Objectives:
The effect of simulated gastrointestinal viscosity, surface tension and pH on dissolution rate of a two commercial products of candesartan cilexetil (CC) were illustrated.
Materials and methods:
In-vitro dissolution of two commercial CC products immediate release of 16 mg CC were applied under two conditions: (1) the requirements of the United States Pharmacopeia (USP), (2) a conditions that is physiologically related to gastrointestinal tract (GIT) mimicking viscous food intake. Solubility of CC in different simulated fluid was measured. Viscosity, surface tension and pH of the investigated dissolution media were also detected. The viscosity of the gel layer was measured during dissolution of CC .
Results:
Dissolution rate of CC was highest in USP medium. It was found that the media type affected the CC dissolution. Non USP media exhibited slower dissolution rate compared to USP specification. Highest viscosity media slower the dissolution rate in one of CC products. Acidic pH showed a significant lowing in dissolution for both CC products. Solubility of CC was affected by solvent type.
Conclusions:
Higher viscosity media slower the dissolution rate of one product, where a gel layer was formed on the tablet surface leading to slow the dissolution rate. The current results showed a variation in dissolution media. That may reveal differences in the dissolution rates of the same drug in different products and different investigated media. Taking this into consideration; the effect of viscosity on the dissolution might lead to better patient’s outcomes when treated by different products.
Keywords: immediate release; dissolution; viscosity; simulated gastrointestinal fluid, gel