Suppliers and packagers for generic pharmaceutical drug: AZATHIOPRINE

AZATHIOPRINE

Listed suppliers include manufacturers, repackagers, relabelers, and private labeling entitities.

Applicant	Tradename	Generic Name	Dosage	NDA	NDA/ANDA	Supplier	Package Code	Package	Marketing Start
Aaipharma Llc	AZASAN	azathioprine	TABLET;ORAL	075252	ANDA	Golden State Medical Supply, Inc.	51407-182-01	100 TABLET in 1 BOTTLE (51407-182-01)	1999-06-07
Aaipharma Llc	AZASAN	azathioprine	TABLET;ORAL	075252	ANDA	Salix Pharmaceuticals	65649-231-41	100 TABLET in 1 BOTTLE (65649-231-41)	2003-04-01
Aaipharma Llc	AZASAN	azathioprine	TABLET;ORAL	075252	ANDA	Salix Pharmaceuticals	65649-241-41	100 TABLET in 1 BOTTLE (65649-241-41)	2003-04-01
Aaipharma Llc	AZASAN	azathioprine	TABLET;ORAL	075252	ANDA	Glenmark Pharmaceuticals, Inc	68462-502-01	100 TABLET in 1 BOTTLE (68462-502-01)	1999-08-01

AZATHIOPRINE SUPPLIER LANDSCAPE

Last updated: February 19, 2026

WHO ARE THE PRIMARY MANUFACTURERS OF AZATHIOPRINE ACTIVE PHARMACEUTICAL INGREDIENT (API)?

The global supply of azathioprine API is concentrated among a limited number of manufacturers. These entities typically possess the specialized manufacturing capabilities and regulatory approvals required for pharmaceutical-grade production. Key players include companies in India and China, which are significant hubs for API manufacturing.

Manufacturer Name	Country of Origin	Key Products Supported	Regulatory Approvals (Examples)
IOL Chemicals and Pharmaceuticals Ltd.	India	Azathioprine API	US FDA, EDQM
Granules India Ltd.	India	Azathioprine API	US FDA, EDQM
Apotex Inc.	Canada	Azathioprine API	US FDA
Zydus Lifesciences Ltd.	India	Azathioprine API	US FDA, EDQM
Aurobindo Pharma Ltd.	India	Azathioprine API	US FDA, EDQM
Anqiu Pharmaceutical Co., Ltd.	China	Azathioprine API	China NMPA
Zhejiang Huahai Pharmaceutical Co., Ltd.	China	Azathioprine API	US FDA, EDQM

Note: Specific regulatory approvals can vary by product and target market. This table provides examples.

WHAT ARE THE CRITICAL QUALITY ATTRIBUTES AND REGULATORY CONSIDERATIONS FOR AZATHIOPRINE API?

The quality of azathioprine API is paramount due to its use in immunosuppressive therapy. Manufacturers must adhere to stringent quality control measures and comply with global pharmaceutical regulations. Key aspects include impurity profiling, particle size distribution, and polymorphic form control.

IMPURITY PROFILE

Azathioprine synthesis can result in various process-related and degradation impurities. Strict limits are set by pharmacopeias and regulatory agencies for these impurities. Common impurities that require monitoring and control include:

• 6-mercaptopurine (6-MP), a primary metabolite and potential degradation product.
• Nitroso compounds.
• Related substances from starting materials or side reactions.

Regulatory bodies like the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) mandate comprehensive impurity testing and quantification. Manufacturers must demonstrate a consistent impurity profile across batches [1].

POLYMORPHISM

Azathioprine exists in different polymorphic forms, which can affect its dissolution rate, bioavailability, and stability. Manufacturers must identify and control the desired polymorphic form throughout the manufacturing process. Characterization techniques such as X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) are used for this purpose. Regulatory filings typically specify the polymorphic form to be used [2].

PARTICLE SIZE DISTRIBUTION (PSD)

The particle size of azathioprine API influences its downstream processing, particularly for solid dosage forms. Consistent PSD is crucial for uniform blending, tablet compression, and dissolution characteristics. Manufacturers employ milling and micronization techniques to achieve the desired PSD, which is then verified using techniques like laser diffraction [3].

REGULATORY FILINGS AND COMPLIANCE

API manufacturers must maintain Drug Master Files (DMFs) or equivalent documentation with regulatory authorities. These filings detail the manufacturing process, quality controls, specifications, and stability data. Changes in the manufacturing process, suppliers of key starting materials, or analytical methods require regulatory notification or approval, impacting the supply chain’s stability. Compliance with Good Manufacturing Practices (GMP) is non-negotiable.

