BIOANALYTICX

PVT (Performance Verification Test) is frequently described as necessary to assess the performance of dissolution apparatuses (paddle and basket). Interestingly, the test quite often fails, i.e., test results often fall outside the expected range, without any known reason or cause.

Commonly described reasons/causes are: worn-out ball bearings, loose motor belts, misalignment of spindles or vessels, inaccurate gap between the bottom of spindle and base of vessel, lack of straightness of spindle rods, wobbling, vibration in the instrument and/or around its surrounding, high/low humidity affecting tablets, inappropriate de-aeration of the medium, inaccuracy in measured rpm, variations in vessel dimensions, mismatch of vessels from different suppliers, not using vessels from the instrument supplier, use of plastic vs. glass vessels, using scratched or not clean vessels, not withdrawing a sample from an appropriate position, not appropriately dropping the tablet or pouring the medium in the vessels, lack of an analyst’s training, in addition, any combination/permutation of these reasons.

 Most interesting is the fact that there has been no experimental evidence available in support of these claims i.e., there is no experimental data available to indicate that these aberrations provided results outside the expected range. To rationalize its continued use, supporters of the PVT maintain the claim that failures indicate potential deficiencies or aberrations, but how?

Drug dissolution testing is an important and critical technique for developing and evaluating the quality of a drug product based on its release characteristics in vivo, i.e., in the human GI tract, in particular the small intestine.

Often dissolution studies are conducted using paddle and basket apparatuses. However, testing using these apparatuses has shown significant frustrations in obtaining relevant results with acceptable variability (reproducibility).

 Significant literature is available describing the flaws of these two apparatuses. One such flaw is that, although generally assumed, these apparatuses have never been validated for their intended purpose, i.e., obtaining relevant and reproducible results.

 Even though these flaws are generally recognized, these apparatuses are in use as a “tradition” because these are the ones most commonly suggested and employed in the past. Another reason for their continued use is an apparent and unfortunate twist in the objective of the dissolution testing. That is, rather than evaluating the dissolution characteristics of a product; it is often suggested to establish the experimental conditions that show the desired dissolution characteristics. Thus, there is a large waste of human and financial recourses in developing drug and product-dependent procedures.

 The practice of obtaining or showing the desired and product-dependent dissolution results has no purpose other than rationalizing the continued use of paddle and basket apparatuses.

 To conduct appropriate dissolution studies, one needs to focus on the true objective of the testing i.e., to observe drug dissolution/release characteristics of a product in vivo. With this objective, things will start to fall in place. This will allow the analyst to use more efficient apparatuses and simple experimental conditions to obtain useful results.