Compounding:- means preparing pharmaceuticals in small scale in laboratory or in pharmacy.
General laboratory procedures
1. Before starting any experiment, make sure that your balance is clean and adjusted to zero reading. The first experiment will tell your how to perform this procedure.
2. Since ingredients are weighed directly from the original container, always use a clean spatula to transfer small amounts of material to weighing paper. Do not waste material.
3. Weighing paper should be labelled with the chemical name and the amount weighed. Use a new weighing paper for each material weighed.
4. Always only weigh or measure one component at a time. If not you might place the wrong cap on container, thus contaminating ingredients.
5. Do not through powders, paper, and greasy or waxy materials in the sink. Use waste containers for this purpose. Large quantities must be wrapped in paper before being place in waste containers.
6. Make sure that you are using the correct ingredients and correct amount. (read each label carefully three times i.e.
When the container is taken from the shelf.
When it is used and
After has been used when we return it.
7. Avoid contamination of all materials.
Ensure all equipment’s are clean before use
Keep the table clear off all unnecessary material
Not leave weighed or measured ingredients uncovered and unlabeled on the table.
8. Broken glass goes into a special container.
9. Replace chemicals as soon as you finished using it. Be considerate, remember you are sharing it with other students.
10. When a liquid is poured from a stock bottle, the label of the stock bottle must be face-up so that the label does not become soiled in the event that the liquid runs down the side of the bottle.
11. Graduate cylinders are not made for dissolving solids; solids must be dissolved in beakers.
“Always follow instructions of instructor”
“Above all, enjoy your time in the laboratory.”
Some equipment used in the laboratory
1. Balance:- used for weighing of ingredients
Balance may be Electronic or dispensing balance
2. Mortar and pestle: either glass or ceramic
Used for preparing medications for patients, mixing and size reduction of ingredients for compounding.
Can be sterized, cleaned with alcohol, or washed with soap and water.
3. Ointment slap or ointment tile: are made up of glass or plastic used for preparing ointments.
4. Ointment spatula or flexible spatula: are type of spatula used for mixing ingredients for preparation of ointment.
5. Watch glass: are made up of glass used for weighing like Iodine, waxy materials, white petrolatum, etc. over in over a weighing balance.
6. Measuring cylinder: are made up of glass of plastic they are used for measuring liquids.
7. Glass rods: are made up of glass used for string ingredients.
8. Water bath: are an apparatus used for heating ingredients by a means of steam.
9. Suppository molds: are equipment used for preparing different strength of ointment.
10. Flasks
11. Funnels
12. Porcelain dish or evaporating dish
13. Dispensing bottles
14. Spatulas
15. Droppers
General procedure for compounding
Criteria-
1. Wear personal protective (Gowon, Masks, Glove, etc.) & hand washing.
2. Clean work row material and Ingredients
3. Collect row material and equipment’s
4. Tare bottles
5. Correct calculation
6. Weighing technique use of paper or watch glass
7. Measuring technique
8. Mixing /levigation of technique
9. Packaging choice of container
10. Labeling
11. Clean work area.
Interpretation of Prescriptions
Prescription is an order signed by a licensed medical practitioner directing the pharmacist to compound and dispenses a medicament.
A complete prescription includes the following:
1. Prescriber’s office information
2. Date of the prescription was written
3. Name of the patient and address
4. Superscription: contains the traditional symbol Rx meaning you take
5. Inscription: contains the list of ingredients and their quantities
6. Transcription: contains the necessary directions to be labeled on the container for use by the patient.
7. Name of the prescriber or his initials
Labeling
The label on dispensed medicine should provide the patient with all the information necessary so that the medicine may be taken or used appropriately.
Information on the label includes:
1. Patients name
2. Name and address of pharmacy
3. Date of dispensing
4. Name, strength and quantity of the preparation
5. Direction for use
6. Storage condition and shelf life ( expiry date)
7. Cautionary and advisory labels.
The information on the labels of dispensed medicines should be accurate legible intelligible adequate and relevant.
