Roles of acid/base nature and molecular weight in drug release from matrices of gelfoam and monoisopropyl ester of poly(vinyl methyl ether–maleic anhydride)

• Published in: Journal of controlled release 1998-12, Vol.56 (1), p.273-283
• Main Authors: Hämäläinen, Kaisa Mari, Määttä, Elsi, Piirainen, Hilkka, Marianne Sarkola, Väisänen, Anne, Ranta, Veli-Pekka, Urtti, Arto
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Buffers; Conjunctiva; Delayed-Action Preparations; Dextrans - administration & dosage; Dextrans - chemistry; Diffusion; Drug release; Esters - administration & dosage; Esters - chemistry; Fluorescein-5-isothiocyanate - administration & dosage; Fluorescein-5-isothiocyanate - analogs & derivatives; Fluorescein-5-isothiocyanate - chemistry; Fluoresceins - administration & dosage; Fluoresceins - chemistry; Furosemide - administration & dosage; Furosemide - chemistry; Gelatin Sponge, Absorbable - administration & dosage; Gelatin Sponge, Absorbable - chemistry; Gelfoam; General pharmacology; Hydrogen-Ion Concentration; Maleates - administration & dosage; Maleates - chemistry; Mannitol - administration & dosage; Mannitol - chemistry; Medical sciences; Molecular Weight; Ocular drug delivery; Ocular insert; Ophthalmic Solutions; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Poly(vinyl methyl ether–maleic anhydride); Polyethylenes - administration & dosage; Polyethylenes - chemistry; Polymer erosion; Sclera; Timolol - administration & dosage; Timolol - chemistry
• ISSN: 0168-3659; 1873-4995
• DOI: 10.1016/S0168-3659(98)00094-7

Ophthalmic drug inserts are usually placed in the conjunctival sac. Being in contact with the conjunctiva, they may provide means to deliver large and hydrophilic molecules, such as peptides and oligonucleotides into the eye. We evaluated Gelfoam and monoisopropyl ester of poly(vinyl methyl ether/maleic anhydride) (PVM/MA) as potential polymers for ocular inserts. Matrices were solvent cast with model drugs that had different p K a, molecular weight and hydrophilicity. Drug release from the matrices as well as charge and swelling of Gelfoam®-matrix were studied. The release of drugs from PVM/MA-matrices was by erosion of the polymer matrix. The molecular weight and other variants of the releasing compound did not affect their release. In Gelfoam®-matrices the release was diffusion controlled and it was affected by the pH of the external solution as well as the charge and molecular weight of the studied compound.