Creams

Creams
Riot S.
Introduction and overview of creams
 In pharmacy the term ‘cream’ is reserved for external
preparations.
 Creams are viscous semi-solid emulsions for external use.
 Medicaments can be dissolved or suspended in creams.
 A cream may be ‘water-in-oil’ or ‘oil-in-water’ depending on the
emulsifying agent used.
 A cream is always miscible with its continuous phase.
 BP definition: Creams are formulated to provide preparations
that are essentially miscible with the skin secretion.
 They are intended to be applied to the skin or certain mucous
membranes for protective, therapeutic or prophylactic purposes,
especially where an occlusive effect is not necessary.
Definition
 Water-in-oil creams (oily  Oil-in-water creams
creams) as bases (aqueous creams) as
 These are produced by bases
emulsifying agents of  These are produced by
natural origin, e.g. synthetic waxes, e.g.
beeswax, wool alcohols or macrogol and
wool fat. cetomacrogol.
 These bases have good  They are the best bases
emollient properties.
to use for rapid absorption
 They are creamy, white or and penetration of drugs.
translucent and rather stiff.
 They are thin, white and
smooth in consistency.
Cream
 Typically of low viscosity, two phase
system (w/o or o/w)
 Appears “creamy white” due to the
scattering of light.
 Traditionally,
it is the w/o cold cream
 Currently and most commonly, it is the o/w
emulsion.
Cold cream
 w/o emulsion frequently using a  formula
borax-beeswax combination as  Water , 34.6%
the emulsifying agent and mineral  Borax ,1
oil or vegetable oil as the oily  methylparaben, 0.25
phase.  Light mineral oil, 50%
 A protective film remains on the  synthetic beeswax,
skin following the evaporation of 13
the water. The slow evaporation of
water gives the skin a cooling  Glyceryl
effect. monostearate, 1
 To prepare, melt white wax,  propylparaben, 0.15.
spermaceti, and almond oil
together, adding host aqueous
solution of sodium borate, and stir
until the mixture is cool.
Trituration
 This is the term applied to the incorporation, into the base, of
finely divided insoluble powders or liquids.
 The powders are placed on the tile and the base is
incorporated using the ‘doubling-up’ technique.
 Liquids are usually incorporated by placing a small amount of
ointment base on a tile and making a ‘well’ in the centre.
Small quantities of liquid are then added and mixed in.
 Take care not to form air pockets that contain liquid, which if
squeezed when using an inappropriate mixing action will
spray fluid on the compounder and surrounding area.
 Trituration can be successfully achieved using a mortar but
this method is usually reserved for large quantities
General method
1. As with other types of emulsion, hygiene is extremely important and all
surfaces, spatulas and other equipment must be thoroughly cleaned with
industrial denatured alcohol (IDA).
 IDA is better than freshly boiled and cooled purified water as it will
quickly evaporate, leaving no residue.
2. Always make an excess as it is never possible to transfer the entire cream
into the final container.
3. Determine which of the ingredients are soluble in/miscible with the
aqueous phase and which with the oily phase.
 Dissolve the water-soluble ingredients in the aqueous phase.
4. Melt the fatty bases in an evaporating dish over a water bath at the lowest
possible temperature.
 Start with the base with the highest melting point.
 These should then be cooled to 60°C (overheating can denature the
emulsifying agent and the stability of the product can be lost).
5. Substances that are soluble/miscible with the oily phase should then be
stirred into the melt.
Method…
 The disperse phase should then be added to the
continuous phase at the same temperature.
 Hence, for an oil-in-water product, add oil to water.
 For a water-in-oil product, add water to oil.
8. Stir the resulting emulsion vigorously without
incorporating air, until the product sets.
 Do not hasten cooling as this produces a poor product.
The incorporation of solids into a cream base
 the solid can be incorporated into the cream as it cools.
 Alternatively, if using a pre-prepared base, soluble and
insoluble solids may be incorporated using the method
employed for insoluble solids.
 Soluble solids should be added to the molten cream at the
lowest possible temperature and the mixture stirred until
cold.
 Insoluble solids should be incorporated using a glass tile
and spatula
 If there is more than one powder to be added, these should be
triturated together in a mortar using the ‘doubling-up’ technique prior
to transfer to a glass tile.
 Coarse powders. A minimum quantity of cream should be
placed in the centre of the glass tile and used to levigate the
powders. A considerable lateral shearing force should be
applied to avoid a gritty product
Incorporation…..
 The powder/fatty base mixture may then either be

