Extemporaneous Dispensing 3 Flashcards
Commonly encountered products
• Solutions
– Homogenous liquid preparations containing one or more dissolved substances
Considerations for solutions
• Solubility of solid constituents – Reference sources? • Solvent to be used • Temperature • pH – Affects stability of final product • Preservative? • Flavourings • Colourings
Solutions – standard method
- Weigh out and measure all ingredients using appropriate equipment
- Calculate the minimum volume of solvent
necessary to dissolve the least soluble ingredient and put roughly this amount of solvent in a flat bottomed beaker - Add the soluble ingredients in ascending order of
solubility (i.e. least soluble ingredient first, most soluble last) and stir until dissolved - Transfer the solution to an appropriate conical measure
- Rinse the beaker with more of the solvent and add the rinsings to the conical measure
- Add any flavourings (usually aromatic products such as peppermint emulsion)
- Make up to the final volume with solvent and stir
Supsensions
• Preparations where one (or more) of the active constituents is suspended in the disperse phase
Considerations for suspensions
• Solubility of solid constituents – Reference sources? • Solvent to be used • Temperature • pH – Affects stability of final product • Preservative? • Flavourings • Suspending agent
Suspending agents
• Tragacanth BP – Usually 0.2% w/v for suspensions • Compound Tragacanth Powder BP – Acacia BP 20%, Tragacanth BP 15%, Starch BP 20%, Sucrose BP 45% – Too sticky for external products – Usually 2% w/v for suspensions • Xanthan gum – Very soluble in cold water – Can be used up to 2% w/v • Methylcellulose – Semi-synthetic polysaccharide – Can be used between 0.5% to 2% w/v
Other suspending agents
- Acacia gum
- Guar gum
- Sodium alginate
- Starch
- Hydroxymethylcellulose
- Sodium carboxymethylcellulose
Suspensions – standard method
- Weigh out and measure all ingredients using
appropriate equipment - Calculate the minimum volume of solvent necessary to dissolve any soluble ingredients and put roughly this amount of solvent in a flat bottomed beaker
- Add the soluble ingredients in ascending order of
solubility (i.e. least soluble ingredient first, most soluble last) and stir until dissolved - Mix any insoluble ingredients with a pestle and mortar using the doubling up method
- Add a small amount of the solution prepared in steps 1 to 3 to the mortar
- Mix to form a smooth paste using the pestle
- Continue adding small quantities of the solvent until a pourable consistency is achieved
- Transfer the contents of the mortar to a conical measure of a suitable size
- Rinse the mortar with more solvent and add the rinsings to the conical measure
- Add any flavourings (usually aromatic products such as peppermint emulsion)
- Make up to the final volume with solvent and stir
Expiry dates – solutions and suspensions
BP 2005 recommendations • ‘Freshly prepared’ – ‘must be made not more than 24 hours before it is issued for use’ – No preservative – Two week expiry • ‘Recently prepared’ – ‘deterioration is likely if the preparation is stored for longer than about 4 weeks at 15oC to 25oC – Preservative – Four week expiry
Creams and Ointments
- Incorporation of solids (usually insoluble) into base
- Incorporation of liquids into base
- Dilution of concentrated product with suitable base
- Very rare that bases have to be made from scratch
• Trituration
– Incorporation of finely divided insoluble powders or liquids into a base
Levigation
– Incorporation of coarse insoluble powders into base
– “Wet grinding”
• Fusion
– Melting of bases before addition of other ingredients
– Need to know melting points of ingredients
– Start with highest melting point and then cool
Creams / Ointments standard method For fine powders:
- Weigh all ingredients using an appropriate balance
- Place powder in centre of glass ointment slab
- Using the doubling up technique incorporate into the base, avoiding air pockets
- Spread thinly on the tile to check for even mixing
- Pack into an appropriate sized ointment jar and weigh
Creams / Ointments standard method
For coarse powders
- Weigh all ingredients using an appropriate balance
- Place powder in centre of glass ointment slab
- Using a small amount of the base, grind the powder until a fine paste is achieved
- Spread thinly on the tile to check for lumps
- Once a fine paste is achieved, incorporate into the remaining base using the doubling up technique avoiding air pockets
- Spread thinly on the tile to check for even mixing
- Pack into an appropriate sized ointment jar and weigh
Creams / Ointments dilutions –
standard method
• Weigh all ingredients using an appropriate balance
• Place the product to be diluted in centre of glass ointment slab
• Using the doubling up technique incorporate into the
base, avoiding air pockets
• Spread thinly on the tile to check for even mixing
• Pack into an appropriate sized ointment jar and weigh
Expiry for creams and ointments
• The standard expiry date is 3 months from the
date of manufacture.
– This is because the cream/ointment bases contain
preservatives in their formulae.
– The exception to this is for diluted creams (not
ointments) where the expiry date becomes one month from the date of manufacture.
– This is because creams are generally diluted with
aqueous cream and the extra aqueous environment is
more susceptible to bacterial growth
Licensed Products - label requirements
- Name of the patient
- Name and address of the pharmacy
- Date of dispensing
- Name of the product (or common name) inc strength and formulation if required
- Directions for use
- Cautionary and advisory labels
- Precautions for use
- KOOROSOC
• Expiry date
– ‘Use before….’ (Add a specific date DD/MM/YYYY)
– ‘Do not use after….’ (Add a specific date DD/MM/YYYY)
• Storage conditions
– ‘Protect from light’
– ‘Store in a fridge
• There are some common warning labels that may need to be included:
– ‘Not to be taken’,
– ‘Do not swallow’
• For anything that should not be swallowed
– ‘For external use only’
– ‘For rectal use only’
– ‘Shake the bottle’
Unlicensed Products label requirements
• All of the above AND
• the quantitative particulars of the product must also be on the label.
– This can be expressed as a % or the quantities used.
