Patients w/ history of micturition syncope. Marked lowering of BP & syncope w/ 1st few doses of therapy. Intraoperative floppy iris syndrome (IFIS) during cataract surgery. Small but statistically significant decreased in hematocrit, Hb, WBC, total protein & albumin. Concomitant use of phosphodiesterase-5 (PDE5) inhibitors. May affect ability to drive or operate machinery. Pregnancy & lactation. Childn.