Grapefruit juice and medications can be a deadly combination

The activity of certain medications can be modified during the consumption of certain foods, there may be an increase in side effects or a decrease in the efficacy of the drug.

Grapefruit juice can significantly increase the absorption of certain drugs in the body.

The mechanism

According to AFSSAPS (French Agency for Sanitary Safety of Health Products), intestinal absorption of certain drugs is regulated in the enterocytes, the cells of the intestine, by the presence of an enzyme, CYP3A4, coupled to a drug transporter, P-glycoprotein (P-up).

CYP3A4 directly metabolizes these drugs into the enterocytes, whereas the P-glycoprotein favors its intestinal rejection.

Certain substances such as bergamot in and 6,7-dihydroxybromamotine present in grapefruit compete with this system thanks to its powerful inhibitory effect of CYP3A4, followed by increased intestinal absorption of the drugs followed by an increase in their effects Adverse reactions leading to an overdose.

Medications at risk

Certain medications used to lower blood cholesterol: simvastatin, and to a lesser extent, atorvastatin. For simvastatin, the bioavailability may be multiplied by a factor of 15, which would amount to a two-week dose.

Immunosuppressant’s (tacrolimus, cyclosporine …), with increased risk of nephrotoxicity, recommended immunosuppressants against graft rejection (tacrolimus, cyclosporine …). A concomitant intake of grapefruit juice, on a regular basis, can damage the kidney.

Cisapride, prescribed to treat reflux, may present a risk of torsades (disturbances of the rate of cardiac activity).

Tips

  • The AFSSAPS recommends avoiding the consumption of pomelo juice 2 hours before taking these medicines and limiting consumption to less than a quarter of a liter per day.
  • Apple juice and orange juice do not cause known interactions.
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