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EXTEMPORANEOUS PREPARATIONS BY SANA GHAYAS

EXTEMPORANEOUS PREPARATIONS BY SANA GHAYAS. LEARNING OBJECTIVES: At the end of this lecture, students will be able to: Know about extemporaneous dispensing. Define different dosage forms

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EXTEMPORANEOUS PREPARATIONS BY SANA GHAYAS

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  1. EXTEMPORANEOUS PREPARATIONSBYSANA GHAYAS

  2. LEARNING OBJECTIVES: At the end of this lecture, students will be able to: • Know about extemporaneous dispensing. • Define different dosage forms • Classify different dosage forms on the basis of their use with examples (solutions, suspensions, creams, emulsions, ointments, paste, gels, suppositories, pessaries, powders, granules, oral unit dosage forms) • Contrast different dosage forms • Dispense different dosage forms extemporaneously with labels. • Evaluate dispensed dosage forms and their labels. • Provide special labels and advice for patients.

  3. Dispensed products grouped into • Solution • Suspension • Emulsion • Creams • Powders and oral unit-dosage forms • Ointments • Pastes & jellies • Suppositories & pessaries

  4. SOLUTIONS: • Homogenous liquid preparations • Containing one or more dissolved ingredients • Designed for internal & external use. FORMULATION OF SOLUTION: Following should be determined before formulating a solution: • Vehicles • Solubility • additives

  5. VEHICLES: Medium in which ingredients of medicine are dissolved or dispersed. • Water • Syrup • Ethanol • Glycerol • Propylene glycol • Acetone • Solvent ether

  6. SOLUBILITY: • “The no. of parts of solvent (by volume) that will dissolve one part (by weight of a solid or volume of a liquid )of the substance. • For oral solutions, ethanol, glycerol and propylene glycol may be used in various combinations with water as cosolvent. • Surfactant can be used for solubilization of poorly water soluble medicaments. E.g. polysorbates.

  7. ADDITIVES • GIT can tolerate solutions with a wide range of pH values. • Hypertonic solutions (potassium citrate mixture BP) should be well diluted before taking orally. • Solutions prepared for mucosal surfaces (nasal drops) usually include sodium chloride to increase tonicity to that of body fluids. • Stabilizers • preservative • Colours • Flavours

  8. SOLUTIONS AS ORAL DOSAGE FORMS: • Elixirs, mixtures & oral solutions contain one or more ingredients dissolved in a suitable vehicle. • If dose less than 5 ml prescribed, oral liquid usually diluted. • Choice of diluent is critical as their inclusion can adversely affect flavour, stability or appearance. • Extemporaneously dispensed products usually diluted with water or syrup, appears as last line in the formula.

  9. SHELF LIFE: • SUPPLY OF PRODUCT WITH SHORT HALF LIFE: • Quantity of product supplied to patient must not exceed that which would be expected to be used with in the shelf life. • CONTAINERS, LABELS AND ADVICE FOR PATIENTS:

  10. MOUTHWASHES AND GARGLES: • These are usually diluted with warm water before use • Most are not intended to be swallowed in significant amounts. • Long shelf life • Stable products • Prepared from stock. • Extemporaneously prepared or poured preparations are supplied in amber colored fluted bottles or medicine bottles for products intended to be swallowed.

  11. SOLUTIONS INSTILLED INTO BODY CAVITIES: • Nasal drops and sprays formulated as iso osmotic with nasal secretions. • Buffered • Shelf life of extemporaneous products • Dispensing: • extemporaneous nasal drops supplied in hexagonal, amber fluted glass bottles with a rubber teat and dropper closure. • Nasal sprays packed in flexible plastic bottles or pressurized containers. • For decongestant drops, patient should “AVOID EXCESSIVE USE” and “AVOID USE IN VERY YOUNG BABIES UNLESS UNDER MEDICAL ADVICE”

  12. EAR DROPS: • Water, glycerol and propylene glycol may be used as vehicles. • They are supplied in glass bottles with a teat and dropper closure or plastic squeeze bottles. ENEMAS: • Used for cleansing, therapeutic or diagnostic purposes. • shelf life • Amber fluted glass bottles used for enemas and disposable bags sealed to a rectal nozzle are for commercial use. • Label is marked as “FOR RECTAL USE ONLY”

  13. SOLUTIONS FOR EXTERNAL USE: • Liniments, lotions and paints are usually stable. • Shelf-life of liniments, lotions and paints • Containers for liniments, lotions and paints • Special labels and advice for patients . • Antiseptic and disinfectant solutions • Shelf-life of antiseptic and disinfectant solutions • Containers for antiseptic and disinfectant solutions • Special labels and advice for patients

