Keith Moore

	For those of us who work in analytical laboratories at contract pharmaceutical development and manufacturing organizations (CDMOs), analyzing dissolution test samples is among the most important work we do. Dissolution is the process of incorporating a solid substance into a solvent (physiological pH aqueous solutions in most cases), forming a solution that allows for identification and measurement as a means of determining the release of a drug from the dosage form. The basic pharmaceutical applications of dissolution include:

 Dissolution is performed immediately after production to confirm critical quality parameters, to ensure uniformity between production batches, and to allow batches to be released. Dissolution also is conducted periodically to verify drug performance during shelf life.

 Dissolution is the only test that measures the availability of API after ingestion, therefore allowing scientists to predict, accurately, the time required for complete release of API from any given dosage form, as well as to potentially predict in-vivo performance.

Optimizing a drug product’s therapeutic effectiveness.

  While some would think that analysis of dissolution samples by high-performance liquid chromatography (HPLC) would always be the most efficient and effective method, analysis by UV spectroscopy does provide for immediate data and trending, as well as significant cost savings.

	UV spectroscopy has long been the pharmaceutical chemist’s traditional method and first option for analyzing the results of dissolution testing for the following reasons:

 HPLC has earned the nickname “high priced liquid chromatography” in some circles because users must pay for the cost of:

		organic solvents for mobile phase solutions

		acquiring and maintaining the equipment

		equipment depreciation incurred by using HPLC

		intangibles (e.g., for using HPLC systems for single-analyte analysis.)

 A single value, absorbance, is used to determine the data. Having a UV coupled with a sipper function allows for quick analysis of samples immediately following the dissolution experiment. In addition, there is no preparation time for mobile phase solutions; indeed, in some cases, moving solutions from test tubes to HPLC vials can increase the potential for analyst errors.  

	Another example is validating the testing procedure. Typically, there are more data to collect for HPLC system suitability parameters (e.g., column plate counts, peak symmetry, etc.) during method validation as compared to UV spectroscopy. This reduces time and delivers cost benefits.  

  Understanding  data  for  trending or understanding potential sources of laboratory errors can be immediate, and issues resolved quickly under supervision.

	Of course, there are situations in which HPLC offers advantages over UV spectroscopy. Depending upon wavelength, type of dosage form (e.g., capsules), and the dissolution medium being used, UV spectroscopy’s capabilities may be limited. Separation via HPLC might be needed for degradation products and excipients that absorb at the same wavelength as the active.

	-- Keith Moore, vice-president of analytical services, Metrics Contract Services


	When referring to this article, please cite it as K. Moore, “UV Spectroscopy Gains Use in Dissolution Testing," 

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Keith Moore, vice-president of analytical services, Metrics Contract Services discusses gains use in dissolution testing.