WHAT IS THE PATENT LANDSCAPE SURROUNDING AZATHIOPRINE?

Azathioprine itself is an old drug with expired primary patents. However, patents can exist for novel formulations, new uses, manufacturing processes, or specific polymorphic forms.

ORIGINAL PATENT EXPIRATIONS

The original patents covering the synthesis and use of azathioprine have long expired. Azathioprine was first synthesized in the late 1950s and became commercially available shortly thereafter. This means the compound itself is in the public domain.

CURRENT PATENT ACTIVITY

While the core molecule is off-patent, ongoing research and development may lead to new patent filings related to:

• Novel Formulations: Patents may cover extended-release formulations, co-formulations with other active ingredients, or improved delivery systems designed to enhance efficacy, reduce side effects, or improve patient compliance.
• New Therapeutic Uses: Research may uncover new indications for azathioprine, leading to patents on its use in treating specific diseases or conditions beyond its established applications.
• Manufacturing Process Improvements: Patents can be granted for more efficient, cost-effective, or environmentally friendly methods of synthesizing azathioprine API, provided they involve novel steps or technologies.
• Specific Polymorphic Forms or Salts: As mentioned, unique crystalline forms or novel salt forms of azathioprine with advantageous properties could be patentable.

Companies seeking to enter the azathioprine market or develop new azathioprine-containing products must conduct thorough freedom-to-operate (FTO) analyses to identify any active patents that could impede their activities.

WHICH COMPANIES MARKET FINISHED DOSAGE FORMS OF AZATHIOPRINE?

The market for finished azathioprine dosage forms (tablets) is served by both originator companies and a significant number of generic manufacturers. The availability of generic versions of azathioprine has increased competition and accessibility.

Brand Name	Generic Name	Marketing Company	Primary Markets
Imuran®	Azathioprine	AbbVie Inc.	Global
Azasan®	Azathioprine	Salix Pharmaceuticals	United States
Azathioprine	Azathioprine	Teva Pharmaceuticals	Global
Azathioprine	Azathioprine	Mylan (Viatris)	Global
Azathioprine	Azathioprine	Sandoz (Novartis)	Global
Azathioprine	Azathioprine	Sun Pharmaceutical Industries	Global
Azathioprine	Azathioprine	Aurobindo Pharma	Global
Azathioprine	Azathioprine	Cipla Limited	Global
Azathioprine	Azathioprine	Dr. Reddy's Laboratories	Global

Note: This list is not exhaustive and reflects major global players. Product availability can vary by region.

WHAT ARE THE KEY SUPPLY CHAIN CONSIDERATIONS AND POTENTIAL RISKS FOR AZATHIOPRINE?

The azathioprine supply chain, like many API supply chains, faces inherent risks that can impact product availability and pricing. These risks often stem from regulatory, geopolitical, and manufacturing-specific factors.

REGULATORY SCRUTINY

Regulatory agencies worldwide, particularly the FDA and EMA, continuously enhance their oversight of API manufacturing. Inspections can uncover GMP deviations, leading to import alerts, product recalls, or manufacturing site shutdowns. Such events can disrupt the supply of azathioprine API and, consequently, finished dosage forms. For example, past issues with specific API manufacturers have led to drug shortages for various pharmaceutical products [4].

GEOPOLITICAL AND ECONOMIC FACTORS

The concentration of API manufacturing in specific geographic regions, notably India and China, exposes the supply chain to geopolitical tensions, trade disputes, and currency fluctuations. Disruptions in these regions, such as natural disasters, pandemics, or labor strikes, can have a ripple effect on global supply. Furthermore, fluctuations in raw material costs and energy prices can impact manufacturing expenses and pricing.

QUALITY CONTROL AND CONSISTENCY

Maintaining consistent API quality is critical. Batch-to-batch variability in impurity profiles or physical characteristics can lead to rejected API batches, manufacturing delays, and increased costs. Pharmaceutical companies rely on robust supplier qualification programs and ongoing quality agreements to mitigate these risks.

RELIANCE ON KEY STARTING MATERIALS (KSMs)

The synthesis of azathioprine relies on specific KSMs. The availability and quality of these KSMs, which may be sourced from different suppliers, are crucial. Any disruption in the KSM supply chain can halt azathioprine API production.

