Convolution/Deconvolution Techniques – Which one to use and why?

As explained in an earlier post, commonly used convolution/deconvolution techniques for IVIVC purposes, link three functions together. The three functions are input (absorption/dissolution results), output (plasma drug concentrations) and weighting function (usually plasma drug concentrations following an intravenous dose).

Deconvolution will be the option one would use when plasma drug concentrations of the test products are available and one would like to determine the in vivo dissolution results. These in vivo dissolution results are compared with the in vitro dissolution results.

Convolution will be the option one would use when in vitro dissolution results are available and one would like to determine plasma drug concentrations of the test product. During the product developmental stage, where a formulator likes to have an idea of potential in vivo output, a convolution technique would be the only choice. For comparison of release (dissolution) characteristics of products for generic developments or product modifications etc., again one may use the convolution technique. In this case, based on obtained dissolution results from two or more products, one would be able to obtain respective plasma drug concentration profiles, which can be compared using standard and accepted parameters of Cmax and area under the plasma drug concentration curves (AUC).

Studies have shown that the convolution technique provides better accuracy of outcome (plasma drug concentrations) than the deconvolution technique.  Moreover, computation-wise, convolution technique could be simplified and calculation may be performed using simple spreadsheet software rather complex mathematical software. Therefore, it is suggested that one may consider convolution as a first choice for developing IVIVC.

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