  14. PHARMACEUTICAL SUSPENSION: • Suspensions are classified as: • Coarse suspensions. • Colloidal suspensions. FORMULATION OF SUSPENSION: • Water is usually vehicle of choice. • Non aqueous vehicle like fractionated coconut oil are occasionally used. • Other additives are buffers, stabilizers, preservatives, colors and flavors. PROPERTIES OF A GOOD PHARMACEUTICAL SUSPENSION

  15. FACTORS AFFECTING PROPERTIES OF A PHARMACEUTICAL SUSPENSION: • Diffusible solids • Stokes law • Control of particle size • Flocculation • poorly wettable solids • In diffusible solids THICKENING AGENTS: • Polysaccharides i.e. acacia gum, tragacanth, sodium alginate, starch. • Water soluble celluloses i.e. methyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose. • Clays i.e. bentonite, aluminium magnesium silicate, hectorite. • Synthetic thickeners i. e. carbomers, colloidal silicon dioxide.

  16. BASIC TECHNIQUES FOR PREPARING PHARMACEUTICAL SUSPENSIONS SUSPENSIONS AS ORAL DOSAGE FORMS • MIXTURES: • Advantages of suspensions as oral dosage forms • Disadvantages of suspensions as oral dosage forms • Shelf life of oral suspensions • Containers for oral suspensions • Special labels and advice for patients

  17. SUSPENSIONS FOR EXTERNAL USE • LOTIONS: • containers for lotions • Special labels and advice for patients • INHALATIONS • Containers for inhalations • Special labels and advice for patients • OTHER TYPES OF DISPENSED PRODUCT • SUSPENSIONS AS 'EMERGENCY' FORMULATIONS

  18. EMULSION: • An emulsion is a disperse system consisting of two immiscible liquids, one of which(disperse phase) is finely divided and distributed through the other (continuous phase). • DETERMINATION OF EMULSION TYPE • To distinguish between O/W and W/O emulsions, following tests may be used: • Miscibility test • Microscopic examination after staining with a oil soluble dye • Microscopic observation under UV radiation • Conductivity measurements

  19. FORMULATION • Emulsifying agents facilitate the production of a dispersion by reducing interfacial tension and maintain the separation of the droplets of the dispersed phase by forming a barrier at the interfaces. • For oral/parenteral administration, O/W emulsions are required • For external use both O/W and W/O systems may be used. • TYPES OF EMULSIFYING AGENTS • Synthetic or semi synthetic substances • Natural products • Finely divided solids • Many of the substances described as thickening agents also act as amulgents.

  20. SYNTHETIC OR SEMI SYNTHETIC SUBSTANCES • They are further classified depending on their ionization in aqueous solution as follows: • Anionic surfactants e.g. alkali metal and ammonium soaps, amine soaps, soaps of divalent & tri valent metals, alkyl phosphate and alkyl sulphates. • Cationic surfactants e.g. quarternary ammonium compounds like cetrimide • Non ionic surfactants e.g. glycol and glycerol esters, sorbitan esters, polysorbates, macrogol ethers and esters • Ampholytic or amphoteric surfactants which are not widely used as emulsifiers in pharmacy. • NATURAL PRODUCTS • FINELY DIVIDED SOLIDS

  21. Choice of an emulsifying agent • Selection of appropriate emulsification system depends on active ingredients incorporated into product and on use of final product and based on theoretical con­siderations and on experience. Formulation by the HLB method • emulgents with high numbers (8-18) produce o/w emulsions and with low numbers (3—6) give w/o emulsions.

  22. OTHER ADDITIVES Antioxidants: e.g. butylatedhydroxyanisole (BHA) or butylatedhydroxytoluene (BHT). Ethyl, propyl or dodecylgallate may also used. Preservatives Desirable properties of a preservative for emulsions Preservatives commonly used in emulsions • Organic acids. • Parahydroxybenzoic acid esters. • Chlorocresol. • Phenethyl alcohol. • Quaternary ammonium compounds. • Chloroform. Colour and flavor • Additional color is rarely necessary. • Flavors are used for oral emulsions.

  23. STABILITY OF EMULSIONS : The main difficulties encountered in practice are listed here. Creaming • This is separation of the emulsion into two regions, one containing more of the disperse phase, e.g. cream on milk. Cracking • This involves coalescence of dispersed globules and separation of the disperse phase as a separate layer. Phase inversion • The most stable range of disperse phase concentrations is 30-60%. • If amount of disperse phase increased until it approaches or exceeds the theoretical maximum of 74% of the total volume then phase inversion may occur, i.e. from o/w to w/o, or from w/o to o/w.

