<prompt> A person has headache profuse sweating. On examination his B.P is 200120 mm Hg. Which of the following shoud not be usedNifedipineSodium nitroprussidePhenoxybenozamineMethyldopa  <response>: Patients who respond to shoacting vasodilators at the time of cardiac catheterization a fall in mean pulmonary aerial pressure 10 mmHg and a final mean pressure 40 mmHg should be treated with calcium channel blockers. Typically, these patients require high doses e.g., nifedipine, 240 mgd, or amlodipine, 20 mgd. Patients may have dramatic reductions in pulmonary aery pressure and pulmonary vascular resistance associated with improved symptoms, regressionof RV hyperophy, and improved survival now documented to exceed 20 years. However, 20 of patients respond to calcium channel blockers in the long term. These drugs are not effective in patients who are not vasoreactive. ref:Harrison;s principles of internal medicine,ed 18,pg no 2079 