Discriminatory Dissolution Method
Before starting about the discriminatory dissolution Method, let us understand about dissolution test in brief.
Why dissolution test are performed?
The drug dissolution is the tests conducted in vitro to predict drug absorption behaviour in vivo or, more precisely mimicking the physiological environment of the GI tract.
The cumulative amount of drug dissolved at different time points is reported as a plot of % drug dissolved versus sampling times. The resulting graph is called as a “dissolution profile “which is used to predict the in vivo drug release and to establish absorption characteristics of drugs from products in humans.
In general, dissolution tests are performed for:
(1) To assess the characteristics of the active pharmaceutical ingredient (API) such as the particle size and the crystal form;
(2) To guide development of new formulations;
(3) To assist in proper formulation selection (selection of excipients) and optimizing the manufacturing process (e.g., compression forces, equipment) during dosage form optimization;
(4) To assess the batch-to-batch quality of a drug product;
(5) To enable the comparison of batches obtained from different production sources;
(6) To ompare new or generic formulations with an existing product;
(7) To assess the stability of the drug product, helping in establishment of shelf life;
(8) To ensure product quality in the case of certain scale-up and post-approval changes (SUPAC) like manufacturing site changes, increase or decrease of batch size, and small quantitative changes in excipients;
(9) To provide a basis for achieving an in vitro–in vivo correlation (predicting product performance in vivo)
(10) To minimize the need for bioequivalence studies (bio-waivers): It is generally considered that if a dissolution profile of a test product matches that of a reference product, then the test product should behave similarly to the reference product in vivo and will be considered as bioequivalent. Conversely, if the profile of the test product is different from that of the reference product, then the test product might behave differently in-vivo and will NOT be considered as bioequivalent.
What is discriminatory dissolution Method and why it is required?
Discriminating Dissolution is a dissolution method which is sensitive to detect the differences in pharmaceutical attributes (formulation and/or manufacturing processes differences)in formulation that affect the dissolution rate that may reflect differences in-vivo. It usually represent dissolution conditions that enable to discriminate between two (or more) different formulations (e.g. which are not bioequivalent).
The discriminatory power of the dissolution method is the ability of the method to detect changes in drug product performance, which is generally demonstrated by determining the effect of deliberate changes in the formulation or process on dissolution characteristics.
A dissolution method with suitable discriminating power is used to indicate any possible changes in the quality of the product before in-vivo performance is affected. For e.g. when you want to evaluate whether certain formulation changes would affect drug dissolution, and therefore, bio performance of drug product, or when you want to compare test to reference formulation (prior to conducting in-vivo studies).
When to develop discriminatory dissolution method?
The systematic development of a discriminatory dissolution method is required much earlier than starting a full-fledged product development. This approach enables the formulator to finalizing the prototype formula and process for further scale-up.
Note: discussion presented here in this article is to explain the concept about discriminatory dissolution method rather than to discuss a particular technique.