No matter how many checks, there's a human trial, and that may not go to plan either: http://news.bbc.co.uk/1/hi/england/london/4811626.stm

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Two men who fell seriously ill following a clinical drugs trial remain in a critical condition but four others are showing signs of improvement.

All six are still in intensive care in Northwick Park Hospital, north-west London, after falling ill on Monday.

TeGenero, which manufactures the anti-inflammatory drug, says it has apologised to the men's families.