As naringin alone is ineffective, the inhibitory effect of grapefruit juice on the metabolism of coumarin is caused by at least one compound other than naringin. The persistency of the primary inhibitor not identified yet can obviously be modulated by the naring(en)in-system.

No abstract

Only grapefruit juice given at high doses (1 L) retards the appearance of the main metabolite of coumarin administered orally but increases its recovery. Due to scopoletin formed from the grapefruit juice, experiments especially with coumarin are strongly affected.

No abstract