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CONTINUING PROFESSIONAL DEVELOPMENT
Sweeteners can be natural or artificial,
and it is important to note that not all
sweeteners are globally acceptable from
a regulatory perspective.
Sucrose is the
most commonly used bulk sweetener,
but has the disadvantages of causing
‘cap lock’ (crystallises between the neck
and cap of medicine bottles), not being
suitable for those needing to restrict
sugar intake, and chronic use associated
with dental caries.
Liquid glucose is another commonly
used sweetener consisting of dextrose,
dextrins, maltose and water.
obtained by incomplete hydrolysis of
starch. Its method of manufacture is
controllable and hence batch-to-batch
variability is insignificant,2 which is
a challenge for many ingredients of
A new generation of sweeteners, such as
acesulfame and stevia, have overcome
the issues of metabolism and toxicity
associated with traditional sweeteners
such as saccharin, aspartame and
Ali, Charoo, Abdallah,
and Walsh, Cram and Woertz, et al14
provide tabulated summaries of
sweeteners, their toxicities, whether
they are generally recognised as safe
(GRAS), and if they are included in
various pharmacopoeias. It is also
important to note that sweetness
intensity varies as a function of time,
e.g. glucose and sorbitol have early
onset sweetness while thaumatin
is late onset.
A combination of
sweeteners may therefore be used in
order to provide sufficient sweetness
and intensity as a function of time, to
mask the unpleasant taste of an API.
A typical binary mixture of sweeteners
that is frequently used synergistically is
Omeprazole oral suspension
Active pharmaceutical ingredient
19N3O3S, MW: 345.4)
is a white or almost white powder that
It is very
slightly soluble in water and sparingly
soluble in alcohol,
and should be
stored protected from light in an airtight
container at 2–8 °C.
Sodium carboxymethylcellulose is
a viscosity-increasing agent16
appears as a white-to-cream coloured,
hygroscopic powder or granules.
It is easily dispersed in water to form a
colloidal solution, insoluble in alcohol,
and in most other organic solvents.
The pH of a 1% solution in water
is between 6.5–8.5.
15 The resulting
viscosity of carboxymethylcellulose
sodium United States Pharmacopoeia
(USP) (medium viscosity) solutions can
vary depending on the lot (batch) of the
powder used. The USP permits the
viscosity of a carboxymethylcellulose
sodium 2% solution to vary from 80% to
120% of the stated value.
It is therefore
important to obtain a certificate of
analysis for the specific lot number
purchased to verify the exact viscosity.
For quality assurance and consistency
purposes, the viscosity value for each
new lot should be noted, and any
necessary adjustments to the formula
made (see Box 1).
Glycerol is a clear, colourless, odourless,
viscous, and hygroscopic liquid that has
a sweet taste, approximately 0.6 times
as sweet as sucrose. In oral solutions,
glycerol is used as a solvent, sweetening
agent, antimicrobial preservative, and
Acesulfame potassium is a colourless
to white-coloured, odourless, crystalline
powder with an intensely sweet taste,
and has an approximate sweetening
power 180–200 times that of sucrose.
It is soluble in water and very slightly
soluble in alcohol,
systems and thus can be used to mask
some APIs with unpleasant taste
Steviol glycosides 95% – Stevioside is
a glycoside extracted from the leaves
of yerba dulce, Stevia rebaudiana
It has about 300 times
the sweetness of sucrose and has been
used as a sweetening agent in foods.
Both the related glycoside, rebaudioside
A (rebiana), and an extract of the leaves
of Stevia rebaudiana, which contains
these and other glycosides, have also
been used as sweetening agents.
Artificial flavours – grape and
marshmallow are artificial flavouring
agents that are available as liquids that,
together with the sweetening agents,
provide an appealing suspension for
children. When selecting flavours, it is
important to check that the flavour does
not contain acidic substances (e.g. citrus
flavours) that would potentially affect
the pH of the formulation. It is also
important to determine if the patient
has any allergies to the ingredients.
SOLUTIONS THROUGH COMPOUNDING
A pharmacist has two lots of carboxymethylcellulose sodium USP (medium
viscosity). The viscosity (of a 2% solution) for lot A is 630 cps, and the viscosity of
lot B is 475 cps. Therefore, using the same concentration of lot B will result in a
lower viscosity. In this example, the pharmacist must increase the amount of lot B
used to achieve the same viscosity as lot A.
A simple calculation can be used to estimate the amount of
carboxymethylcellulose sodium USP (medium viscosity) to achieve a similar
Using the 2% solution viscosities above: 2% solution of lot A = 630 cps, 2% solution
of lot B = 475 cps. Therefore, you will need to use 1.33 (630/475) times as much
of lot B to achieve the same viscosity, i.e. a 2.66% solution of lot B will have an
equivalent viscosity to a 2% solution of lot A.
Note: 1 centipoise (cps) = 1 millipascal seconds (mPa-s)
In the SI system, viscosity should be referred to in Pa-s. mPa-s is commonly used because the viscosity of
water at 20 °C is virtually 1 mPa-s, which is equivalent to 1 cps. Although cps is no longer an official unit,
its use is still relatively common.18
Box 1. Case study – calculation
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