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Azasan Azathioprine 100 mg Tablet, 100-count — NDC 65649-0241-41 package photo
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Azasan Azathioprine 100 mg Tablet, 100-count — NDC 65649-241-41 (Billing 65649-0241-41)

by Salix Pharmaceuticals · 100 TABLET in 1 BOTTLE

This is a package of 100 tablets of Azasan Azathioprine 100 mg Tablet from Salix Pharmaceuticals, marketed since Apr 2003 and currently FDA-listed. It is this product's only package size.

NDC 65649-0241-41
🏷️ FDA NDC (as labeled) 65649-241-41 billing pads the product segment with a zero
Rx only Generic On market Non-controlled ⇄ Compare with another NDC
🗂️ FDA directory synced Oct 8, 2026 · this listing last changed Jul 24, 2026 · sources: openFDA · FDA label (DailyMed) · FDA Orange & Purple Book · First Databank · CMS NADAC, ASP, Medicare & Medicaid · RxNorm
📋 All sources & update times →

This page is curated, coded, and maintained by

Compiled from public FDA, CMS, DailyMed, NADAC, and related drug data sources. Editorial policy

NDC database record

One package, one record: these facts belong to NDC 65649-241-41 alone.

Record
FDA NDC Directory package listing · Human prescription drug
Code segments
65649 labeler · 241 product · 41 package
Package marketed since
Apr 1, 2003
Sample package
No — commercial package
Listing certified through
Dec 31, 2026
Billing quantity
100 EA per package
Barcode (UPC)
0365649231414
FDA record last changed
Jul 24, 2026

Identity & classification

Regulatory identifiers FDA, NLM and CMS codes for this package

FDA NDC (as labeled) 65649-241-41
Product NDC 65649-241
11-digit billing NDC 65649024141
NCPDP billing unit EA — each (per item)
RxCUI 359228, 359229, 404475, 404476
UNII MRK240IY2L
UPC 0365649231414
Application # ANDA075252
SPL Set ID 9050af7a-19c6-4670-937a-9445605de995
Established class (EPC) Purine Antimetabolite
Mechanism of action Nucleic Acid Synthesis Inhibitors
Chemical class Nucleosides; Purines
DEA schedule Non-controlled
Marketing category ANDA
Marketing status On market
FDA listing status Listed (active directory)
Marketing start 2003-04-01
Route ORAL
Dosage form TABLET
Substance AZATHIOPRINE
TE code (Orange Book) AB · RLD · RS

Drug-database identifiers Medi-Span GPI and First Databank GCN / HICL / AHFS classification

GPI-14 99406010000325
GPI class Azasan
GCN Seq No 051794
GCN 19173
HICL code 004523
Ingredient (HICL) Azathioprine
HIC1 code Z
Therapeutic class — broad (HIC1) Body As A Whole
HIC2 code Z2
Therapeutic class — intermediate (HIC2) Antihistamines, Antiserotonins, Immunosuppressants
HIC3 code Z2E
Therapeutic class — specific (HIC3) Immunosuppressives
AHFS code 90:28.08.92
AHFS class Antimetabolites, Immunosupp Therapy Misc
FDB label name AZASAN 100 MG TABLET
FDB brand name Azasan
Legend status F — Federal legend — prescription drug or device
Quick answers
  • GSN (GCN sequence number): 051794
  • GCN: 19173
  • GPI-14 (Medi-Span): 99406010000325
  • HICL (First Databank): 004523
  • AHFS class code: 90:28.08.92
  • RxCUI (RxNorm): 359228
Why two NDCs? The FDA registers this code as 65649-241-41 — a 5-3-2 layout, and that's what's printed on the package and shown on DailyMed. For insurance claims, every NDC is standardized to a uniform 11-digit 5-4-2 format by adding a zero to the product segment → 65649-0241-41. Same drug, same package — only the format differs.
Where does this data come from?
Identifiers from the FDA openFDA NDC Directory and Structured Product Labeling; RxCUI from RxNorm (NLM); GPI from Medi-Span; GCN / HIC / AHFS / legend from First Databank.

RxNorm drug class

This medicine belongs to the Purine Antimetabolite class.

Pharmacologic class Purine Antimetabolite
Drug family (ATC) Other immunosuppressants
How it works Nucleic Acid Synthesis Inhibitors
Where does this data come from?
Therapeutic classes from RxNorm RxClass (U.S. National Library of Medicine) — Established Pharmacologic Class (FDA), ATC drug family (WHO) and mechanism of action, matched by this product’s RxCUI.

Clinical

Label name AZASAN 100 MG TABLET Ingredient Azathioprine
📗 Our plain-language guide HelloPharmacist
  • It helps prevent your body from rejecting a transplanted kidney, and it is also used to reduce the signs and symptoms of active rheumatoid arthritis. It works by calming down the i...
  • The tablets (Imuran, Azasan or generic azathioprine) are taken by mouth, usually once daily, though for rheumatoid arthritis the day's dose may be split in two. Follow your prescri...
  • It usually takes about 6 to 8 weeks, and your doctor will want to give it at least 12 weeks before deciding whether it is helping. Keep taking it as directed in the meantime.
  • How long before it works for my arthritis?
📖 Read our full Azathioprine guide →
1
Nutrient depletion considerations

Azathioprine may be associated with lower levels of 1 nutrient — worth a chat with your pharmacist, not a cause for alarm.

🧪 Full Azathioprine nutrient depletion report →
An association is not a deficiency. Educational only — don't start or stop anything without professional guidance.
Where does this data come from?
Plain-language summary from MedlinePlus (U.S. National Library of Medicine); supplement & herbal interactions and nutrient depletion data from the Natural Medicines database; our full guide is HelloPharmacist editorial content.

