If you use GenX brand (generic) colistin, they also have a program where you send in a copy of your prescription and a box top to get a free bottle of Source Cf vitamins too. I take one adult cf source vitamin and one chewable (kid's) vitamin each day, because the chewables have more vitamin D.
The prices are better, too, if you order straight from the company:
90 count chewables are $29.95
60 count soft gels are $18.95
And the shipping is free if you order 3 bottles at a time <img src="i/expressions/face-icon-small-smile.gif" border="0"> . This is where I get mine from.
<a target=_blank class=ftalternatingbarlinklarge href="http://www.sourcecf.com/">Source CF</a>