Presenter: Carmelo Scarpignato, MD, DSc, PharmD, MPH

Original Date: June 4, 2016

A “generic drug” has been designated by the World Health Organization as a medicinal product, which is interchangeable with the “original drug”, covered by patent (designated also as “branded drug”), in terms of both formulation (pharmaceutical interchangeability/ equivalence) and utilization in the clinical practice (therapeutic interchangeability/equivalence). Although the development and approval process of generic medicinal products is driven by specific and very detailed guidelines, some uncertainties do exist, stemming from the issue that the procedures, dictated by guidelines to get license for producing and marketing generic drugs, do not enforce the performance of efficacy clinical trials for the intended therapeutic indications. Rifaximin is an antibiotic, locally acting in the gastrointestinal tract, which may exist in different crystal as well as amorphous forms. The branded rifaximin formulation contains the polymorph rifaximin-α, whose systemic bioavailability is very limited. Recent studies demonstrate different systemic bioavailability of generic and branded formulations of rifaximin. As a consequence, the therapeutic results obtained with rifaximin-α should not be translated sic et simpliciter to the generic formulations of rifaximin, which do not claim containing only rifaximin-α and will display significantly higher systemic absorption in both health and disease.

0.5 Pharmacology and 0.5 General (Total 1.0 CEUs) approved by OBNM