INTELLECTUAL PROPERTY (IP) PROTECTION

While the basic azathioprine molecule is off-patent, navigating the landscape of process patents, formulation patents, and use patents is essential for new market entrants or those developing improved products. Infringement of existing IP can lead to costly litigation and market access restrictions.

HOW HAS THE PRICING OF AZATHIOPRINE EVOLVED?

The pricing of azathioprine has significantly shifted since its introduction. As an established drug with a long history of use and the availability of numerous generic alternatives, its pricing is now primarily driven by generic competition and manufacturing costs.

EARLY MARKET EXCLUSIVITY

When azathioprine (marketed as Imuran®) was first introduced in the late 1950s and early 1960s, it benefited from patent protection and market exclusivity, allowing for premium pricing.

GENERIC EROSION

Following the expiry of its primary patents, generic versions of azathioprine entered the market. This led to a substantial decrease in the price of the drug as multiple manufacturers competed. The price of generic azathioprine is now highly competitive.

CURRENT PRICING DYNAMICS

Current pricing is influenced by:

• Manufacturing Costs: The cost of raw materials, energy, labor, and compliance with regulatory standards by API and finished dosage form manufacturers.
• Competition: The number of generic manufacturers active in the market directly impacts price. A highly fragmented market with many suppliers generally leads to lower prices.
• Volume: Large-volume purchasers, such as hospital systems and government formularies, can negotiate lower prices.
• Formulation: While standard azathioprine tablets are commoditized, any novel formulations with added therapeutic benefits or unique delivery mechanisms could command higher prices, assuming patent protection.

For the standard generic azathioprine tablets, pricing is largely dictated by production costs and competitive pressures, making it a cost-effective therapeutic option.

KEY TAKEAWAYS

• Azathioprine API manufacturing is concentrated among a limited number of global suppliers, primarily in India and China.
• Stringent regulatory requirements for impurity profiling, polymorphism, and particle size distribution are critical for API quality and market access.
• While the core azathioprine molecule is off-patent, patents may exist for novel formulations, new uses, and manufacturing process improvements.
• The market for finished azathioprine dosage forms is dominated by generic products, leading to competitive pricing.
• Supply chain risks include regulatory scrutiny, geopolitical factors, and reliance on key starting material suppliers.
• Azathioprine pricing has transitioned from premium originator pricing to highly competitive generic pricing.

FAQS

1. What is the primary indication for azathioprine?

Azathioprine is primarily used as an immunosuppressive agent to prevent organ transplant rejection and to treat autoimmune diseases such as rheumatoid arthritis, Crohn's disease, and ulcerative colitis.

2. How is azathioprine typically supplied in terms of dosage forms?

Azathioprine is most commonly supplied as oral tablets, typically in strengths of 25 mg and 50 mg. It is also available in injectable formulations for intravenous administration.

3. Are there any major known drug shortages of azathioprine API or finished products?

Drug shortages can occur periodically for various pharmaceutical products, including azathioprine, due to manufacturing issues, quality problems, or demand fluctuations. Pharmaceutical companies and regulatory agencies monitor and report such shortages.

4. What is the difference between azathioprine and its active metabolite, 6-mercaptopurine?

Azathioprine is a prodrug that is converted in the body to 6-mercaptopurine (6-MP). 6-MP is the pharmacologically active compound responsible for the immunosuppressive effects.

5. What are the significant side effects associated with azathioprine therapy?

Common side effects include bone marrow suppression (leading to reduced white blood cell and platelet counts), nausea, vomiting, liver toxicity, and an increased risk of infections. Long-term use may also be associated with an increased risk of certain cancers.

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Citations

[1] U.S. Food and Drug Administration. (n.d.). ICH Q3A(R2): Impurities in New Drug Substances. Retrieved from https://www.fda.gov/drugs/guidance-compliance-regulatory-information/ich-guidelines

[2] European Medicines Agency. (n.d.). Guidelines on the requirements for the quality and stability of finished medicinal products and active substances. Retrieved from https://www.ema.europa.eu/en/human-regulatory/research-and-development/scientific-guidelines/quality-quality-and-affordability-of-medicines

[3] International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. (2009). ICH Q6A: Specifications: Test Procedures and Acceptance Criteria for New Drug Substances and New Drug Products: Chemical Substances. Retrieved from https://www.ich.org/page/quality-guidelines

[4] U.S. Food and Drug Administration. (n.d.). Drug Shortages. Retrieved from https://www.fda.gov/drugs/drug-shortages