Ever wondered why grapefruit juice interacts with many drugs???
Grapefruit juice contains compounds called furanocoumarins (mainly bergamottin and 6’,7’- dihydroxybergamottin), which strongly inhibit the intestinal enzyme CYP3A4.
This enzyme is responsible for the first-pass metabolism of nearly 50% of commonly used drugs When CYP3A4 is inhibited, the drug is not broken down properly in the gut therefore drug concentrations increases in the bloodstream, increasing the risk of toxicity.
Multiple Mechanisms Make It a High-Risk Food
1. CYP3A4 Inhibition
Reduces metabolism of many drugs (e g., statins, calcium channel blockers, benzodiazepines).Even one glass can inhibit the enzyme for up to 72 hours, making the interaction long-lasting.
2. P-glycoprotein (P-gp) Inhibition
P-gp normally pumps drugs back into the intestinal lumen. Grapefruit inhibits P-gp therefore more drug absorption takes place.
3. OATP Transporter Inhibition
These transporters help absorb certain drugs. Grapefruit blocks them leading to reduced absorption of some medicines (e.g., fexofenadine). So, paradoxically, grapefruit can either increase or decrease drug levels depending on the mechanism.
In short,
Grapefruit juice is like a powerful "off switch for major drug metabolizing enzymes and transporters.Since many medicines depend on those systems, grapefruit ends up interacting with an unusually wide range of drugs.
Thank you for sharing your experience