Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
AZATHIOPRINE SODIUM vs LUPKYNIS
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Azathioprine is a prodrug of 6-mercaptopurine. It inhibits purine synthesis by interfering with the synthesis of DNA, RNA, and cellular proteins, thereby suppressing immune responses.
Calcineurin inhibitor immunosuppressant that binds to cyclophilin A, inhibiting calcineurin activity, which prevents dephosphorylation and activation of nuclear factor of activated T-cells (NFAT), thereby reducing cytokine production and T-cell activation.
Renal transplantation (adjunctive immunosuppression),Rheumatoid arthritis (active, severe, not responsive to conventional therapy),Off-label: Inflammatory bowel disease (Crohn's disease, ulcerative colitis), autoimmune hepatitis, systemic lupus erythematosus, vasculitis, myasthenia gravis, pemphigus vulgaris
Treatment of lupus nephritis in combination with a background immunosuppressive therapy
1-2 mg/kg/day IV or oral, initially; maintenance 0.5-1 mg/kg/day IV or oral. For severe organ rejection: 3-5 mg/kg/day IV.
23.7 mg orally twice daily with food.
Terminal elimination half-life of azathioprine is approximately 3-5 hours; its active metabolite 6-mercaptopurine has a half-life of 0.5-1.5 hours. However, the pharmacodynamic effect (immunosuppression) persists longer due to intracellular accumulation of thioguanine nucleotides.
Terminal elimination half-life approximately 30 hours; supports once-daily dosing; steady-state reached by day 4.
Primarily metabolized by xanthine oxidase (XO) and thiopurine methyltransferase (TPMT) to active and inactive metabolites. Also metabolized by aldehyde oxidase and glutathione S-transferase. Concomitant use with allopurinol (XO inhibitor) requires dose reduction.
Primarily metabolized by CYP3A4; minor contribution from CYP3A5.
Primarily renal: approximately 50% as unchanged drug and metabolites (6-mercaptopurine, thiouric acid) within 24 hours. Biliary/fecal excretion accounts for minor fraction (<5%).
Primarily hepatic metabolism; <1% excreted unchanged in urine; approximately 66% of total radioactivity recovered in feces (mainly metabolites) and 22% in urine (mainly metabolites).
Approximately 30% bound to serum proteins, primarily albumin.
Greater than 99% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
Apparent volume of distribution is 0.6-1.0 L/kg, indicating distribution into total body water and tissues.
Apparent Vd/F ~24 L (approximately 0.34 L/kg assuming 70 kg); indicates distribution into tissues.
Oral bioavailability of azathioprine is approximately 60-70% (range 27-82%) due to first-pass metabolism. Intravenous administration yields 100% bioavailability.
Oral bioavailability approximately 35% (range 20–50%) under fasting conditions; high-fat meal reduces Cmax and AUC by about 50%.
GFR 50-80 m L/min: no adjustment. GFR 30-50 m L/min: reduce dose by 25% to 50%. GFR 10-30 m L/min: reduce dose by 50% to 75%. GFR <10 m L/min: avoid or use with extreme caution.
No dose adjustment required for GFR ≥30 m L/min. Avoid use in severe renal impairment (GFR <30 m L/min) due to lack of data.
Child-Pugh class A: no adjustment. Child-Pugh class B: reduce dose by 50%. Child-Pugh class C: avoid use.
Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose to 15.8 mg orally twice daily. Child-Pugh Class C: Not recommended.
2-5 mg/kg/day IV or oral, divided every 12-24 hours; dose based on body weight (mg/kg).
Safety and efficacy not established in pediatric patients; no approved dose.
Start at lower end of dosing range; monitor renal function and adjust accordingly. Consider reduced initial dose (e.g., 1 mg/kg/day) due to age-related decreased renal function.
No specific dose adjustment required; monitor renal function due to age-related decline.
