03/03/05
Spiked
Animal testing for drug safety is unreliable
At the spiked-event 'Drugs and health' that
took place at the Society of Chemical Industry
on 22 February 2005, Diarmuid Jeffreys, Charles
Medawar, and Richard Sullivan gave excellent
presentations, in which they raised many disturbing
facets of drug regulation and safety that are
worthy of attention.
All three speakers agreed that society needs
new drugs, but that we need a culture change
in the pharmaceutical enterprise. There was unanimous
concern about the lack of openness and transparency,
and the corrosive influence of the commercial
imperative. There is, however, one component
of drug safety testing which has a significant
impact on safety but which has so far fallen
outside the radar of the debate. That component
is animal testing.
The primary safety screen for all new drugs
is animal tests, from which the regulatory authorities
require evidence of safety in one rodent and
one non-rodent species. These tests were mandated
in the wake of the thalidomide tragedy, in the
hope that they would prevent another such disaster.
But have they lived up to their promise?
In the light of recent tragedies such as Vioxx
- where a drug shown to be safe and even beneficial
to the heart in animals has gone on to cause
as many as 140,000 heart attacks and strokes
in humans - it appears that animals are an inadequate
safety screen. Many studies, comparing drug side
effects in humans and in animals, have found
animal tests to be less predictive than tossing
a coin. Even the Handbook of Laboratory Animal
Science admits that 'uncritical reliance on the
results of animal tests can be dangerously misleading
and has cost the health and lives of tens of
thousands of humans'.
State-of-the-art human-based tests could have
prevented the Vioxx tragedy. In order to protect
the public from another Vioxx in future, an assessment
needs to be made of the relative performance
of the various methods of safety testing available.
Substantial evidence exists that animal tests
are inadequate for the task, but incredibly,
this has never been systematically investigated.
The only responsible course of action is to evaluate
animal testing scientifically, in an independent
and transparent manner. 83 per cent of GPs in
a 2004 survey would 'support an independent scientific
evaluation of the clinical relevance of animal
experimentation'. Many MPs are currently calling
for such an evaluation, in an early day motion
on Animal testing of drugs.
Meanwhile, there are many superior methods of
assessing drug safety, which should be required
during the safety testing of new drugs. These
include micro-dose studies, endorsed by the European
Agency for the Evaluation of Medicinal Products
in January 2003; pharmacogenetic analyses, using
DNA chips; and human clinical pharmacology assessments,
employing human tissues in slico modelling and
sensitive and appropriate biomarkers, before
and during clinical trials.
If these methods were employed in place of animal
testing, we would see significant reductions
in the number of drugs failing in clinical trials,
and in the numbers of adverse drug reactions.
Kathy Archibald, director, Europeans for Medical
Progress, UK |
