Much like outsourced call centres, the rapid growth of drug testing in poor countries such as Nigeria and India has been driven chiefly by simple economics.

On average, a new drug costs more than $1 billion (£500 million) to license and bring to market.

Once launched, it has only a limited patent life, so there is enormous commercial pressure on pharmaceutical companies to accelerate development and introduce drugs as quickly as possible, maximizing sales and profits before their patents expire. More than half the development costs are linked directly to the four phases of clinical trials in which medicines are tested on human beings for safety and efficacy.

Conducting these drug trials in a developing country significantly reduces the cost and also speeds up the process because willing patients are easy to find and cheap to recruit. Final phase-III trials before approval is sought are particularly costly because they often involve tens of thousands of people. A trial that costs $30,000 per patient in the United States or Britain might cost $3,000 in Eastern Europe, and even less in India or Africa.

Critics of the industry cite another motive for big Western drug companies – the opportunity to conduct trials in a murkier regulatory environment, with less red tape and little scrutiny.

A series of scandals over drug testing in wealthier countries – including the disastrous British trials at Northwick Park in which six patients suffered multiple organ failure and two fell critically ill, have made testing in the UK ever more bureaucratic and made a shift to countries such as India an increasingly attractive proposition.

Now there are signs of a pendulum swing in the other direction. As Nigeria launches its own court battle with Pfizer over events in Kano in 1996, India is planning to tighten up restrictions on its flourishing human drug trial industry. Politicians in Delhi are drafting a Bill to give regulators the power to prosecute companies with five-year jail terms and significant fines for violating approved procedures.

Times Recommends

• Lies and cover-up at MG Rover exposed by report
• High oil prices push manufacturing costs up
• Primark founder steps down as chief executive