TY - CHAP M1 - Book, Section TI - Adrenoceptor Agonists & Sympathomimetic Drugs A1 - Biaggioni, Italo A2 - Katzung, Bertram G. A2 - Vanderah, Todd W. Y1 - 2021 N1 - T2 - Basic & Clinical Pharmacology, 15e AB - CASE STUDYA 68-year-old man presents with a complaint of light-headedness on standing that is worse after meals and in hot environments*. Symptoms started about 4 years ago and have slowly progressed to the point that he is disabled. He has fainted several times but always recovers consciousness almost as soon as he falls. Other symptoms include slight worsening of constipation, urinary retention out of proportion to prostate size, and decreased sweating. He is otherwise healthy with no history of hypertension, diabetes, or Parkinson disease. Because of urinary retention, he was placed on the α1A antagonist tamsulosin, but the fainting spells got worse. Physical examination is unremarkable except for a blood pressure of 167/84 mm Hg supine and 106/55 mm Hg standing. There was an inadequate compensatory increase in heart rate (from 84 to 88 bpm), considering the magnitude of orthostatic hypotension. There is no evidence of peripheral neuropathy or parkinsonian features. Laboratory examinations are negative except for a low plasma norepinephrine (98 pg/mL; normal for his age 250–400 pg/mL). A diagnosis of pure autonomic failure is made, based on the clinical picture and the absence of drugs that could induce orthostatic hypotension and diseases commonly associated with autonomic neuropathy (eg, diabetes, Parkinson disease). What precautions should this patient observe in using sympathomimetic drugs? Can such drugs be used in his treatment? SN - PB - McGraw-Hill CY - New York, NY Y2 - 2024/03/29 UR - accessmedicine.mhmedical.com/content.aspx?aid=1176462236 ER -