Pharmaceutics Ii Lab Exam I Review

Pharmaceutics II Lab Exam I Review: Suspensions and Lotions: • Suspension is a preparation containing finely dispersed particles distributed uniformly throughout a vehicle where the drug is maximally soluble • Coarse dispersions: suspensions and lotions  10-50 microns • Fine dispersions: gels and magmas  0.5-10 microns • Suspensions are easier to swallow and have flexibility of administered doses compared to solids • Suspensions must have SHAKE WELL auxiliary label • Suspensions must easily redisperse, have consistent particle size and pour readily and evenly • Suspensions are more stable and better tasting than solutions • Pharmaceutical lotions must have EXTERNAL USE ONLY auxiliary label • Water is the most common vehicle in a pharmaceutical lotion • Wetting agents are used to reduce surface tension (glycerin and alcohol) • Calamine is used to treat dermatitis, hives, chicken pox and poison ivy • Suspending agent-used to avoid formation of a cake Bentonite Magma-made from clay; works best at alkaline pH Methylcellulose-synthetically derived from plants; very inert/consistent OraPlus-commercially available suspending agent; cellulose based • Calcium Hydroxide is Lime Water; do not shake • Zinc Oxide is the main ingredient in Calamine powder • Menthol: drying agent • Calamine is a color protectant and astringent Emulsions: • Emulsions are dispersions in which the dispersed phase is composed of small globules of a liquid distributed in an immiscible liquid • Internal phase-dispersed phase External phase-continuous phase/dispersion medium Emulsifying agent-surfactant/gum • A good emulsifying agent must: 1. be compatible w/ other ingredients

2. 3. 4. 5.

not interfere w/ stability or efficacy non-toxic have little odor, taste or color be stable

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HLB: hydrophile-lipophile balance; HLB numbers define a substance’s polarity • Creaming: migration of one substance to the top of the emulsion; movement of aggregated droplets • Cracking: destruction of emulsion system; irreversible separation of internal phase in emulsion • Coalescence: union of two different particles; happens when emulsion is shaken  irreversibly fused • Aggregation: droplets first clump together • Thixotrophy: when fluids resume a solid state after agitation by remaining undisturbed • Interfacial tension-force needed to oppose natural pull of the molecules • Emulsions must have SHAKE WELL auxiliary label • O/W emulsions: 1° Emulsion: 4-2-1 (Oil-Water-Gum) -ex. Mineral Oil emulsion • W/O emulstions (aka Lime Water Emulsion): need one part VEGETABLE OIL and one part LIME WATER (calcium hydroxide soln.) • Emulsifier is formed by the oleic acid and calcium hydroxide; together they form calcium oleate • 3 Methods of Emulsion Compounding: a. Continental/dry gum b. English/wet gum c. Bottle/Forbes bottle • Emulsions become physically unstable when: a. internal/dispersed phase forms aggregates of globules b. large globules/aggregates form concentrate layer in internal phase c. if all or parts of internal phase separate as result of coalescing • Stability of emulsion increased by: a. Reducing particle size (d2) b. Adjusting viscosity of external phase (η) c. Reducing the density of differences between the phases (ρ1ρ2) • Mineral Oil Emulsion-lubricating carthartic -pure mineral oil 15ml; mineral oil emulsion 30ml Hand Lotion:

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Triethanolamine and stearic acid form the emulsifier triethanolamine stearate Mineral oil acts as a protectant; lanolin is an emollient/softener

Ointments: • Aquaphor may take up to 3 times its weight in water • Alcohol should NOT be used to dissolve substances that will be incorporated into an ointment. When the alcohol evaporates, sharp crystals may form • Do NOT use metal spatulas w/ corrosive substances (salicylic acid) •