Pricing

A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.

Price systemPer eachPer package
Retail pharmacies payNADAC · weekly Not in the retail survey — common for institutional, discontinued, or low-volume packs.
Medicaid paysCMS SDUD · 12 mo No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data.
Medicare drug plans payPart D · Q2 2026 $5.94 $593.76 / 100 tablets
Medicare Part B allowsASP · J7500 $0.136 / J7500 unit —
Where does this data come from?
NADAC (National Average Drug Acquisition Cost) is the CMS weekly pharmacy-acquisition-cost survey — what pharmacies pay. ASP (Average Sales Price) is the CMS Medicare Part B drug-payment file, published quarterly. Medicaid pays is computed by us from CMS State Drug Utilization Data (total reimbursed ÷ units, trailing 12 months) — gross of rebates and inclusive of dispensing fees, so it reflects what Medicaid paid, not an acquisition cost. Medicare drug plans pay is the median negotiated point-of-sale unit cost across plans listing this NDC in the CMS quarterly Prescription Drug Plan pricing files, before rebates. The VA pays is the federal contract price (FSS, and the statutory Big 4 ceiling where listed) from the VA National Acquisition Center pharmaceutical price file. All are free public government data; each measures a different payer, so the figures are not directly comparable.

Billing & reimbursement

FDA NDC (as labeled)65649-241-41
11-digit billing NDC65649-0241-41
Format5-3-2 as registered → padded to 5-4-2 for billing (zero added to the product segment)
HCPCS J-codeJ7500
DescriptorAZATHIOPRINE, ORAL, 50 MG
Billing units / pkg2 units
How the units are derivedThis package is 100 EA; the HCPCS unit is 50 MG, so one package = 2 billing units.
Medicare Part B spend (2026 (Q1))$20,737 · 6,362 claims · $3.26 per claim (all NDCs under J7500)
Crosswalk sourcePDAC NDC-HCPCS crosswalk (DME MAC / DMEPOS)
Where does this data come from?
The HCPCS J-code crosswalk comes from the CMS ASP NDC-HCPCS crosswalk and the DMEPDAC (DME MAC) NDC-HCPCS crosswalk — free public CMS data. Billing units are derived from the code’s descriptor and the package amount.

Packaging — all sizes for this product

Package NDCDescription Marketing startMarketing endStatus
65649-0241-41 You're viewing this Main listing 100 TABLET in 1 BOTTLE 2003-04-01 — Active

Therapeutic equivalents

ProductLabelerPackNADAC/unitTEStatusPrice vs. this
Azathioprine 100 mg 60219-2037-01 Amneal 100 tablets $3.315 AB Availability likely —
Azathioprine 100 mg 68382-0120-01 Zydus 100 tablets $3.315 AB Availability likely —
Azathioprine 100 mg 68682-0241-01 Oceanside 100 tablets $6.142 AB FDA listed —
Azathioprine 100 mg 42291-0063-01 AvKARE 100 tablets — AB FDA listed —
Azasan 100 mgthis 65649-0241-41 Salix 100 tablets — AB FDA listed —
Azathioprine 100 mg 67877-0495-01 Ascend 100 tablets — AB FDA listed —
Azathioprine 100 mg 70771-1141-01 Zydus 100 tablets — AB FDA listed —
About this product: this is a generic version of the medicine. FDA equivalence ratings are shown when available, and other versions are listed above, least expensive first.
Where does this data come from?
Equivalents are other NDCs of the same ingredient, form and route from the openFDA NDC Directory, ranked least-expensive-first by NADAC. Therapeutic-equivalence (AB) ratings come from the FDA Orange Book; biologics use the FDA Purple Book for biosimilar & interchangeable status.

Availability & generic status

🏛️
2003
On the market since
Apr 2003
📍
2026
Currently FDA-listed
23 years listed
🔓
·
Generic on the market
this product is a generic
✅This is a generic drug

This product is an FDA-approved generic. Other versions of the same drug are listed under Therapeutic equivalents, least expensive first.

Where does this data come from?
Patents and exclusivity from the FDA Orange Book (small-molecule drugs), refreshed from public FDA data. Generic launch timing is an estimate, not a guarantee.

What it looks like

Color yellow
ShapeDiamond
Size14 mm
ScoringScored — splits in 2
One label can cover several strengths, so colors may be combined — always confirm a loose pill against the dispensed prescription label or a pharmacist.
Where does this data come from?
Physical description (imprint, shape, color, scoring, coating) from this product’s FDA Structured Product Labeling (SPL), mirrored from DailyMed / openFDA.

Inactive Ingredients / Excipients

Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.

🧪 Avoiding an ingredient? See Azathioprine inactive ingredients by manufacturer: every current product's list side by side, so you can ask your pharmacy for the version that does not list it.

💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.

  • UNII EWQ57Q8I5X
    Lactose monohydrate is a natural sugar derived from milk. It serves as a filler and binder in tablets and capsules, helping create the proper size, texture, and consistency of the medicine.
  • UNII 70097M6I30
    Magnesium stearate is a salt made from magnesium and stearic acid, a fatty substance. It's used in tablets and capsules as a lubricant and glidant to help ingredients flow smoothly during manufacturing and prevent sticking.
  • UNII FZ989GH94E
    Povidone is a synthetic polymer made from a plastic-like material. It acts as a binder to hold tablet ingredients together and as a disintegrant to help the tablet break apart in your stomach so the medicine can be absorbed.
  • UNII O8232NY3SJ
    A plant-based carbohydrate derived from corn kernels. It acts as a filler to add bulk, a binder to hold ingredients together, and a disintegrant to help the tablet break apart in your stomach for absorption.
  • UNII 4ELV7Z65AP
    Stearic acid is a fatty acid derived from plant or animal sources. It acts as a binder and lubricant in tablets and capsules, helping them hold together and flow smoothly during manufacturing.

