Formulation methods for suspension PDF

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Formulation methods for suspension    

Suspension Containing Diffusible Solids Suspension Containing Indiffusible Solids Suspension Containing Poorly Wettable Solids Suspension Produced by Chemical Reaction

 Suspension Containing Diffusible Solids   

Some insoluble solids are light & easily wettable. On that reason, they readily mix with water & on shaking, diffuse through the liquid for long enough to ensure even distribution in each dose. Such substance are known as diffusible or dispersible solids.

List of diffusible solids commonly used in oral preparations     

Calcium Carbonate. Antacid Light Kaolin…treat diarrhea Light Magnesium Carbonate. Laxative Magnesium Trisilicate…antacid Rhubarb Powder…digestive problems

 Suspension Containing Indiffusible Solids  

Indiffusible particles will not distributed in a vehicle long enough. So that the correcting this problem is to increases the viscosity of the vehicle by adding a thickening agent.

Used Internally Indiffusible solids  Aspirin. Fever & pain  Chalk. Antacid  Phenobarbiton. Sedative  Sulphadimidine. chalmydia Used Externally Indiffusible solids  Calamine. Pain & itching  Hydrocortisone. Inflammation  Sulphur. Antibacterial  Zinc oxide. Irritation

 Suspension Containing Poorly Wettable Solids     

Some substance e.g. sulphur & hydrocortisone are both insoluble in water & poorly wetted by it. they produce clumps & it is difficult to disperse in aqueous liquids. They Also produce foam on shaking because they are stabilized by the film of unwettable solid at the liquid /air interface. for that reason, satisfactory wetting agent are added, they reduce the interfacial energy between the solid & liquid. those agents are adsorbed at the solid/liquid interface in such a way that the affinity of the particles for the surrounding medium is increased, while the interparticular forces are decreased.

 Suspension produced by chemical reactions      

Chemical reaction method is used to produce insoluble active constituents in the lotion. in that method highly diluted solutions of reacting substance are mixed together. So as to form very finely divided precipitates that can be easily distributed throughout the liquid on shaking. Precipitates formed are generally diffusible in nature therefore no need any suspending agent. Zinc sulphide lotion B.P.C produced by this method....