Mode of action in heart disease

In heart disease, the renin-angiotensin-aldosterone system (RAAS) is activated, which leads to progression of heart failure. Fortekor (benazepril hydrochloride) is an ACE inhibitor, which means it blocks the RAAS by inhibiting the angiotensin-converting enzyme. This, in turn, blocks the formation of angiotensin II and the release of aldosterone.

Fortekor reduces the workload on the heart and makes it more efficient. It does this in the following ways:

  • Reduces peripheral vasoconstriction and prolongs vasodilation
    - Blocks formation of angiotensin II (a potent vasoconstrictor) and inhibits degradation of bradykinin (a potent vasodilator)
    - Improves forward flow from the heart, thus reducing regurgitation of blood into the left atrium
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  • Blocks aldosterone release
    - Less retention of sodium and water
    - Reduces volume overload, which reduces the workload on the heart and helps reduce congestion
  •  Attenuates effects of the sympathetic nervous system (SNS)
    - SNS is responsible for increasing heart rate and loss of sinus arrhythmia
  • Reduces cardiac remodelling
    - By blocking formation of angiotensin II, Fortekor prevents its harmful effects on the myocardium: hypertrophy, fibrosis (scarring) and necrosis (death) of heart muscle cells

Dual elimination

Fortekor is removed from the body both via the kidneys and the liver; in other words, it has dual elimination.

Where Fortekor is eliminated:

Dog: liver 50%/ kidneys 50%

Cat: liver 85%/ kidneys 15%

This is in contrast to other ACE inhibitors:

Enalapril is excreted 85-95% by the kidneys (dogs)

Ramipril is excreted 60% by the liver and 40% by the kidneys (dogs)

Dogs with heart failure often have compromised renal function: over half of dogs with congestive heart failure are azotaemic. This means that the glomerular filtration rate is reduced and the dog cannot eliminate waste products, including any medications that are excreted through the kidneys, efficiently.

In animals with compromised renal function, there is a risk that drugs which are excreted almost entirely through the kidneys could accumulate, i.e. effectively an overdose. Therefore, drugs excreted through the kidneys may require dose adjustment.

A study has shown that, in both cats and dogs with renal compromise, there is no increased exposure to benazeprilat, therefore no dose adjustment of Fortekor is required.