Iron for ACE inhibitor-induced cough
Iron supplements might prevent angiotensin-converting
enzyme (ACE) inhibitor-induced dry cough, researchers in Korea suggest.
Persistent dry cough is the most troublesome and
frequent side effect of ACE inhibitor therapy, occurring in up to 39 per
cent of patients, say Dr Sang Chol Lee, Sungkyunkwan University school
of medicine, Seoul, and colleagues.
Although the mechanism that causes ACE inhibitor-induced
cough is not fully understood, it is known that administration of ACE
inhibitors increases nitric oxide generation, they say. Nitric oxide (which
has inflammatory effects on bronchial epithelial cells) is generated by
the haem-related enzyme, nitric oxide synthase. Activity of this enzyme
is reduced by an increased concentration of iron.
The researchers tested the hypothesis that iron
supplementation would reduce ACE inhibitor-induced cough in 19 patients.
After a two-week observation period, patients received either 256mg ferrous
sulphate or placebo for four weeks. They recorded the severity of cough
in a diary using a scoring system graded from 0 (no cough) to 4, (severe
cough that interferes with daily life and sleep).
Mean daily cough score was significantly reduced
by iron supplementation from 3.07±0.7 in the observation period to 1.69±1.10
at the end of the treatment period (p<0.01). No significant change
was found in the placebo group.
“This dramatic effect of iron supplementation on
dry cough may require further explanation, but according to our hypothesis
and the results of previous studies, iron may be the key element in the
control of the dry cough mechanism,” the researchers conclude (Hypertension
2001;38:166).
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