Pharmaceutical Technology: Controlled Drug Release, Volume 2

MULTIPARTICULATES [CH. 10 119
Micromatrices were recovered from the system by filtration and successive washing with suitable
non-solvent (Table 1) and dried in air.
In vitro dissolution
Drug release profiles of micromatrices and microcapsules were evaluated using a modified USP
XXI dissolution apparatus under changing pH conditions. A pH profile [6] from 1.2 to 7.5 was
achieved using hydrochloric acid, anhydrous sodium carbonate and bicarbonate in distilled water.
Micromatrices and microcapsules were taken in the dissolution basket covered with 100 mesh
muslin cloth. Initially, 500 ml of dissolution fluid was used and 5 ml aliquots were removed at
specified time intervals to evaluate the percentage of drug released. The dissolved drug was
assayed at 271 nm using a UV-visible 200–20 Hitachi spectrophotometer (Table 2).
Table 2—In vitro drug release profile of microcapsules and micromatrices
Core:coat=l:2.
Scanning electron microscopy
As the developed dosage forms are transparent to the electron beam, the samples were coated with
(carbon-gold)-gold layer under vacuum. An ISA-60A scanning electron microscope and a polar
vapour coater unit were for gold coating.
In vivo evaluation
Six healthy volunteers, three males and three females, aged 20–25 years, and weighing 50–60 kg,
participated in the study. Female volunteers were non-pregnant. All subjects were non-smokers.
After informed consent was obtained, all subjects refrained from tea, coffee, carbonated beverage
and chocolate for six days before and during the study.
The subjects fasted overnight and the developed dosage forms equivalent to 250 mg
theophylline were administered at 7 a.m. with 100 ml water. The subjects were not permitted to