Why our testing of antibiotics and other drugs may not be safe

It is a cruel irony that side effects of medicines designed to help us are now one of our leading causes of death, hospitalising a million Britons and costing the NHS £2 billion a year.
 
Antibiotics cause almost one in five hospital admissions from adverse drug reactions. This is particularly galling since so many antibiotics are prescribed unnecessarily; often for viral infections against which they have no effect. Not only do some patients then suffer side effects for no benefit but they can also develop antibiotic resistance.

The World Health Organisation says antibiotic resistance – caused by overuse in medicine and in agriculture – is one of the leading public health threats on the planet. Norway has shown that the problem can be solved by reducing antibiotic use: cutting theirs dramatically has made Norway the most infection-free country in the world.

Human guinea pigs
 
An important factor contributing to the poor safety record of so many drugs, including antibiotics, is our reliance on safety testing in animals. The government insists that all new drugs are shown to be safe in two species of animals before they can be given to humans. However, many studies have shown that animal tests – even in both dogs and monkeys – are no more predictive for humans than tossing a coin.
 
This means that volunteers and patients in clinical trials are the real guinea pigs bearing the brunt of weeding out unsafe medicines. More than nine out of ten new medicines fail in clinical trials because they are either ineffective or dangerous in humans, despite appearing to be safe in animal tests. The drug that nearly killed six young men at Northwick Park Hospital in 2006 had been shown to be safe – even at doses 500 times higher – in monkeys.
 
Safer human tests
 
Fortunately, there are many new technologies that allow medicines to be tested in a human context, using human tissues or DNA or volunteers, though in ways much less risky than current clinical trials.
 
Initial safety screens use human cells to conduct a broad range of tests for any signs of damage to the cells or their genes. Any cell type can be used, for example heart cells are used to reveal whether a drug may have ill effects on the heart. Liver cells are the most frequently used because most drugs are metabolised by the liver and liver damage is one of the main reasons why new drugs fail in clinical trials or are withdrawn from the market. Cambridge University spin-out company SimuGen has used liver cells to identify drug toxicities to the liver that were missed by animal tests.
 
Fresh human tissues are even more valuable than cell lines in providing a test system that is as close as possible to testing in real patients but without safety concerns. Any tissue of the body can be used to show how a new drug is likely to affect a particular organ. In addition, different tissues can be combined, along with a circulating blood substitute, to mimic the human body in miniature. This ‘quasi-vivo’ approach, pioneered by companies such as Sheffield-based Kirkstall, allows metabolism to be modelled in vitro. Florida-based VaxDesign uses donated human blood cells to grow ‘miniature immune systems’ which provide ‘a clinical trial in a test tube’ for testing vaccines without exposing a single person. 
 
One of the best ways of finding out how a new drug will behave in the human body is to give it to volunteers at a minute, safe dose. Then, by using incredibly sensitive measuring devices, scientists can monitor where the drug goes and how it is broken down in the human system. Microdosing is an exciting breakthrough in drug testing, using machines so sensitive that they could detect a litre of liquid after it had been diluted in all the oceans of the world!
 
MPs bill to end animal tests
 
Safer Medicines Campaign believes that drug trial volunteers should be protected from risks by making sure before clinical trials that new drugs are as safe as possible. There is substantial and accumulating evidence that new technologies based on human biology are more accurate and reliable than animal tests, with the added bonus of being much faster and cheaper as well. For example, Glasgow-based Biopta points out that inaccurate predictions based on animal models are the biggest cause of drug failure in humans. Biopta’s CEO Dr David Bunton says: ‘for every £1 spent on human tissue study, you can expect to save from £6 to £80.’
 
Yet despite their obvious advantages, these tests are not required by the government, while animal tests are. The Safety of Medicines Bill calls for a comparison of animal tests with the latest human biology-based tests, to show which are more effective at predicting the safety of medicines for patients. 148 MPs have already signed Early Day Motion 475 in support of this proposal. You can help – please ask your MP to sign if they haven’t already -  see the Safer Medicines website for details.
 
Green MP and Safer Medicines patron Dr Caroline Lucas says: ‘More reliable methods will benefit everyone. A national strategy to replace outdated animal tests is urgently needed to improve the safety of medicines’.

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