title: Drug release profiles and microstructural characterization of cast and freeze dried vitamin B12 buccal films by positron annihilation lifetime spectroscopy.
abstract: Solvent cast and freeze dried films, containing the water-soluble vitamin B12 as model drug were prepared from two polymers, sodium alginate (SA), and Carbopol 71G (CP). The proportion of the CP was changed in the films. The microstructural characterization of various samples was carried out by positron annihilation lifetime spectroscopy (PALS). The drug release kinetics of untreated and stored samples was evaluated by the conventionally applied semi-empirical power law. Correlation was found between the changes of the characteristic parameters of the drug release and the ortho-positronium (o-Ps) lifetime values of polymer samples. The results indicated that the increase of CP concentration, the freeze-drying process and the storage at 75% R.H. decreased the rate of drug release. The PALS method enabled the distinction between the micro- and macrostructural factors influencing the drug release profile of polymer films.
authors.affiliation: University Pharmacy Department of Pharmacy Administration, Semmelweis University, Hőgyes Endre Street 7-9, H-1092 Budapest, Hungary; Gedeon Richter Plc., Formulation R&D, Gyömrői Street 19-21, H-1103 Budapest, Hungary.
authors.forename: Barnabás
authors.initials: B
authors.lastname: Szabó
authors.affiliation: Department of Pharmaceutics, Semmelweis University, Hőgyes E. Street 9, H-1092 Budapest, Hungary.
authors.forename: Nikolett
authors.initials: N
authors.lastname: Kállai
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Hőgyes E. Street 7, H-1092 Budapest, Hungary.
authors.forename: Gergő
authors.initials: G
authors.lastname: Tóth
authors.affiliation: University Pharmacy Department of Pharmacy Administration, Semmelweis University, Hőgyes Endre Street 7-9, H-1092 Budapest, Hungary.
authors.forename: Gergely
authors.initials: G
authors.lastname: Hetényi
authors.affiliation: University Pharmacy Department of Pharmacy Administration, Semmelweis University, Hőgyes Endre Street 7-9, H-1092 Budapest, Hungary. Electronic address: zelko.romana@pharma.semmelweis-univ.hu.
authors.forename: Romána
authors.initials: R
authors.lastname: Zelkó
mesh_terms: D000179:Acrylates / Q000737:chemistry; D000278:Administration, Buccal; D000464:Alginates / Q000737:chemistry; D004304:Dosage Forms; D005612:Freeze Drying / Q000379:methods; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D007700:Kinetics; D011108:Polymers / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013057:Spectrum Analysis / Q000379:methods*; D014805:Vitamin B 12 / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000179:Acrylates; D000464:Alginates; D004304:Dosage Forms; D006603:Hexuronic Acids; D011108:Polymers; D012997:Solvents; C492578:carbopol 71G; D014867:Water; D020723:Glucuronic Acid; D014805:Vitamin B 12
keywords: Cast film; Dissolution; Freeze-drying; Positron annihilation lifetime spectroscopy (PALS); Vitamin B(12)