  24. COMPOUNDING OF EMULSIONS AND CREAMS • Basic techniques are: • Weighing • Measuring of liquids • Mixing • On small scale mortar and pestle are used producing globule size larger than 10 µm. • Homogenizers are used for extemporaneously prepared emulsions. EMULSIONS AS ORAL DOSAGE FORMS • Shelf-life of oral emulsions • Containers for oral emulsions • Special labels and advice for patients

  25. EMULSIONS FOR EXTERNAL USE: • Liniments and lotions are liquid or semi liquid emulsions designed for application to skin. • Shelf-life of applications, liniments and lotions • Containers for applications, liniments and lotions • Special labels and advice for patients

  26. CREAMS: • They are viscous semi solids for external use. • They may be W/O or O/W emulsions. • GENERAL COMPOUNDING PROCEDURE FOR CREAMS • DILUTED CREAMS • SHELF-LIFE OF CREAMS • CONTAINERS FOR CREAMS • SPECIAL LABELS AND ADVICE FOR PATIENTS

  27. OINTMENTS PASTES AND GELS: • Ointments are greasy preparations. • Gels are transparent or translucent, non greasy, aqueous preparations. • Pastes contain a higher proportion of finely powdered medicament than ointments or gels BASES FOR OINTMENTS AND OINTMENT TYPE PASTES They may be classified into four main groups: • HYDROCARBON BASES • ABSORPTION BASES • WATER MISCIBLE BASES • WATER SOLUBLE BASES

  28. OTHER ADDITIVES FOR OINTMENTS AND PASTES • These include: • Antioxidants like BHT, BHA, EDTA and must be compatible with the medicaments incorporated into the base. • Preservatives, which may not be required in anhydrous ointments. Examples are sorbic acid, quaternary ammonium compounds etc.

  29. FORMULATION OF GELS: • Gelling agents are either organic hydrocolloids or hydrophilic inorganic substances. • Slightly viscous gels may be used as replacement solutions for body secretions i.e. artificial saliva and tears. • More viscous gels may be used as lubricants for catheters, examination gloves and surgical instruments. • Those designed for surgical or ophthalmic use must be supplied sterile.

  30. TRAGACANTH GELS: Concentration of tragacanth from 2%-5% produce gels of increasing viscosity. SODIUM ALGINATE GELS: A concentration of 1.5% produces fluid gels and 5-10% gels are suitable as dermatological vehicles. PECTIN GELS CELLULOSE DERIVATIVES: POLYVINYL ALCOHOLS: The required concentration is usually between 10% and 20%, depending on the grade of PVA and the desired viscosity.

  31. OTHER ADDITIVES FOR GELS: • HUMECTANTS: Like glycerol, propylene glycol or sorbitol solution may be added to retain water, otherwise skin formation may occur. • PRESERVATIVES: like methyl and propylhydroxybenzoates either alone or in combination are suitable for gels containing pectin, carmellose sodium, sodium alginate, tragacanth, etc. • CHELATING AGENTS: like EDTA may be used for protection against heavy metals.

  32. COMPOUNDING OF OINTMENTS AND PASTES • The basic techniques are weighing, measuring of liquids, size reduction, size separation and mixing. • MIXING BY FUSION • PREPARATION OF MEDICATED OINTMENT AND PASTES BY FUSION • MIXING BY TRITURATION

  33. SHELF LIFE OF OINTMENTS, PASTES AND GELS • CONTAINERS FOR OINTMENTS, PASTES AND GELS • Extemporaneously prepared ointments and pastes are usually packed in screw capped amber glass or plastic pots. • SPECIAL LABELS FOR OINTMENTS, PASTES AND GELS • Store in a cool place. • Sterile. • The labels for collapsible tubes should be fixed to the upper(nozle) end of the tube.

  34. SUPPOSITORIES: • They are solid medicated preparations designed for insertion into rectum. • They melt, dissolve or disperse and exerts a local or systemic effect. • Pessaries similar solid medicated preparations designed for insertion into the vagina. • Usually used to provide local effect. • FORMULATION OF SUPPOSITORIES AND PESSARIES: • There are two main classes of suppository base: • Fatty bases designed to melt at body temperature. • Water soluble or water miscible bases designed to dissolve or disperse within the body.

  35. PROPERTIES OF IDEAL SUPPOSITORY BASE: • FATTY BASES: • Theobroma oil (cocoa butter): • Advantages of theobroma oil include: • Disadvantages of theobroma oil include: • Polymorphism • Adherence to the mould • Softening point too low for hot climates • Melting point reduced by soluble ingredients • Rancidity on storage • Poor water-absorbing ability • Leakage from the body • expense

  36. (b) Synthetic hard fat: • They include mixture of mono-, di- and tri-glycerides of saturated fatty acids. Advantages of these bases over theobroma oil: Disadvantages of synthetic bases include:

  37. (2)Water soluble and water miscible bases: • glycero-gelatin • Mixture of glycerol and water gelled by the addition of gelatin. (b)Gelatin • Two type of gelatin are used in pharmaceutical preparations: • Type A which behaves as a cationic agent and most effective at pH 3.2. • Type B which behaves as a anionic agent and most effective at pH 7-8. (c) Macrogols (polyethylene glycols) • Mixtures of macrogols can be used as bases for suppositories and pessaries.

