2015 ACVIM Forum Research Abstract Program

This study showed that the decrease in SBP associated with amlodipine treatment was independently and positively associated with the plasma amlodipine concentration. Cats that required a higher dose to control their SBP below 160 mmHg had a significantly higher SBP at diagnosis of hypertension and therefore required a greater decrease in SBP in order to achieve normotensive control. Administration of the higher dose needed to achieve the target SBP was associated with proportionately higher plasma amlodipine concentrations, suggesting that the difference in dose of amlodipine required is unlikely to be due to a difference in individual cat pharmacokinetics or owner compliance. Based on these results it could be suggested that cats with a SBP≥200 mmHg should be started on 1.25 mg amlodipine daily. Further studies are warranted to determine whether differences exist in the pathophysi-ological mechanisms underlying hypertension in the more severely hypertensive group. Sucralfate is a gastroprotectant that has been reported to impair absorption of certain antimicrobials. Our objective was to determine if co-administration of sucralfate and a fluoroquinolone impairs fluoroquinolone bioavailability in dogs and to determine the effect of a 2-hour delay of sucralfate on fluoroquinolone pharmacokinetics. Five Greyhounds were incorporated into a randomized crossover design and administered either ciprofloxacin (25 mg/kg PO) or enrofloxacin (5 mg/kg PO) alone, concurrent sucralfate (1 g oral suspension PO) with ciprofloxacin or enrofloxacin, or sucralfate administered 2 hours after either fluoroquinolone. Fluoroquinolone concentrations were evaluated with liquid chromatography/mass spectrometry. Area under the curve (AUC), time to maximum plasma concentration (T MAX ), and maximum plasma concentration (C MAX ) were compared between groups. Dogs had variable absorption of ciprofloxacin (AUC range: 5.52-22.47 hour lg/mL) compared with enrofloxacin (3.86-7.50 hour lg/mL). Relative bioavailability (%F) of ciprofloxacin was 48% when administered concurrently with sucralfate (with one dog at 8%), and improved to 87% when sucralfate was delayed by 2 hours. In contrast, no significant difference in absorption was demonstrated based on AUC or C MAX when enrofloxacin was administered concurrently with sucralfate as compared with enrofloxacin alone, and %F for concurrent administration was 104%. This study confirmed that oral bioavailability of ciprofloxacin is variable, which could lead to treatment failures or drug toxicity in some treated dogs. When sucralfate and ciprofloxacin are both indicated, a 2 hour delay should be considered to allow improved bioavailability. On the contrary, no drug interaction was documented for concurrent sucralfate and enrofloxacin, and concurrent administration may improve compliance. Transdermal mirtazapine (TM) would be beneficial for ill cats intolerant of pill administration. The purpose of this study was to evaluate the pharmacodynamics of transdermal mirtazapine (TM) in client-owned cats.