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CONTINUING PROFESSIONAL DEVELOPMENT
SOLUTIONS THROUGH COMPOUNDING
The ‘natural products’
trend and self-preserving
In recent times, consumer demand
for natural products, and willingness
to pay significant premiums for these
products, has resulted in both the
food and cosmetic industry seeking
to include natural preservatives,
antioxidants, and other such natural
ingredients in their products.
10 This new
trend for ‘natural products’ has also
resulted in increased research focussed
on identifying novel ingredients from
‘Hurdle technology’ is a term used to
describe the intelligent combination
of different preservation factors or
hurdles to deteriorate the growth
12 It has been
used in the food industry since the
1970s, for controlling product safety,
and more recently for producing
self-preserving cosmetics. The concept
is familiar to pharmacists, for example,
preservative-free aqueous formulations,
such as preservative-free eye drops
for dry eye syndrome, can be made
microbiologically stable by sterile
production and appropriate packaging.
In cosmetics, the term ‘preservative-free’
commonly means that the product
does not contain substances classified
as preservatives according to cosmetic
legislation. The term ‘self-preserving’
is therefore used, when traditional
preservatives have been replaced by
other ingredients with antimicrobial
properties, that have not yet been
recognised as preservatives in
The principles of Hurdle technology
(Figure 1) can be summarised as12:
• Adherence to current good
manufacturing practice (GMP)
(e.g. preparation under strict aseptic
• Choice of appropriate packaging (e.g.
tubes as opposed to wide neck jars).
• Careful choice of the emulsion
form (e.g. w/o emulsions are less
susceptible than o/w).
• Low water activity (i.e. minimising
water content, since microbes require
water for growth).
unfavourable for microbes (only useful
for certain products e.g. hair dyes).
• Use of multifunctional ingredients
(e.g. many ingredients including
alcohols, essential oils, extracts
and surfactants have antimicrobial
properties – therefore it may be
possible to decrease or to eliminate
the use of traditional/chemical
preservatives, through careful
selection of these ingredients).
for sensitive skin
In a recent study,6 it has been suggested
that patients with atopic dermatitis
be advised to treat their skin with
ointments, which are unlikely to
contain antimicrobial preservatives, and
when using creams, lotions and other
products containing preservatives,
they should choose those products
containing the least allergenic
preservatives, such as parabens.
It is important to remember basic
principles of preservation, including13
• Topical products containing water,
such as lotions and creams, are more
susceptible to microbial attack than
• Preservatives should be concentrated
in the aqueous phase in lotions
and creams; they will lose their
effectiveness if they partition into the
• The un-ionised form of the
preservative is active; consideration
should be given to the pH of the
preparation to ensure that most of
the preservative is present in the
un-ionised state (e.g. benzoic acid
requires an acidic pH to remain in the
Simple ointment white (100 g) Wool alcohols ointment (100 g)
cetostearyl alcohol 5 g
white soft paraffin 17 g
white soft paraffin 85 g
1. Accurately measure the required amount of each ingredient.
2. Melt together and stir until cold.
3. Package and label.
Note: Ensure packaging and equipment is clean and work as aseptically as possible.
Yellow soft paraffin can be used in place of white soft paraffin. Do not exceed
a temperature of 65 °C during the melting process for wool alcohols ointment.
The proportions of the paraffins may be varied to produce an ointment with an
appropriate consistency, especially for very cold or hot and humid climates.
Figure 2. Formula and method of preparation for water-free preparations
Figure 1. Principles of Hurdle technology
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