5 inactive ingredients listed in the exact product block matched to this NDC.

Where does this data come from?
Data sourced from official FDA Structured Product Labeling (SPL) via DailyMed — ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.

Inactive ingredient FAQ

Are inactive ingredients the same for every manufacturer?
No. Inactive ingredients can differ by manufacturer, dosage form, strength, and package / product version.
Why might an inactive ingredient be missing?
Some SPLs do not provide a complete structured inactive-ingredient list, and older or unusual labels may only include the information in narrative text.
Can inactive ingredients matter?
Yes. They can matter for allergies, intolerances, dyes, gluten / lactose concerns, preservatives, and formulation differences — but confirm with a pharmacist or the manufacturer when it’s clinically important.

Manufacturer & labeler

LabelerSalix Pharmaceuticals
Application holderAAIPHARMA LLC
FDA applicationANDA075252 (ANDA)
Labeler code65649
First marketedApr 2003
Product typeHuman Prescription Drug
Portfolio2 products on file

More NDCs from Salix Pharmaceuticals labeler code 65649

The labeler markets the product; the application holder owns the FDA approval. They’re often the same company but can differ (e.g. a repackager or an authorized generic). A mailing address / phone appears here when the manufacturer includes it in the product’s FDA label (not all do).
Where does this data come from?
Labeler, application holder and registered establishment from the FDA openFDA NDC Directory and Drugs@FDA; address/contact from the product’s FDA label.

Full prescribing information FDA SPL

The complete FDA label for this product — the official prescribing information, verbatim, section by section. Very long sections are excerpted here and marked; the full text is on DailyMed (linked in the sources below). Jump with a chip, search within the label, or expand everything.
🚨 Boxed Warning 🎯 Indications and Usage ⏱️ Dosage and Administration ⛔ Contraindications ⚠️ Warnings 🤒 Adverse Reactions 🆘 Overdosage 🧬 Clinical Pharmacology 📦 How Supplied / Storage and Handling 📋 Description ⚠️ Precautions 📚 References 📄 Package Label / Principal Display Panel
🚨 Boxed Warning 77 words ▾

WARNING - MALIGNANCY Chronic immunosuppression with AZASAN, a purine antimetabolite increases risk of malignancy in humans. Reports of malignancy include post-transplant lymphoma and hepatosplenic T-cell lymphoma (HSTCL) in patients with inflammatory bowel disease. Physicians using this drug should be very familiar with this risk as well as with the mutagenic potential to both men and women and with possible hematologic toxicities.

Physicians should inform patients of the risk of malignancy with AZASAN ® . See WARNINGS .

🎯 Indications and Usage 161 words ▾

INDICATIONS AND USAGE: AZASAN is indicated as an adjunct for the prevention of rejection in renal homotransplantation. It is also indicated for the management of active rheumatoid arthritis to reduce signs and symptoms. Renal Homotransplantation: AZASAN is indicated as an adjunct for the prevention of rejection in renal homotransplantation.

Experience with over 16,000 transplants shows a 5-year patient survival of 35% to 55%, but this is dependent on donor, match for HLA antigens, anti-donor or anti-B-cell alloantigen antibody, and other variables. The effect of AZASAN on these variables has not been tested in controlled trials. Rheumatoid Arthritis: AZASAN is indicated for the treatment of active rheumatoid arthritis (RA) to reduce signs and symptoms.

Aspirin, non-steroidal anti-inflammatory drugs and/or low dose glucocorticoids may be continued during treatment with AZASAN. The combined use of AZASAN with disease modifying anti-rheumatic drugs (DMARDs) has not been studied for either added benefit or unexpected adverse effects. The use of AZASAN with these agents cannot be recommended.

⏱️ Dosage and Administration ~2 min read ▾

DOSAGE AND ADMINISTRATION: Renal Homotransplantation: The dose of AZASAN required to prevent rejection and minimize toxicity will vary with individual patients; this necessitates careful management. The initial dose is usually 3 to 5 mg/kg daily, beginning at the time of transplant. AZASAN is usually given as a single daily dose on the day of, and in a minority of cases 1 to 3 days before, transplantation.

Dose reduction to maintenance levels of 1 to 3 mg/kg daily is usually possible. The dose of AZASAN should not be increased to toxic levels because of threatened rejection. Discontinuation may be necessary for severe hematologic or other toxicity, even if rejection of the homograft may be a consequence of drug withdrawal.

Rheumatoid Arthritis: AZASAN is usually given on a daily basis. The initial dose should be approximately 1.0 mg/kg (50 to 100 mg) given as a single dose or on a twice-daily schedule. The dose may be increased, beginning at 6 to 8 weeks and thereafter by steps at 4-week intervals, if there are no serious toxicities and if initial response is unsatisfactory.

Dose increments should be 0.5 mg/kg daily, up to a maximum dose of 2.5 mg/kg per day. Therapeutic response occurs after several weeks of treatment, usually 6 to 8; an adequate trial should be a minimum of 12 weeks. Patients not improved after 12 weeks can be considered refractory.

AZASAN may be continued long-term in patients with clinical response, but patients should be monitored carefully, and gradual dosage reduction should be attempted to reduce risk of toxicities. Maintenance therapy should be at the lowest effective dose, and the dose given can be lowered decrementally with changes of 0.5 mg/kg or approximately 25 mg daily every 4 weeks while other therapy is kept constant. The optimum duration of maintenance AZASAN has not been determined.

