1INTRODUCTIONADVANTAGES AND DISADVANTAGES OF POWDERSDRUG POWDER FORMULATIONCLASSIFICATION OF POWDERSPOWDERS FOR EXTERNAL USECONCLUSIONREFERENCES
Introduction2Powders are the simplest dosageforms and the basis of many othersolid dosage forms such as tablets,capsules, etc.Powders were originally designed asa convenient mode of administeringhard vegetable drugs such as roots,barks and woods.
3DEFINITION:Powders are intimate mixtures ofdry, finely divided drugs and/orchemicals that may be intendedfor internal or external use (e.g.external applications to the skin).
Advantages of powdersAdvantages of powders4Used both internally and externally.Good chemical stability compared with fluids.Rapid onset of action.Easy to swallow even in large bulk, especially if mixed withdrink food.Easy to carry than the liquid dosage forms.It is suitable for small children and elderly patients.Economical.
5Disadvantages of powdersDisadvantages of powdersNot suitable for drugs unstable in atmosphericconditions.Not suitable for bitter, nauseating, deliquescent andhygroscopic drugs.The dispensing of powder is a time consuming.Quantity less than 100 mg or so, cannot be weighedconveniently on dispensing balance.
6DRUG POWDER FORMULATIONTo obtain powder as raw material from an original drug (animal,vegetable drugs, or animal or synthetic chemical entities) bydifferent methods of division.Mixing of various powders with or without excipients as afunction of the powders’ characteristics (e.g., flow properties).Packaging of the finished product for an easy patient’s use.Formulation of powders as dosage forms is performedaccording to the following steps:
OBTENTION OF POWDERS AS RAW MATERIALS:1.Coarse division- Reduces lump drugs into fragment ofdifferent sizes.2.Communition- Reduces the size, gives particle size smallerthan that coarse division.7
7OBTENTION OF POWDERS AS RAW MATERIALS:Coarse division- Reduces lump drugs into fragment ofdifferent sizes.Communition- Reduces the size, gives particle size smallerthan that coarse division.Methods and Equipment:1.COARSE DIVISION8
8Methods and Equipment:COARSE DIVISION:2. COMMUNITION:
11Powder Characterization:Particle size:This parameter influences the dissolution rate of the drug in-vivo, which in turn influences absorption rate and the onset oftherapeutic activity.Powders with different particle sizes have different flow andpacking properties, which alter the volume of powders duringeach event. To avoid such problems, the particle size of drugsshould be defined during formulation and must be as uniform aspossible.
12PARTICLE SIZE ANALYSIS Sieving. Microscopy. Sedimentation Rate. Coulter Counter. Gas Adsorption.FLOW PROPERTIES:Flow properties of powders are important parameters in mixing andsegregation phenomena, essentially during storage.Flow properties depend on particle size, nature of particles, shapeand moisture content.
13Flow properties depend on particle size, nature of particles,shape and moisture content.It is determined by angle of repose, bulk or tapped density.The excipients must posses the following properties:Optimal particle size distribution,High flowability,High compressibility,Optimal capacity for a drug,
14Physiologically inert,Resistant to heat, humidity, and oxidation,Tasteless and odourless.Some of the excipients areMagnesium stearate ,PEG6000,Calcium stearate ,Glycerol palmito stearate ,
15MIXING OF POWDERSThe aim of mixing is to obtain a homogeneous associationof several solid products.Factors influencing the mixing of powders- nature of surface,density, particle size, particle shape, particle charge and proportionof materials.If these factors are not under control, segregation (demixing) canoccur.Types of segregation include percolation, trajectory anddensification.
16METHODS OF POWDER MIXINGSpatulation (spatula + tile)Trituration (mortar + pestle)Geometric dilution:Entire quantity of potent drug (x volume) + (xvolume) of the diluents + (2x volume) of thediluents + (4x volume) of the diluents………repeated until all the diluents are used.Tumbling (wide mouth closed container)
17Packed in sifter top containers, pressurized containers, flat metalboxes.LABELLING:FOR EXTERNAL USE ONLYPACKING
18Bulk powders for external use:Bulk powders for internal use.Simple and compound powders for internal use.Powders enclosed in catchets and capsules.Compressed powders(tablets).
19Bulk powders for external use:1.Dusting powders:They are meant for external application to the skin and generallyapplied in a very fine state of subdivision to avoid local irritationThey are of two types :(a) Medical :They are used for superficial skin conditions, they shouldnot be used for application to open wounds or application orbroken skin.The label should clearly specify this point. We need notsterilise the ingredients of these powders but we must be sure thatthey are not containing pathogens.
20(b) Surgical:These powders must be sterile because they are usedin body cavities and are applied on wounds. Theyare sprayed on burnt areas and are placed on theumbilical cords of infants.These powders usually contain an antibacterialagent. The diluent is sterilizable maize starch, which is alsocalled as absorbable dusting powder.Function:Lubricants, protective, adsorbents, antiseptic, astringents.
102. SNUFFS:Definition:These are finely divided solid dosageforms of medicaments inhaled into nostrils.Function:Decongestion, Antiseptic,BronchodilatorPackaging:Dispensed in flat metal boxes with hinged21
22Dental powders are applied with the help of a tooth brush for cleaningthe surface of the teeth.Dental powders contain detergents, abrasives, antiseptics and colouringand flavouring agents incorporated in a suitable base.Base is calcium carbonate. The detergent is in the form of soap and theabrasive action is provided by finely powdered pumice stoneEssential oils are added to provide flavour and freshness to the mouth aswell as antiseptic action.3.DENTAL POWDERS:
23Insufflations are the medicated dusting powders introducedinto body cavities such as ears, nose, throat and vaginawith the help of a device called an insufflator.It sprays the powder into a stream of finely dividedparticles all over the site of application.
24Powder Dosage Forms are versatile, flexible in dosagestrengths, relatively stable, and also convenient tomanufacture, store, handle and use.It is possible to reduce them to desired particle size and thusfacilitate rapid absorption. Thus from biopharmaceuticalconsiderations POWDERS are convenient and useful forprescribing drugs.
26251.Jean-Mark Aiache and Erick Beyssac, Encyclopedia of PharmaceuticalTechnology, 3rd Edition, volume 5, Powders as Dosage forms, pages 2971-2982.2.Loyd V.Allen, Jr., Nicholas G. Popovich and Howard C. Ansel , Ansel’sPharmaceutical Dosage Forms & Drug Delivery Systems, Solid DosageForms, pages 186-198.3. R M Mehta, Dispensing Pharmacy, Solid Dosage Forms, pages 108-124.C.V.S Subramanyam, J.Thimma Shetty, Sarasija Suresh and V. Kusumdevi,4. Pharmaceutical Engineering Principles and Practices, Size Reduction,Mixing, Pages 144-173,199-223
27265.Michael E. Aulton, Aulton’s Pharmaceutics The Design andManufacture of Medicines, 3rd edition, Powder and Granules pages406-409.6. C.V.S Subrahmanyam, Textbook of Physical Pharmaceutics, 2ndedition, Micrometrics, pages 181-230.