1. Accurate: the label should be checked immediately after writing and again prior to fixing to container.
2. Legible:- the label should be type written or printed or written neatly with pen
3. Intelligible: the information should be completely unambiguous and arranged to avoid confusion. The terms should be readily understandable by the lay person.
4. Adequate and relevant: care should be taken to avoid causing confusion and anxiety. Too much information on the label may mean that none of it is noted.
Note that the size of the label should be related to the size of the container.
Formulation of liquid dosage forms
• Dosage forms are the means by which drug molecules are delivered to sites of action within the body. Types of dosage forms
• Base on the physical nature of the products dosage forms are classified into 3 groups
1. Liquid dosage forms: - solution, suspension and emulsions.
2. Semi –solid dosage forms: - ointments pastes, creams, jellies.
3. Solid dosage forms: - powders, granules capsules, tablets, suppositories etc.
Solutions
Solution are homogenous liquid preparation containing one or more dissolved ingredients and are used for a variety of purposes as both internal and external dosage forms.
1. Solution taken orally:- mixtures, elixirs, syrups, linctuses draughts
2. Solution used in mouth and throat: - mouth washes and gargles, throat paints, throat sprays.
3. Solution instilled into body cavities: douches, enemas, eardrops, eyes, drops, nasal drops, nasal sprays.
4. Solution applied to body surface: collodions, liniments, lotion and paints.
• In addition to the active ingredient (medicaments), solutions also contain vehicles and adjuncts.
• The vehicle is the medium in which the ingredient of a medicine are dissolved or dispersed for solution this is the solvent. E.g. water, aromatic waters, alcohol, glycerol, syrup, etc.
• Water is the vehicle of choice for the majority of pharmaceutical solution. Because water is generally available, relatively inexpensive, palatable and non- toxic for oral use and non-irritant for external use. It also acts as a solvent for a wide range of substances.
• The adjuncts are additives that are added to improve the quality of the preparations. E.g. chemical stabilizers, colorants, flavorings, preservatives, etc.
Aromatic water
• Aromatic waters are aqueous solutions usually saturated of volatile oils or other volatile substances that are characterized by very low water solubility’s. E.g. Chloroform.
• Aromatic waters are used externally as perfumes (e.g. Rose water) and internally as flavoring agents (e.g. peppermint water, cinnamon water has been used as carminative and chloroform water was used in expectorant preparations).
Practical
1. (a) chloroform water BP. 88
Chloroform ---------------- 2.5 ml
Water FBC to --------------- 1000ml
Send 100ml
(b) double strength chloroform water BP. 88
Chloroform ---------------- 5 ml
Water FBC to --------------- 1000ml
Send 100ml
Compounding: dissolve the chloroform in Purified water by shaking.
1. Peppermint water
Pepper min oil --------------- 0.2 ml
Water FBC to --------------- 100ml
Send 50ml
Compounding: dissolve the oil in purified water by shaking
1. Spirits
• Sprits also known as essences are alcoholic or aqueous alcoholic solutions of volatile substances. Like the aromatic water the active ingredients in the sprits may be a solid, liquid or gas. The volatile substance in the majority of case is volatile oils.
• Some sprits are used internally for their medical value a few medically by inhalation. But a large number are used as flavoring agents.
Practical
Peppermint spirit
Ingredient Master formula
Peppermint oil 100ml
Ethanol (90%) 1000ml
Send 30 ml.
Compounding: dissolve the peppermint oil in ethanol. Add sufficient ethanol to produce the final volume. If the solution is not clear shake with previously sterilized talc and filter.
Action and uses: the spirit is an effective carminative. Also, mixed with other drugs or preparation, it may be used as a flavor.
Ingredient Master formula
Chloroform 50ml
Ethanol (90%) 1000ml
Send 40ml
Chloroform sprit
Compounding: mix the chloroform with the ethanol.
