Vasorex 5 mg tablets. Sold individually. Amlodipine besylate is classified as a calcium channel blocker medication, and it is effectively used in veterinary medicine to treat hypertension in cats and dogs. The mechanism of action is through the inhibition of calcium entry into smooth muscle cells. Amlodipine has a relative degree of vascular selectivity. It is administered to cats who are also suffering from kidney disease. Veterinary script required.