IN-VITRO CHARACTERIZATION OF A CONTROLLED-RELEASE CHLORPHENIRAMINE MALEATE DELIVERY SYSTEM PREPARED BY THE AIR-SUSPENSION TECHNIQUE

Non-pareil cores were spray-coated with a chlorpheniramine maleate (an alkylamine antihistamine) layer and a Eudragit(R) NE30D overcoat in a Wurster air-suspension apparatus. In vitro dissolution studies demons trated that drug release was a function of polymer membrane thickness. Polyethylene glycol 6000, as a hydrophillic additive, increased the i n vitro release of chlorpheniramine maleate from the pellets. Pellets coated with 8.30% Eudragit(R) NE30D, 0.50% talc and 1.00% polyethylene glycol 6000 were found to display desirable controlled release charac teristics for chlorpheniramine maleate over the 8-h testing period, wh ich were also comparable with that of Dykatuss(R) capsules. The contro lled release pellets exhibited first-order release characteristics for chlorpheniramine maleate. Reproducibility of the manufacturing condit ions employed in the study were confirmed thus ensuring reproducibilit y of drug release characteristics between batches of chlorpheniramine maleate pellets. Drug release from the pellets was shown to be indepen dent of the dissolution method and medium used. Pellets displayed no s ignificant change in drug release characteristics relative to the init ial drug release data when stored for 12 weeks at room temperature (20 +/- 2 degrees C) and for 8 weeks at a low temperature (5 +/- 1 degree s C). However, pellets stored at 37 degrees C with 80% relative humidi ty and at 40 +/- 2 degrees C showed a slower in vitro drug release aft er 8-week storage and therefore failed to maintain their initial drug release profile.