Bilastine Form I vs Form II: What’s the Difference?

July 9, 2025

Bilastine Form I vs Form II: What’s the Difference?

In the increasingly demanding world of pharmaceutical ingredient manufacturing, subtle variations in molecular structure and physical characteristics can significantly impact drug formulation, stability, and regulatory compliance.

One case that underscores these nuances is the comparison between Bilastine Form I vs Form II, two polymorphic forms of the nonsedating antihistamine widely used to treat allergic rhinitis and chronic urticaria.

For pharmaceutical buyers, researchers, and formulation scientists, understanding the implications of polymorphism is critical not just in terms of performance, but also shelf life, bioavailability, processability, and global regulatory acceptance.

As a WHO-GMP certified API manufacturer in India with over 80 years of pharmaceutical heritage, BioSynth is well-positioned to provide clarity and confidence when sourcing Bilastine and other specialized active pharmaceutical ingredients.

This article dives into the technical differences between Bilastine Form I and Form II, explores their significance in drug development and manufacturing, and explains how BioSynth ensures a reliable, high-quality API supply for global markets.

What Is Bilastine?

Bilastine is a second-generation H1 antihistamine used primarily for the symptomatic treatment of allergic conjunctivitis, seasonal allergic rhinitis, and urticaria. It is preferred over first-generation antihistamines due to its:

High receptor selectivity
Long half-life (~14.5 hours)
Minimal sedation
Favorable safety profile
Nonhepatic metabolism

Introduced relatively recently, Bilastine has gained wide global adoption, leading to greater scrutiny on the API’s polymorphic profile and its impact on formulation performance.

What Are Bilastine Polymorphs?

In crystalline substances like APIs, a polymorph refers to the ability of a compound to exist in more than one crystalline form. While chemically identical, polymorphs differ in:

Crystal lattice arrangement
Melting point
Solubility and dissolution rate
Bulk density and compressibility
Stability profiles

These differences are not just academic; they can affect:

Bioavailability
Shelf life
Manufacturing consistency
Regulatory approval

Thus, distinguishing between Bilastine Form I vs Form II is critical during formulation development and API sourcing.

Bilastine Form I vs Form II: Structural and Functional Differences

Property	Form I	Form II
Crystal Structure	Stable orthorhombic form	Metastable monoclinic form
Thermal Stability	Higher thermal stability	Lower thermal stability
Solubility	Moderate (formulation-friendly)	Higher but less consistent
Flow Properties	Superior flow and compatibility	Slightly inferior flow
Regulatory Preference	Widely accepted in DMFs and dossiers	Under evaluation in some regions

Form I is typically considered more thermodynamically stable, with better handling and scaleup characteristics.

Form II, while showing slightly higher solubility in some dissolution profiles, is less stable and might present challenges in long-term API storage and processing.

Why Understanding Bilastine Form Matters in API Sourcing

For buyers & formulation teams, the choice between Bilastine Form I vs Form II is not trivial. You must consider:

Regulatory Acceptability

Most regulated markets, including the EU and Japan, scrutinize the specific polymorph form disclosed in the DMF (Drug Master File).

Form I, being more documented and stable, is commonly accepted under such filings.

Formulation and Process Compatibility

Compressibility, blend uniformity, and granulation behavior during tableting can differ based on polymorphism.

Form I offers predictable behavior with flowability advantages ideal for high-volume production.

Shelf Life and Supply Chain

A stable form ensures longer shelf life, reducing risks of recrystallization or form conversion during transportation and storage, which is especially relevant in global API sourcing.

BioSynth: A Trusted Partner for Bilastine and Specialized APIs

As one of the most experienced bulk drug manufacturers in India, BioSynth brings unique strengths to the global API market:

Established in 1943 with over 80 years of pharmaceutical manufacturing heritage.
WHO-GMP, ISO 9001:2015, and compliance-driven operations.
Proven expertise in polymorph control and solid-state chemistry.
Advanced manufacturing plants in Hyderabad serve over 20 export countries.
The product portfolio includes APIs for antihistamines, antipsychotics, TB drugs, cardiovascular, and diabetics.

