Size Reduction (Pharmaceutics)

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Size “Reduction”:

Size “ Reduction ” V V S Narayana Reddy Karri Lecturer Dept of Pharmaceutics JSS College of Pharmacy, Ootacamund ( JSS University, Mysore ) Rocklands Udhagamandalam.

Importance of Particle size reduction:

Importance of Particle size reduction To increase the rate of dissolution, since particle size decreases surface area increases To allow the rapid penetration of solvent in case of crude drugs for the extraction of active constituents To get uniform powder size, for uniform mixing of drugs To increase the absorption of drug, the smaller the particle size the greater is the rate of absorption To improve the stability of dosage forms such as suspensions

Factors affecting size reduction:

Factors affecting size reduction Hardness Toughness Stickiness Moisture content Purity required Physiological effect (Potent drug contamination) Ratio of feed size to product size

CUTTING Cutting Mill:

CUTTING Cutting Mill Principle: Cutting by knifes Uses: Size reduction (Coarse) of soft materials such as roots, peels and wood before extraction

COMPRESSION Roller mill:

COMPRESSION Roller mill Principle: Compression of materials by applying pressure Uses: Crushing of seeds for the extraction of fixed oil. Also used to crush the soft tissues, for help in penetration of solvent during extraction process

IMPACT 1. Hammer Mill:

IMPACT 1. Hammer Mill Hammer Principle: Impact Uses: Produce coarse to moderately fine particles of all types material except sticky material.

IMPACT 2. Disintegrator:

IMPACT 2. Disintegrator Dust Bag (High velocity Dust Collected) Undulating (wavy) Inner Surface Beaters Sieve Shaft/Disc (500-7000 rpm) Steel Drum Principle: Impact Uses: Produce coarse to moderately fine particles of all types material except sticky material.

COM-IMPACT-ATTRITION Ball Mill:

COM-IMPACT-ATTRITION Ball Mill Hollow Cylinder Material Steel Balls (30-50% Vol ) Rotate longitudinal axis

COM-IMPACT-ATTRITION Ball Mill…..:

COM-IMPACT-ATTRITION Ball Mill…..

COM-IMPACT-ATTRITION Ball Mill….:

COM-IMPACT-ATTRITION Ball Mill…. LOW SPEED (Roll each other) CORRECT SPEED (Roll + Impact) HIGH SPEED (Centrifugal force) Principle: Impact+attriton Uses ( ADV ): Produce very fine powders. Both wet and dry grinding DIS-ADV Noisy Wear occurs leads to contamination

COM-IMPACT-ATTRITION Fluid Energy Mill:

COM-IMPACT-ATTRITION Fluid Energy Mill Principle: Impact+attriton Uses ( ADV ): Grind heat sensitive material to fine powder. Drug which require high purity. Size of powder can be controlled, no wear-no contamination, grind heat sensitive drugs Loop of pipe (20-200 mm dia ) Inlet for feed

MISCELLANEOUS MILLS Edge Runner Mill:

MISCELLANEOUS MILLS Edge Runner Mill Principle: crushing by stones and shear forces Uses ( ADV ): Grind to fine powder Less attention during grinding 2 heavy rollers Bed (stone) Horizontal shaft

Levigation:

Levigation Process of wet grinding (Paste) Lab scale: Mortar and pestle Large scale: Colloidal mill or edge runner mill Elutriation

Selection of Degree of Size:

Selection of Degree of Size Drugs to be administered in powders an suspensions in mixtures are reduced to fine powders. Drugs to injected in suspension form are reduced to very fine powder. Drugs which are to extracted need size reduction, which depends on: Solvent or Menstrum : Water (More penetration 60%) VS Alcohol. Drug/ menstrum ratio: Physical character of the drug and localization of the constituents: Process:

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