Uses and actions: flavoring agent and preservative
Tinctures
• Tinctures are alcoholic or hydro alcoholic solution of principles extracted from natural sources or of pure chemical merely dissolved in these solvent systems an example of the latter being iodine tincture.
• Tinctures vary widely in their method of preparation the strength of their volatile ingredients their alcoholic content and their intended use
• Tinctures are prepared by a number of processes: maceration (process M) percolation (process p) solution and dilution.
Iodine Tincture
Ingredient Master formula
Iodine 25g
Potassium iodide 25g
Purified water 25mg
Ethanol (90%) to 1000ml
Send 50ml
Compounding: dissolve the potassium iodide and the iodide in the purified water and add sufficient ethanol (90%) to produce 1000ml.
Actions and uses: antiseptic.
Syrups
• Syrups are concentrated aqueous solutions of sucrose other sugars or sweetening agents to which small quantities of suitable polyhydric alcohols may be added to retard crystallization or to increase the solubility of the other ingredients
• Syrups usually contain aromatic or other flavoring materials.
Practical
Simple syrup, USP
Sucrose --------- 647.4 g Sucrose------- 850g
Purified water to ------ 1000g Purified water to ----- 1000ml
Send 50ml
Methods of preparation
a. Hot process: place the sucrose in dish, add the water and dissolve the sucrose by heating on a water bath stirring continuously. When dissolution of the sucrose is complete allow the solution formed to cool and add sufficient boiling purified water to make up for that lost by evaporation. Then strain the syrup while still warm to make up for that lost by evaporation. Then strain the syrup while still warm though a fine muslin supported in a funnel in to a bottle which is capable of nearly filling and shake the bottle occasionally until the content is quite coil.
b. Cold process: place the sucrose in a suitable percolator, the neck of which is nearly filled with loosely packed cotton moistened after packing with a few drops of water. Pour carefully about 450ml of purified water upon the sucrose and regulate the outflow to a steady drip of percolate. Return the percolate if necessary until all the sucrose has dissolved. Then wash the inside and the cotton with sufficient purified water to bring the volume of the percolate to 100 ml and mix.
c. Alternatively the sucrose may be dissolved more rapidly in the proper amount of water by agitation in a graduated bottle.
N.B syrup made without heat is practically colorless while syrups made with heat have pale amber color due to the levulose formed as a result of hydrolysis of sucrose.
Chloral hydrate Syrup
Chloral syrup B.P.C 68
Chloral hydrate 200g
Water FBC 200ml
syrup to 1000ml
Ft. syrup send 20ml
Sig. Two 5 ml
Compounding: dissolve the chloral hydrate in the water and add syrup to volume.
Note: chloral hydrate is volatile and sensitive to light so the syrup must be recently prepared.
Action and uses: hypnotic
Ferrous sulfate syrup USP
Ingredients Master formula
Ferrous sulfate 40g
Citric acid hydrous 2.1g
Peppermint spirit 2ml
Sucrose 825g
Purified water to 1000ml
Ft. syrup send 50ml
Sig. Two 5 ml
Formulation: the peppermint spirit used as the source of flavor has a persisting effect which makes the somewhat unpleasant ferruginous taste of the Fe2. Care must be taken in preparing aqueous solution of ferrous salts since Fe2+ is readily oxidized by dissolved oxygen to form Fe3+ which precipitates as basic ferric salts discoloring the solution. Ferrous sulphate is dissolve in purified water containing some sucrose which provides a reducing environment thereby in inhibiting auto- oxidation. If all of the sucrose were added the solution would be too viscous to allow perfect filtration. Citric acid is included in the formulation to prevent discoloration of the syrup i.e. a change from a green to a reddish brown tint it does this by preferentially chelating Fe3+.
Compounding: dissolve the ferrous sulfide water and filter the solution until clear filtrate and add purified water to make 1000 ml mix and filter if necessary through a placed get of cotton.
Actions and uses: Hematinic.
Iodine Solution (Lugols solution)
Ingredients master formula
Iodine 50g
Potassium iodide 100g
Water up to 1000ml
Sent 100ml
Method:
Potassium iodide and Iodine are dissolved in small portion of purified
Water by stirring & shaking till dissolve completely.
