In-Vitro Binding Studies
Many locally acting gastrointestinal drugs — phosphate binders, bile acid sequestrants and potassium binders among them — work by binding target molecules within the GI tract and are not intended to be absorbed into systemic circulation. Because the standard pharmacokinetic bioequivalence (BE) approach depends on measuring systemic drug exposure, it does not apply to these products.
Both US FDA and EMA have independently developed alternative approaches in which in-vitro binding studies directly assess a generic product's binding performance against the reference product, generally alongside dissolution and other mechanism-specific tests. DALPL's Pharma Testing Division designs, develops and validates in-vitro binding bioequivalence studies aligned to current FDA and EMA expectations.
Why In-Vitro Binding Testing
For locally acting GI products, binding performance at the site of action can be more directly assessed through mechanism-specific in-vitro studies than through conventional systemic pharmacokinetic measurements.
Direct Assessment of Binding Performance
Confirms a generic product binds its target GI-tract molecule — such as phosphate, potassium or bile acids — at a rate and extent equivalent to the reference product.
For Locally Acting Products
Used specifically for drugs that act locally and are not systemically absorbed, where conventional pharmacokinetic BE studies cannot be used.
Mechanism-Specific Bioequivalence
Recognised by both FDA, through a general framework plus drug-specific guidances, and EMA, through its GI equivalence guideline, as an acceptable surrogate for clinical efficacy when excipients are not critical and dissolution/disintegration profiles are comparable.
Our In-Vitro Binding Study Services
Targeted in-vitro assays engineered to characterize binding profiles for specific gastrointestinal targets.
Equilibrium Binding Studies
Multiple pH conditions, minimum eight concentration levels and a fixed incubation time. Evaluation includes the Langmuir binding constant (k1), capacity constant (k2), and 90% confidence intervals.
Kinetic Binding Studies
Multiple pH conditions, three concentration levels and a minimum of eight time intervals. Test/reference bound-ratio comparison is performed across time points.
Method Development & Validation
Method development and validation for in-vitro bioequivalence models specific to each drug's binding mechanism.
Product Development Support
Product development support from method feasibility through BE-study execution.
Study Methodologies
A detailed breakdown of the two core study approaches utilized in our in-vitro binding testing.
Equilibrium Binding
Assess equilibrium binding behaviour under multiple pH conditions and concentration levels.
- Multiple pH conditions
- Minimum eight concentration levels
- Fixed incubation time
- Langmuir binding constant (k1)
- Capacity constant (k2)
- 90% confidence intervals
Kinetic Binding
Assess how binding behaviour changes over time under defined concentration and pH conditions.
- Multiple pH conditions
- Three concentration levels
- Minimum eight time intervals
- Test/reference bound-ratio comparison across time points
From Binding Mechanism to Bioequivalence
We deploy a structured mechanism-specific pathway to directly support generic product regulatory submission.
Drugs We've Developed Methods For
DALPL brings direct laboratory experience developing and validating in-vitro binding studies for the following locally acting gastrointestinal products:
Why DALPL
Delivering high-accuracy impurity profiling with uncompromised regulatory integrity.
Frequently Asked Questions
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Get an In-Vitro Binding Study Quote
Speak with our Pharma Testing team about your locally acting gastrointestinal product, binding mechanism and bioequivalence study requirements.