The aim of the present study is to determine the distribution coefficient of the given drug in different pH mediums.

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INTRODUCTION:

Distribution coefficient (D) is the ratio of concentrations of a compound (ionized plus un-ionized) in the two phases of a mixture of two immiscible solvents at equilibrium. Hence these coefficients are a measure of differential solubility of the compound between two solvents.  

Distribution Coefficient, D = [Unionised] (o) / [Unionised] (aq) + [Ionised] (aq)

Log D = log10 (Distribution Coefficient)

Log D is related to Log P and the pKa by the following equations:

for acids

for bases

A drug's distribution coefficient strongly affects how easily the drug can reach its intended target in the body, how strong an effect it will have once it reaches its target, and how long it will remain in the body in an active form. Lipophilicity (as measured by its Distribution Coefficient) is also a major structural factor that influences the pharmacokinetic and pharmacodynamic behavior of compounds. Thus lipophilicity is a key factor determining in vivo behavior of drugs.

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Pharmacokinetics:  Permeation of physiological membranes

(Absorption, distribution)

. Plasma protein binding

. Volume of distribution

Pharmacodynamics:  Target recognition

. Target affinity

. Target specificity

The aim of the present study is to determine the distribution coefficient of the given drug in different pH mediums.

MATERIALS AND METHODS:

Apparatus: 10 ml volumetric flasks, beaker, pipette (10 ml), spatula.

Chemicals: 0.2 M Sodium hydroxide, 0.2 M boric acid, 0.2 M potassium hydrogen phthalate, 0.2 M hydrochloric acid, 0.2 M potassium chloride, distilled water, test drug.

      Instruments: Weighing Balance, JASCO UV-Visible Spectrophotometer, pH meter.

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