Grapefruit Juice Mixed With Prescription Drugs Can Be Deadly

Many prescription drugs have severe side effects when they are mixed with grapefruit juice, and the number of these medications is rapidly growing, however, doctors are often unaware of the side effects, according to a new study published in the Canadian Medical Association Journal (CMAJ).

Serious side effects of mixing grapefruit juice with certain prescription drugs include:

• respiratory failure
• gastrointestinal bleeding
• bone marrow suppression in patients with weak immune systems
• renal toxicity
• acute kidney failure
• sudden death
• According to the new findings, over 85 different medications may have interactions with grapefruit, and 43 can have harmful effects. Seville oranges, which is found in marmalade, as well as limes and pomelos have the active ingredients, or furanocoumarins - substances which naturally occur in grapefruit. They irreversibly inhibit the drug metabolizing CYP3A4 enzyme that inactivates the effects of approximately half of all medications.
  
  Medications that mix with these substances have three traits:
  • They are given as oral drugs.
  • They possess very low to middle bioavailability (the percentage of the oral dose of the medication which is soaked into the blood circulation unaltered).
  • They go through drug metabolism in the gastrointestinal tract by CYP3A4.
  For low bioavailability drugs, consuming just one grapefruit can multiply the dosage effect of that medication several times, and this interaction can take place regardless of whether the grapefruit was eaten hours before the drug was taken. Therefore, a moderate amount of grapefruit can impact interacting medications which are taken only once a day at any hour during when the dose is taken.
  
  Taking regular amounts of medications on a daily basis can increase side effects. For example, when Simvastin, a popular statin, is mixed with one 200-mL glass of grapefruit juice for 3 days, it results in a 330% systematic concentration of the medication in comparison with water.
  
  Adults over the age of 45 are the most common buyers of grapefruit and also tend to be prescribed the most medications. The population of adults over 45 is extremely large, therefore, many of these interactions are likely to occur. The report notes that older adults are more likely to have decreased capability to endure extreme systematic drug concentrations, making them more likely to experience these adverse effects.