Eating fruits and vegetables is essential to living a long and healthy life, yet research has shown they can cause dangerous interactions with medicines. According to the July issue of General Dentistry, the Academy of General Dentistry's (AGD) clinical, peer-reviewed journal, foods can increase or decrease the activity and toxicity of orally-administered drugs (intravenous drugs are not altered).
One of the most studied of these interactions is the inhibition of CYP3A4 enzymes caused by grapefruit or its juice. CYP3A4 enzymes are responsible for the metabolism of more than 60 percent of orally-administered drugs. Drugs that interact with grapefruit include anti-infectives, anti-inflammatories, cardiovascular agents, central nervous system agents, estrogens, gastrointestinal agents, Histamine H1 antagonists, immunosuppressives, and erectile dysfunction drugs. Dental patients in particular should be aware of interactions with the sedatives triazolam, midazolam and diazepam which could cause excessive sedation.
As little as 6.0 oz of grapefruit juice may lower the amount of a drug needed to produce the desired effect, which could cause an overdose. The blood that absorbs nutrients passes through the liver before reaching the general circulatory system (the first-pass). The ability of a drug to successfully pass from the GI tract to the plasma is called its bioavailability. Grapefruit juice inhibits first-pass drug metabolism, increasing bioavailability.