The drug Ketotifen has been used for more than 30 years in the treatment of asthma and allergies.
Now, researchers at the Duke-NUS Graduate Medical School are testing its efficacy in treating the more severe symptoms of dengue haemorrhagic fever (DHF), in the first trial of its kind worldwide.
The clinical trial is being conducted in collaboration with Singapore General Hospital and the National University Hospital.
Although fatality rates for dengue patients are relatively low, dengue fever can sometimes manifest as the more severe DHF, which may cause significant bleeding and low blood pressure.
In some cases, vascular fluid leakage into various body cavities may interfere with heart or lung functions and cause organ failure.
Assistant Professor Ashley St. John and her team at Duke-NUS found a strong correlation between the severity of DHF symptoms and the levels of chymase, an enzyme released only by mast cells, a feature of the immune system similar to white blood cells but found in tissue instead of blood.
They tested the application of Ketotifen, which is known to inhibit mast cell activation, on mice carrying the dengue virus. Ketotifen was found to be effective in lowering vascular leakage in mice with mast cells to levels similar to uninfected subjects'.
Clinical trials have been successfully conducted on seven dengue patients so far, all of whom have reported no side effects.
The trial, led by Professor Paul Tambyah of the National University of Singapore's Yong Loo Lin School of Medicine, aims to test the effects of Ketotifen against a placebo in 110 patients over two years.
Dengue fever afflicts 390 million people worldwide every year, and up to 30 per cent of cases are fatal. Since the start of this year, 3,349 cases have been reported by the National Environment Agency in Singapore, with over 100 new cases every week.
This article was first published on June 5, 2015.
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