AZASAN can be discontinued abruptly, but delayed effects are possible. Patients with TPMT and/or NUDT15 Deficiency Consider testing for TPMT and NUDT15 deficiency in patients who experience severe bone marrow toxicities. Early drug discontinuation may be considered in patients with abnormal CBC results that do not respond to dose reduction (see CLINICAL PHARMACOLOGY , WARNINGS: Cytopenias , and PRECAUTIONS: Laboratory Tests ).

Homozygous deficiency in either TPMT or NUDT15 Because of the risk of increased toxicity, consider alternative therapies for patients who are known to have TPMT or NUDT15 deficiency (see CLINICAL PHARMACOLOGY , WARNINGS: Cytopenias , and PRECAUTIONS: Laboratory Tests ). Heterozygous deficiency in TPMT and/or NUDT15 Because of the risk of increased toxicity, dosage reduction is recommended in patients known to have heterozygous deficiency of TPMT or NUDT15. Patients who are heterozygous for both TPMT and NUDT15 deficiency may require more substantial dosage reductions (see CLINICAL PHARMACOLOGY , WARNINGS: Cytopenias , and PRECAUTIONS: Laboratory Tests ).

Use in Renal Dysfunction: Relatively oliguric patients, especially those with tubular necrosis in the immediate postcadaveric transplant period, may have delayed clearance of AZASAN or its metabolites, may be particularly sensitive to this drug, and are usually given lower doses. Procedures for proper handling and disposal of this immunosuppressive antimetabolite drug should be considered. Several guidelines on this subject have been published.

15-21 There is no general agreement that all of the procedures recommended in the guidelines are necessary or appropriate.

⛔ Contraindications 52 words ▾

CONTRAINDICATIONS: AZASAN should not be given to patients who have shown hypersensitivity to the drug. AZASAN should not be used for treating rheumatoid arthritis in pregnant women. Patients with rheumatoid arthritis previously treated with alkylating agents (cyclophosphamide, chlorambucil, melphalan, or others) may have a prohibitive risk of malignancy if treated with AZASAN.

⚠️ Warnings ~3 min read ▾

WARNINGS: Malignancy Patients receiving immunosuppressants, including AZASAN, are at increased risk of developing lymphoma and other malignancies, particularly of the skin. Physicians should inform patients of the risk of malignancy with AZASAN. As usual for patients with increased risk for skin cancer, exposure to sunlight and ultraviolet light should be limited by wearing protective clothing and using a sunscreen with a high protection factor.

Post-transplant Renal transplant patients are known to have an increased risk of malignancy, predominantly skin cancer and reticulum cell or lymphomatous tumors. The risk of post-transplant lymphomas may be increased in patients who receive aggressive treatment with immunosuppressive drugs, including AZASAN. Therefore, immunosuppressive drug therapy should be maintained at the lowest effective levels.

Rheumatoid Arthritis Information is available on the risk of malignancy with the use of AZASAN in rheumatoid arthritis (see ADVERSE REACTIONS ). It has not been possible to define the precise risk of malignancy due to AZASAN. The data suggest the risk may be elevated in patients with rheumatoid arthritis, though lower than for renal transplant patients.

However, acute myelogenous leukemia as well as solid tumors have been reported in patients with rheumatoid arthritis who have received AZASAN. Inflammatory Bowel Disease Postmarketing cases of hepatosplenic T-cell lymphoma (HSTCL), a rare type of T-cell lymphoma, have been reported in patients treated with AZASAN. These cases have had a very aggressive disease course and have been fatal.

The majority of reported cases have occurred in patients with Crohn’s disease or ulcerative colitis and the majority were in adolescent and young adult males. Some of the patients were treated with AZASAN as monotherapy and some had received concomitant treatment with a TNFα blocker at or prior to diagnosis. The safety and efficacy of AZASAN for the treatment of Crohn’s disease and ulcerative colitis have not been established.

Cytopenias Severe leukopenia, thrombocytopenia, anemias including macrocytic anemia, and/or pancytopenia may occur in patients being treated with AZASAN. Severe bone marrow suppression may also occur. Hematologic toxicities are dose-related and may be more severe in renal transplant patients whose homograft is undergoing rejection.

It is suggested that patients on AZASAN have complete blood counts, including platelet counts, weekly during the first month, twice monthly for the second and third months of treatment, then monthly or more frequently if dosage alterations or other therapy changes are necessary. Delayed hematologic suppression may occur. Prompt reduction in dosage or temporary withdrawal of the drug may be necessary if there is a rapid fall in or persistently low leukocyte count, or other evidence of bone marrow depression.

Leukopenia does not correlate with therapeutic effect; therefore, the dose should not be increased intentionally to lower the white blood cell count. TPMT or NUDT15 Deficiency Patients with thiopurine S-methyl transferase (TPMT) or nucleotide diphosphatase (NUDT15) deficiency may be at an increased risk of severe and life-threatening myelotoxicity if receiving conventional doses of AZASAN (see CLINICAL PHARMACOLOGY ). Death associated with pancytopenia has been reported in patients with absent TPMT activity receiving azathioprine.

In patients with severe myelosuppression, consider evaluation for TPMT and NUDT15 deficiency (see PRECAUTIONS: Laboratory Tests ). Consider alternative therapy in patients with homozygous TPMT or NUDT15 deficiency and reduced dosages in patients with heterozygous deficiency (see DOSAGE AND ADMINISTRATION ). Serious Infections Patients receiving immunosuppressants, including AZASAN, are at increased risk for bacterial, viral, fungal, protozoal, and opportunistic infections, including reactivation of latent infections.

These infections may lead to serious, including fatal outcom… [Excerpted — this section continues on DailyMed.]

