Polymorph Solubility in Pyridazino Indole Derivative

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Solution Overview

Problem

The limited solubility of crystalline Form I of 7-chloro-N,N,5-trimethyl-4-oxo-3-phenyl-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide hinders its administration and storage, and results in limited absorption of the drug in standard formulations.

Innovation Solution

A novel crystalline form, Form II, with greater solubility and dissolution rates is developed, which is prepared through controlled crystallization conditions, such as heating in a lower alcohol or dissolving in dichloromethane and precipitating with solvents like ethanol or hexanes, maintaining stability under normal and stress conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If crystalline Form I is used, then the compound can be isolated and stored, but the solubility is limited (less than 0.01 mg/ml in aqueous solutions and less than 3 mg/ml in non-aqueous solvents)

Engineering Contradiction:
Improvestability of crystalline formVSAvoidsolubility
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by modifying the crystalline structure parameters of the compound to create a new polymorphic form (Form II) with different physical properties. Specifically, the crystal lattice arrangement and intermolecular interactions are changed to achieve higher solubility while maintaining stability, directly resolving the contradiction between solubility and crystalline stability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes phase transitions by transforming the compound from one crystalline phase (Form I) to another crystalline phase (Form II). This polymorphic transition results in a new solid form with improved solubility characteristics while maintaining the stability required for pharmaceutical storage and handling

Inventive Principle:
Principle #36Phase transitions

2Ease of operation

If standard formulations are used with crystalline Form I, then the drug can be administered, but the absorption is limited due to low solubility

Engineering Contradiction:
ImproveadministrabilityVSAvoidabsorption
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The patent changes the physical parameter of the drug substance by creating crystalline Form II with enhanced solubility properties. This parameter change directly improves the absorption characteristic while maintaining the ease of administration through standard formulation routes

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If crystalline Form II is prepared through controlled crystallization, then the solubility and dissolution rates are improved, but the preparation process becomes more complex

Engineering Contradiction:
ImprovesolubilityVSAvoidpreparation process complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent employs controlled phase transition during crystallization to obtain Form II. By carefully controlling the crystallization conditions (temperature, solvent system, cooling rate), the process achieves the desired polymorphic form with improved solubility while managing the complexity through established pharmaceutical manufacturing techniques

Inventive Principle:
Principle #36Phase transitions

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

Form II exhibits higher solubility and stability compared to Form I, ensuring effective bioavailability and pharmaceutical suitability without converting to other forms under storage conditions, thus improving drug absorption and formulation efficacy.

Implementation Method 1

crystallization of 7-chloro-N,N,5-trimethyl-4-oxo-3-phenyl-3,5-dihydro-4H-pyridazino[4,5-b]indole-1-acetamide under suitable conditions

Methodology Applied
Scientific EffectCrystallization: Crystallisation

Implementation Method 2

dissolving in dichloromethane and precipitating with solvents like ethanol or hexanes

Methodology Applied
Scientific EffectSolvation: Solvation

Data Source

PatentEP1924585B1Novel crystalline form of a pyridazino [4 , 5-b] indole derivative
Publication Date: 2011.11.02 SANOFI AVENTIS US LLC
  • EP1924585B1 patent drawingFigure 1
  • EP1924585B1 patent drawingFigure 2
  • EP1924585B1 patent drawingFigure 3

AI summary

Disclosed are a novel crystalline form of 7-chloro-N,N,5-trimethyl-4-oxo-3-phenyl- 3,5-dihydro-4H-pyridazino[4,5--]indole-l-acetamide, processes of preparing said crystalline form of 7-chloro-N,N,5-trimethyl-4-oxo-3-phenyl-3,5-dihydro-4H-pyridazino[4,5-o]indole-l- acetamide, compositions comprising said form in admixture with one or more pharmaceutically acceptable excipients, and uses for the same.