Albumin microsphere as a drug delivery system for dexamethasone: pharmacokinetics in sheep, residue amount in cows and distribution in rats.
The aim of this study was to evaluate the potential use of albumin microspheres as a drug delivery system to provide sustained release of dexamethasone in vivo. Pharmacokinetic studies were carried out in sheep and tissue distribution in rats given dexamethasone in two injectable forms--water suspension of dexamethasone associated with albumin microspheres and water-ethanol solution of dexamethasone. When dexamethasone was associated with albumin microspheres the amount of free dexamethasone, available for absorption did not reach the high values typical of the pattern of release of dexamethasone from water-ethanol solution. The time of withdrawal in lactating cows after i.m. administration of DXM-AM was found to be 5 days. The release of dexamethasone from the albumin microspheres was accomplished gradually thus allowing sustained levels of the corticosteroid to be maintained for several days in blood plasma, milk, liver, kidney and muscles.