Dr.N.DamodharanProfessor and head

Department of pharmaceuticsSRM college of pharmacy

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Definition:

Result of mixing of two or more antagonistic

substances

formation of undesirable products.

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Reasons for Incompatibility:

Interaction of one drug with other drug

Interaction of drug with additives

Dosage errors

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Types of incompatibility

Physical

Chemical

Therapeutic

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PHYSICAL INCOMPATIBILITY

Immiscibilty

InsolubilityPrecipitationLiqeufactionPhysical complexion

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Chemical incompatibility – two types

1.Tolerated

2. Adjusted

3. Intentional

4. Unintentional

Precipitate yeilding interactions

Diffusible precipitate—Method A—to overcome

Indiffusible precipitate –Method B –to overcome

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Chemical incompatibility

-- Alkaloidal

Alkaloidal salt with alkaline substances

Alkaloidal salts with soluble iodides

Alkaloidal salts with tannins

Alkaloidal salts with salicylates

Alkaloidal salts with soluble iodides and bromides

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- Soluble salicyates incompatibility

Soluble salicylates with ferric salts

Soluble salicylate with alkali bicarbonates

-- Soluble iodides incompatibility

Oxidation of iodides with ferric salts

Oxidation of iodides with Potassium chlorate

Oxidation of iodides with quinine sulphate

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- Chemical incompatibilities causing evolution of carbon dioxide

Soluble bicarbonate with soluble calcium and magnesium salts

Bismuth subnitrate and sodium bicarbonate

Borax with sodium bicarbonate and glycerin.

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Miscellaneous chemical incompatibilites

Soluble barbiturates with ammonium bromide

Potassium chlorate with oxidisible substances

Incompatibility of emulsifying agents

Colour stability of dyes

Incompatibilities of liquorice liquid extract

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THERAPEUTIC INCOMPATIBILITY:

Prescribing certain drugs to patient with the intention

To produce specific degree of pharmacological action

but the nature or intensity of action produced is

different from that intended by prescriber.

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REASONS:

Wrong dose

Wrong drug

Wrong dosage form

Wrong route

Synergism

Antagonism

Contraindication

Drug interactions

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