DISINTEGRATION AND GEL-FORMING BEHAVIOR OF CARBOMER AND ITS SODIUM-SALT USED AS EXCIPIENTS FOR DIRECT COMPRESSION

Poly(acrylic acid) polymers such as carbomer (Carbopol 934P, C934P) an d its sodium salt (Carbopol EX-161, NaC934P) were studied as excipient s for direct compression, with the aim of preparing tablet formulation s with fast disintegration of the poly(acrylates) and rapid drug relea se characteristics Erythrosin was included in the tablets as a hydroph ilic model drug. Tablets composed of C934P and the disintegrant sodium starch glycolate in amounts up to 50% showed a very slow disintegrati on time (about 5 h) and low dissolution of erythrosin (13% after 1.5 h ). Replacement of C934P by NaC934P resulted in a threefold reduction o f the disintegration time and almost total release of erythrosin after 2 h, clue to the higher solubility of NaC934P as compared to C934P. T ablets consisting of the freeze dried sodium salt of carbomer (FNaC934 P) with 50% starch glycolate showed a rapid disintegration time of 24 min and complete dissolution of erythrosin within 30 min. For these FN aC934P tablet formulations no substantial differences were observed be tween sodium starch glycolate, polyvinylpyrrolidone or sodium croscarm ellose as disintegrants. In conclusion, the poly(acrylate) FNaC934P is a suitable excipient for direct compression of tablets with rapidly d isintegrating and drug releasing properties, and may be useful in form ulations intended to deactivate intestinal luminal protease activities .