PTF is a safe, generally well-tolerated drug currently indicated for symptomatic and functional relief of intermittent claudication presumed due to chronic occlusive arterial disease of the limbs. A number of small studies in patients across a range of renal disease states show that PTF can reduce proteinuria, an important component of treatment of CKD. It is not known, however, if the drug will slow progression of CKD as measured by glomerular filtration rate.