Solubility of drugs physical pharmaceutics Notes

  Solubility of drugs

Important topics

1. Factors affecting solubility of drugs

2. Association and solvation

3. Miscibility partial miscibility and complete

4. Distribution law and application

5. Diffusion principle in biological system

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Videos for important topics

1. Factors influencing solubility 

There are various factors which affect the solubility of drugs like

1. Particle size

2. Temperature

3. Pressure

4. Polarity

5. Polymorphism

2. Solvation and association

Solvation is the process of attraction and association of molecules of a solvent with molecules or ions of a solute. As ions dissolve in a solvent, they spread out and become surrounded by solvent molecules

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Association is a chemical reaction whereby ions of opposite electrical charge come together in solution to form a distinct chemical entity

3. Solute and solvent interaction

Solute-Solvent Interactions Affect Solubility. The relation between the solute and solvent is very important in determining solubility

4. Solubility parameter

Hildebrand solubility parameter provides a numerical estimate of the degree of interaction between materials and can be a good indication of solubility, particularly for nonpolar materials such as many polymers

 The Hansen solubility parameter system ... where δs, δd, δp, and δh are the solubility parameters corresponding to the solvent

5.  Solubility of liquid in liquid

6. Partial miscibility

A pair of liquids is considered partially miscible if there is a set of compositions over which the liquids will form a two-phase liquid system. 

7. Distribution law

Distribution law or the Nernst's distribution law gives a generalisation which governs the distribution of a solute between two non miscible solvents

8. Diffusion principles in biological system

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