2.8. In Vitro Dissolution Study

Dissolution studies of CLX crude powder, PM and CLX-NC were performed in Distek 7100 automated dissolution test apparatus (Distek Inc., North Brunswick, NJ, USA). The temperature and paddle speed were set at 37 °C and 100 rpm, respectively. The dissolution media included hydrochloric acid solution (pH 1.2), phthalate buffer (pH 4.6), phosphate buffer (pH 6.8) and distilled water. 0.3% (w/v) SDS was added into each medium to maintain the sink condition. The samples (equivalent to 50 mg CLX) were added into the vessels containing 900 mL dissolution medium. 2 mL of dissolution medium were withdrawn at the predetermined time intervals of 5, 10, 20, 30, 45, 60 and 120 min, and immediately replaced with equal volume of fresh dissolution medium. The collected sample was centrifuged at 12,000 g for 10 min to remove the undissolved drug. The supernatant was used to determine the content of CLX by HPLC assay. Each sample was measured in triplicate.