🤒 Adverse Reactions ~3 min read ▾

ADVERSE REACTIONS: The principal and potentially serious toxic effects of AZASAN are hematologic and gastrointestinal. The risks of secondary infection and malignancy are also significant (see WARNINGS ). The frequency and severity of adverse reactions depend on the dose and duration of AZASAN as well as on the patient’s underlying disease or concomitant therapies.

The incidence of hematologic toxicities and neoplasia encountered in groups of renal homograft recipients is significantly higher than that in studies employing AZASAN for rheumatoid arthritis. The relative incidences in clinical studies are summarized below: Toxicity Renal Homograft Rheumatoid Arthritis Leukopenia (any degree) >50% 28% <2500 cells/mm 3 16% 5.3% Infections 20% <1% Neoplasia * Lymphoma 0.5% Others 2.8% *Data on the rate and risk of neoplasia among persons with rheumatoid arthritis treated with azathioprine are limited.

The incidence of lymphoproliferative disease in patients with RA appears to be significantly higher than that in the general population. In one completed study, the rate of lymphoproliferative disease in RA patients receiving higher than recommended doses of azathioprine (5 mg/kg per day) was 1.8 cases per 1000 patient-years of follow-up, compared with 0.8 cases per 1000 patient-years of follow-up in those not receiving azathioprine. However, the proportion of the increased risk attributable to the azathioprine dosage or to other therapies (i.e., alkylating agents) received by patients treated with azathioprine cannot be determined.

Hematologic: Leukopenia and/or thrombocytopenia are dose-dependent and may occur late in the course of therapy with AZASAN. Dose reduction or temporary withdrawal may result in reversal of these toxicities. Infection may occur as a secondary manifestation of bone marrow suppression or leukopenia, but the incidence of infection in renal homotransplantation is 30 to 60 times that in rheumatoid arthritis.

Anemias, including macrocytic anemia, and/or bleeding have been reported. Patients with low or absent TPMT or NUDT15 activity are at increased risk for severe, life-threatening myelosuppression from AZASAN (see CLINICAL PHARMACOLOGY , WARNINGS: Cytopenias , and PRECAUTIONS , Laboratory Tests , DOSAGE AND ADMINISTRATION ). Gastrointestinal: Nausea and vomiting may occur within the first few months of therapy with AZASAN, and occurred in approximately 12% of 676 rheumatoid arthritis patients.

The frequency of gastric disturbance often can be reduced by administration of the drug in divided doses and/or after meals. However, in some patients, nausea and vomiting may be severe and may be accompanied by symptoms such as diarrhea, fever, malaise, and myalgias (see PRECAUTIONS ). Vomiting with abdominal pain may occur rarely with a hypersensitivity pancreatitis.

Hepatotoxicity manifest by elevation of serum alkaline phosphatase, bilirubin, and/or serum transaminases is known to occur following azathioprine use, primarily in allograft recipients. Hepatotoxicity has been uncommon (less than 1%) in rheumatoid arthritis patients. Hepatotoxicity following transplantation most often occurs within 6 months of transplantation and is generally reversible after interruption of AZASAN.

A rare, but life-threatening hepatic veno-occlusive disease associated with chronic administration of azathioprine has been described in transplant patients and in one patient receiving AZASAN for panuveitis. 11, 12, 13 Periodic measurement of serum transaminases, alkaline phosphatase, and bilirubin is indicated for early detection of hepatotoxicity. If hepatic veno-occlusive disease is clinically suspected, AZASAN should be permanently withdrawn.

Others: Additional side effects of low frequency have been reported. These include skin rashes, alopecia, fever, arthralgias, diarrhea, steatorrhea, negative nitrogen balance, reversible interstitial pneumonitis, hepatosplenic T-cell lymphoma (see Warnings - Malignancy ), and Sweet’s Syndrome (acute fe… [Excerpted — this section continues on DailyMed.]

🆘 Overdosage 111 words ▾

OVERDOSAGE: The oral LD 50 s for single doses of AZASAN in mice and rats are 2500 mg/kg and 400 mg/kg, respectively. Very large doses of this antimetabolite may lead to marrow hypoplasia, bleeding, infection, and death. About 30% of AZASAN is bound to serum proteins, but approximately 45% is removed during an 8-hour hemodialysis.

14 A single case has been reported of a renal transplant patient who ingested a single dose of 7500 mg AZASAN. The immediate toxic reactions were nausea, vomiting, and diarrhea, followed by mild leukopenia and mild abnormalities in liver function. The white blood cell count, SGOT, and bilirubin returned to normal 6 days after the overdose.

🧬 Clinical Pharmacology ~3 min read ▾

CLINICAL PHARMACOLOGY: Azathioprine is well absorbed following oral administration. Maximum serum radioactivity occurs at 1 to 2 hours after oral 35 S-azathioprine and decays with a half-life of 5 hours. This is not an estimate of the half-life of azathioprine itself, but is the decay rate for all 35 S-containing metabolites of the drug.

Because of extensive metabolism, only a fraction of the radioactivity is present as azathioprine. Usual doses produce blood levels of azathioprine, and of mercaptopurine derived from it, which are low (<1 mcg/mL). Blood levels are of little predictive value for therapy since the magnitude and duration of clinical effects correlate with thiopurine nucleotide levels in tissues rather than with plasma drug levels.

Azathioprine and mercaptopurine are moderately bound to serum proteins (30%) and are partially dialyzable. See OVERDOSAGE . Azathioprine is metabolized to 6-mercaptopurine (6-MP).

Both compounds are rapidly eliminated from blood and are oxidized or methylated in erythrocytes and liver; no azathioprine or mercaptopurine is detectable in urine after 8 hours. Activation of 6-mercaptopurine occurs via hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and a series of multi-enzymatic processes involving kinases to form 6-thioguanine nucleotides (6-TGNs) as major metabolites. The cytotoxicity of azathioprine is due, in part, to the incorporation of 6-TGN into DNA.

