title: Formulation and characterization of hydrochlorothiazide solid lipid microparticles based on lipid matrices of Irvingia fat.
abstract: BACKGROUND
  The purpose of this study was to improve the solubilization, bioavailability, and permeability of hydrochlorothiazide (HCTZ) by the formulation and characterization of HCTZ solid lipid microparticles (SLMs) based on fat derived from Irvingia gabonensis var. excelsa (Irvingia wombolu) and Phospholipon(®)90G (P90G).
  
  
  METHODS
  Irvingia fat was extracted from the nut of I. gabonensis var. excelsa using petroleum ether (40-60°C). HCTZ loaded SLM were formulated using hot homogenization method with 5% w/w Irvingia fat/P90G at each of 1:0, 9:1, 4:1, and 3:1 ratios, 1% w/w HCTZ, 1.5% w/w Labrasol(®) surfactant and distilled water. Subsequently, particle size analysis, pH, syringeability, drug encapsulation efficiency (EE%), yield, freeze-thaw cycle test, drug release, diffusion, and kinetics were evaluated.
  
  
  RESULTS
  The SLM dispersions showed a particle size range of 10.15 ± 2.36 to 13.50 ± 6.88 μm and pH of 5.6-6.4 while dispersions containing 3:1 Irvingia fat/P90G passed through most of the needles (18G, 21G, and 22G) after syringeability studies. A single freeze-thaw cycle caused loss of physical integrity. The EE% of the SLMs were ≥80%, with high yield. The highest drug release and diffusion was observed with SLMs prepared with 3:1 Irvingia fat-P90G mixture (HDP3) and Higuchi model best described the kinetics of the HCTZ release by Fickian diffusion.
  
  
  CONCLUSIONS
  The release and permeability of HCTZ was improved by its incorporation into Irvingia fat and P90G (3:1) as SLMs.
authors.affiliation: Department of Pharmaceutical Technology and Industrial Pharmacy, University of Nigeria, Nsukka, Enugu, Nigeria.
authors.forename: Chukwuma O
authors.initials: CO
authors.lastname: Agubata
authors.affiliation: Department of Pharmaceutical Technology and Industrial Pharmacy, University of Nigeria, Nsukka, Enugu, Nigeria.
authors.forename: Salome A
authors.initials: SA
authors.lastname: Chime
authors.affiliation: Department of Pharmaceutics, University of Nigeria, Nsukka, Enugu, Nigeria.
authors.forename: Franklin C
authors.initials: FC
authors.lastname: Kenechukwu
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Technology, Nnamdi Azikiwe University, Awka, Anambra, Nigeria.
authors.forename: Ifeanyi T
authors.initials: IT
authors.lastname: Nzekwe
authors.affiliation: Department of Pharmaceutical Technology and Industrial Pharmacy, University of Nigeria, Nsukka, Enugu, Nigeria.
authors.forename: Godswill C
authors.initials: GC
authors.lastname: Onunkwo
keywords: Encapsulation efficiency; Fickian diffusion; homogenization