For drugs with an active metabolite, the therapeutic consequence of first-pass metabolism depends on the contributions of the drug and the metabolite to the desired and undesired effects.

• 对于那些生成活性代谢物的药物来讲；经过首过代谢的治疗上的重要性取决于药物和代谢物所引起的期望的和非期望的效应.