Sufficient Water is added to make the required volume
Use: Goiter
Compound iodine paint (mand’l paint)
Ingredient Master formula
Potassium Iodide 25.0g
Iodine 12.5g
Alcohol 90% 40.01ml
Water 25.0ml
Peppermint Oil 4.0ml
Glycerol to 1000ml
Mitt. 40 ml.
Sig store in cool place. Shake the bottle before use.
Not to be swallowed in large quantities.
Compounding: put the water into a 50ml conical measure. Dissolve the potassium iodide (it dissolves very readily in water and need not be powdered). Add the iodine and stir until complete dissolved. Although iodine is only slightly soluble n water it is readily soluble in aqueous solution of iodine. In a small measure dissolve the peppermint oil in the alcohol and transfer it to the iodine solution and mix well. Make up to the volume with glycerol and mix toughly. If the iodine solution is not well. Mixed with the glycerol the preparation is streaky.
Note: because of the high viscosity of the vehicle this preparation is best made entirely in a measure. For the same reason an excess should be prepared since it is impossible to transfer the entire contents of the measure to a bottle. A glass or a counterbalanced watch glass and a vulcanite spatula must be used for weighing the iodine
Actions and used: Antiseptic in the treatment of pharyngitis and tonstilis.
Suspension
Suspension are disperse systems in which finely divided drug practices (called the disperse phase) are distributed thought out a vehicle (called dispersion medium or continues phase) in which the drug exhibits a minimum degree of solubility.
It in include both powders in dry from to be place in suspension and drugs suspended in liquid vehicles.
Suspension can be classified in to coarse suspension in which the particles are large than 1um in diameter.
Major applications: suspension dosage forms can be administered orally injected parentally (intramuscularly or subcutaneously) or applied externally (topically) to the skin eye ear etc.
The physical properties of suspensions and their design depend upon the nature of the dispersed phase the dispersion medium and the pharmaceutical adjuncts/ additives.
The drug particles (dispersed phase) is suspension could be
o Diffusible solids
o In diffusible solids or
o Poorly wettable solids
General methods of preparation of suspension
1. Carefully tare(calibrate) the container to the required volume
2. Finely powder any solid ingredient not already in fine powder
3. Mix the insoluble powders in a mortar adding first the ingredient of
4. Smallest bulk and diluting it with the others in increasing order of bulk using amounts approximately equal to bulk already in the mortar (geometric dilution).
5. Add enough vehicles to produce a smooth paste.
6. Add non-volatile solid ingredients dissolved in part of the vehicle and mix well
7. Dilute with a vehicle until pourable. Examine the suspension critically and if it contains foreign particle strain through muslin. (Before use rinse the fabric with a little vehicle to detach loose fibers).
8. Transfer it to the tarred bottle a measure is not used because complete and accurate transfer of a suspension is not possible once it has been made up to volume.
9. Add any volatile solid ingredients previously dissolved in some of the vehicle and mix well.
10. Add any liquid ingredients raise the measures and mix well after each addition.
11. Rinse the mortar and pestle with successive volumes of the vehicle until they are quite clean transferring the rinsing to the bottle.
12. Make up to volume with the vehicle and shake thoroughly
Containers and labeling
• Suspensions are generally packed in well closed containers appropriate to the class of dispensed medicine be it mixture lotion ear drop, enema etc.
• If the preparation is particularly viscous a wide mouthed container may be used.
• Containers of suspensions should be of suitable size to allow shaking of the products.
• Labels for suspensions includes:
- Shake well before use
- Store in cool place(not refrigerator)
- Also expiry dates for suspensions that should be prepared recently is one month and if diluted two weeks.
Suspensions containing diffusible solids
• Diffusible solid (also called dispersible solids) are light and easily wettable solids. They readily mix with water and on shaking diffuse evenly through the liquid for long enough for a dose to be measured.(Ensure even distribution in each dose.)
