The bioavailability of dihydropyridine calcium channel blockers following oral administration was shown to be increased by concomitant intake of grapefruit juice for all drugs of this class tested up to now. Here we report a randomized crossover interaction study on the effects of grapefruit juice on the pharmacokinetics of nimodipine and its metabolites. Eight healthy young men (4 smokers/4 nonsmokers) were included. Nimodipine was given as a single 30 mg tablet (Nimotop) with either 250 ml of water or 250 ml of grapefruit juice (751 mg naringin/l). Drug concentrations in plasma withdrawn up to 24 hours postdose were measured by GC-ECD, and model-independent pharmacokinetic parameters were estimated. The study was handled as an equivalence problem. Point estimators and ANOVA based 90% confidence intervals (CI) were calculated for the test (= grapefruit juice period) to reference (= water period) ratios using dose-normalized concentrations. The absence of a relevant interaction was assumed if the CIs were within the - range. Cmax for nimodipine reached 124% of the reference period (90% CI -), AUC was increased to 151% (90% CI 114%-200%), respectively. The null hypothesis "relevant interaction" thus could not be rejected for the primary pharmacokinetic parameters AUC and Cmax. The ratios of metabolite AUC to parent drug AUC were slightly reduced with grapefruit juice intake. Additionally, there was evidence for a more pronounced hemodynamic response in the grapefruit juice period. To avoid the interaction, nimodipine should not be taken with grapefruit juice.
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Grapefruit can seem like an acquired taste. Their bulbous size; bitter pith (the white stuff that surrounds the fruit); and tart taste can be off-putting to those who are more accustomed to their sweeter citrus cousins, like the orange. But consider adding this superfood to your regular rotation of healthy foods. Considered to be one of the 20 Best Foods to Eat for Breakfast , you don't actually have to limit your intake to the early morning hours. Grapefruit are supremely portable and make a great snack (with very few calories) that fills you up while also relieving thirst due to its high water content.