6-MP undergoes two major inactivation routes. One is thiol methylation, which is catalyzed by the enzyme thiopurine S-methyltransferase (TPMT), to form the inactive metabolite methyl-6-MP (6-MeMP). Another inactivation pathway is oxidation, which is catalyzed by xanthine oxidase (XO) to form 6-thiouric acid.

The nucleotide diphosphatase (NUDT15) enzyme is involved in conversion of the 6-TGNs to inactive 6-TG monophosphates. TPMT activity correlates inversely with 6-TGN levels in erythrocytes and presumably other hematopoietic tissues, since these cells have negligible xanthine oxidase (involved in the other inactivation pathway) activities. Genetic polymorphisms influence TPMT and NUDT15 activity.

Several published studies indicate that patients with reduced TPMT or NUDT15 activity receiving usual doses of 6-MP or azathioprine, accumulate excessive cellular concentrations of active 6-TGNs, and are at higher risk for severe myelosupression. Because of the risk of toxicity, patients with TPMT or NUDT15 deficiency require alternative therapy or dose modification (see DOSAGE AND ADMINISTRATION ). Approximately 0.3% (1:300) of patients of European or African ancestry have two loss-of-function alleles of the TPMT gene and have little or no TPMT activity (homozygous deficient or poor metabolizers), and approximately 10% of patients have one loss-of-function TPMT allele leading to intermediate TPMT activity (heterozygous deficient or intermediate metabolizers).

The TPMT*2, TPMT*3A, and TPMT*3C alleles account for about 95% of individuals with reduced levels of TPMT activity. NUDT15 deficiency is detected in <1% of patients of European or African ancestry. Among patients of East Asian ancestry (i.e., Chinese, Japanese, Vietnamese), 2% have two loss-of-function alleles of the NUDT15 gene, and approximately 21% have one loss-of-function allele.

The p.R139C variant of NUDT15 (present on the *2 and *3 alleles) is the most commonly observed, but other less common loss-of-function NUDT15 alleles have been observed. Inhibition of xanthine oxidase (XO) may cause increased plasma concentrations of azathioprine or its metabolites leading to toxicity (see PRECAUTIONS: Drug Interactions ). Proportions of metabolites are different in individual patients, and this presumably accounts for variable magnitude and duration of drug effects.

Renal clearance is probably not important in predicting biological effectiveness or toxicities, although dose reduction is practiced in patients with poor renal function. Homograft Survival: The use of azathioprine for… [Excerpted — this section continues on DailyMed.]

📦 How Supplied / Storage and Handling 89 words ▾

HOW SUPPLIED: AZASAN Tablets, USP are available in: 75 mg, triangle-shaped, yellow, scored tablets, debossed with “75 mg” on one side, and “N” on the other side. 100 count bottles (NDC 65649-231-41) 100 mg, diamond-shaped, yellow, scored tablets, debossed with “100 mg” on one side, and “N” on the other side. 100 count bottles (NDC 65649-241-41) Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].

Store in a dry place and protect from light. Dispense in a tight, light-resistant container as defined in the USP.

📋 Description 134 words ▾

DESCRIPTION: AZASAN ® (azathioprine), an immunosuppressive antimetabolite, is available in tablet form for oral administration. Each scored tablet contains 75 mg or 100 mg azathioprine and the inactive ingredients lactose monohydrate, pregelatinized starch, povidone, corn starch, magnesium stearate, and stearic acid. Azathioprine is chemically 6-[(1-methyl-4-nitro-1 H-imidazol-5-yl)thio]-1 H-purine.

The structural formula of azathioprine is: It is an imidazolyl derivative of 6-mercaptopurine and many of its biological effects are similar to those of the parent compound. Azathioprine is insoluble in water, but may be dissolved with addition of one molar equivalent of alkali. Azathioprine is stable in solution at neutral or acid pH but hydrolysis to mercaptopurine occurs in excess sodium hydroxide (0.1N), especially on warming.

Conversion to mercaptopurine also occurs in the presence of sulfhydryl compounds such as cysteine, glutathione, and hydrogen sulfide. chem structure

⚠️ Precautions ~3 min read ▾

PRECAUTIONS: General: A gastrointestinal hypersensitivity reaction characterized by severe nausea and vomiting has been reported. These symptoms may also be accompanied by diarrhea, rash, fever, malaise, myalgias, elevations in liver enzymes, and occasionally, hypotension. Symptoms of gastrointestinal toxicity most often develop within the first several weeks of therapy with AZASAN and are reversible upon discontinuation of the drug.

The reaction can recur within hours after re-challenge with a single dose of AZASAN. Information for Patients: Patients being started on AZASAN should be informed of the necessity of periodic blood counts while they are receiving the drug and should be encouraged to report any unusual bleeding or bruising to their physician. They should be informed of the danger of infection while receiving AZASAN and asked to report signs and symptoms of infection to their physician.

Careful dosage instructions should be given to the patient, especially when AZASAN is being administered in the presence of impaired renal function or concomitantly with allopurinol (see Drug Interactions subsection and DOSAGE AND ADMINISTRATION ). Patients should be advised of the potential risks of the use of AZASAN during pregnancy and during the nursing period. The increased risk of malignancy following therapy with AZASAN should be explained to the patient.

Laboratory Tests: Complete Blood Count (CBC) Monitoring: Patients on AZASAN should have complete blood counts, including platelet counts, weekly during the first month, twice monthly for the second and third months of treatment, then monthly or more frequently if dosage alterations or other therapy changes are necessary. TPMT and NUDT15 Testing: Consider genotyping or phenotyping patients for TPMT deficiency and genotyping for NUDT15 deficiency in patients with severe myelosuppression. TPMT and NUDT15 testing cannot substitute for complete blood count (CBC) monitoring in patients receiving AZASAN.

