Evaluation and preparation of controlled release lipid micropheres of sulphamethizole by a congealable disperse phase...

A congealable disperse phase encapsulation method was used to prepare controlled release lipid microspheres of sulphamethizole as a model drug. Hydrogenated cotton seed oil (HCSO) and stearic acid were employed as the lipid matrix materials. Tween 60 was the droplet stabilizer used to form microspheres. In in vitro dissolution tests, the drug release was found to be affected by the type of lipid material depending on hydrophilicity. Generally, an initial rapid release followed by a slower release of the drug from the lipid microspheres was observed. Lipid microspheres were also compressed in the tablet form to prevent the initial rapid release of the drug. But the drug release drastically decreased. To achieve a controlled release of the drug. Eudragit L as a channeling agent was added internally to HCSO-microspheres. Although the drug release increased, the controlled release pattern was not achieved. The external addition of polyethyleneglycole 4000 to HCSO-microspheres before compressing tablets, did not produce an affirmative change in the release profile. The lipid microspheres prepared by stearic acid released all of the drug within 1 h. Upon compression, the drug release was very low. Therefore, stearic acid-microspheres were compressed in the tablet form adding disintegrating agents, sodium alginate and Ac-Di-Sol (cross-linked sodium carboxymethylcellulose). A pH-dependent drug release was obtained from the tablets containing sodium alginate. With the tablets of stearic acid-microspheres containing Ac-Di-Sol, the controlled release could be achieved due to gradual disintegration from the tablet to aggregates, and to individual microspheres. Furthermore, in vivo study on 6 healthy volunteers confirmed the controlled release pattern of this dosage form.