The Effect of Eudragit and Enteric Polymer Composite on the Release of Nicardipine

(Received: May 16, 2006; Accepted: July 27, 2006)

   The purpose of this study was to investigate the sustained release of nicardipine/polymer solid dispersions prepared by solvent evaporation method.  The release pattern of drug from solid dispersions was evaluated by the dissolution test in both dissolution medium of phosphate buffer pH 6.8 or gastric acid fluid pH 1.2, and was compared with a commercial long acting product Perdipine®.  The results showed that the formulations with lower ratio of Nicardipine/Eudragit RS (N/RS) (below 1/5) had sustained release effect in gastric acid fluid (pH 1.2).  The release rate of formulation of N/RS = 1/5 was slightly faster than that of Perdipine® in gastric acid fluid in the early stage.  On the contrary, the release rate was lower than that of Perdipine® in phosphate buffer (pH 6.8).  The enteric polymers such as HPMCAS-LF grade (HPMCAS) and hydroxypropyl methylcellulose phthalate, HP-55 grade (HPMCP) were incorporated into the formulation of NC/ERS = 1/5 solid dispersion to improve the drug release in both dissolution medium.  It was found that the dissolution efficiencies of drug were increased 2.35-21.08 folds with the addition of 20-40% of enteric polymer in pH 6.8 media.  Among these formulations of  N/RS/HPMCP = 1/3.5/1.5 had similar dissolution pattern with Perdipine® in either medium of phosphate buffer or gastric acid fluid (f2 values were above 50), showing that the sustained release dosage form of nicardipine solid dispersions could be developed by using the combination of Eudragit RS and enteric polymer.

Key words: Nicardipine, Eudragit, Enteric polymer, Dissolution test