Study On The Application Of Carbopol In Sustained Release Solid Oral Dosage Forms

Nicotinic acid (niacin) was used as a water-soluble drug model to investigate the application of Carbopol on sustained release oral matrix tablets. Carbopol934P. 974P and 971 P are the oral pharmaceutical grades of Carbomer and currently being utilized as polymeric matrices for controlling drug release in pharmaceutical dosage forms. The swelling and adhesiveness of Carbopol in different mediums were investigated .The result indicated the swelling of Carbopol was significantly different in simulated gastric fluid(SGF) and simulated intestic fluid(SIF).The adhesiveness of Carbopol was strongly affected by pH and ionic strength compared with HPMCK4m. The influence of composition factors and dissolution conditions on in vitro dissolution behavior was evaluated. The result showed dissolution rate was affected by the content and type of Carbopol, filler, dissolution method, pH and ionic strength of dissolution medium, but the particle size of Carbopol and hardness of tablets had little influence. A novel wet granulation method- Carbopol extragranular addition was studied in details. It is a simple and manageable process compared with general wet granulation and has the advantage of avoiding agglomeration of Carbopol during granulation. The formulation of sustained release nicotinic acid tablet (SRNAT) using the combination of Carbopol974P and HPMCK4m was screened. It has similar in vitro dissolution characteristics to the imported tablet. Pharmacokinetic studies were carried out in six healthy rabbits after a single oral administration of the self-prepared and imported SRNAT in a randomized crossover way. The results demonstrated that the two preparations were bioequivalent.