title: Nanoemulsion containing dapsone for topical administration: a study of in vitro release and epidermal permeation.
abstract: BACKGROUND
  Topical administration of dapsone can be an alternative route for treatment of leprosy and can also provide new therapeutic applications for an established drug. However, the physicochemical properties of dapsone make it difficult to incorporate into conventional formulations. The current study was directed toward developing a stable nanoemulsion that contains dapsone which can be adapted for topical use.
  
  
  METHODS
  Nanoemulsions were prepared using isopropyl myristate or n-methyl-pyrrolidone as the oil phase, and characterized according to their mean droplet size, conductivity, refractive index, pH, drug content, and stability. The in vitro release of dapsone and its ability to permeate the epidermis were also evaluated.
  
  
  RESULTS
  Physicochemical characterization demonstrated that nanosystems were formed, which had a uniform droplet distribution and a pH compatible with the skin surface. Use of n-methyl-pyrrolidone provided a greater nanoemulsion region and higher solubilization of dapsone, and increased the in vitro release rate when compared with a nanoemulsion prepared using isopropyl myristate. However, use of isopropyl myristate promoted an increase in in vitro epidermal permeation that followed the Higuchi model. This demonstrates the ability of a nanosystem to influence permeation of dapsone through the skin barrier. Furthermore, the nanoemulsions developed and evaluated here had ideal physicochemical stability over a 3-month period.
  
  
  CONCLUSIONS
  Incorporation of dapsone into a nanoemulsion may be a promising system for enabling topical delivery of dapsone, while minimizing skin permeation, for the treatment of acne. The method developed here used isopropyl myristate as the oil phase, and promoted permeation of dapsone through the skin barrier for the treatment of leprosy upon use of n-methyl-pyrrolidone as the oil phase.
authors: Department of Pharmaceutics, Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors: Vinécius Raphael de Almeida
authors: VR
authors: Borges
authors: Alice
authors: A
authors: Simon
authors: Adrian Ricardo Cuello
authors: AR
authors: Sena
authors: Lúcio Mendes
authors: LM
authors: Cabral
authors: Valéria Pereira
authors: VP
authors: de Sousa
mesh_terms: D000279:Administration, Cutaneous; D000704:Analysis of Variance; D000818:Animals; D003622:Dapsone / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D004355:Drug Stability; D004553:Electric Conductivity; D004655:Emulsions / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics; D004817:Epidermis / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009226:Myristates / Q000737:chemistry; D050997:Nanomedicine / Q000379:methods; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D010316:Particle Size; D011760:Pyrrolidinones / Q000737:chemistry; D015203:Reproducibility of Results; D012869:Skin Absorption; D013552:Swine
chemical_list: D004655:Emulsions; D009226:Myristates; D011760:Pyrrolidinones; C008205:isopropyl myristate; D003622:Dapsone; C038678:N-methylpyrrolidone
keywords: dapsone; nanoemulsion; permeation; release; topical