title: Formulation, optimization, and evaluation of self-emulsifying drug delivery systems of nevirapine.
abstract: BACKGROUND
  The aim of the present study was to formulate and optimize the self-emulsifying drug delivery systems (SEDDS) of nevirapine (NVP) by use of 2(2) factorial designs to enhance the oral absorption of NVP by improving its solubility, dissolution rate, and diffusion profile. SEDDS are the isotropic mixtures of oil, surfactant, co-surfactant and drug that form oil in water microemulsion when introduced into the aqueous phase under gentle agitation.
  
  
  METHODS
  Solubility of NVP in different oils, surfactants, and co-surfactants was determined for the screening of excipients. Pseudo-ternary phase diagrams were constructed by the aqueous titration method, and formulations were developed based on the optimum excipient combinations with the help of data obtained through the maximum micro emulsion region containing combinations of oil, surfactant, and co-surfactant. The formulations of SEDDS were optimized by 2(2) factorial designs.
  
  
  RESULTS
  The optimum formulation of SEDDS contains 32.5% oleic acid, 44.16% tween 20, and 11.9% polyethylene glycol 600 as oil, surfactant, and co-surfactant respectively. The SEDDS was evaluated for the following drug content, self-emulsification time, rheological properties, zeta potential, in vitro diffusion studies, thermodynamic stability studies, and in vitro dissolution studies. An increase in dissolution was achieved by SEDDS compared to pure form of NVP.
  
  
  CONCLUSIONS
  Overall, this study suggests that the dissolution and oral bioavailability of NVP could be improved by SEDDS technology.
authors.affiliation: Department of Pharmaceutics, Bapatla College of Pharmacy, Bapatla, Guntur, Andhra Pradesh, India.
authors.forename: Ramprasad
authors.initials: R
authors.lastname: Chintalapudi
authors.affiliation: Department of Pharmaceutics, Bapatla College of Pharmacy, Bapatla, Guntur, Andhra Pradesh, India.
authors.forename: T E G K
authors.initials: TE
authors.lastname: Murthy
authors.affiliation: Department of Pharmaceutics, Bapatla College of Pharmacy, Bapatla, Guntur, Andhra Pradesh, India.
authors.forename: K Rajya
authors.initials: KR
authors.lastname: Lakshmi
authors.affiliation: Department of Pharmaceutical Analysis, Nirmala College of Pharmacy, Mangalagiri, Guntur, Andhra Pradesh, India.
authors.forename: G Ganesh
authors.initials: GG
authors.lastname: Manohar
keywords: 22 factorial designs; nevirapine; oleic acid; polyethylene glycol 600; self-emulsifying drug delivery systems; tween 20