MALIGNANCY: Immunosuppression increases risk of lymphoma and other malignancies, particularly skin cancers. Monitor for neoplasia, especially in renal transplant patients.
Increased risk of infection and lymphoma; increased risk of nephrotoxicity and hypertension; increased risk of neurotoxicity.
Hematotoxicity (leukopenia, thrombocytopenia, anemia) - monitor CBC. Hepatotoxicity - monitor liver function tests. Increased infection risk. Pancreatitis. Hypersensitivity reactions. Increased risk of malignancy (skin cancer, lymphoma). Use with caution in renal/hepatic impairment. Test for TPMT deficiency before use.
Nephrotoxicity and hypertension require regular monitoring. Neurotoxicity including posterior reversible encephalopathy syndrome (PRES). Increased susceptibility to infections including opportunistic infections. Malignancies including lymphoma. Monitor for Epstein-Barr virus serology. Use with caution with CYP3A4 inhibitors and inducers. Avoid live vaccines.
Hypersensitivity to azathioprine or 6-mercaptopurine. Severe active infection. Pregnancy (FDA Category D), especially first trimester. Lactation. Concomitant use with allopurinol (unless dose adjusted). TPMT deficiency (increased risk of severe myelotoxicity).
Concurrent use with chronic immunosuppressive therapies other than mycophenolate mofetil (MMF) or mycophenolic acid (MPA). Known hypersensitivity to voclosporin or any component of the formulation.
Avoid raw or undercooked meats and fish to reduce infection risk; no specific dietary restrictions; grapefruit juice has no known interaction.
Avoid grapefruit and grapefruit juice as they increase voclosporin exposure. No other specific food interactions are known.
FDA Category D. Hematologic toxicity and immunosuppression in the neonate. Increased risk of congenital malformations (cleft palate, skeletal anomalies) and fetal growth restriction. First trimester exposure associated with highest risk; second and third trimester risks include intrauterine growth restriction and preterm birth.
LUPKYNIS (voclosporin) is a calcineurin inhibitor. Based on animal studies, there is a risk of fetal harm in all trimesters. In rats and rabbits, voclosporin administration during organogenesis resulted in increased embryofetal mortality and reduced fetal weight at maternally toxic doses. There are no adequate human studies. Avoid use during pregnancy unless potential benefit outweighs risk.
Contraindicated during breastfeeding due to potential immunosuppression and hematologic toxicity in the nursing infant. M/P ratio: Not established.
It is unknown if voclosporin is excreted in human milk. In animal studies, voclosporin and its metabolites were detected in milk of lactating rats. No M/P ratio available for humans. Due to potential for serious adverse reactions in nursing infants, advise women not to breastfeed during treatment and for 4 weeks after last dose.
Azathioprine dose may need to be reduced due to increased clearance in pregnancy; monitor 6-thioguanine nucleotide levels. Empiric dose adjustments not standardized; titrate to maintain therapeutic effect while minimizing myelotoxicity.
No specific dose adjustments are established for pregnancy. However, pregnancy can increase voclosporin clearance due to expanded plasma volume and enhanced metabolism. Consider therapeutic drug monitoring if available, and adjust dose to maintain therapeutic trough levels (target 30-60 ng/m L) as needed.
Monitor CBC and LFTs weekly for first month, then biweekly for next 2 months, then monthly; dose reduction required with allopurinol coadministration (reduce to 25% of usual dose); screen for TPMT and NUDT15 deficiency before initiating therapy; avoid live vaccines; increased risk of lymphoproliferative disorders; use sun protection due to photosensitivity; pregnancy category D.
Monitor for hematuria, proteinuria, and e GFR during treatment. Lupkynis (voclosporin) is a calcineurin inhibitor; do not co-administer with other CNIs or strong CYP3A4 inhibitors. Reduce dose in patients with e GFR <45 m L/min per 1.73 m². Concomitant use with mycophenolate mofetil and corticosteroids is standard. Check blood pressure and serum potassium regularly. Live vaccines contraindicated.