• Examples of diffusible solids are light kaolin magnesium trisilicate light magnesium carbonate and calcium carbonate.
Practical
Pediatric kaolin mixture, BP 1988
Ingredient Master formula
Light kaolin 200g
Amaranth solution 10ml
Benzoic acid solution 20ml
Raspberry syrup 200ml
Chloroform water (D.S) 500ml
Water to 1000ml
M.S.A. send 50ml.
Sig. 1tsp t.i.d.
Formulation: the kaolin should preferably be sterilized to remove any contaminating soil pathogens.
Kaolin is a diffusible solid and therefore no additional suspending agent is required although the raspberry syrup increases the viscosity of the vehicle.
Benzoic acid solution and chloroform water act as preservatives. The raspberry syrup provides a flavor and amaranth solution color which is attractive to children.
Compounding: first tare the final container because if the syrup and a little of the chloroform water. Add the amaranth solution and mix well.
If the dye is added at a later stage in the preparation it will not penetrate in to the powder and white specks will be visible in the final product. Dilute the suspension until pourable and while specks will be visible in the final product. Dilute the suspension until pourable and transfer to the bottle. Although it is advisable to add volatile ingredients such as chloroform water before making up to volume with water. Add the benzoic acid solution to the bottle and make up to volume and shake thoroughly.
Storage and shelf life: unless the kaolin has been sterilized the preparation should be recently prepared.
Container: amber medicine bottle.
Advice for patients when dispensed: shake the bottle.
Maintain fluid intake in diarrhea. If the product is counter prescribed the patient should seek medical advice if the condition persists.
Actions and uses: anti diarrhea mixture for children.
Magnesium sulfate mixture BP. (magnesium sulfate oral suspension)
Ingredient Master formula Scaled quantities
Magnesium sulfate 400 g
light magnesium carbonate 50g
Concentrated peppermint emulsion 25g
Double strength chloroform water 300ml
Water FBC sufficient to produce 1000ml
Mitt 50ml
Sig. 10 ml t.i.d. shake the bottle before use
Formulation: magnesium sulfate mixture is a suspension containing 40% w/v magnesium sulfate and 5%w/v of light magnesium carbonate. Both these solids act as laxatives by preventing the normal absorption of water from the intestine with the result that the bulky fluid contents distend the bowel active reflex peristalsis excited and evacuation of the contents of the intestine occur. Active reflex peristalsis excited and evacuation of the contents of the intestine occur. Peppermint provides flavoring and act as a carminative and chloroform water acts as flavoring preservative and vehicle light magnesium carbonate is a diffusible solid and no extra thickening agent is required.
Compounding: first tare the final container and select a mortar of sufficient size to allow for adequate mixing of the product. Mix the magnesium sulfate and light magnesium carbonate in the mortar. This method is to be preferred to making a separate solution of the magnesium sulfated which is time consuming. Add enough vehicle to make a smooth paste and dilute with the vehicle unit sufficiently pour able to transfer to the bottle. The volatile peppermint emulsion should be added to the bottle before making up to final volume.
The mixture may also be prepared from a pre packed mix of the two powder ingredients with the addition of the appropriate amount of peppermint emulsion and chloroform water.
Storage and shelf life: the mixture should be recently prepared.
Container: amber medicine bottle.
Advice for patients when dispends: shake the bottle
Actions and uses: as laxative.
B. Suspensions containing in diffusible solids
In diffusible solids will not remain evenly distributed in a vehicle long enough to ensure uniformity of dose. Examples include chalk, zinc oxide, calamine aspirin and phenobarbitone.
The simplest way of correcting this problem is to increase the viscosity of the formation of aggregates that settle rapids
The thickening agents used to stabilize suspensions is substances that spontaneously from colloidal dispersions in aqueous media because of their affinity to water. There are three major groups of thickening agents:
1. Polysaccharides include acacia, tragacnath, methylcellulose, sodium alginate, microcrystalline cellulose sodium carboxymethyl cellulose starch etc.
