title: Cationic surfactants-modified natural zeolites: improvement of the excipients functionality.
abstract: BACKGROUND
  In this study an investigation of cationic surfactants-modified natural zeolites as drug formulation excipient was performed.
  
  
  OBJECTIVE
  The aim of this work was to carry out a study of the purified natural zeolitic tuff with high amount of clinoptilolite as a potential carrier for molecules of pharmaceutical interest.
  
  
  METHODS
  Two cationic surfactants (benzalkonium chloride and hexadecyltrimethylammonium bromide) were used for modification of the zeolitic surface in two levels (equal to and twice as external cation-exchange capacity of the zeolitic tuff). Prepared samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric, high-performance liquid chromatography analysis, and powder flow determination. Different surfactant/zeolite composites were used for additional investigation of three model drugs: diclofenac diethylamine, diclofenac sodium, and ibuprofen by means of adsorption isotherm measurements in aqueous solutions.
  
  
  RESULTS
  The modified zeolites with two levels of surfactant coverage within the short activation time were prepared. Determination of flow properties showed that modification of zeolitic surface reflected on powder flow characteristics. Investigation of the model drugs adsorption on the obtained composites revealed that a variation between adsorption levels was influenced by the surfactant type and the amount present at the surface of the composites.
  
  
  CONCLUSIONS
  In vitro release profiles of the drugs from the zeolite-surfactant-drug composites revealed that sustained drug release could be attained over a period of 8 hours. The presented results for drug uptake by surfactant-zeolite composites and the afterward drug release demonstrated the potential use of investigated modified natural zeolite as excipients for advanced excipients in drug formulations.
authors.affiliation: Department of Pharmaceutical Technology and Cosmetology, Faculty of Pharmacy, University of Belgrade, Belgrade, Serbia. danina@pharmacy.bg.ac.rs
authors.forename: Danina
authors.initials: D
authors.lastname: Krajisnik
authors.forename: Maja
authors.initials: M
authors.lastname: Milojević
authors.forename: Anđelija
authors.initials: A
authors.lastname: Malenović
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Daković
authors.forename: Svetlana
authors.initials: S
authors.lastname: Ibrić
authors.forename: Snezana
authors.initials: S
authors.lastname: Savić
authors.forename: Vera
authors.initials: V
authors.lastname: Dondur
authors.forename: Srđan
authors.initials: S
authors.lastname: Matijasević
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Radulović
authors.forename: Rolf
authors.initials: R
authors.lastname: Daniels
authors.forename: Jela
authors.initials: J
authors.lastname: Milić
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry; D001548:Benzalkonium Compounds / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D004008:Diclofenac / Q000031:analogs & derivatives / Q000737:chemistry; D005079:Excipients; D007052:Ibuprofen / Q000737:chemistry; D011208:Powders / Q000032:analysis / Q000737:chemistry; D012995:Solubility; D013501:Surface-Active Agents / Q000737:chemistry; D017641:Zeolites / Q000737:chemistry
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D001548:Benzalkonium Compounds; D002412:Cations; D002593:Cetrimonium Compounds; D005079:Excipients; D011208:Powders; D013501:Surface-Active Agents; D017641:Zeolites; D004008:Diclofenac; D007052:Ibuprofen; D000077286:Cetrimonium