Formulation support dissolution testing

To further explore some complexities associated with decisions on the value of dissolution tests, it is postulated that for the selected formulation, in vitro dissolution is likely to be a more sensitive tool for studying formulation differences than in vivo bioequivalence studies. The following arguments can be made to support this postulate. 

Drug materials administered orally are required to dissolve in the GI fluids before absorption can take place. Dissolution occurs most rapidly from the primary particles of the drug substance, hence the importance of rapid disintegration to this state. However, disintegration studies only demonstrate that a tablet will break up when immersed in fluid there are many other factors that can influence the dissolution of a material. A carefully designed dissolution test will, therefore, be a better indication of the performance of a dosage form. The design of dissolution tests and the correlation between in vitro dissolution and in vivo performance is discussed in Chapter 7, Biopharmaceutical Support in Formulation Development . The optimisation of the dissolution of a substance is discussed in Chapter 8. 

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