title: Slow release of two antibiotics of veterinary interest from PVA hydrogels.
abstract: Two antibiotics, tylosin tartrate and oxytetracycline hydrochloride, were entrapped in poly(vinyl alcohol) (PVA) hydrogels (MW 31,000-50,000) by a cryogen procedure obtaining a controlled release system suitable for veterinary application. It was found that at a low drug matrix loading (10 mg/ml), the in vitro release rate of both antibiotics could be reduced by a previous freeze drying of the gel, while no reduction in drug rate took place in heavily loaded matrices (300 mg/ml). When PVA hydrogels containing tylosin were administered to rats per os the drug could not be detected in the blood, but it was found in organs,: liver, kidneys, and muscles, for up to 120 h. On the other hand, when the same amount of drug was administered orally as powder, no appreciable organ accumulation was detected, while the drug was found in faeces and urine. These data show that PVA hydrogels can be a suitable slow release system for tylosin administration. Oxytetracycline could also be quantitatively entrapped and released from PVA hydrogels, but once administered per os to rats, it was not detected in blood or organs.
authors.affiliation: Department of Pharmaceutical Sciences, University of Padova, Via Marzolo, 5, 35131, Padova, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Moretto
authors.forename: L
authors.initials: L
authors.lastname: Tesolin
authors.forename: F
authors.initials: F
authors.lastname: Marsilio
authors.forename: M
authors.initials: M
authors.lastname: Schiavon
authors.forename: M
authors.initials: M
authors.lastname: Berna
authors.forename: F M
authors.initials: FM
authors.lastname: Veronese
mesh_terms: D000284:Administration, Oral; D000818:Animals; D016503:Drug Delivery Systems; D004355:Drug Stability; D005615:Freezing; D007274:Injections, Intraperitoneal; D010118:Oxytetracycline / Q000008:administration & dosage*; D011142:Polyvinyl Alcohol / Q000008:administration & dosage / Q000737:chemistry*; D051381:Rats; D014018:Tissue Distribution; D015645:Tylosin / Q000008:administration & dosage* / Q000493:pharmacokinetics
chemical_list: C062364:polyvinyl alcohol hydrogel; D011142:Polyvinyl Alcohol; D010118:Oxytetracycline; D015645:Tylosin