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The effects last because grapefruit-mediated inhibition of drug metabolizing enzymes, like CYP3A4, is irreversible; [30] that is, once the grapefruit has "broken" the enzyme, the intestinal cells must produce more of the enzyme to restore their capacity to metabolize drugs that the enzyme is used to metabolize. [19]
This prevents oxidative metabolism of certain drugs by the enzyme, resulting in an elevated concentration of drug in the bloodstream. Under normal circumstances, the grapefruit juice effect is considered to be a negative interaction, and patients are often warned not to consume grapefruit or its juice when taking medication.
Cytochrome P450 3A4 (abbreviated CYP3A4) (EC 1.14.13.97) is an important enzyme in the body, mainly found in the liver and in the intestine, which in humans is encoded by CYP3A4 gene. It oxidizes small foreign organic molecules ( xenobiotics ), such as toxins or drugs, so that they can be removed from the body.
For example, when the blood pressure drug felodipine is taken with grapefruit juice rather than water, levels of the medication in the blood can more than double and result in headache, irregular ...
One interaction occurs from grapefruit furanocoumarins, such as bergamottin and 6',7'-Dihydroxybergamottin, which occur in both flesh and peel. Furanocoumarins inhibit the CYP3A4 enzyme (among others from the cytochrome P450 enzyme family responsible for metabolizing 90% of drugs). [ 22 ]
Grapefruit juice can act as an enzyme inhibitor, affecting the metabolism of drugs.. In pharmaceutical sciences, drug interactions occur when a drug's mechanism of action is affected by the concomitant administration of substances such as foods, beverages, or other drugs.
Ritonavir. This antiretroviral medication inhibits CYP3A4 and may increase the effects of Cialis in the body. Alpha-blockers. When taken with Cialis, alpha-blockers can cause a drop in blood pressure.
Grapefruit and grapefruit juice have been found to interact with numerous drugs, in many cases resulting in adverse effects. [4] This happens in two ways: one is that grapefruit can block an enzyme which metabolizes medication, [5] and if the drug is not metabolized, then the level of the drug in the blood can become too high, leading to an adverse effect. [5]