Sheep Treatment to Help Victims of Overdose

A herd of Australian sheep in Wales is being used as a biological factory to create a new treatment for overdose victims.

Developed by Protherics UK, the technique may also alleviate Crohn's disease and heart conditions as well as preventing transplant organs from being rejected.

The technology involves creating an immunogen that mimics the actions of a drug for which an antibody is required. The compound is injected into the sheep whose immune systems multiply the number of antibodies required to combat the invader. These are extracted by blood transfusion and adapted for use in humans.

In the initial trials the company developed a compound, a molecule similar to a tricyclic antidepressant, which has been used to treat people who have overdosed on drugs. The sheep processed the compound and the unwanted red cells were extracted to create a serum.

The remaining immunoglobulin is modified before the serum is injected into the patient. The immunoglobulin immediately identifies the antidepressant material in the blood and adheres to it. The metabolites and other toxic materials produced by the interaction of the antidepressants with the body are also attacked making them inactive.

At present, there is no treatment for antidepressant overdose and patients invariably die. One particular hazard is when children swallow their parents' medication mistaking brightly coloured tablets for sweets.

Clinical trials have been carried out on a few patients but opportunities are rare because such therapy can only be used in emergencies. Nevertheless, the company aims to have a drug on the market by the end of 2001.

Another product recently launched by Protherics UK using the sheep as the biological factory is Mylotarg, an antibody-based treatment for acute leukaemia.