Liquid extracts and tinctures are evaporated to syrupy mass in a china dish. Lactose or some
other suitable diluent is mixed and then continue the evaporation to dryness. Mix other ingredients.
Another alternative is to substitute a liquid extract by a dry extract.
Incorporation of extracts
Some plant extracts are available as powders or as powders or as semisolid (for example, liquid
extract of liquorice). In this case, powdered extracts have no problems and treated generally as
powders. Semisolid extract should be mixed with an equal quantity of lactose and reduced to a dry
powder by evaporation before incorporation with other ingredients. Careful heating, if present, to save
potency of the extract is required.
Incompatible salts
Chemically incompatible salts when triturated together produce discoloration, chemical
deterioration or loss of potency. To avoid this problem; minimum pressure is used while compounding
such materials. Use a convenient method for mixing the powder like tumbling in a jar or spatulation on a
sheet paper. Each substance should be powdered separately in a clean mortar and then combined with
other ingredients gently. Otherwise such materials are powdered and dispensed separately.
Potent drugs
The substances having a maximum dose of less than one grain and poisonous substances are
regarded as the potent drugs. Small quantities of potent drugs should not be weighed on dispensing
balance. The potent drug is triturated with some diluent such as lactose in definite proportion to make a
weighable quantity for each powder. Generally potent drug is reduced to fine powder and to this a
equal quantity of diluent is mixed by thorough trituration in a mortar. Then the rest of diluent is
incorporated in successive portions with thorough trituration each time. The whole of the diluent should
never be added to the drug at one time otherwise the potent drug will not be mixed uniformly and
thoroughly in the diluent.
For example: Dispense the following powder
Codiene phosphate 10mg
Make powder
The quantity of codeiene phosphate prescribed is very small and it is not possible to weigh it on
dispensing balance. Minimum weighable quantity is 100mg
Finely powder and weigh 100mg of codeine phosphate and 900mg of lactose. Mix them in
ascending order of their weight on a piece of paper with powder spatula. Out of 1.0 g of triturate, weigh
100 mg of each powder and pack of powder paper. Prepare five such powder, label and dispense.
Granulation powders
These are certain solid medicaments which are required to be administered orally in large dose.
They cannot be prescribed in tablets and capsules because a large number of them will be required to
take as a single dose, which is not possible. These medicaments are difficult to dispense as such in