Take exactly as prescribed, do not stop without consulting your doctor.,Report any signs of infection (fever, sore throat, easy bruising or bleeding) immediately.,Use effective contraception during treatment and for at least 3 months after stopping.,Avoid live vaccines (e.g., MMR, varicella, nasal flu) while on this medication.,Limit sun exposure and use broad-spectrum sunscreen and protective clothing.,Do not take allopurinol without your doctor's knowledge.,Attend all scheduled blood tests to monitor for side effects.,May cause nausea; take with food if upset stomach occurs.
Take exactly as prescribed; do not stop or change dose without consulting your doctor.,You will need regular blood and urine tests to monitor kidney function and drug levels.,Report any signs of infection (fever, sore throat), high blood pressure (severe headache, vision changes), or changes in urine output/color.,Avoid grapefruit and grapefruit juice during treatment.,Do not receive live vaccines while taking this medication.,Use effective contraception during treatment and for 12 weeks after last dose if of childbearing potential.,Tell your doctor about all medications, including over-the-counter drugs and supplements.
"Azathioprine may reduce the therapeutic efficacy and cardiotoxic effects of digitoxin by accelerating its metabolism through induction of cytochrome P450 enzymes, particularly CYP3A4. This interaction can lead to decreased digitoxin serum concentrations, potentially resulting in loss of heart rate control in patients with atrial fibrillation or heart failure. Conversely, the cardiotoxic risk of digitoxin is diminished, but the therapeutic goal may be compromised."
"Azathioprine and fingolimod both suppress lymphocyte function, leading to additive or synergistic immunosuppression. This combination increases the risk of severe infections, including opportunistic infections, due to profound immune system suppression. Clinically, patients may present with prolonged lymphopenia, increased susceptibility to infections, and potential reactivation of latent viruses such as JC virus (causing progressive multifocal leukoencephalopathy) or cytomegalovirus."
"Azathioprine, an immunosuppressant that acts as a prodrug for 6-mercaptopurine, can increase the myelosuppressive effects of benazepril, an ACE inhibitor. This interaction is likely due to additive bone marrow suppression, leading to an elevated risk of leukopenia, anemia, and thrombocytopenia, especially in patients with renal impairment or concomitant use of other myelosuppressive agents."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about AZATHIOPRINE SODIUM vs LUPKYNIS, answered by our medical review team.
AZATHIOPRINE SODIUM is a Immunosuppressant that works by Azathioprine is a prodrug of 6-mercaptopurine. It inhibits purine synthesis by interfering with the synthesis of DNA, RNA, and cellular proteins, thereby suppressing immune responses.. LUPKYNIS is a Calcineurin Inhibitor Immunosuppressant that works by Calcineurin inhibitor immunosuppressant that binds to cyclophilin A, inhibiting calcineurin activity, which prevents dephosphorylation and activation of nuclear factor of activated T-cells (NFAT), thereby reducing cytokine production and T-cell activation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between AZATHIOPRINE SODIUM and LUPKYNIS 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 AZATHIOPRINE SODIUM is: 1-2 mg/kg/day IV or oral, initially; maintenance 0.5-1 mg/kg/day IV or oral. For severe organ rejection: 3-5 mg/kg/day IV.. The standard adult dose of LUPKYNIS is: 23.7 mg orally twice daily with food.. 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 AZATHIOPRINE SODIUM and LUPKYNIS 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. AZATHIOPRINE SODIUM is classified as Category D/X. FDA Category D. Hematologic toxicity and immunosuppression in the neonate. Increased risk of congenital malformations (cleft palate, skeletal anomalies) and fetal growth restrictio. LUPKYNIS is classified as Category C. LUPKYNIS (voclosporin) is a calcineurin inhibitor. Based on animal studies, there is a risk of fetal harm in all trimesters. In rats and rabbits, voclosporin administration during . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.