ABSTRACT
Since the introduction of USP compendial dissolution equipment
in the 1970s, dissolution studies have become the main tool used
by pharmaceutical scientists when attempting to understand the
relationship between formulation performance and the complex
gastrointestinal physiological factors which influence oral absorp-
tion. Since the first description in 1951 by Edwards of how
dissolution can impact the absorption of a drug substance in the
gastrointestinal tract,1,2 scientists have continued to adapt both
dissolution equipment and methodology to more closely mimic the
luminal environment particularly with regards to media composi-
tion, and hydrodynamics/physical stress. The basket (USP apparatus
1) and paddle (USP apparatus 2) compendial apparatus have been at
the forefront of this effort and despite their limitations,3 have proved
very useful in understanding how formulation type, composition,
and process variation can impact drug release. Over the last two
decades of pharmaceutical research,4,5 the emergence in industrial
drug development pipelines of a dominant class of poorly soluble
compounds has created a multifaceted challenge to the continued
use of compendial apparatus to accurately predict oral formulation
performance and has driven the need to improve the biorelevance of
media and equipment. The concurrent development of increasingly
sophisticated oral drug delivery systems6 to improve absorption of
poorly soluble compounds has added another layer of complexity
which needs to be adequately addressed by dissolution approaches
seeking to provide robust predictions of in vivo performance.
