A team of Irish scientists discovered the world's first successful drug inthe fight against leprosy, writes Mary Mulvihill.
Ever gone looking for one thing, only to find something else entirely unexpected? So it was with a team of Irish researchers in the 1940s and 1950s who set out to find a chemical cure for tuberculosis, but found instead a cure for leprosy.
Their compound, Clofazimine, went on to become the standard drug in the fight against leprosy, and 20 years later it is still recommended by the World Health Organization.
The notion of treating infections with chemicals began in the early 20th century, after German chemist Paul Ehrlich discovered arsenic compounds that killed the parasite that causes syphilis.
In 1943 the Irish Medical Research Council (MRC) wondered if Ehrlich's "magic bullet" approach would work against tuberculosis. TB infection was rife in Ireland then, and there was as yet no effective drug treatment.
So a team of MRC chemists, led by Cork-born Vincent Barry (1908-75), began the painstaking work of making and testing thousands of chemicals in the hope of identifying possible new drugs. Most of the compounds were extracted from plants and the work, which took several years, was done initially in laboratories at UCD and later at TCD.
Many compounds looked promising initially, but all turned out to be useless, except one that proved to be very effective against TB in mice. Labelled B663, it was a modified form of a red dye that they had extracted from a lichen.
Sadly, their hopes were raised only to be dashed, when it eventually became clear that B663 was no good at fighting human TB. Fortunately for TB patients, by this stage new treatments based on antibiotics had become available.
It was then that the MRC scientists spotted similarities between TB in mice and leprosy. The two diseases are not as far apart as you might think, for the bacteria that cause them are close cousins.
Sure enough, when B663 was tested against leprosy in humans the results were spectacular, so much so that 22 countries asked to join the clinical trial. In 1981 the new Irish drug, by then named Clofazimine, won the UNESCO prize for science. The MRC team was praised for their "outstanding contribution to scientific and technical development in developing countries".
Clofazimine is still used by the WHO to treat leprosy in a three-drug cocktail with dapsone and rifampicin. It is also now being tested as a possible cancer drug and to promote wound-healing.
All this came from the MRC's painstaking screening of thousands of chemicals. In the 1980s the MRC was replaced by the Health Research Board (www.hrb.ie).