Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OFIRMEV vs ASTAGRAF XL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
OFIRMEV (acetaminophen) is a para-aminophenol derivative with analgesic and antipyretic activity. Its mechanism of action is not fully understood, but it is thought to involve inhibition of cyclooxygenase (COX) enzymes in the central nervous system, with minimal peripheral COX inhibition. It may also act on serotonergic pathways and cannabinoid receptors.
Calcineurin inhibitor that binds to FKBP-12, forming a complex that inhibits calcineurin, thereby preventing dephosphorylation and nuclear translocation of NFAT, which reduces T-cell activation and cytokine production (e.g., IL-2).
Management of mild to moderate pain,Management of moderate to severe pain with adjunctive opioid analgesics,Reduction of fever
Prophylaxis of organ rejection in kidney transplant recipients,Prophylaxis of organ rejection in liver transplant recipients,Prophylaxis of organ rejection in heart transplant recipients
IV: 1000 mg every 6 hours or 650 mg every 4 hours; maximum single dose: 1000 mg; minimum dosing interval: 4 hours; maximum daily dose: 4000 mg.
Initial oral dose of 0.1-0.15 mg/kg/day divided every 12 hours, with subsequent adjustments based on trough levels. Typical maintenance dose 0.05-0.15 mg/kg/day.
Terminal elimination half-life is 2-3 hours in adults (2.5-3 hours in children). Clinically, dosing every 4-6 hours is needed to maintain therapeutic levels.
Terminal elimination half-life is approximately 43 hours (range 15.8–68.6 hours) in adult kidney transplant recipients. This long half-life supports once-daily dosing. In liver transplant patients, half-life ranges from 12 to 42 hours.
Acetaminophen is primarily metabolized in the liver via conjugation with glucuronide (50-60%) and sulfate (20-30%). A minor amount is oxidized by cytochrome P450 (CYP2E1, CYP1A2, CYP3A4) to a toxic reactive metabolite (NAPQI), which is normally detoxified by glutathione. At toxic doses, glutathione is depleted, leading to NAPQI accumulation and hepatotoxicity.
Primarily hepatic via CYP3A4 and CYP3A5; undergoes extensive first-pass metabolism. Substrate of P-glycoprotein.
Primarily renal (85% as sulfate and glucuronide conjugates, 10% as unchanged drug). Less than 5% fecal/biliary.
Primarily fecal (94.6%) via biliary elimination. Renal excretion accounts for approximately 2.4% of the dose, mainly as metabolites. Less than 1% is excreted unchanged in urine.
10-25% bound to albumin at therapeutic concentrations.
Approximately 99% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
0.8-1.0 L/kg. Indicates distribution into total body water.
Volume of distribution is 3.5–4.5 L/kg (wide distribution, indicating extensive tissue binding). High Vd reflects distribution into erythrocytes, lymphocytes, and tissues.
100% (intravenous); not applicable for other routes as OFIRMEV is IV only.
Oral bioavailability is highly variable, approximately 20–30% (range 5–89%). Absorption is incomplete and inconsistent; food decreases absorption by up to 33%. The modified-release formulation (Astagraf XL) has a lower peak and more sustained absorption compared to immediate-release.
No dose adjustment required for GFR ≥30 m L/min. For GFR <30 m L/min, extend dosing interval to every 8 hours; maximum daily dose 3000 mg.
For GFR <30 m L/min: reduce dose by 50% and monitor trough levels closely. No adjustment for GFR >30 m L/min.
Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce total daily dose by 50% (max 2000 mg/day). Child-Pugh Class C: Contraindicated or use with extreme caution; reduce dose to 50% of standard and extend interval to every 8 hours; maximum 2000 mg/day.
Child-Pugh Class A: no adjustment. Class B: reduce dose by 25%. Class C: reduce dose by 50% and monitor trough levels frequently.
Weight-based: <10 kg: 7.5 mg/kg/dose every 6 hours; 10-50 kg: 15 mg/kg/dose every 6 hours; >50 kg: 1000 mg every 6 hours or 650 mg every 4 hours. Maximum single dose: 15 mg/kg (up to 1000 mg); maximum daily dose: 75 mg/kg (up to 4000 mg).
Initial oral dose 0.15-0.2 mg/kg/day divided every 12 hours. Adjust to target trough levels of 5-15 ng/m L. Maximum dose 0.3 mg/kg/day.
No specific dose adjustment; consider reduced renal function. For Cr Cl <30 m L/min, extend interval to every 8 hours. Maximum daily dose: 3000 mg in frail elderly or with comorbidities.
Start at lower end of adult dosing range (0.05 mg/kg/day) and titrate slowly due to reduced renal function and increased risk of adverse effects. Monitor trough levels 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 4000 mg per day, and often involve more than one acetaminophen-containing product.
Increased susceptibility to infection and possible development of lymphoma and other malignancies, particularly of the skin, due to immunosuppression. Increased nephrotoxicity, especially when used with other nephrotoxic drugs.
Risk of serious hepatotoxicity, especially with doses >4000 mg/day or in patients with underlying liver disease,Risk of severe skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalized exanthematous pustulosis) – discontinue at first sign of rash,Risk of hypersensitivity reactions including anaphylaxis,Use caution in patients with severe hepatic impairment, active hepatic disease, or alcoholism,Avoid concurrent use of other acetaminophen-containing products
Nephrotoxicity, neurotoxicity (tremor, headache, seizures), hypertension, hyperkalemia, hyperglycemia, increased risk of infections and malignancies (especially skin), and lymphoproliferative disorders. Monitor blood pressure, renal function, electrolytes, and drug levels.
