Abstract

FORMULATION & EVALUATION OF SOLID DISPERSION OF CELECOXIB

Udit Yadav*, Popin Kumar, Yogita Tyagi, Shraddha S. Raghav and Praveen Kumar Ashok

ABSTRACT

Several steps can be distinguished as critical ones in order to achieve adequate bioavailability after oral administration of an active pharmaceutical ingredient (API). Firstly, the drug substance needs to be dissolved in the fluids of the gastro-intestinal tract. After dissolution, an absorptive step is necessary to transport the API to the blood stream. This can occur either passively or actively, but efflux mechanism and presystemic metabolism can counteract the uptake and thereby reduce the bioavailability. When the drug passes the gastrointestinal membranes, it enters the hepatic portal circulation. Here first pass metabolism can result in API metabolites that can be more or less active than the original API. Subsequently the drug reaches the general circulation and can be distributed and transported to its site of action. A final step is the excretion of the drug out of the body. (Lipinski et al., 2000) The pharmaceutical industry today looks toward a more rational approach with respect to drug discovery. This leads to overall problems with both solubility and permeability of the newly discovered molecules (Lipinski et al., 2000). Obviously the interpretation of solubility and permeability has to be seen as a function of the drug potency. A drug substance is considered highly permeable when the extent of absorption in humans is determined to be 90% or more of the administered dose based on a mass-balance determination or in comparison to an intravenous dose. A drug is considered highly soluble when the highest dose strength is soluble in 250 ml or less of aqueous media over the pH range of 1 to 7.5. Another important factor is the dissolution rate, an API needs to be dissolved prior to its absorption (FDA guidance, 2012).

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