Medical instructions : drug interaction routes

Alteration of metabolism in the gastrointestinal (GI) tract

1. MAOs-tyramine

- Tyramine protects the intestinal wall and liver against pressor action of amine in the
food and when it is been metabolized by MAO then unmetabolized tyramine can
accumulate and provoke hypertension. So avoiding food having much tyramine
together with MAO is recommended. Such as aged cheeses, pickled fish, Italian green
beans, alcoholic beverages etc.

2. Grapefruit juice

- Grapefruit inhibit the action of liver enzyme cytochrome P-450 enzyme to avoid the
lowering action and enhance the concentration of the concerned medicine of first pass
metabolism such as calcium channel blockers (Amlodipine, Felodipine, nisoldipine),
statins (lovastatin) and immunosuppressant (cyclosporine) because their
bioavailability is low and liver can destroy them. So grapefruit is potent to enhance
the bioavailability.