Pharmaceutical powders.pptx

introduction
classification
method of preparation
advantages
disadvantages

1. POWDERS

2.   Introduction Pharmaceutical powders are solid dosage forms of medicament in which one or more drugs are dispensed in finely divided state with or without excipients. They are available in crystalline or amorphous form.

3. Advantages It is used both internally and externally . It is more stable than liquid dosage form . It is convenient for the physician to prescribe a specific amount of powder. Onset of action is faster as compared to tablet, capsules because it is easily dissolved in body fluids . Easy to carry . Easy to administration to the patient orally by dissolving in suitable liquids.

4. Disadvantage Drugs that have bitter taste , nausea and unpleasant taste cannot be administered in powder form. Deliquescent and hygroscopic drugs cannot be dispensed in powder form they are packed in double wrapping. Drugs which get affected by atmospheric condition are not suitable for dispense. Quantity less than 100 mg cannot be weighed conveniently.

5. Divided powder Method of preparation Reduction of particle size of all ingredients to the same range to prevent stratification (separation of the large and small particles) Sieving Weighing each ingredient Mixing Packaging During powdering, weighing and mixing, there is loss of powder which cannot be avoided. Therefore, while calculating the quantity of ingredients calculate for one extra powder than required.

6. Size reduction Is the process of reducing large solid units or substance into smaller unit mass, coarse particles or fine particles. It is also termed comminution, grinding or pulverization. Smaller particle size and increased surface area, leads to: Uniform distribution of the drug substance in a powder mixture or solid dosage form to ensure dose to dose content uniformity . Size reduction on large scale Compression: positive pressure, e.g., nut crusher, ball mill Impact: material is stationary and hit by an object ,e.g., hammer mill Shear: cutting force, e.g., scissors, colloid mill Attrition: breaking the edges of the solid either by impact or particle collisions ( fluid energy mill and roller mill ). Hammer mil l

7. Sieving Weighing each ingredient Mixing of powders The powders may be mixed by any one of the following methods: (mixing methods) Spatulation Trituration Geometric dilution Sifting Tumbling

8. Spatulation In this method, the mixing of powders is done by the movement of a spatula throughout the powders on a sheet of a paper or on a porcelain tile. The method is very useful in mixing: Small amount of powder Solid substances that liquify or form eutectic mixtures, when in close and prolonged contact with one another since very little compression or compact results. This method is not suitable for large quantities of powders or for powders containing one or more potent substances because homogenous blending may not occur.

9. Trituration It is used both to reduce particle size and mix powders. If particle size reduction is desired along with mixing of powders, a porcelain mortar with a rough inner surface is preferred to a glass mortar with a smooth working surface. A glass mortar may be preferred for chemicals that may strain a porcelain surface and for simple mixture of substances without special need for comminution. A glass mortar cleans more readily after use.

10. Geometric dilution The method is used when potent substances are to mixed with a large amount of diluent . The potent drug is placed upon an approximately equal amount of the dilute in a mortar and the substances are slightly mixed by trituration. A second portion of diluent equal in volume to the powder mixture in the mortar is added and trituration is repeated. The process is continued, adding diluent equal in volume to the mixture in the mortar at each step, until all the diluent is incorporated.

11. For example, if 100 mg of potent drug is required to be mixed with 900 mg of lactose, then according to geometric dilution, the following procedure should be followed: 100 mg of a potent drug + 100 mg of lactose = 200 mg of mixture 200 mg of the mixture + 200 mg of lactose= 400 mg of mixture 400 mg of the mixture + 400 mg of lactose= 800 mg of mixture 800 mg of the mixture + remaining portion of lactose= 1000 mg of mixture. Sifting The powders are mixed by passing through sifters. This process results in a light fluffy product and is generally not acceptable incorporation of potent drugs into a diluent base.

12. Tumbling It is the process of mixing powders in a large container rotated by an electronic motor. These blenders are widely employed in industry as large volume powder mixers.

13. Packaging Powders may be wrapped in paper or dispensed in bulk powder in a wide mouth container. Wrapping of powders:-White glazed paper is generally used for wrapping. The wrapping should be done on a clean tile or large sheet of a glazed paper to protect the product.

14. CLASSIFICATION OF POWDERS Bulk powder for internal use Bulk powder for external use Simple and compound powder for internal use Powders enclosed in cachets and capsules Compressed powders (tablets)

15. Bulk powder for internal use Powders are dispensed in bulk, when accuracy of dosage is not important. Bulk powder contains several doses of powder. They are supplied in wide mouthed containers that permits easy removal of a spoonful of powder. The non potent substances which are supplied in bulk are antacids and laxatives etc.

16. Bulk powders for external use Bulk powders meant for external use are non potent substances. These powders are supplied in cardboard, glass or plastic containers, which are often designed for the specific method of application. The dusting powders are preferably supplied in perforated or sifter top containers. The container should bear a label indicating that the powder is meant for external application.

