Many medications interact with grapefruit juice- I assume the vertex drugs do (or might) as well.
<div class="FTQUOTE"><begin quote><b>How Does Grapefruit Juice Affect Medications?</b>
The cells that line your small intestine contain an enzyme called CYP3A4. This enzyme helps break down dozens of medications. Certain substances in grapefruit juice inhibit CYP3A4 and hence allow more of a medication to enter your blood stream.
Having too much medicine in your blood could result in serious side effects or a drug overdose. For example, if you take a statin (such as Lipitor) to help lower cholesterol, having too much of it in your body could increase your risk for a serious muscle disorder or liver damage.</end quote></div>
from: <a target=_blank class=ftalternatingbarlinklarge href="http://drugs.about.com/od/medicationabcs/a/gjuice_drugs.htm">Grapefruit Juice: Is It Safe With Your Drug?</a>