Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
ACEPHEN vs UPTRAVI
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
ACEPHEN (acetaminophen) is a para-aminophenol derivative with analgesic and antipyretic activity. Its mechanism involves inhibition of cyclooxygenase (COX) enzymes in the central nervous system, particularly COX-2, reducing prostaglandin synthesis. It has weak peripheral COX inhibition and minimal anti-inflammatory effect.
Uptravi (selexipag) is a prostacyclin receptor (IP receptor) agonist. Selexipag and its active metabolite, ACT-333679, selectively bind to the IP receptor, leading to vasodilation, inhibition of platelet aggregation, and antiproliferative effects on smooth muscle cells.
Mild to moderate pain,Fever
Treatment of pulmonary arterial hypertension (PAH, WHO Group I) to delay disease progression and reduce the risk of hospitalization,Off-label: None established
325-650 mg orally every 4-6 hours as needed; maximum 4 g/day.
Initial dose 200 mcg orally twice daily, titrated in increments of 200 mcg twice daily at weekly intervals to a maximum of 1600 mcg twice daily.
Terminal elimination half-life: 1.0-1.5 hours in adults with normal renal function. Prolonged to 2-5 hours in hepatic impairment or elderly; requires dose adjustment in severe hepatic disease.
Terminal elimination half-life is approximately 7–9 hours in healthy subjects, but prolonged in patients with hepatic impairment (Child-Pugh class A: ~11 hours; class B: ~16 hours). Steady-state is reached within 2–4 days of twice-daily dosing.
Acetaminophen is primarily metabolized in the liver via glucuronidation (UGT1A1, UGT1A6, UGT1A9) and sulfation (SULT1A1, SULT1A3). A minor fraction is oxidized by cytochrome P450 enzymes (CYP2E1, CYP1A2, CYP3A4) to a reactive toxic metabolite (NAPQI), which is normally detoxified by conjugation with glutathione.
Selexipag is hydrolyzed by carboxylesterases (mainly CES1 and CES2) to its active metabolite, ACT-333679. Both are further metabolized by CYP3A4 and CYP2C8. ACT-333679 is also a substrate for UGT1A3 and UGT2B7.
Renal: 90-95% as unchanged drug; tubular secretion and glomerular filtration. Biliary/fecal: <5%.
Primarily hepatic metabolism; renal excretion of unchanged drug is <1%. Fecal excretion accounts for approximately 70% of total elimination, mainly as metabolites. Biliary excretion contributes to fecal elimination.
Approximately 10-20% bound to serum albumin; extensive tissue binding.
99% bound to plasma proteins, primarily to albumin and alpha-1-acid glycoprotein.
Apparent Vd: 0.5-0.7 L/kg (30-40 L in a 70 kg adult). Distributions into CSF and breast milk.
Approximately 0.3 L/kg in healthy subjects, indicating distribution primarily within the vascular space and well-perfused tissues.
Oral: 85-90% (first-pass metabolism minimal). Rectal: approximately 70-80% of oral bioavailability.
Oral bioavailability is approximately 50–60% due to first-pass metabolism. Food does not significantly affect absorption.
GFR 10-50 m L/min: 650 mg every 6 hours; GFR <10 m L/min: 650 mg every 8 hours.
No dose adjustment required for mild to moderate renal impairment (e GFR ≥15 m L/min/1.73 m²). Not studied in severe renal impairment (e GFR <15 m L/min/1.73 m²) or on dialysis; use caution.
Child-Pugh Class A: no adjustment; Child-Pugh Class B: maximum 2 g/day; Child-Pugh Class C: maximum 1 g/day.
Mild hepatic impairment (Child-Pugh A): No dose adjustment. Moderate hepatic impairment (Child-Pugh B): Initial dose 200 mcg once daily, titrate cautiously. Severe hepatic impairment (Child-Pugh C): Not recommended.
10-15 mg/kg/dose orally every 4-6 hours; maximum 75 mg/kg/day or 4 g/day, whichever is less.
Not indicated for pediatric patients; safety and efficacy not established in patients <18 years.
Start at lowest effective dose (325 mg every 6 hours); avoid exceeding 3 g/day unless closely monitored.
No specific dose adjustment recommended; elderly patients may have increased sensitivity, monitor closely.
Acetaminophen has been associated with cases of acute liver failure, at times resulting in liver transplant and death. Most of the cases of liver injury are associated with the use of acetaminophen at doses that exceed 4,000 milligrams per day, and often involve more than one acetaminophen-containing product.
None.
Risk of severe liver injury with doses >4000 mg/day; use caution with hepatic impairment, chronic alcoholism, malnutrition, or concomitant hepatotoxic drugs; avoid exceeding recommended dose; limit use to 10 days for pain or 3 days for fever unless directed by physician; serious skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis) have occurred.
Pulmonary edema may occur; consider the possibility of pulmonary veno-occlusive disease (PVOD) if symptoms develop,Hepatic impairment: Avoid use in severe hepatic impairment (Child-Pugh Class C),Concomitant use with strong CYP2C8 inhibitors (e.g., gemfibrozil) increases exposure; reduce dose or consider alternative,Concomitant use with strong CYP3A4 inducers (e.g., rifampin) may reduce efficacy; monitor for loss of effect
Hypersensitivity to acetaminophen or any component of the formulation; severe hepatic impairment or active liver disease.
