Grapefruit juice vs. grape juice

MJ Cyriac

 Department of Dermatology and Venereology, Medical College, Kottayam, India

Correspondence Address:
M J Cyriac
Department of Dermatology and Venereology, Medical College, Kottayam
India

Sir,

While reading the article ′Drugs in dermatological practice: Relationship to food′[1] I saw that it is advised not to take cyclosporin with grape juice. I would like to point out that it is grapefruit juice and not grape juice which produces elevated serum concentrations of cyclosporin.[2] In fact many western hospitals have removed grapefruit juice from their inpatient menus to avoid the risk of drug interactions.

Grapefruit (Citrus X paradisi) is a citrus fruit which inhibits the CYP3A4 pathway in the small intestinal wall when either fresh or frozen grapefruit is eaten or grapefruit juice is drunk.[3] This inhibition may be due to Bergamottin, a furocoumarin compound or due to other flavonoids present in it. This results in elevation of serum concentrations of all drugs which are metabolized via the CYP3A4 pathway including cyclosporine, felodipine, nifedipine, saquinavir, midazolam, triazolam, terazosin, ethinyloestradiol,17-beta oestradiol, prednisone, lovastatin, simvastatin etc. Absence of 6,7-Dihydrobergamottin in orange juice probably accounts for the absence of CYP inhibitory effects.[4] Pronounced elevation of the maximal plasma concentrations are seen with drugs that have high first pass metabolism (metabolism of a drug during its passage from the site of absorption into the systemic circulation- at the small intestinal wall and in the liver in case of orally administered drugs). In fact, this inhibitory effect of grapefruit juice on the metabolism of cyclosporin may be used to achieve therapeutic plasma concentrations of the drug at lower dosage levels than usual, but this is not recommended as the effect varies with different batches of grapefruit.

1.	Smitha Prabhu, SD Shenoi. Drugs in dermatological practice: Relationship to food. Indian J Dermatol Venereol Leprol 2003;69:305-6 [Google Scholar]
2.	Shapiro LE, Shear NH. Drug Interactions. In: Wolverton SE, editor. Comprehensive Dermatological Drug Therapy. WB Saunders; 2001. p. 848-71. [Google Scholar]
3.	Roller L. Drugs and grapefruit juice(letter). Clin Pharmacol Ther 1998;1:87. [Google Scholar]
4.	Hollander AA, van der Woude FJ, Cohen AF. Effect of grapefruit juice on blood cyclosporin concentration (letter). Lancet 1995;346:123. [Google Scholar]