Accurate phenotyping (red blood cell TPMT activity) results are not possible in patients who have received recent blood transfusions (see CLINICAL PHARMACOLOGY , WARNINGS: Cytopenias , ADVERSE REACTIONS and DOSAGE AND ADMINISTRATION sections). Drug Interactions: Use with Xanthine Oxidase (XO) Inhibitors: One of the pathways for inactivation of azathioprine is inhibited by XO inhibitors (allopurinol or febuxostat). Patients receiving AZASAN and allopurinol concomitantly should have a dose reduction of AZASAN, to approximately 1/3 to 1/4 the usual dose.

Concomitant use of AZASAN with febuxostat is not recommended. Inhibition of XO may cause increased plasma concentrations of azathioprine or its metabolite, 6-MP, leading to toxicity. It is recommended that a further dose reduction or alternative therapies be considered for patients with low or absent TPMT activity receiving AZASAN and xanthine oxidase inhibitors because both TPMT and XO inactivation pathways are affected (see CLINICAL PHARMACOLOGY , WARNINGS , PRECAUTIONS: Laboratory Tests and ADVERSE REACTIONS sections).

Use with Aminosalicylates: There is in vitro evidence that aminosalicylate derivatives (e.g., sulphasalazine, mesalazine, or olsalazine) inhibit the TPMT enzyme. Concomitant use of these agents with AZASAN should be done with caution. Use with Other Agents Affecting Myelopoesis: Drugs which may affect leukocyte production, including co-trimoxazole, may lead to exaggerated leukopenia, especially in renal transplant recipients.

Use with Angiotensin-Converting Enzyme Inhibitors: The use of angiotensin-converting enzyme inhibitors to control hypertension in patients on azathioprine has been reported to induce anemia and severe leukopenia. Use with Warfarin: AZASAN may inhibit the anticoagulant effect of warfarin. Use with Ribavirin: The use of ribavirin for hepatitis C in patients receiving azathioprine has been reported to induce severe pancytopenia and may increase the risk of azathioprine-related myelotoxicity.

Inosine… [Excerpted — this section continues on DailyMed.]

📚 References ~2 min read ▾

REFERENCES: 1. Clark JM. The mutagenicity of azathioprine in mice, Drosophila melanogaster, and Neurospora crassa.

Mutat Res. 1975; 28:87-99. 2.

Data on file, Sebela Ireland Ltd. 3. Tagatz GE, Simmons RL.

Pregnancy after renal transplantation. Ann Intern Med. 1975; 82:113-114.

Editorial Notes. 4. Coté CJ, Meuwissen HJ, Pickering RJ.

Effects on the neonate of prednisone and azathioprine administered to the mother during pregnancy. J Pediatr. 1974; 85:324-328.

5. DeWitte DB, Buick MK, Cyran SE, et al. Neonatal pancytopenia and severe combined immunodeficiency associated with antenatal administration of azathioprine and prednisone.

J Pediatr. 1984; 105:625-628. 6.

Williamson RA, Karp LE. Azathioprine teratogenicity: review of the literature and case report. Obstet Gynecol.

1981; 58:247-250. 7. Tallent MB, Simmons RL, Najarian JS.

Birth defects in child of male recipient of kidney transplant. JAMA. 1970; 211:1854-1855.

8. Data on file, Sebela Ireland Ltd. 9.

Saarikoski S, Seppälä M. Immunosuppression during pregnancy: transmission of azathioprine and its metabolites from the mother to the fetus. Am J Obstet Gynecol.

1973; 115:1100-1106. 10. Coulam CB, Moyer TP, Jiang NS, et al.

Breast-feeding after renal transplantation. Transplant Proc. 1982; 14: 605-609.

11. Read AE, Wiesner RH, LaBrecque DR, et al. Hepatic veno-occlusive disease associated with renal transplantation and azathioprine therapy.

Ann Intern Med . 1986; 104:651-655. 12.

Katzka DA, Saul SH, Jorkasky D, et al. Azathioprine and hepatic veno-occlusive disease in renal transplant patients. Gastroenterology.

1986; 90:446-454. 13. Weitz H, Gokel JM, Loeshke K, et al.

Veno-occlusive disease of the liver in patients receiving immunosuppressive therapy. Virchows Arch A Pathol Anat Histol. 1982; 395:245-256.

14. Schusziarra V, Ziekursch V, Schlamp R, et al. Pharmacokinetics of azathioprine under haemodialysis.

Int J Clin Pharmacol Biopharm. 1976; 14:298-302. 15.

Recommendations for the safe handling of parenteral antineoplastic drugs. Washington, DC: Division of Safety; Clinical Center Pharmacy Department and Cancer Nursing Services, National Institute of Health; 1992. US Dept of Health and Human Services.

Public Health Service Publication NIH 92-2621. 16. AMA Council on Scientific Affairs.

Guidelines for handling parenteral antineoplastics. JAMA. 1985; 253:1590-1592.

17. National Study Commission on Cytotoxic Exposure. Recommendations for handling cytotoxic agents.

1987. Available from Louis P. Jeffrey, Chairman, National Study Commission on Cytotoxic Exposure.

Massachusetts College of Pharmacy and Allied Health Sciences, 179 Longwood Avenue, Boston, MA 02115. 18. Clinical Oncological Society of Australia.

Guidelines and recommendations for safe handling of antineoplastic agents. Med J Aust. 1983; 1:426-428.

19. Jones RB, Frank R, Mass T. Safe handling of chemotherapeutic agents: a report from The Mount Sinai Medical Center.

CA Cancer J for Clinicians. 1983; 33:258-263. 20.

