<prompt> First dose hypotension is caused by :PrazosinClonidineSodium nitroprussidePropranolol  <response>: Ans. is a Prazosin Prazosin is a highly selective alpha1 blockerIt dilates arterioles more than veinsIt is effective orally It causes first dose hypotension It is primarily used as an antihypertensiveIts initial dose should be low 