Severe hepatic impairment (Child-Pugh Class C),Concomitant use with strong CYP2C8 inhibitors (e.g., gemfibrozil)
Alcohol: increased risk of hepatotoxicity. Avoid concurrent use. Food: no significant interaction, but taking with food may reduce minor gastrointestinal irritation.
Avoid grapefruit juice as it may increase systemic exposure to UPTRAVI. Take with or without food, but consistent timing with meals is recommended to maintain stable drug levels.
Pregnancy Category C. First trimester: potential risk of neural tube defects and orofacial clefts (limited human data, animal studies show embryotoxicity). Second and third trimesters: NSAID exposure associated with oligohydramnios, premature ductus arteriosus constriction, and fetal renal impairment. Avoid in third trimester.
In animal studies, UPTRAVI (selexipag) and its active metabolite showed developmental toxicity including reduced fetal weights and increased skeletal variations at maternal toxic doses. No adequate and well-controlled studies in pregnant women. Risk cannot be ruled out. First trimester: potential teratogenicity based on animal data. Second and third trimesters: may cause fetal harm due to pharmacological action (IP receptor agonist) potentially affecting uterine blood flow.
Excreted into breast milk in low concentrations (M/P ratio approximately 0.10). Considered compatible with breastfeeding; however, use lowest effective dose for shortest duration given potential for neonatal adverse effects (e.g., thrombocytopenia, renal dysfunction).
No data on presence in human milk, effects on breastfed infant, or milk production. M/P ratio is unknown. The active metabolite is potentially excreted in animal milk. Due to potential for serious adverse reactions, breastfeeding is not recommended during treatment and for at least 2 days after final dose.
No standard dose adjustments recommended; however, due to increased plasma volume and metabolism in pregnancy, higher doses may be required to achieve therapeutic effect. Avoid near term.
No pharmacokinetic studies in pregnant women. Pregnancy may alter drug metabolism (e.g., increased clearance, Vd). No specific dose adjustment recommendations; use only if benefit outweighs risk. Close clinical monitoring for efficacy and tolerability.
ACEPHEN (acetaminophen) is commonly used for mild to moderate pain and fever. Avoid exceeding 4 g/day in adults to prevent hepatotoxicity. In patients with hepatic impairment, reduce maximum daily dose to 2 g. Consider acetylcysteine for overdose. Onset of action is 15-30 minutes orally.
Titrate to maximum tolerated dose up to 1600 mg twice daily. Monitor for signs of pulmonary edema (PPH with veno-occlusive disease). Co-administration with strong CYP2C8 inhibitors (e.g., gemfibrozil) reduces UPTRAVI clearance; decrease dose by 50% during co-administration. Avoid abrupt discontinuation; taper if possible. May cause orthostatic hypotension; assess blood pressure regularly. UPTRAVI is a prodrug of the active metabolite ACT-333679, a selective prostacyclin receptor (IP receptor) agonist.
Do not exceed 4000 mg (4 grams) in 24 hours.,Avoid drinking alcohol while taking this medication.,Do not combine with other products containing acetaminophen.,Take with food if stomach upset occurs.,Seek immediate medical help if you experience symptoms of liver damage: yellowing of skin/eyes, dark urine, severe abdominal pain.
Take exactly as prescribed; do not crush or split tablets.,Do not stop taking this medication suddenly; consult your doctor if you need to discontinue.,Avoid grapefruit juice as it may increase drug exposure.,Report any severe headaches, jaw pain, or flushing to your healthcare provider.,Use caution when driving or operating machinery until you know how this medication affects you.,Store at room temperature away from moisture and heat.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about ACEPHEN vs UPTRAVI, answered by our medical review team.
ACEPHEN is a Non-Opioid Analgesic that works by ACEPHEN (acetaminophen) is a para-aminophenol derivative with analgesic and antipyretic activity. Its mechanism involves inhibition of cyclooxygenase (COX) enzymes in the central nervous system, particularly COX-2, reducing prostaglandin synthesis. It has weak peripheral COX inhibition and minimal anti-inflammatory effect.. UPTRAVI is a Prostacyclin Receptor Agonist that works by Uptravi (selexipag) is a prostacyclin receptor (IP receptor) agonist. Selexipag and its active metabolite, ACT-333679, selectively bind to the IP receptor, leading to vasodilation, inhibition of platelet aggregation, and antiproliferative effects on smooth muscle cells.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between ACEPHEN and UPTRAVI 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 ACEPHEN is: 325-650 mg orally every 4-6 hours as needed; maximum 4 g/day.. The standard adult dose of UPTRAVI is: Initial dose 200 mcg orally twice daily, titrated in increments of 200 mcg twice daily at weekly intervals to a maximum of 1600 mcg 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 ACEPHEN and UPTRAVI 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. ACEPHEN is classified as Category C. Pregnancy Category C. First trimester: potential risk of neural tube defects and orofacial clefts (limited human data, animal studies show embryotoxicity). Second and third trimest. UPTRAVI is classified as Category C. In animal studies, UPTRAVI (selexipag) and its active metabolite showed developmental toxicity including reduced fetal weights and increased skeletal variations at maternal toxic d. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.