Cilazapril is an ACE-inhibitor used to treat high blood pressure. It is not available in the U.S., but it is used in Canada and parts of Europe. Cilazapril can be used to delay the onset of kidney failure in Alport syndrome.

How cilazapril works

Alport syndrome is a serious heritable disease characterized by kidney disease, hearing loss, and eye abnormalities.

Cilazapril blocks the activity of an enzyme called angiotensin-converting-enzyme (ACE). This enzyme converts a hormone called angiotensin 1 into another hormone called angiotensin 2.

Angiotensin 2 is a vasoconstrictor, or agent that causes blood vessels to tighten, causing blood pressure to rise.

Angiotensin 2 also stimulates the release of a hormone called aldosterone. Aldosterone signals the kidney to absorb water and sodium from urine before it reaches the bladder and is released. This increases blood volume, which — in turn — increases blood pressure.

Finally, angiotensin 2 breaks down a protein called bradykinin, a vasodilator or agent that widens blood vessels. Degrading bradykinin causes blood vessels to tighten or narrow, which again raises blood pressure.

Cilazapril is a pro-drug; once ingested it is metabolized by the liver to produce another drug. The metabolized form is sometimes called cilazaprilat, which competes for the active site of ACE. ACE that becomes bound to cilazaprilat is not available to bind angiotensin 1 and convert it to angiotensin 2.

By inhibiting the activity of ACE, cilazapril works through several mechanisms to lower blood pressure. In Alport syndrome, this can ease the strain on the kidneys, delaying the development of end-stage kidney disease or kidney failure.

Cilazapril in clinical trials

A clinical trial, results of which were published in the Archives of Endocrinology and Metabolism in 2008, looked at the effect of cilazapril in women with diabetes and early signs of kidney problems. A total of 49 patients randomly received either cilazapril alone or cilazapril in combination with hydrochlorothiazide (a diuretic) and amlodipine (a calcium channel blocker) for 24 weeks. In both groups, blood pressure and levels of protein in the urine, a marker of kidney dysfunction, were lower at study’s end.

Although no clinical trials assessing cilazapril specifically in Alport syndrome patients have been conducted, it is among the ACE-inhibitors recommended as first-line treatments for the disease.

Other information

Cilazapril is generally well-tolerated and has similar side effects to other ACE-inhibitors. These include dizziness, cough, and nausea. Neutropenia (or loss of neutrophils, a type of immune cell) has been reported in some patients taking cilazapril.

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