Hi,
When it comes to grapefruit I would stick to the real thing. Grapefruit inhibits a liver enzyme called cytochrome p450 that is needed to break certain chemicals down including many drugs including xanax (I think). These medications usually come with warnings telling you to eliminate grapefruit from your diet if you are taking these meds. Consumption of grapefruit would cause these drugs to build up in your body (as they are not being broken down as they should) and you can OD and cause your body severe damage. The worry is that the pills may be more concentrated for this inhibitory action than grapefruit itself.