2. Inorganic agents include bentonite veegum hectorite aluminium hydroxide etc
3. Synthetic agents include carboxyvinyl polymer(carbomer) colloidal silicon dioxide etc.
Calamine Lotion B.P.
Ingredients master formula
Calamine 15g
Zinc Oxide 5g
Bentonite 3g
Sodium Citrate 0.5g
Liquid phenol 0.5g
Glycerin 5ml
Purified Water to 100ml
Procedure:
1) Dissolve Sodium Citrate in 35ml Purified Water
2) Weigh Calamine, Zinc Oxide and Bentonite & triturate it with Sodium. Citrate solution.
3) Add Liquid phenol, the Glycerin and sufficient quantity of water to make up the required volume.
4) Write Label
Use: Astringent & protective.
Phenolated calamine lotion usp
Ingredient Master formula Scaled quantities
Calamine 80g
Zinc oxide 80g
Bentonite 20g
Glycerin 20ml
Liquefied phenol 10ml
Calcium hydroxide solution to 1000ml Mitt. 50ml
Formulation: calamine (basic znCo3 suitable colored with Fe2O3) and zinc oxide are mildly astringent and soothing to the skin. Both are in diffusible solids and therefore bentonite is included as thickening agents which causes marked flocculation of the calamine and make it very difficult to pour form that bottle. Calcium hydroxide solution is included to cause partial deflocculating of the calamine and so make the preparation more pourable. Liquefied phenol acts as a preservative and glycerol as emollient (assists application) miscible with the aqueous vehicle.
Note: liquefied phenol is very caustic so do not use mouth to pipette the liquid. Use a small measuring cylinder or a treated pipette.
Compounding: first tare the final container and select a large mortar. Mix the dry powers in the mortar until evenly dispersed. It is important that the bentonite is well distributed in the in diffusible powders. Use the calcium hydroxide solution to make a smooth paste and to dilute the formed paste for transfer to the bottle. Add the glycerol and liquid phenol to the bottle and make up to final volume with the vehicle.
Strong and shelf life: the preparation is stable cool storage is advised because of the volatile preservative.
Advice for patients when dispensed: shake the bottle for external use only. The lotion is applied to the skin as required and allowed to dry.
Action and uses: cooling lotion useful for treating mild sunburn.
OINTEMENTS
Ointments are semisolid preparations intended for external application to the skin or mucous membranes.
Ointments may be medicated or non- medicated the later type being commonly referred to as ointment bases and are used as such for their emollient or lubricant effect of used as vehicles in preparation of medicated ointments.
• Hydrocarbon bases
• Absorption bases
• Water-miscible bases
• Water soluble bases
Preparation
Ointments are not applied primary to irritated areas it is an on broken wound rule that these preparations must contain granular or gritty particles, which might cause further irritation regardless of the condition of the skin.
Ointments must be smooth and free from granular or gritty particles.
Three types of equipment are available for the preparation of ointments
1. Ointment slab and spatula
2. Mortar and pestle
3. Ointment fill
Two techniques are used mixing ointments
Mixing by fusion
On a small scale fusion is usually carried out in an evaporating basin a water bath.
Fusion is necessary when waxes, hard paraffin, fatty alcohols, fatty acids or any hard wax- like material is included in the formula.
Fusion is used also when a medicament is soluble in the melted base
Mixing by trituration
This method is applicable when the medicament is a solid insoluble in the bases or liquid present in small amount
Trituration may become out with an ointment tile and spatula or using a mortar and pestle
Packaging
Ointments are dispensed in either ointment or collapsible tube. However ointments prepared extemporaneously are usually packed in ointment jar.
The ointment should be packed and the top surface should be smoothed neatly.
Ointments jars should be closed tightly when not in use particularly if the ointment consisting water to prevent loss though operation.
Storage
Ointments should be stored in a cool place to prevent softening and eventually liquefiable in the base
Insoluble medicament may settle to the bottom of the container if the ointment is permit to liquefy.
