Randomized placebo-controlled clinical trial of a chewable formulation of amlodipine for the treatment of hypertension in client-owned cats

Background

There is an unmet clinical need for a cat‐specific formulation of amlodipine to treat hypertensive cats.

Objectives

To assess the efficacy of chewable amlodipine tablets in reducing systolic blood pressure (SBP) in cats diagnosed with systemic arterial hypertension.

Animals

Seventy‐seven client‐owned cats with systemic hypertension were included (median age 14 years).

Methods

The study was randomized, double‐blinded, and placebo‐controlled. Forty‐two cats received 0.125–0.50 mg/kg amlodipine once daily for 28 days; 35 cats received placebo. After 28 days all cats continued with amlodipine for 2–3 months in an open‐label phase. Blood pressure was measured using high definition oscillometry. A responder was defined as a cat showing a decrease of SBP to <150 mmHg at 28 days or a decrease from baseline ≥15%.

Results

Sixty‐one cats completed the study. The responder rate was 63% in amlodipine group and 18% in placebo group. Cats receiving amlodipine were 7.9 (95% CI 2.6–24.1) times more likely to be classified as responders when compared to those receiving placebo (P < .001). From a mean (±SD) baseline value of 181 (±12) mmHg, SBP decreased to 154 (±17) mmHg with amlodipine and to 170 (±21) mmHg with placebo (P < .001). The voluntary acceptance rate of amlodipine formulation was 73%.

Conclusions and Clinical Importance

The chewable amlodipine tablet effectively reduced SBP compared with placebo in hypertensive cats, and was well‐tolerated. It can be used concomitantly with angiotensin‐converting enzyme inhibitors and in cats with chronic kidney disease.

Bioavailability of detomidine administered sublingually to horses as an oromucosal gel

The objective of the study was to determine the absorption, bioavailability and sedative effect of detomidine administered to horses as an oromucosal gel compared to intravenous and intramuscular administration of detomidine injectable solution. The study was open and randomized, with three sequences crossover design. Nine healthy horses were given 40 μg/kg detomidine intravenously, intramuscularly or administered under the tongue with a 7-day wash-out period between treatments. Blood samples were collected before and after drug administration for the measurement of detomidine concentrations in serum. The effects of the route of administration on heart rate and rhythm were evaluated and the depth of sedation assessed. Mean (±SD) bioavailability of detomidine was 22% (±5.3%) after sublingual administration and 38.2% (±7.9%) after intramuscular administration. The sedative effects correlated with detomidine concentrations regardless of the route of administration. We conclude that less detomidine is absorbed when given sublingually than when given intramuscularly, because part of it does not reach the circulation. Sublingual administration of detomidine oromucosal gel at 40 μg/kg produces safe sedation in horses. Slow absorption leads to fewer and less pronounced adverse effects than the more rapid absorption after intramuscular injection.