VPT 311: General and Systemic Veterinary Pharmacology (2+1)

INDIRECTLY ACTING VASODILATOR DRUGS

• This consists of two groups namely
  • those that inhibit sympathetically mediated vasoconstriction. Drugs can inhibit sympathetic pathway at any point from the central nervous system to the peripheral nervous terminal. Prazosin a selective α₁ adrenergic antagonist reduces mean arterial pressure.
  • those that inhibit rennin-angiotensin system

Renin inhibitors

• Several drugs inhibit release of rennin, but this mechanism of action is not of importance.
• Renin activity inhibitors like enalkiren have been developed. But their clinical use is not appreciable.

ACE inhibitors

• Captopril was the first ACE inhibitor to be developed. Other ACE inhibitors include enlapril, lisinopril, ramipril, perindopril and trandolaprl.
• These drugs are useful in hypertension, cardiac failure, myocardial infarction, diabetic nephropathy and progressive renal failure.

Angiotensin II receptor subtype antagonists

• Losartan is a orally active pure antagonist of AT₁ receptor.
• They are being tried in elderly patients with heart failure.