T. Govender et al., MICROENCAPSULATED EUDRAGIT(R) RS30D-COATED CONTROLLED-RELEASE PELLETS- THE INFLUENCE OF DISSOLUTION VARIABLES AND TOPOGRAPHICAL EVALUATION, Journal of microencapsulation, 14(1), 1997, pp. 1-13
Citations number
15
Categorie Soggetti
Pharmacology & Pharmacy","Chemistry Applied","Engineering, Chemical
The air suspension technique was employed to prepare Eudragit(R) RS30D
-coated controlled-release pellets of salbutamol. Drug release in diss
olution studies can be dependent on the dissolution method and medium
used. Thus, the aim of this study was to investigate the influence of
various dissolution methods and dissolution medium pH values on drug r
elease from a batch of pellets which displayed controlled drug-release
characteristics over an 8-h period in deionized water using the rotat
ing basket method. In vitro testing using the official USP XXII (rotat
ing basket and rotating paddle) and nonofficial (rotating bottle) meth
ods showed drug release to be independent of the method used. The prep
ared pellets displayed pH-dependent drug-release characteristics when
tested in hydrochloric acid (pH 1.5), phosphate buffer (pH 6.8) and de
ionized water (pH 7.2). Also, in vitro testing, which exposed the pell
ets to a changing pH gradient that simulated the gastrointestinal pH c
onditions following oral administration, was used to confirm the drug-
release characteristics. The results showed controlled-release charact
eristics to be maintained, with the drug being released over an 8-h pe
riod. Scanning electron microscopic evaluation proved useful in the el
ucidation of the physical characteristics of the controlled-release pe
llets as well as in the identification of a possible mode of drug tran
sfer into the dissolution medium.