3.3. Macerates: The comminuted drug is left to stand, with occasional stirring, for 30 minutes
after the required quantity of water has been poured on to it at room temperature. The
extract is then strained and made up to the prescribed weight with rinsings.
3.4. Tinctures: Tinctures are extracts from drug plants prepared with ethanol of varying
concentration, ether or mixtures of these, perhaps with certain additives, in such a way
that one part of drug is extracted with more than two parts, but at most ten parts, of
extraction liquid.
3.5. Fluid extracts: Like tinctures, they are liquid preparations, the difference being that they
are more concentrated.
3.6. Dry extracts: They are usually very hygroscopic and should therefore be ground and
mixed under conditions which exclude moisture as much as possible. Intermediate and end
product must also be stored under dry conditions.
There are also liquid, semisolid, solid and controlled release formulations or
preparations. The other dose forms are injections, implants, ocular preparations, inhalations
and transdermal systems. Liquid formulations may be solutions, emulsions, colloids or
suspensions in the increasing order of particle size. They may be intended for administration
parenterally, orally or topically including administration into body cavities. Homogeneity for
the formulations is very important, particularly where the active ingredient is present in lower
concentration.
A generalised production scheme include the following (Kraisintu, 1997):
- Pre-processing: Washing, particle size optimisation, moisture reduction, refinement or
concentration. - Solublisation: Insolubles removal, product stabilisation.
- Primary extraction: Primary contaminations removal.
- Purification: Secondary contaminations removal, decolourisation, concentration,
recemization - Derivatization (optional): Chemical modification.
- Drying(optional): Lyophilization or spray drying
Compounding of drugs
According to the guidelines of formulations, a prescription is composed of four different
component parts of ingredients as given below (Jiaxiang, 1997). - The principal ingredient which provides the principal curative action
- The adjuvent which strengthen the principal action
- The auxillary ingredient which relieves secondary symptoms or tempers the action of
principle ingredient - The conductant which directs action to the affected conduit or site. It may also be a less
significant auxillary ingredient.
The introduction of a polyvalent pilot plant has been the most significant contribution
of UNIDO to the development of the industrial utilisation of medicinal and aromatic plants in
developing countries. The gap that prevented the transfer of processes and products
developed on a laboratory to industry can be bridged by introducing pilot plant processing
facility and multidisciplinary teamwork. Many research and development institutions in
developing countries lacked the support of their engineering counter parts and most research
therefore was confined to academic pursuits. If one is to undertake commercial production of
herbal medicines, the vital role played by chemical engineers in translating laboratory
findings to industrial scale outputs through pilot scale process parameter development has to
be recognised.
Developing countries need to build up technological and scientific capabilities to
develop and improve the production of medicinal principles for use in their countries and to
conduct R&D to develop products for export thereby, enabling countries to supply new
markets which are being created as a result of consumer orientation of societies, increasing
affluence and demand for green products. Sustainable use of this renewable natural resource