Drug testing and dissolution methodology are imperative in development of new drug products. These are crucial to quality assurance for existing products and can be a key tool in the approval of new multisource drug products, said Dr B R Jagashetty, drugs controller, government of Karantaka.

In his key note address at a one-day seminar organised by the Society for Pharmaceutical Dissolution Science (South Chapter) & JSS University, Mysore, Dr Jagashetty said that dissolution is the primary quality control test to determine whether a drug product can release its active pharmaceutical ingredients (APIs) in a timely manner. So it is vital for the academia, pharma industry and instrument manufacturers to embark on knowledge transfer in the area of dissolution.

The factors that influence dissolution of drug products are the properties of the API, quality-design of the drug and the conditions under which the test is run. It is here that the dissolution test parameters like choice of apparatus, stir/dip/flow rate, dissolution medium, duration of test, sampling method and analysis are important for the results, he added.

Properties of the API important to dissolution include its solubility, which is usually an aqueous buffer solution and could also contain surfactants as well. There is need to see if the API is hydrophilic or hydrophobic, assess API particle size, whether the API is crystalline or amorphous in the drug, check if there are polymorphs and identity it thereafter. Standardization of the method is also crucial to obtain the desired results, said Dr Jagashetty.

Highlighting the applications of dissolution, he said that it is an aid for formulation design. It is also a quality control measure immediately after production for batch release which could check performance of the drug during the shelf life. It could also predict performance under various dosing conditions.

Further, dissolution helps verify that the quality of a product is not adversely affected when there is a change in excipients or manufacturing method. The methodology is also used to obtain approval for a multisource drug products like for instance generic versions.

Noting the challenges of dissolution, he said that many APIs are poorly soluble, creating dissolution problems. In such cases, there is need to adjust the pH of the medium, add a surfactant to the medium, increase the volume of the dissolution medium and the duration of the dissolution test.

“In the recent past, dissolution has gained greater importance, due to generic drugs which are considered to be of great importance to the world considering the healthcare cost. India has been progressing well in exports of generics to the US and Europe markets. Of late the cost of generics is just the one-tenth of the branded versions, because of Hhatch-Waxman Act,” said Dr Jagashetty.

So long, the generic industry used dissolution testing as a quality control tool to ensure consistent performance and high quality of drugs. In the past, dissolution has been a test meant only for the efficacy assessment of the solid orals. But in recent years, dissolution has been used to test the efficacy of non-oral dosage forms. Now equipment manufacturers have to ensure modifying the system with flow through USP Type 4, where tablet or any dosage unit could be tested for dissolution ability using varied pH ranges and meeting the physiological conditions, concluded Dr Jagashetty.