![]() ![]() The effect of some CYP3A4 inhibitors dissipates with repeated administration, because they produce a time-dependent induction of CYP3A4 via up-regulation of CYP3A messenger RNA and protein, which appears not to be the case with grapefruit juice. 4, 10 Action of Grapefruit Juice on Intestinal CYP Enzymes Third, in standard dose amounts, grapefruit juice has no effect on the pharmacokinetics of these medications when they are intravenously administered. An interaction involving hepatic CYP3A would be expected to influence drug half-life. 9 Second, grapefruit juice increases the area under the plasma concentration time curve, a calculable measure of whole-body medication exposure, with minimal if any change in drug half-life. Hepatic CYP3A is at best moderately affected by grapefruit juice administration and only with its chronic administration. Only the CYP3A isoforms localized to mucosal cells of the small intestine are inhibited by grapefruit juice. First, medications interacting with grapefruit juice typically are subject to metabolism by the enterocyte CYP3A4 enzyme system. Several findings point to grapefruit juice having a principal effect on the intestinal CYP system with a minor effect at the hepatic level. 4–8 The emphasis in this review will be on the interaction between grapefruit juice and calcium channel blockers (CCB). 3 This literature has been extensively reviewed, and the reader is directed to several of these reviews for additional information. ![]() 2 This singular observation has fueled a large volume of grapefruit juice–drug interaction research, with in excess of 225 publications involving more than 25 drugs appearing in the scientific literature. 1, 2 This interaction was discovered by coincidence in the course of an ethanol–drug interaction study in which grapefruit juice was used to mask the taste of the ethanol vehicle. This interaction substantially increased the systemic exposure to felodipine and by this amplified its pharmacodynamic effects. In 1989, it was noted that co-administration of the calcium antagonist felodipine with usual doses of commercially available grapefruit juice substantially decreased the pre-systemic clearance of felodipine. Seville oranges (used in orange marmalade), pomelos and tangelos (a cross between tangerines and grapefruits) may also have similar effects, so it is best to avoid these fruits when taking Amlodipine.Calcium channel blockers, grapefruit juice, felodipine, bergamottin, 6′, 7′-dihydroxybergamottin, flavanoids, furanocoumarins Grapefruits are the primary fruit to avoid when taking Amlodipine, including red, pink, white and or Blanco varieties. Severe cases of dizziness, headaches, vomiting, joint pain, tiredness are possible, as well as liver and muscle damage leading to kidney failure in severe cases.Ĭan I eat citrus fruit while taking Amlodipine? ![]() What happens if I eat grapefruit while taking Amlodipine?Įating grapefruit while on Amlodipine can cause the same side effects as if you were taking a much higher dose of the drug. These higher levels of Amlodipine mean more potent effects of the drug and more substantial side effects. Blocking these enzymes causes the drug to stay around for longer, allowing too much Amlodipine to enter your bloodstream. Eating grapefruit can block the action of these essential enzymes. People have varying levels of these enzymes in their body, so eating grapefruit can affect people differently, even when they both take Amlodipine. Amlodipine is broken down by enzymes (CYP3A4) in the lower intestine. Grapefruit and grapefruit juice can interact with Amlodipine. ![]()
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