November 22

The Biter Bit

Killing mosquitoes of the genus Anopheles, the sort that transmit malaria, is a serious business—so serious that some doctors would like to do it by using people as bait. Their idea is to dose those in malarious areas with a drug called ivermectin. This will not protect the dosees directly, for it does not act on the parasite that causes the disease. But it may protect them indirectly, by making their blood poisonous to Anopheles. Mosquitoes do not tend to fly far from the place they hatch, and experiments suggest that if most of a village’s inhabitants were to take ivermectin they could collectively do serious damage to the local Anopheles population. That would substantially reduce the number of cases of malaria in an area.

Whether this is ethical is debated. Ivermectin is used routinely to treat filariasis, river blindness, scabies and several other diseases. But drugging healthy people is generally frowned on. At the moment, though, there is a more practical objection. Ivermectin does not hang around in the body long enough to make a concerted anti-mosquito campaign that relies on it look like a realistic proposition. And it is this that Robert Langer of the Massachusetts Institute of Technology and Giovanni Traverso at Brigham and Women’s Hospital, in Boston, hope to change. As they report in Science Translational Medicine, they think they have devised a means to keep ivermectin concentrations in the blood at mosquito-killing levels for far longer than has previously been possible.

The starting point for their device is a material called poly E-caprolactone (PCL). They melted this and blended it with powdered ivermectin. Then they tested the resulting composite in an acidic solution intended to mimic conditions found in the human stomach, to see how well it protected the drug, and also the rate at which ivermectin migrated out of it. They found that the PCL did indeed protect the ivermectin from the acid. It also let the drug diffuse out steadily over the course of 14 days.

Source: The Economist (link opens in a new window)

Health Care
drugs, global health, infectious diseases, malaria, pharmaceutical industry