The fact that six young men are seriously or critically ill after volunteering for a Phase I drug trial is a tragedy. It is an extremely rare occurrence, almost without precedent in hundreds of such trials that take place every year. It is important to wait for the results of the enquiry before jumping to any conclusions about what went wrong this time. I hope the enquiry will be both quick and thorough.

Many journalists have outlined the drug testing process, including the animal tests which should ensure that those first volunteers are not exposed to serious risk.

"Something is identified that looks promising. Work in the lab confirms that it has an effect on, say, tissue samples or a virus. The scientists get excited. Once they have done all they can to establish what the product does and how, and whether it is helpful or harmful, the animal tests begin. The point of the animal tests - generally on rats or mice - is to prevent what happened at Northwick Park. If the mice die or exhibit disturbed behaviour, it’s time to think again. As of 2004, the Medicines and Healthcare Products Regulatory Authority, which licenses drugs in the UK, has to see the results before it will allow any human trials to begin.”
From test tube to medicine cabinet, The Guardian, 16 March 2006

Mike Hanlon’s article - Yes, there are risks but these tests are VITAL - also makes a lot of sense:

"If animal testing was banned either drug companies would not risk producing new medicines at all, or human trials would have to begin without the benefit of prior human testing - in which case we are going to see a lot more disasters like the one in North West London.”
Daily Mail, 16 March 2006

One thing is clear: if the animal tests were not done then volunteers in phase I trials would face serious or deadly side effects on a daily basis.