  38. OTHER ADDITIVES • Antioxidants can be added to prevent oxidation which must be compatible with the medicament. • Water miscible or water soluble bases should include preservative which must be challenged with appropriate micro organisms to test its efficacy. • Emulsifying agents (wool fat, macrogols) may be included to facilitate incorporation of aqueous solutions or polar liquids but with caution. • Hardening agents are added to the base to raise the melting point. • Viscosity modifiers reduce the sedimentation rate.

  39. CHOICE OF SUPPOSITORY OR PESSARY BASE • COMPOUNDING OF SUPPOSITORY OR PESSARY BASE

  40. SUPPOSITORY OR PESSARY MOULDS • For small scale, metal moulds are used having 6 cavities usually. • Normal capacities of commonly used moulds include 1, 2, 4 and 8 g.

  41. DISPLACEMENT VALUES Use of displacement values (Method for determining displacement value) Using a nominal 1 g mould, Prepare and weigh six suppositories of unmedicated base = ag Prepare base containing 30% medicament, fill six moulds and weigh six suppositories = bg Calculate the amount of base, cg and medicament d g in the six suppositories c = 70% b and d = 30% b Therefore the amount of base displaced by displacement value = __d______ a-c For example: Weight of six unmedicatedsuppos. = 6.0 gWeight of six suppos. Containing 30% drug = 7.5 g Base = 70% of 7.5 = 5.25 Drug = 30% of 7.5 = 2.25 Base displaced by 2.25 g = 6 - 5.25 = 0.75 g Therefore the displacement value of the drug = 2.25/0.75 =3 Method for using displacement value Required: to prepare for 8 suppositories each containing 300 mg drug of displacement value 3 using a nominal 1 g mould. Total amount of drugs required = 8 x 300 mg = 2.4 g This will displace 2.4/3= 0.8 g of base Therefore amount of base required = 8-0.8 = 7.2 g

  42. MOULD LUBRICATION Preparation of suppositories with a fatty base • Calculate the quantities required. • Prepare the mould. • Prepare the base. • Prepare the medicament. • Melt the base. • Incorporate the medicament. • Fill the mould. • Remove the excess. • Open the mould. Preparation of suppositories with a macrogol base

  43. Preparation of suppositories with a glycero-gelatin base • Calculate the quantities required. • Prepare the mould. • Prepare the medicament. • Prepare the base. • Heat treatment of the base. • Adjustment of base to weight. • Incorporate any medicament. • Fill the mould.

  44. SHELF LIFE: • Stable preparations if the packaging provides adequate protection and that the storage temperature is low. CONTAINERS LABEL AND ADVICE • Store in a cool place. • For rectal use only. • For vaginal use only. EXAMPLES • Compound bismuth subgallate suppositories BP • Dimenhydrinate suppositories • Glycerol suppositories BP

  45. POWDERS: • Undivided oral powders. • Divided oral powders. • Granules for oral administration. • Dusting powders for external use. • FORMULATION OF POWDERS AND GRANULES: • COMPOUNDING: • Basic techniques of compounding of powders and granules are: • Weighing • Size reduction • Size separation • Mixing

  46. PREPARATION OF UNDIVIDED ORAL POWDERS: • PREPARATION OF DIVIDED ORAL POWDERS: • WRAPPING DIVIDED POWDERS: • PREPARATION OF GRANULES: On small scale, granules are made with a mortar and pestle and suitable sieves. • PREPARATION OF DUSTING POWDERS: They are prepared using method as for undivided oral powders. Sieve size should be 180 µm.

  47. ORAL POWDERS AS DOSAGE FORMS: 1. UNDIVIDED POWDERS AS ORAL DOSAGE FORMS: • Relatively few medicaments are formulated as undivided/divided powders. • ADVANTAGES AND DISADVANTAGES OF UNDIVIDED POWDERS: • SHELF LIFE OF UNDIVIDED POWDERS: • Undivided powder are suitably packaged and stored. • Remain stable over a long period. • CONTAINERS OF UNDIVIDED POWDERS: • Plain glass jars with close fitting closures and a 5 ml measuring spoon should be supplied for undivided powders. • SPECIAL LABEL AND ADVICE FOR PATIENTS: 2. DIVIDED POWDERS AS ORAL DOSAGE FORMS: • SHELF LIFE OF DIVIDED POWDERS: • CONTAINERS OF DIVIDED POWDERS: • SPECIAL LABEL AND ADVICE FOR PATIENTS:

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