Question

Case Study - 3

A child, who has been successfully treated for seizure disorders with oral phenytoin for several years, has had severe diarrhea for the past 2 weeks. Subsequent to this, the patient had a seizure. Evaluation of serum phenytoin at the same time of the seizure revealed a low value. The dose was increased until serum concentrations were within the therapeutic range. The diarrhea was resolved. Several days after this, the patient had another seizure.

The diarrhea caused an inability to absorb the drug, enter the hepatic portal system to travel to the liver before entering the circulation.

Of the following terms, which refers to the normal physiological process of drug absorption into circulation?

A		Biotransformation
B		First Pass Metabolism
C		Cytochrome P450 enzyme metabolism
D		Conjugation of glycine, glutathione, phosphate, sulfate

Answer 1

B. First Pass Metabolism

First pass metabolism is the phenomenon of drug metabolism in which the concentration of the drug is greatly reduced before entering the systemic circulation.