Which class of medications is commonly known to interact with grapefruit, including examples such as diltiazem, nifedipine, and verapamil?

• A. Calcium channel blockers (diltiazem, nifedipine, verapamil)
• B. Statins
• C. Caffeine
• D. SSRIs

Answer: (A)

Grapefruit products block an enzyme in the lining of the gut (CYP3A4) that normally helps metabolize many drugs as they’re absorbed. When this enzyme is inhibited, more of the drug enters the bloodstream, increasing its effects and potential toxicity. Calcium channel blockers like diltiazem, nifedipine, and verapamil are well known to be affected this way, so grapefruit can raise their levels in the body. That can lead to stronger blood pressure-lowering effects, dizziness, fainting, or edema, and sometimes slowed heart rate.

Most importantly for practice, the instruction here points to the class that consistently shows this interaction with the drugs listed, so avoiding grapefruit juice is typically advised while taking these medications. While other drugs can be affected by grapefruit in some cases (such as certain statins), the combination with the listed calcium channel blockers best fits this interaction pattern, and caffeine or SSRIs do not have the same clinically significant grapefruit interaction.