Excessive heat or cold may cause an emulsion base to separate into two phases.
a. Simple ointment BP
Ingredients master Formula Reduced Formula
Wool fat 50g
Hard paraffin 30g
Cetostearyl alcohol 50g
Yellow or white soft paraffin 850g
Send 25g
Formulation: simple ointment is an absorption base prepared by fusion . yellow or white soft paraffin is chosen according to the color of the finished product. In this case there is no dark colored ingredient to be added. White soft paraffin should be used.
Compounding: grate the hard paraffin and weigh out the ingredient for the base. place to melt an evaporating dish on a water –bath. stir gently to aid melting and to mix the ingredients. When homogenous, remove from the beat and continue to stri gently until cold .
NB. Weigh the wool fat and the soft paraffin using waxed papers to allow full recovery of the materials.
Storage: store in cool places
Action and use: ointment base emollient
a. Sulfur ointment BP
Ingredients master formula reduced formula
Precipitated sulphur, finely sifted 100g
Simple ointment 900g
Send 25 g
Compounding: weigh out the amount of precipitate sulphur required and place it on the center ointment tile, weigh the required amount of simple ointment (using a piece of waxed paper) and place it on side of the tile Take a portion of the base (about two to three times the weight of the powder) and levigate it with the sulphur until there is no sign of any gritty particles (this can checked for by spreading a thin layer on the tile). Gradually incorporate the reaming base in geometrically and continue levigation until uniformly mixed. Finally, collect the ointment to gather the center of the tile using the spatula and pack into an ointment jar.
Storage and shelf life : store in a cool place .
An expire date of 4 weeks is appropriate.
For External use only.
Container: wide – mounted amber jar with a grease proof paper disc
Advice for patient when dispensed: the skin should be cleansed prior to application and t ointment applied sparingly to the affected area .
Action and uses: mild antiseptic used in the treatment of acne and scabies.
a. Whitfield’s Ointment
Ingredients master formula reduced formula
Benzoic acid, in fine powder 60 g
Salicylic Acid, in fine powder 30g
Emulsifying ointment 910 g
Send 20gm
Compounding: sift the medicament through separate 180µm sieves. Note that salicylic acid very irritant to the respiratory tract and precautions should be taking to avoid inhalation. Weigh the powders after sifting and mix them. Then place them on an ointment tile and levigate with two or three times their weight of the base until homogenous. Gradually incorporate the reaming base.
Storage shelf life: store in a cool place.
Container: wide – mouthed amber jar with a greaseproof paper disc.
Advice for patients when dispensed: the ointment should be applied sparingly to the affected area. Is should not be applied to the broken or inflamed skin.
Actions and uses: topical anti-fungal preparation
Pastes
Pastes are ointment-like preparations intended for external application .most paste differ from ointments in containing large amounts of finely powdered solids, thus they are usually stiffer than ointments, less greasy and more absorptive.
They are applied generously, either with a spatula or spread on lint or other dressing and are not removed for long periods.
Compounding and packaging
For all practical purposes, pastes are prepared in the same manner as ointments
Pastes are generally packed in glass ointment jars.
They are often too viscous for easy extrusion from tubes.
Zinc oxide paste. U.S.P
Ingredients master formula reduced formula
Zinc oxide, finely sifted 250g
Starch, finely sifted 250g
White petrolatum 500g
Send 20g
Compounding: melt the base with a minimum of heat and sift the powders through separate 180 µm sieves. Mix the required weight of powders in a warm mortar. Triturate with a little melted base until smooth, gradually adding the rest of the base and until cooled.
NB. The paste is much easier to manipulate in a warm mortar
Storage: store in a cool place
Container: wide – mouthed amber jar with grease proof paper disc.
Advice for patient when dispensed: the paste should be spread thickly on white lint and applied to the affected area.
Actions and uses: absorbent, protectant and mild astringent used for variety of dermatological conditions including eczema and psoriasis either alone or with additional medicaments.
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