Drugs Interacting with GFJ

Where applicable, the clinical relevance of GFJ interactions in the present paper was assessed according to the PhRMA classification (111). If not otherwise stated studies are performed with human subjects. An overview is given in Table 2. 

The effects of GFJ were studied for clarithromycin (115) and erythromycin (116). A decrease in the time to reach the maximal plasma concentration (Tmax) was found for clarithromycin. The exposure of erythromycin was mildly increased when administered concomitantly with GFJ. It seems unlikely that the reported interactions with the above drugs would be relevant in a clinical setting. 

Data derived from studies performed with coumarin are inconsistent. In one study, the percentage of 7-hydroxycoumarin excreted in urine was decreased (117) in a second study the appearance of the metabolite was delayed when 300 mL GFJ were given concomitantly, but the recovery in urine was unchanged (118), whereas four times 250 mL juice in 30-minute intervals increased the recovery by 100%. The delay in appearance of the metabolite could also be confirmed in a third study (119). A study performed with 

Terfenadine 240 mL DS GFJ with terfenadine intake or 2 hr after Concentrations were not quantifiable in control group SS increase in QTc interval in GFJ group (7) 

Coumarin 300 mL GFJ 30 min before or with drug administration Percentage of excreated 7-hydroxycoumarin in urine [ N/A (117) 

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