title: Observations in simultaneous microencapsulation of 5-fluorouracil and leucovorin for combined pH-dependent release.
abstract: 5-Fluorouracil (5-FU) in combination with leucovorin (LV) is nowadays the standard treatment in colon cancer and would be a candidate to be delivered orally to the colon. Eudragit P-4135F or Eudragit RS100 were used separately to prepare microspheres by an oil/oil emulsification process trapping 5-FU and LV simultaneously. Scanning electron microscopy permitted a structural analysis, process parameters were analyzed and drug loading and release profiles were recorded. Particle size varied between 123 (RS100) and 146 microm (P-4135F). Generally, higher encapsulation rates were found with RS100 (5-FU, 60.3+/-9.7%; LV, 81.4+/-8.6%) compared to P-4135F (5-FU, 48.3+/-2.0%; LV, 55.4+/-2.7%). Microparticles made from Eudragit RS100 released the incorporated drug combination within 8 h not exhibiting general differences between the kinetics of both drugs. P-4135F was found to maintain the undesired 5-FU release at pH 6.8 lower than 25% within 4 h while at pH 7.4, a nearly immediate release (within 15 min) was observed. Although the release was similar at pH 7.4, at pH 6.8 LV showed a distinct initial drug loss of about 60% and a complete release within 2 h. SEM analyses revealed a substantial presence of LV crystals on the particle surface provoking a distinct burst effect of LV. These observations were concluded to be related to the high lipophilicity of P-4135F provoking a separation between P-4135F and LV during the preparation process.
authors.affiliation: Laboratory of Pharmaceutical Engineering, Gifu Pharmaceutical University, Gifu, Japan.
authors.forename: Alf
authors.initials: A
authors.lastname: Lamprecht
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kawashima
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000493:pharmacokinetics; D004339:Drug Compounding / Q000379:methods; D005472:Fluorouracil / Q000008:administration & dosage / Q000493:pharmacokinetics; D006863:Hydrogen-Ion Concentration; D002955:Leucovorin / Q000008:administration & dosage / Q000493:pharmacokinetics; D008863:Microspheres
chemical_list: D003692:Delayed-Action Preparations; D002955:Leucovorin; D005472:Fluorouracil