The aim of this work was to prepare pH-dependent clarithromycin microsphere formulation by emulsion solvent evaporation method, employing Eudragit(®) L-100. Prepared microspheres were evaluated by carrying out in vitro release and in vivo pharmacokinetics studies. Drug-polymer interactions were studied by differential scanning calorimetry, X-ray diffractometry analyses and results showed that clarithromycin was molecularly dispersed in the polymer. The particle size distribution of microspheres was found over the range of 10~50 μm. The drug is hardly released in the HCl solution pH 1.2 in the first 2 h, but is rapidly released in phosphate buffer pH 7.2, and the cumulated release reached 98.1 % at 8 h. The pharmacokinetic profiles were conducted open, randomized, two-period crossover design with a 7-day interval between doses in healthy beagle dogs. The results indicated that the extent of absorption of the clarithromycin-load microspheres was the same as pure drug, but different in the rate of drug absorption in vivo.
Keywords: Clarithromycin; Emulsion solvent evaporation; Eudragit L-100; Microsphere; Pharmacokinetics.