Grapefruit juice consumption interacts with which classes of medications?

• A. Calcium channel blockers, immunosuppressants, antihistamines
• B. Antibiotics, statins only
• C. Antipsychotics and antidepressants only
• D. Anticoagulants only

Answer: (A)

Grapefruit juice blocks enzymes in the intestinal wall that normally break down many drugs, causing higher and longer-lasting drug levels in the bloodstream. This effect is especially important for medications that are metabo­lized by intestinal CYP3A4 or transported across the gut lining. The three groups most notably affected include certain calcium channel blockers, which can lead to excessive blood pressure-lowering effects; immunosuppressants like cyclosporine, where higher levels increase toxicity risks such as kidney injury; and some antihistamines such as terfenadine, where elevated levels can trigger dangerous heart rhythms. While other drug classes can also interact with grapefruit juice in some cases, the combination of calcium channel blockers, immunosuppressants, and antihistamines represents the most well-documented and clinically significant pattern of interaction.