Known hypersensitivity to acetaminophen or any component of the formulation,Severe hepatic impairment or active liver disease (relative contraindication without black box)
Hypersensitivity to tacrolimus or any component of the formulation; concurrent use with cyclosporine or other calcineurin inhibitors.
No known food interactions. However, avoid excessive alcohol consumption as it may increase the risk of liver damage.
Grapefruit juice significantly increases tacrolimus AUC and Cmax; avoid concurrent use. High-fat meals may decrease absorption; maintain consistent fat intake with each dose to ensure stable levels. Avoid taking with alcohol or herbal supplements like St. John's wort, which may reduce efficacy.
Acetaminophen (OFIRMEV) is generally considered low risk across all trimesters. No increased risk of major congenital anomalies has been consistently demonstrated. Chronic high-dose use in third trimester may be associated with preterm birth or low birth weight. Avoid prolonged use above recommended doses.
Tacrolimus is classified as FDA Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. In animal studies, tacrolimus caused maternal toxicity and embryotoxicity at doses higher than those used clinically. First trimester exposure is associated with an increased risk of congenital anomalies, including cardiac malformations. Second and third trimester use has been linked with intrauterine growth restriction, preterm delivery, and transient neonatal hyperkalemia and renal dysfunction. Postnatal immunosuppression in the neonate may occur.
Acetaminophen is excreted in breast milk in low concentrations (M/P ratio approximately 0.9-1.0). Considered compatible with breastfeeding; peak milk levels occur 1-2 hours after maternal dosing. Use lowest effective dose for shortest duration.
Tacrolimus is excreted into human breast milk with a milk-to-plasma (M/P) ratio of approximately 0.3. Limited data suggest low infant exposure (relative infant dose 0.5% of maternal weight-adjusted dose). However, because of potential for infant immunosuppression and growth effects, breastfeeding is generally not recommended unless benefits outweigh risks. Monitor infant for trough levels if breastfeeding.
No dose adjustment required during pregnancy. Pharmacokinetic changes in pregnancy (increased volume of distribution, clearance) may lead to lower peak concentrations but standard dosing remains effective. Maximum single dose: 1 g; maximum daily dose: 4 g.
Pregnancy increases tacrolimus clearance due to expanded plasma volume and altered cytochrome P450 3A4 activity. Dose requirements may increase by 25-50% during the second and third trimesters. Therapeutic drug monitoring is essential, targeting trough levels 5-10 ng/m L. Postpartum, doses should be reduced to prepregnancy levels within 1-2 weeks as clearance normalizes.
OFIRMEV (acetaminophen) injection is an IV formulation of acetaminophen used for pain and fever management. It is a prodrug that requires no hepatic conversion, providing rapid onset of action. Monitor for hepatotoxicity; maximum daily dose is 4 grams in adults but lower in patients with hepatic impairment or malnutrition. Do not exceed 1 gram per dose. Hypotension and anaphylaxis have been reported. Not interchangeable with oral acetaminophen due to dose equivalency. Use with caution in patients with alcohol use disorder.
Monitor trough levels 5-15 ng/m L; avoid using with sirolimus due to increased risk of thrombotic microangiopathy; conversion from tacrolimus immediate-release is 1:1 (mg:mg) but monitor levels closely for 2 weeks; administer consistently with or without food to avoid fluctuations.
OFIRMEV is given intravenously for pain or fever.,Do not take additional acetaminophen-containing medications while receiving OFIRMEV.,Report any signs of allergic reaction (rash, itching, swelling, trouble breathing).,Seek immediate medical attention if you experience severe abdominal pain, yellowing of skin or eyes, or dark urine.,Inform your healthcare provider about all medications you are taking, especially blood thinners.
Take at the same time every day, consistently with or without food.,Do not crush, chew, or split the extended-release capsules; swallow whole.,Avoid grapefruit and grapefruit juice as they can increase drug levels and toxicity.,Report signs of infection (fever, sore throat), tremors, or changes in urine output immediately.,Minimize sun exposure and use sunscreen due to increased risk of skin cancer.,Do not change brand or formulation without consulting your transplant team.,Keep all appointments for blood level monitoring.
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 OFIRMEV vs ASTAGRAF XL, answered by our medical review team.
OFIRMEV is a Non-opioid Analgesic that works by OFIRMEV (acetaminophen) is a para-aminophenol derivative with analgesic and antipyretic activity. Its mechanism of action is not fully understood, but it is thought to involve inhibition of cyclooxygenase (COX) enzymes in the central nervous system, with minimal peripheral COX inhibition. It may also act on serotonergic pathways and cannabinoid receptors.. ASTAGRAF XL is a Immunosuppressant, Calcineurin Inhibitor that works by Calcineurin inhibitor that binds to FKBP-12, forming a complex that inhibits calcineurin, thereby preventing dephosphorylation and nuclear translocation of NFAT, which reduces T-cell activation and cytokine production (e.g., IL-2).. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between OFIRMEV and ASTAGRAF XL 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 OFIRMEV is: IV: 1000 mg every 6 hours or 650 mg every 4 hours; maximum single dose: 1000 mg; minimum dosing interval: 4 hours; maximum daily dose: 4000 mg.. The standard adult dose of ASTAGRAF XL is: Initial oral dose of 0.1-0.15 mg/kg/day divided every 12 hours, with subsequent adjustments based on trough levels. Typical maintenance dose 0.05-0.15 mg/kg/day.. 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 OFIRMEV and ASTAGRAF XL 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. OFIRMEV is classified as Category C. Acetaminophen (OFIRMEV) is generally considered low risk across all trimesters. No increased risk of major congenital anomalies has been consistently demonstrated. Chronic high-dos. ASTAGRAF XL is classified as Category C. Tacrolimus is classified as FDA Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. In animal studies, tacrolimus caused maternal toxicity an. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.