In vitro release testing (IVRT) for semi-solid dosage forms (e.g. creams, lotions, gels, and ointments) has been around for more than thirty years, first appearing in the literature in the late 1970s and early 1980s.  During the last decade however, we have seen a substantial upsurge in the amount of public literature relating to the technique, and over the last few years, growth and reference to IVRT has seemed exponential.  It’s safe to say at this point in late 2014 that everybody’s doing it, and if you’re not, then you’re missing the boat and it’s time to hop on.

Why such rapid growth?  As you might expect, there are a variety of factors contributing to recent evolution in the area, but the most obvious is simply that the FDA is now asking for the data far more frequently.  Performance testing has been lacking for semi-solid dosage forms, and we’ve relied largely on measurement of physical and chemical parameters of these formulations (e.g. pH, viscosity, and other rheological measurements) to compare batches and lots of drug product to one another.  Historically (i.e. since the mid to late 1990s), the agency has required IVRT data to support scale-up and post-approval changes for semi-solid dosage forms, so if you haven’t read the SUPAC-SS guidance document published in 1997, it’s time you did.  Find it at the FDA website, or just click here:  (  During the last few years though, agency requests for IVRT data have reached well beyond the breadth of SUPAC, and we’re now implementing the technique as a BA/BE surrogate, and talking about how to set IVRT specifications as we face the challenging and exciting implementation of IVRT as a quality control release test for semi-solid drug products.

The surge in IVRT around the world is not just because regulatory agencies are asking though, they’re asking for a reason:  IVRT has a variety of uses and applications, and lends a critical hand in each phase of product development for semi-solid dosage forms.  Technical teams at Tergus have developed, validated, and implemented methods for all stages of product development, including early formulation screening, optimization throughout clinical evaluation, and to support post launch activities.  Developing the methods early in the lifetime of a product builds the body of data necessary to properly implement the method during later stages to support activities such as product release, stability assessment, and SUPAC.  So if IVRT methods are not a standard component of drug product development within your organization, the time is now to begin creating a better understanding of how your products are performing.