文档介绍：Pharmaceutical preformulation
Dr J E Newbery
******@
reference
Aulton ‘Pharmaceutics’
Second edition (2002)
pp 113-138.
Preformulation programme
Wide range of potential dosage forms
(add some examples here….
All with similar aims
Stability
Release of active
Dosage uniformity
Purpose of programme
To measure physical and chemical properties of the active agent in order to guide
Type of formulation
Route of administration
Manufacturing processes
Topic areas
UV assay (spectroscopy)
Solubility
Partition
Melting behaviour
Stability (heat/light/pH etc)
Microscopy
Powder pression behaviour
patibility
Limited quantities
Preformulation is done fairly early in the product development cycle. Only limited amounts of material may be available.
Very accurate measurements are not required at this stage.
Many processes have been automated.
UV spectroscopy
Although the majority of active pharmaceutical substances are white powders, they mainly have spectroscopic activity in the UV region of the spectrum.
This area corresponds in energy to values similar to chemical bond strengths. Best results are obtained from molecules with double bonds.
UV spectroscopy
The spectrum has a peak of maximum absorbance (in this case at 230 nm).
The height of this peak is directly proportional to the concentration of the substance
Use of the UV spectrum
Although a typical UV spectrum is of only limited use in the identification of a substance, it has great utility as an assay method.
Solubility measurement
The solubility of a substance is an important property that depends on three factors:
The nature of the substance
The solvent
The temperature