7. Agree not to use any other investigational medications or approved or unapproved therapies to treat RP and its symptoms while participating in this study. Such medications include, but are not limited to: other dosages forms of nitroglycerin, eg, isosorbide dinitrate, fenoldopam mesylate, milrinone lactate, nifedipine, diltiazem, felodipine, nimodipine, nisoldipine, fluoxetine, pregabalin, and verapamil. Use of phosphodiesterase 5 inhibitors (eg, sildenafil, tadalafil, vardenafil) is excluded unless being used intermittently for male erectile dysfunction and not taken within 48 hours of scheduled study drug dosing