title: A comparative study of the effect of spray drying and hot-melt extrusion on the properties of amorphous solid dispersions containing felodipine.
abstract: OBJECTIVE
  To compare the properties of solid dispersions of felodipine for oral bioavailability enhancement using two different polymers, polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose acetate succinate (HPMCAS), by hot-melt extrusion (HME) and spray drying.
  
  
  METHODS
  Felodipine solid dispersions were prepared by HME and spray drying techniques. PVP and HPMCAS were used as polymer matrices at different drug : polymer ratios (1 : 1, 1 : 2 and 1 : 3). Detailed characterization was performed using differential scanning calorimetry, powder X-ray diffractometry, scanning electron microscopy and in-vitro dissolution testing. Dissolution profiles were evaluated in the presence of sodium dodecyl sulphate. Stability of different solid dispersions was studied under accelerated conditions (40°C/75% RH) over 8 weeks.
  
  
  RESULTS
  Spray-dried formulations were found to release felodipine faster than melt extruded formulations for both polymer matrices. Solid dispersions containing HMPCAS exhibited higher drug release rates and better wettability than those produced with a PVP matrix. No significant differences in stability were observed except with HPMCAS at a 1 : 1 ratio, where crystallization was detected in spray-dried formulations.
  
  
  CONCLUSIONS
  Solid dispersions of felodipine produced by spray drying exhibited more rapid drug release than corresponding melt extruded formulations, although in some cases improved stability was observed for melt extruded formulations.
authors.affiliation: Centre for Pharmaceutical Engineering Science, School of Life Sciences, University of Bradford, Bradford, UK.
authors.forename: Osama
authors.initials: O
authors.lastname: Mahmah
authors.forename: Rami
authors.initials: R
authors.lastname: Tabbakh
authors.forename: Adrian
authors.initials: A
authors.lastname: Kelly
authors.forename: Anant
authors.initials: A
authors.lastname: Paradkar
mesh_terms: D001682:Biological Availability; D002626:Chemistry, Pharmaceutical; D003890:Desiccation; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding / Q000379:methods*; D004355:Drug Stability; D015736:Felodipine / Q000008:administration & dosage / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D011205:Povidone / Q000737:chemistry*; D012995:Solubility; D012996:Solutions; D017155:Wettability
chemical_list: D004337:Drug Carriers; D012996:Solutions; C048331:hydroxypropylmethylcellulose acetate succinate; D008747:Methylcellulose; D011205:Povidone; D015736:Felodipine
keywords: dissolution rate; hot-melt extrusion; solid dispersion; spray drying; stability