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Evaluating a chewable medication for hypertension in cats

Huhtinen M, Derre G, et al. Randomized placebo-controlled clinical trial of a chewable formulation of amlodipine for the treatment of hypertension in client-owned cats. J Vet Intern Med. 2015 Apr 9.

One condition of concern secondary to acute or chronic kidney disease is systemic hypertension. Other disease conditions in cats that can lead to hypertension are hyperthyroidism, diabetes mellitus (DM), primary hyperaldosteronism, and pheochromocytoma. One in five cats with hypertension may have idiopathic hypertension, where no underlying disease is determined. When blood pressure increases are sustained over long periods of time, injury can occur to certain organs (kidneys, eyes, brain, and heart). This is referred to target organ damage (TOD) and occurs in people too.

The categories of hypertension are determined by the risk of TOD: minimal (<150/95 mmHg), mild (150-159/95-99 mmHg), moderate (160-179/100-119 mmHg), and severe (>180/120 mmHg). Treating for hypertension is to aim for a reduction in blood pressure to <150/95 mmHg). The current treatment of choice for hypertension in cats is amlodipine at a dose of 0.125 mg-0.25 mg/kg once daily. Amlodipine is not approved for veterinary use so human use products have been used off-label in cats. Dosing cats with small portions of tablets can be a challenge for clients in the best of times. In this study, the authors’ plan was to determine the efficacy of chewable (immediate release tablet similar to that used in humans) tablets in cats.

The study was performed in 42 cats that received 0.125 -0.50 mg/kg once daily for 28 days; 35 cats received placebo. After the 28 days, all cats continued with the amlodipine for another 2 to 3 months. Sixty-one cats completed the study. The rate of response in the amlodipine was 63% and 18% in the placebo group. The cats accepted the formulation voluntarily at a rate of 73%. The results indicated that the chewable amlodipine tablet did effectively reduce the systolic blood pressure compared to placebo in cats with hypertension and was well tolerated. This product can also be used along with other anti-hypertensives such as angiotension-converting inhibitors and in cats with chronic kidney disease. (VT)

See also:
Snyder PS. Amlodipine: a randomized, blinded clinical trial in 9 cats with systemic hypertension. J Vet Intern Med. 1998 May-Jun; 12(3):157-162.