Serum concentrations and clinical effects of atorvastatin in patients taking grapefruit juice daily

To determine whether customary exposure to grapefruit juice (GFJ) alters serum concentrations, effectiveness, and potential adverse effects of atorvastatin in patients requiring the medication.

Patients receiving extended treatment with atorvastatin (10, 20 or 40 mg day(-1)) at a stable dose received 300 ml day(-1) of 100% GFJ for a period of 90 days. One cohort of patients (arm A, n= 60) continued on their current dose of atorvastatin; the second cohort (arm B, n= 70) reduced the daily dose by 50%. Serum atorvastatin, lipid profile, liver functions, and creatine phosphokinase (CPK) were measured at baseline and at 30, 60, and 90 days after starting GFJ.

In Arm A patients, co-ingestion of GFJ significantly elevated serum atorvastatin by 19% to 26% compared with baseline. Changes in lipid profile relative to baseline were negligible. There were no adverse effects on liver function tests or CPK. In arm B patients, serum atorvastatin declined by 12% to 25% compared to baseline, with a small but significant unfavourable effect in serum lipid profile. There were no adverse effects on liver function tests or CPK.

In patients on extended stable atorvastatin treatment, addition of daily GFJ in typical quantities slightly elevates serum atorvastatin concentrations, but has no meaningful effect on the serum lipid profile, and causes no detectable adverse liver or muscle effects. Reduction of atorvastatin dosage when moderate amounts of GFJ are co-ingested does not appear to be necessary.