Which Alpha 1 adrenergic antagonist is used to treat BPH and can cross Floppy Iris syndrome?

Tamsulosin is the correct choice because it specifically targets the alpha-1A adrenergic receptors located in the prostate and bladder neck, making it particularly effective in treating benign prostatic hyperplasia (BPH). One of the notable characteristics of tamsulosin is its association with floppy iris syndrome, a condition that can complicate cataract surgery. This syndrome occurs due to the relaxation of smooth muscle in the iris, which may lead to complications during the procedure.

While all the options listed are alpha-1 adrenergic antagonists used to manage BPH, their effects and receptor selectivity vary. Tamsulosin's selectivity for the alpha-1A receptor means it does not cause as much vascular smooth muscle relaxation compared to others like doxazosin and terazosin, which can also affect blood pressure and may lead to different side effects. Consequently, in the context of floppy iris syndrome, tamsulosin is specifically noted for its potential impact during cataract surgery, differentiating it from the other alpha-1 antagonists listed.