title: Liposomal drugs dispersed in hydrogels. Effect of liposome, drug and gel properties on drug release kinetics.
abstract: Release of calcein and griseofulvin (GRF) from control (gels in which solutes are dissolved in) and liposomal gels was studied using agarose-assisted immobilization as a technique to separate gels from drug-receptor compartments. Liposomes composed of phosphatidylcholine (PC) or distearoyl-glycero-PC and cholesterol (DSPC/Chol), and incorporating calcein or GRF were prepared by thin film hydration. After cleaning the liposomes they were dispersed in different hydrogels (carbopol 974 [1, 1.5 or 2% (w/w)], hydroxylethyl-cellulose (HEC) [4% (w/w)], or a mixture of the two), and release of calcein or GRF was followed by fluorescence or photometric technique, respectively. Results show that calcein release from liposomal gels is slower compared to control gels, and can be further retarded by using rigid-membrane liposomes (faster release from PC-liposome compared to DSPC/Chol-liposome gels). Additionally, calcein release is not affected by the lipid amount loaded (in the range from 2 to 8 mg/ml), therefore solute loading can be controlled according to needs. Oppositely, GRF release from liposomal gels is determined by drug loading. At high drug loading levels (compared to GRF aqueous solubility), GRF is released with constant rate from liposomal gels irrespective of liposome type (PC or DSPC/Chol). Thereby, for amphiphilic/lipophilic drugs, drug properties (solubility, log P) determine the system behavior. Calcein and GRF release from control carbopol gels is faster compared to HEC and mixture gels. The same is true for calcein in liposomal gels. Carbopol gel rheological properties were found to be significantly different (compared to the other gels), implying that these characteristics are important for drug diffusion from gels.
authors.affiliation: Laboratory of Pharmaceutical Technology, Department of Pharmacy, School of Health Sciences, University of Patras, 26510 Rio, Greece.
authors.forename: Spyridon
authors.initials: S
authors.lastname: Mourtas
authors.forename: Styliani
authors.initials: S
authors.lastname: Fotopoulou
authors.forename: Stela
authors.initials: S
authors.lastname: Duraj
authors.forename: Vassiliki
authors.initials: V
authors.lastname: Sfika
authors.forename: Christos
authors.initials: C
authors.lastname: Tsakiroglou
authors.forename: Sophia G
authors.initials: SG
authors.lastname: Antimisiaris
mesh_terms: D004337:Drug Carriers / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods; D004355:Drug Stability; D005452:Fluoresceins / Q000737:chemistry; D006118:Griseofulvin / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D005452:Fluoresceins; D020100:Hydrogels; D008081:Liposomes; D004364:Pharmaceutical Preparations; D010713:Phosphatidylcholines; D006118:Griseofulvin; C007740:fluorexon