid alcohol while taking this medication.,Do not use with other acetaminophen-containing products.,May cause dizziness or drowsiness; avoid driving until you know how you react.,Common side effects include constipation, nausea, and drowsiness.,Seek emergency if signs of allergic reaction or difficulty breathing occur.
"Dutasteride, a 5α-reductase inhibitor, may inhibit cytochrome P450 enzymes, particularly CYP3A4, which is involved in the metabolism of sulfisoxazole. This inhibition can lead to decreased clearance of sulfisoxazole, resulting in elevated plasma concentrations. Increased sulfisoxazole levels may potentiate its adverse effects, including hypersensitivity reactions, crystalluria, and hematologic toxicity such as agranulocytosis."
"Concomitant use of dutasteride, a 5α-reductase inhibitor, with nelfinavir, a protease inhibitor and potent CYP3A4 inhibitor, is predicted to increase the serum concentration of nelfinavir. This occurs because dutasteride may inhibit the metabolism of nelfinavir via competition for CYP3A4, leading to elevated nelfinavir levels and an increased risk of adverse effects such as gastrointestinal disturbances, hepatotoxicity, and metabolic complications. Clinical monitoring for toxicity and dose adjustments are warranted."
"Dutasteride, a 5α-reductase inhibitor, is metabolized primarily by CYP3A4 and to a lesser extent by CYP2D6. Itraconazole is a potent inhibitor of CYP3A4 and also inhibits P-glycoprotein. Coadministration leads to significantly increased serum concentrations of dutasteride, raising the risk of adverse effects such as gynecomastia, sexual dysfunction, and depression. The effect on itraconazole levels is minimal and clinically irrelevant."
"Pirenzepine, a selective M1 muscarinic antagonist, reduces gastrointestinal motility and secretions, while codeine, an opioid agonist, also decreases gastrointestinal motility via mu-opioid receptors. Concurrent use leads to additive anticholinergic and opioid effects, resulting in enhanced risk of severe constipation, paralytic ileus, and central nervous system depression. Clinically, patients may experience exacerbated sedation, respiratory depression, and urinary retention."
"Ropinirole, a non-ergoline dopamine agonist used in Parkinson's disease and restless legs syndrome, may reduce the analgesic efficacy of codeine. This is likely due to pharmacodynamic antagonism at central dopamine and opioid receptors, as well as potential pharmacokinetic interactions that decrease the conversion of codeine to its active metabolite morphine via CYP2D6 inhibition by ropinirole. The resultant blunted opioid response can lead to inadequate pain control, necessitating dose adjustment or alternative therapy."
"Vemurafenib induces CYP3A4, significantly reducing the plasma concentrations of codeine, which is metabolized via CYP3A4 to its active metabolite morphine. This may diminish codeine's analgesic efficacy, potentially leading to inadequate pain control. Additionally, reduced formation of morphine may lower the risk of opioid-related adverse effects."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about DUTASTERIDE vs ACETAMINOPHEN AND CODEINE PHOSPHATE, answered by our medical review team.
DUTASTERIDE is a 5-alpha Reductase Inhibitor that works by Competitive inhibitor of type II and type I 5α-reductase isoenzymes, blocking conversion of testosterone to dihydrotestosterone (DHT) in prostate, hair follicles, and other tissues.. ACETAMINOPHEN AND CODEINE PHOSPHATE is a Opioid Agonist that works by Acetaminophen: centrally acting analgesic and antipyretic, possibly via inhibition of cyclooxygenase (COX) and modulation of cannabinoid receptors. Codeine: prodrug converted to morphine; mu-opioid receptor agonist.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DUTASTERIDE and ACETAMINOPHEN AND CODEINE PHOSPHATE 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 DUTASTERIDE is: 0.5 mg orally once daily.. The standard adult dose of ACETAMINOPHEN AND CODEINE PHOSPHATE is: One or two tablets (acetaminophen 300 mg/codeine 30 mg per tablet) orally every 4-6 hours as needed for pain; maximum 12 tablets 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 DUTASTERIDE and ACETAMINOPHEN AND CODEINE PHOSPHATE 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. DUTASTERIDE is classified as Category D/X. Dutasteride is contraindicated in pregnancy. It is a 5α-reductase inhibitor that can inhibit the conversion of testosterone to dihydrotestosterone (DHT), potentially causing abnorm. ACETAMINOPHEN AND CODEINE PHOSPHATE is classified as Category D/X. Acetaminophen is considered low risk in all trimesters at therapeutic doses; chronic high doses may be associated with adverse outcomes. Codeine is associated with risk of respirat. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.