returned to the evaporating basin with the remaining
cream and stirred until cold or the remaining cream
in the evaporating basin may be allowed to cool and
triturated with the powder/cream mixture on the tile.
 Fine powders may be triturated into the otherwise

finished cream on a glass tile.
 Small amounts of powder should be added to an equal
amount of cream, i.e. using the ‘doubling-up’ technique.
 These should be well triturated
The incorporation of liquids into a cream base
 Non-volatile, miscible liquids may be mixed with the molten cream in the
evaporating basin.
 Alternatively, if a pre-prepared base is used, then incorporate as for
volatile or immiscible liquids.
 Volatile or immiscible liquids, e.g. coal tar solutions, should be triturated
with the cream on the glass tile.
 A very small amount of the cream should be placed on the glass tile
and a ‘well’ made in the centre.
 Traditionally, small quantities of liquid should be gently folded in to avoid
splashing.
 An alternative method is to spread a small amount of the cream on the
tile and then score it with a spatula. Then add small quantities of the
liquid and fold into the base gently.
 If using coal tar or other volatile ingredients, these should not be
weighed until immediately before use and the beaker in which it has
been weighed should be covered with a watch glass to prevent
evaporation.
 In addition, always remember that volatile ingredients should not be
added to molten bases
Examples :The preparation of Dermovate Cream 25%
Use of the product

 Dermovate contains 0.05% clobetasol propionate, a corticosteroid for topical
application for the short-term treatment of severe resistant inflammatory skin
disorders.
 It is usually applied thinly 1–2 times daily for up to 4 weeks.
 Maximum 50 g of 0.05% preparation per week (BNF 51st edn, p 577).
Is it safe and suitable for the intended purpose?
 It is reasonably common to dilute proprietary creams to produce less potent
products for the treatment of inflammatory skin disorders.
 This is a 1 in 4 dilution (1:3) of a potent topical steroid. Therefore, so
long as the dilution is stable the product will be safe and suitable for the
intended purpose.
Calculation of formula for preparation
 Prepare 50 g of Dermovate Cream 1:3.
 Product formula (i.e. the diluent to use) must be decided by
the compounder.
 Refer to a diluent directory which in this case states
that, although the dilution of the product is not
recommended by the manufacturer, in cases where it
is insisted upon, the following may be used:
 Aqueous Cream BP: Only stable if less than 50% of
the resultant cream.
 Therefore unsuitable for this formulation.
 Buffered Cream BP: May be used but can raise the
pH of the resulting cream.
 Cetomacrogol Cream (Formula A) BPC
 No problems with dilution recorded.
Formula…
 Therefore the diluent of choice would be Cetomacrogol
Cream (Formula A) BPC in this instance.
 Note: Suitable sources to provide information on the dilution
of creams and ointments would be:
 National Pharmacy Association Diluent Directory
 product data sheet (Summary of Product Characteristics – SPC)
 reports in the pharmaceutical literature
 personal contact with product manufacturer
Method of preparation
 Weigh 15 g Dermovate Cream and 45 g Cetomacrogol Cream
(Formula A) BPC and transfer to a glass tile.
 Triturate the Dermovate Cream with the Cetomacrogol Cream
using a spatula.
 Weigh 50 g of the final cream
 Pack into a collapsible tube or amber glass jar, label and
dispense to the patient
 When triturating the creams together remember the principle of
‘doubling-up’ in order to achieve an adequate mix of the active
Dermovate Cream and the base cream.
 Choice of container
 A collapsible tube or plain amber jar would be most
suitable
Labelling considerations
Title
 The product is unofficial, therefore the following title would be suitable:
‘Dermovate Cream 25% w/w’.
 Quantitative particulars: They would be expressed per container (i.e. per
50 g):The product contains:
 Dermovate Cream 25%
 Cetomacrogol Cream (Formula A) BPC 75%
 Product-specific cautions :‘For external use only’ will need to be added to

the label as the product is a cream for external use.
 Directions to patient – ‘Apply TWICE a day.’
 The BNF recommends the following caution: ‘To be spread
thinly…’.
 Discard date: The product is a cream and so would normally
attract a 4-week discard date.
 However, as the product is a diluted proprietary cream, it is
common to assign a shorter 2-week discard date.
Sample label
Advice to patient
•The patient would be advised to apply the cream thinly/ sparingly twice a
day.
•In addition, the discard date and the fact that the product is for external
use only would be highlighted to the patient.

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 The powder/fatty base mixture may then either be

 Fine powders may be triturated into the otherwise

Use of the product

 Product-specific cautions :‘For external use only’ will need to be added to

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