Penzerol is a strong and mostly effective truth serum when used on humans. Only those with unusually strong wills – or alien DNA – can resist its effects.
Of course, it does have a nasty side effect of potentially causing permanent brain damage, and as with most drugs, too great a dose is fatal.
Unusually, it is part of a suite of other drugs intended to be used together, notably sedatives which help prevent the heightened physical responses that interrogation so often entails from getting in the way of actually obtaining information.
Related Drugs: Red Skeezix