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Drugs that should be mixed with another substance before incorporation: 1. LCD: none 2. Peru Balsam: Castor Oil 3. Coal Tar: Tween 80 4. Iodine Crystals: NaI or KI Four classes of ointment bases w/ examples: 1. Oleaginous: petrolatum 2. Absorption: hydrophilic petrolatum 3. Water removal: hydrophilic ointment 4. Water soluble: polyethylene glycol ointment Levigation is used to reduce particle size Incorporation is mixing together of various items (one ointment is incorporated into another) -levigation is done prior to incorporation P. auerginosa and Staph aureus are two main microorganisms whose presence must be controlled in topical preparations LCD: liquoris carbonis detergens Tween 80 is also called polysorbate 80 -an oily liquid that is a nonionic surfactant -effective in dispersing the water-insoluble components of coal tar upon admixture with an aqueous preparation Coal Tar is used to treat eczema and psoriasis Trituration-reducing substances to fine particles using mortar and pestle Pulverization-reduction of particle size of a substance using a second substance which can be removed (ex. Camphor and alcohol)

Reconstitution of Powders and Dose Meassurement: 1. Calculate volume powder takes up 2. Calculate amount of drug in bottle

3. Calculate new volume needed 4. Calculate amount of water needed Chemical Triethanolamine Stearate Methylparaben Sulfur Bentonite Magma Mineral Oil Calamine Hydrocortisone Petrolatum Lanolin

Description Emulsifying agent Anti-microbial preservative Scabicide, Keratolytic Clay based suspending agent Levigating agent; laxative Astringent; protectant Anti-inflammatory Ointment base (or vehicle) Emollient/softener

Basic Rules for Compounding Ointments 1. A good ointment contains the required drug in a uniform distribution throughout and is free of grittiness. It must be neatly finished and packaged. 2. When compounding an ointment on a tile, confine the ointment to as small an area as possible to prevent loss of ointment over the edge. 3. When packaging an ointment, pack it firmly from the bottom of the jar up to avoid air pockets. The top of the ointment should be neatly finished (smoothed) and the lip and threds of the jar wiped clean. Upon opening a jar, no ointment should be visible on the inside lid. 4. To achieve uniform distribution of insoluble powders (zinc oxide, precipitated sulfur, talc) in an ointment, it is often necessary to use a small amount of a levigating agent compatible with the base. Only enough levigating agent is added to make a thick past so that the insoluble powder may be properly levigated. One of the best agents is liquid petrolatum (mineral oil.) A small portion of the base may also be acceptable. It is impossible to levigate a substance once it has been added to the bulk of an ointment. 5. Water soluble substances (resorcinol, urea) may be dissolved in a small amount of water, taken up into aquaphor or wool fat and then incorporated into the base. Aquaphor may take up to 3 times its weight in water. (We generally recommend equal parts.) It may be used in amounts up to equal portions of the amount of liquid to be taken up. (ex. If 6ml of an aqueous solution is to be incorporated into an ointment the amount of aquaphor to be used for this purpose should be between 2 and 6g.) An aqueous solution may be directly incorporated into the base if it is a water absorbable base. *Chemicals that are not stable in water (most antibiotics) must only be put in oleaginous bases and may not be dissolved in water regardless of solubility.* 6. Single ingredients soluble in mineral oil (menthol, camphor, or thymol) may be dissolved in a small amount prior to incorporation into an oleaginous base. If two (or more) ingredients that form a eutectic are in a formula the eutectic should be allowed to form a liquid on the ointment tile and then be taken up with the base. 7. Alcohol should NOT be used to dissolve substances that will be incorporated into an ointment. When the alcohol evaporates sharp crystals may form. 8. Do NOT use metal spatulas with corrosive substances (salicylic acid, iodine, phenol) or chemicals that may cause discoloration (resorcinol, tannic acid, organic dyes.) These will corrode (ruin) the stainless steel.

9. Certain substances require special handling techniques: a. Iodine crystals should never be incorporated directly into an ointment base. The iodine crystals should first be dissolved in a solution containing potassium iodide, or sodium iodide. This soln is then incorporated into aquaphor, wool fat, or and appropriate absorption base. b. When coal tar is to be incorporated into an oleaginous base it should be first mixed with an equal amount of polysorbate 80 (tween 80) to permit uniform dispersion into the product. This is not true of LCD (Coal Tar Soln which contains 20% coal tar) which may be incorporated directly into a base using an absorption base when necessary. c. When peru balsam (which isn’t used much anymore) is to be incorporated into an oleaginous base, it should be first mixed with an equal amount of castor oil to permit uniform dispersion into the product. 10. Do not add colors or perfumes unless specified by the prescriber. Bases should not be changed unless absolutely necessary. (keep changes to a minimum)