Due to proven similarities in biotransformation between man and minipig, minipig seems to be the experimental animal of choice for preclinical pharmacokinetic studies when an experiment with a drug exhibiting a great first pass bioelimination (like 5-aminosalicylic acid) is to be realised. On the other hand, both minipig and dog may be suitable species for a pharmacokinetic study with a drug characterized by a small extent of first pass biotransformation (like atenolol).