17. The bulk powders which are commonly used for external application are as follows: Dusting powders Effervescent powders Insufflations Snuffs Dentifrices

18. Dusting powders These are meant for the external application to the skin and are generally applied in a very fine state of subdivision to avoid local irritation. Hence, dusting powders should be passed through seive no. 80 to enhance their effectiveness. Dusting powders are of 2 types: Medical Surgical Characteristics No local irritation Flow easily Spread uniformly Good covering capacity Goof adsorptive and absorptivecapacity

19. Medical dusting powders are used for superficial skin conditions , whereas surgical dusting powder are used in body cavities and also on major wounds as a result of burns and umbilical cords of infants. Medical & Surgical dusting powders before use must be sterilized by dry heat method at 160 C for 2 hrs. In the preparation of dusting powder the talc or kaolin, starch are used commonly because these are chemically inert. But , such ingredients are readily contaminated with pathogenic bacteria so, these must be sterilized before their use by dry heat sterilization method.

20. The dusting powders are dispensed in sifter or aerosol containers. Dusting powders are generally non- toxic but inhalation of its fine powdered ingredients by infants may lead to pulmonary inflammation. So proper care should be taken while handling. Use : Antiseptic, Astringent, Absorbent, Antiperspirant

21. Insufflations: These are medicated dusting powder meant for introduction into body cavities such as, nose, throat, ears & vagina with the help of an apparatus “Insufflator ”. Nowadays , the insufflations are available in the form of pressure aerosols & these aerosols used for potent drugs. Insufflations are used to produce a local effect in the treatment of ear, nose, throat infection with antibiotics or to produce a systemic effect from a drug that is destroyed in the gut .

22. Disadvantages : Non uniform dosage Particles stick to each other and to wall of the insufflator

23. Snuffs: These are finely divided solid dosage form of medicament which are inhaled into nostrils for antiseptic , bronchodilator & decongestion action . Snuffs are dispensed in flat metal boxes or glass container with hinged lid . Dentifrices (tooth powders): These are applied on tooth surface with help of brush. They contains suitable detergent or soap, some abrasive substance & suitable flavoring agents are involved. Abrasive agents such as calcium sulphate , calcium carbonate, sodium carbonate & sodium chloride are use in fine powder.

24. Effervescent powders Effervescent granules/ powders/ salts are the forms of medication for internal use consisting of a powdered or granulated mixture of citric acid, tartaric acid, or sodium biphosphate , sod. Bicarbonate The presence of water the acid and base react to liberate CO 2 and produce effervescence. Storage: Effervescent powders should be kept in tightly closed containers. Advantages: It masks the bitter and nauseous taste. It promotes gastric secretions. It acts as a carminative. Minimum moisture

25. Sugar : as sweetening agents Medicaments : therapeutic action it should be anhydrous and soluble in water. Preparation method : 1- Wet method 2- Dry method

26. Examples of effervescent powders Citric acid Tartaric acid Malic acid Fumaric acid Adipic acid Sodium bicarbonate Sodium carbonate Potassium bicarbonate Potassium carbonate

27. Simple and compound powders for internal use In this form of powder, each individual dose is enclosed in paper. The number of ingredient is one i.e. simple powder while more than one i.e. compound powder. The minimum quantit y of each powder should not be less then 100 mg for it can be handled conveniently by patient & can be weighed accurately . Simple powder : In simple powder contains only one ingredient either in crystalline form or amorphous form. If powder present in crystalline form then it is reduced to fine powder , weighed the powder & divided into number of doses & wrapped as individual dose.

28. Compound powders: contains two or more than two substances which are mixed together. Then divided into desired number of individual doses which are dispensed into each powder paper . Powders Enclosed in cachets Cachets are solid dosage form of drug & cachets are also called as wafer capsules . These are moulded from rice paper, which is made by pouring a mixture of rice flour and water between two hot, polishes, revolving cylinders. The water evaporates and a sheet of wafer is formed. They are quite hard to swallow as such but they are softened by dipping in water for a few seconds and then placed on the tongue and swallowed with a draught of water. After swallowing cachet gets disintegrate and drug is released.

29. Compressed tablets or tablet triturates or moulded tablets These are powders moulded into tablets . They are flat, circular disc & usually contains potent drug which is mixed with lactose, dextrose or some other diluents . The apparatus is made up of stainless steel or plastic. It consist of upper & lower perforated plates which is having an exactly the same number of holes as that of number of pegs in a lower plate. The lower plate also have two large pegs which ensure correct fitting of the plates. The moulds are available in several sizes having a capacity ranging from 30 to 250 mg. Generally 50 to 250 tablet triturates can be prepared at a time from a tablet triturate mould .

30. The powder with diluents are mixed together & made a stiff paste with the help of alcohol 60 %. Then , paste is introduced on upper plate with the help of spatula & fill all the holes & removes excess. This plate is placed over the lower plate. Then little pressure is applied over the top plate which will force the plate move downward, leaving the mould tablet on the projected pegs. Then , prepared tablets dried in hot air oven or by keeping in warm place.