RT Journal Article SR Electronic T1 Disposition of growth hormone-releasing peptide (SK&F 110679) in rat and dog following intravenous or subcutaneous administration. JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 90 OP 98 VO 22 IS 1 A1 C B Davis A1 C S Crysler A1 V K Boppana A1 K L Fong A1 G L Joseph A1 J J Urbanski A1 R A Macia A1 G R Rhodes YR 1994 UL http://dmd.aspetjournals.org/content/22/1/90.abstract AB The disposition of growth hormone releasing peptide (SK&F 110679) has been studied in male Sprague-Dawley rats and in male and female beagle dogs following intravenous (iv) and subcutaneous (sc) administration. Mass balance/excretion of [3H]SK&F 110679 was assessed in bile duct-exteriorized rats from which radiolabeled biliary and urinary excreta were quantified and characterized. [3H]SK&F 110679 was excreted, predominantly in the bile, and to a large extent as intact peptide following either iv or sc administration. Although the extent of biliary excretion of radiolabel was similar following iv or sc administration (60-70% of the dose), the rate was significantly higher following iv administration. Using a specific plasma HPLC/fluorescence assay, the iv and sc pharmacokinetics of SK&F 110679 were investigated in both species. Following iv bolus administration, biphasic plasma concentration-time profiles were observed, and the initial phases were characterized by 2-4 min half-lives. Systemic plasma clearance was 27 ml/min/kg in the rat (0.4 mg/kg dose) and 17 ml/min/kg in the dog (0.5 mg/kg dose). High sc bioavailability (89-103%) was observed in both species; an apparent terminal half-life of 1 hr likely reflected slow absorption from the injection site.