Disintegration time is the time required for the tablet to break down into particles which can pass through a sieve while agitated in a specified fluid. Indicates the time to break down into small particles. Not necessarily solution. In the process of tablet manufacturer the drug is often formulated into a granular state (that is small but not fine) particles. This is done as the granule often has better flow properties than the a fine powder and there is less de-mixing leading to better uniformity. The granules are then compressed to produce the tablet. The disintegration test may lead to an end point of tablet to granule only, although the granules may be larger than the seive opening.
Figure 13.7.1 Movie Illustrating Table Disintegration
Dissolution
The time is takes for the drug to dissolve from the dosage form is a measure of drug dissolution.
Numerous factors affect dissolution. Thus the dissolution medium,
agitation and temperature are carefully controlled. The dissolution
medium maybe water, simulated gastric juice, or 0.1M HCl. The
temperature is usually 37°C. The apparatus and specifications
may be found in the U.S.P. The U.S.P. methods are official however
there is a wide variety of methods based on other apparatus. These
are used because they may be faster, cheaper, easier, sensitive to a
particular problem for a particular drug, or developed by a
particular investigator.
Dissolution tests are used as quality control to measure
variability between batches which maybe reflected by in vivo
performance. Thus the in vitro test may be a quick method of ensuring
in vivo performance. Thus there has been considerable work aimed at
defining the in vitro/in vivo correlation.
