title: Improvement of stability of polidocanol foam for nonsurgical permanent contraception.
abstract: BACKGROUND
  Polidocanol foam (PF), used clinically as a venous sclerosant, has recently been studied as a safe and inexpensive means for permanent contraception. Delivering the sclerosant to the fallopian tubes as a foam rather than a liquid increases the surface areas and thus enhances the desired epithelial disrupting activity of the agent. However, the foam is inherently unstable and degrades with time. Therefore, increasing foam stability and thus duration of the agent exposure time could increase epithelial effect while allowing reduction in agent concentration and potential toxicity.
  
  
  METHODS
  We studied methods to improve foam properties that might improve safety and efficacy of PF for intrauterine application. Several types of microporous filters adapted to a syringe-based foaming device were used to study the effect of pore structures on the formation of PF. The foam drainage time and bubble size were characterized. The addition of benzalkonium chloride (BZK) to polidocanol was also investigated for its effects on foam characteristics.
  
  
  RESULTS
  A syringe-based foaming device adapted with an inline filter produced smaller bubble PF with a longer foam drainage time. PF generated with a circular pore filter lasts longer than with a noncircular pore filter. The addition of 0.01% of BZK also improved the stability of PF.
  
  
  CONCLUSIONS
  The stability of PF is affected by the pore characteristics of the filter used for foam generation and enhanced by the presence of a small amount of BZK. The improved foam, if shown to be efficacious in animal models of contraception, could lead to a safe, simple and inexpensive method alternative to surgical contraception.
authors.affiliation: Oregon Biomedical Engineering Institute, Wilsonville, OR 97070, USA. Electronic address: guoj@ohsu.edu.
authors.forename: Jian Xin
authors.initials: JX
authors.lastname: Guo
authors.affiliation: Oregon Biomedical Engineering Institute, Wilsonville, OR 97070, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Lucchesi
authors.affiliation: Oregon Biomedical Engineering Institute, Wilsonville, OR 97070, USA.
authors.forename: Kenton W
authors.initials: KW
authors.lastname: Gregory
mesh_terms: D000282:Administration, Intravaginal; D001548:Benzalkonium Compounds / Q000737:chemistry; D003271:Contraceptive Agents, Female / Q000008:administration & dosage / Q000737:chemistry*; D004339:Drug Compounding / Q000295:instrumentation; D004355:Drug Stability; D005260:Female; D006801:Humans; D007700:Kinetics; D008422:Materials Testing; D008851:Micropore Filters; D008855:Microscopy, Electron, Scanning; D000077423:Polidocanol; D011092:Polyethylene Glycols / Q000008:administration & dosage / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D011310:Preservatives, Pharmaceutical / Q000737:chemistry; D012597:Sclerosing Solutions / Q000008:administration & dosage / Q000737:chemistry; D013246:Sterilization, Tubal; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry; D014014:Tissue Adhesives / Q000008:administration & dosage / Q000737:chemistry*; D014622:Vaginal Creams, Foams, and Jellies / Q000008:administration & dosage / Q000737:chemistry
chemical_list: D001548:Benzalkonium Compounds; D003271:Contraceptive Agents, Female; D011108:Polymers; D011310:Preservatives, Pharmaceutical; D012597:Sclerosing Solutions; D013501:Surface-Active Agents; D014014:Tissue Adhesives; D014622:Vaginal Creams, Foams, and Jellies; D000077423:Polidocanol; D011092:Polyethylene Glycols
keywords: Benzalkonium chloride; Female; Permanent contraception; Polidocanol foam; Stability; Tubal occlusion