Trihexyphenidyl Extended Release Pellets with Acid Microenvironment
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Solution Overview
Problem
Trihexyphenidyl hydrochloride exhibits poor solubility at pH greater than or equal to 5, leading to variable blood plasma levels and side effects due to high peak serum concentrations and low trough-to-peak concentration ratios, necessitating the development of extended release compositions that maintain therapeutic concentrations for extended periods with minimal lag time and reduced side effects.
Innovation Solution
The development of pharmaceutical pellet compositions with a core comprising organic acids, a drug layer containing trihexyphenidyl hydrochloride, and a functional coat comprising nonionic water-insoluble polymers and pore formers, which create an acid microenvironment to improve solubility and control drug release, providing a sustained therapeutic plasma concentration with minimal initial burst release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If trihexyphenidyl hydrochloride is administered as immediate release formulation, then rapid onset of action is achieved, but high peak serum concentrations cause side effects and variable plasma levels
Solution Approach 1:
The immediate release tablet is segmented into multiple extended release pellets, each containing a portion of the total drug dose. This segmentation allows the drug to be released gradually over time rather than all at once, maintaining rapid onset while reducing peak concentrations and side effects.
Solution Approach 2:
The extended release formulation provides periodic release of the drug from the pellets over a 24-hour period, maintaining therapeutic plasma levels through sustained release rather than a single bolus dose, thereby reducing peak concentrations and associated side effects.
2Duration of action of moving object
If trihexyphenidyl hydrochloride is administered as extended release formulation, then sustained therapeutic concentrations are maintained, but lag time may increase
Solution Approach 1:
The pellets are pre-coated with enteric polymer and functional coating materials during manufacturing, creating a structure that rapidly disintegrates in the gastrointestinal tract upon administration. This preliminary preparation ensures minimal lag time while maintaining extended release characteristics.
Solution Approach 2:
The functional coating layer has different properties from the enteric coating, with the functional coating being more permeable to facilitate rapid initial drug release. This local quality differentiation ensures quick onset while the overall pellet structure maintains extended release over 24 hours.
3Quantity of substance
If trihexyphenidyl hydrochloride is administered at high doses to maintain therapeutic levels, then plasma concentrations are sufficient, but trough-to-peak concentration ratios decrease causing side effects
Solution Approach 1:
The extended release formulation provides continuous release of the drug over 24 hours, maintaining steady plasma concentrations without the peaks and troughs associated with immediate release dosing. This continuous action reduces the trough-to-peak ratio variability and minimizes side effects while maintaining therapeutic levels.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compositions achieve extended release of trihexyphenidyl hydrochloride for 12 to 24 hours, maintaining therapeutic plasma levels with reduced side effects and improved patient compliance by stabilizing plasma concentrations and minimizing peak serum concentrations.
Implementation Method 1
The compositions provide an acid microenvironment that improves the solubility of trihexyphenidyl (THP) at a pH greater than or equal to about 5
Implementation Method 2
a functional coat comprising nonionic water-insoluble polymers and pore formers, which create an acid microenvironment to improve solubility and control drug release
Implementation Method 3
a functional coat comprising nonionic water-insoluble polymers and pore formers
Data Source
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AI summary
The present disclosure provides extended release trihexyphenidyl compositions suitable for once- or twice-daily administration. The compositions comprise a core comprising organic acid that is coated with a t least one drug layer comprising trihexyphenidyl hydrochloride, and a functional coat over the drug-layered core. The extended release compositions of the disclosure provide extended release of trihexyphenidyl hydrochloride, with reduced Cmax, and a Cmin : Cmax ratio of ≥ 0.4, while maintaining a therapeutically effective concentration for a period of at least about 16 hours. The compositions of the disclosure improve solubility of trihexyphenidyl hydrochloride, at a pH of greater than or equal to 5, to maintain its minimum effective concentration at such pH. In certain embodiments, the compositions of the disclosure comprise an IR drug layer to provide extended release with a minimal lag time, while maintaining a therapeutically effective concentration of trihexyphenidyl hydrochloride for a period of at least about 16 hours.