BioSynth’s Commitment to Polymorphic Consistency and Quality Control

Controlled polymorphism is central to ensuring API quality and performance. At BioSynth:

1. Polymorph Identification and Validation

Using XRPD, DSC, and TGA analysis, we accurately identify and confirm the polymorph form during development and production stages.

2. Robust Solid-State Control

Solid-state chemistry teams at BioSynth ensure that Form I is controlled right from crystallization parameters, avoiding unexpected conversions.

3. Batch-to-Batch Consistency

Every batch of Bilastine is tested for polymorph integrity, complying with pharmacopeial specifications and meeting global regulatory expectations.

PAS Sodium to Bilastine: Specialized API Manufacturing Capabilities

Bilastine is part of a broader therapeutic capability set at BioSynth. Below is an overview:

Therapeutic Segment vs Product List

Therapeutic Area	Key APIs Manufactured by BioSynth
Antitubercular (TB)	Bedaquiline, PAS Sodium
Antihistamines	Bilastine (Form I and II)
Cardiovascular	Carvedilol
Antipsychotic	Amisulpride
Antidiabetic	Empagliflozin, Dapagliflozin

Each of these APIs is manufactured under stringent GMP protocols, with full traceability, stability data packages, and tech transfer support.

Regulatory Considerations When Importing APIs from India

Buyers sourcing APIs like Bilastine from India should evaluate:

GMP Accreditation

Verify WHO-GMP and other applicable local GMPs, such as EU GMP or US FDA (if required by market).

DMF Filing Status

Check if the manufacturer has CEP, USDMF, or Canadian DMFs for the specific API and polymorph.

Proper Labeling and COAs

Ensure polymorph designation is consistently recorded in the COA (Certificate of Analysis) and batch release documents.

Stability Data Reports

Confirm availability of long-term and accelerated stability data, especially for APIs with multiple polymorphs.

QbD-based Manufacturing Practices

Manufacturers using Quality by Design approaches ensure robust control over polymorph production and process validation.

Bilastine Market Trends: API Pricing, Availability, and Emerging Demand

Global demand for Bilastine API is rising for several reasons:

Blockbuster drug sales in the EU and Latin America.
Increased generic formulations.
Health insurance and OTC inclusion across regulated markets.

However, API pricing trends show fluctuations due to:

Raw material price volatility
Logistics disruptions
New polymorph patent filings

Working with a reliable Indian API exporter like BioSynth ensures:

Transparent pricing
Warehouse-based stock availability
Technical support documents for regulatory filings

Conclusion: Choose the Right Bilastine API Partner

When evaluating Bilastine Form I vs Form II, the decision must be based on factors beyond just chemical structure.

Regulatory compatibility, manufacturing control, API stability, and supply reliability all play pivotal roles in formulation success.

BioSynth, with its decades of scientific research, WHO-GMP infrastructure, and international customer trust, offers a regulated, scalable, and solid Form I Bilastine API that meets global formulation needs.

Contact BioSynth today for Bilastine Form I samples, DMF support, technical dossiers, or custom bulk quotes, your trusted partner in polymorph precision and pharmaceutical progress.

Frequently Asked Questions (FAQs)

What Is The Difference Between Bilastine Form I And Form II?

They are polymorphs (different crystalline forms) of the same chemical entity. Form I is more stable and widely accepted in regulatory filings, while Form II may have higher solubility but less consistent form behavior.

Is Bilastine Form I Suitable For High-Speed Tablet Manufacturing?

Yes. BioSynth’s Form I demonstrates reliable flow and compressibility, making it ideal for direct compression or wet granulation methods.

Do Regulatory Authorities Care About The Specific Bilastine Form Used?

Absolutely. Regulatory agencies expect consistent formulation profiles; variances in polymorphs can affect bioequivalence and stability, and therefore must be disclosed and justified in NDAs/ANDAs or MAAs.

Can Biosynth Supply DMFs for Bilastine?

Yes. BioSynth supports global clients with complete regulatory documentation, stability studies, and DMF filings on request.

BioSynth: 80+ Years of Excellence in API Manufacturing Trusted by Scientists, Backed by GMP, and Driven by Science.