American Society of Hospital Pharmacists. ASHP technical assistance bulletin on handling cytotoxic and hazardous drugs. Am J Hosp Pharm.

1990; 47:1033-1049. 21. Yodaiken RE, Bennett D.

OSHA Work-Practice guidelines for personnel dealing with cytotoxic (antineoplastic) drugs. Am J Hosp Pharm, 1996; 43:1193-1204. Distributed by: Salix Pharmaceuticals, a division of Bausch Health US, LLC Bridgewater, NJ 08807 USA Manufactured by: Alcami Corporation Wilmington, NC 28405 USA AZASAN is a registered trademark of Bausch Health Companies Inc. or its affiliates. © 2025 Salix Pharmaceuticals, Inc. or its affiliates Rev.

09/2025 90006501 PC3290L

📄 Package Label / Principal Display Panel 54 words ▾

PACKAGE LABEL - PRINCIPAL DISPLAY PANEL - Azasan 100 mg Tablets NDC 65649-241-41 Rx Only AZASAN (azathioprine) Tablets, USP 100 mg 100 Tablets Salix 100 mg label

PACKAGE LABEL - PRINICPAL DISPLAY PANEL - Azasan 75 mg Tablets NDC 65649-231-41 Rx Only AZASAN (azathioprine) Tablets, USP 75 mg 100 Tablets Salix 75 mg label

Source: FDA Structured Product Labeling, mirrored from DailyMed / openFDA. Prefer the government’s original formatting? View this label on DailyMed ↗

Medicare Part D spend CMS · PART D · 2025 (Q1-Q4)

Medicare Part D (outpatient prescription) spending for Azasan — the program that covers self-administered drugs. 1 manufacturer.
⚠️ Drug-level data: CMS publishes Part D spending by drug, not by NDC — these figures combine every manufacturer, strength and package size sold under the name Azasan. That’s a different level of aggregation than the Medicaid card above, which is specific to this exact 11-digit NDC (pack size included), so the two aren’t directly comparable.
Total Part D spend
$43.2K
Claims incl. refills
73
Beneficiaries
21
Spend / beneficiary
$2,057.77
Spend / claim
$591.96
💵 About the dollar figures: spending is what Part D plans paid before confidential manufacturer rebates, so the program’s real net cost is lower. A blank patient count means fewer than 11 people — CMS hides counts that small to protect privacy. Source: CMS Medicare Quarterly Part D Spending by Drug (data.cms.gov), updated quarterly.

About this NDC listing & data coverage

Finished prescription product
What data is (and isn’t) available for this NDC — tap to expand
NDC identity (package / product / labeler codes) ✓ Available
Labeler ✓ Available
Product & package description ✓ Available
Marketing category & status ✓ Available
Active ingredient / dosage form / route ✓ Available
FDA label (SPL via DailyMed) ✓ Available
Package photos ✓ Available
Inactive ingredients (structured) ✓ Available
NADAC pharmacy acquisition price (CMS) — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey.
Orange Book / therapeutic-equivalence data ✓ Available
HCPCS J-code billing crosswalk ✓ Available
Medicaid utilization (CMS SDUD) — Not published for this NDC CMS reports utilization only for NDCs with Medicaid claims above its privacy threshold.
“Not published” reflects what the public FDA / CMS / NLM sources provide for this exact package code — it is a property of the data feeds, not a judgment about the product.

Questions about this listing

Why is there no price listed?
The pricing shown on our NDC pages comes from CMS NADAC, a voluntary survey of retail community pharmacy invoices. CMS does not publish a NADAC for every NDC — packages outside the retail survey (institutional and hospital products, bulk packages, discontinued items, and many OTC items) may never receive one. A missing price reflects the survey's scope, not this product's actual cost, and does not mean the product is free or unavailable.
Is the NDC printed on the package the same as the 11-digit billing NDC?
Yes, they identify this exact package in different formats. The form printed on the packaging and shown on DailyMed is the one the FDA registered. Insurance claims use a fixed 11-digit 5-4-2 format, so the short segment is padded with a leading zero and the dashes are dropped. The Identity section at the top of this page lists each form of this code.
Is this package still being marketed?
Yes, per the latest FDA NDC Directory data on this page: this package is listed as actively marketed, with no marketing end date reported by Salix Pharmaceuticals. Listing status can change — the directory data on this page refreshes weekly.
Who lists this product with the FDA?
Salix Pharmaceuticals is the labeler of record for this NDC — the company under whose FDA-assigned code the package is listed. The labeler may be the manufacturer itself or a distributor marketing the product under its own code.
Do I need a prescription for this product?
This NDC is listed with FDA as a prescription product, so it is dispensed under a prescriber's order. Your pharmacist can tell you whether any over-the-counter forms of the same medication exist.
Does this product have a billing J-code?
Yes — this NDC cross-references HCPCS code J7500 for medical-claim billing (typically used when a product is administered in a clinical setting rather than dispensed at a retail pharmacy). See the Billing section on this page.
This page identifies an FDA-listed package (the NDC) and reports public regulatory and pricing data about the listing. It is reference information, not a medical recommendation — talk to your pharmacist or prescriber about your own medication.
Where does this data come from?
Listing facts (marketing category, packager status, marketing dates) from the FDA openFDA NDC Directory; label availability from DailyMed; pricing coverage from CMS NADAC; equivalence scope from the FDA Orange Book.
← 65649-0231-41 · Salix 65649-0301-03 · Salix →
For educational and professional reference only — not medical advice. Pricing reflects published NADAC and CMS ASP (free public data) and may differ from your acquisition cost; always verify before billing or dispensing.