Calculate Molarity of a solution using a mg/g term?

I have to prepare a 10E-8 M solution of dexamethasone, that have a 392.47 (http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&N5=SEARCH_CONCAT_PNO|BRAND_KEY&N4=D2915|SIGMA&N25=0&QS=ON&F=SPEC). This product have a carrier and it specifies this: Contains approx. 65 mg dexamethasone per gram; balance 2-hydroxypropyl-β-cyclodextrin. The flask of the chemical says 70.7 mg/g. I'm confused and I don't know exactly how to prepare this solution. I would appreciate any help! thanks!