59-291 Section 3, Lecture 2 Diuretics: -increase in Na + excretion (naturesis) Thiazide and Related diuretics -decreased PVR due to decreases muscle contraction -an economical and effective treatment -protect against osteoporosis Loop diuretics -used in patients with poor kidney function where thiazide derivatives will not be effective 1
vasodilators β-antagonists α-antagonists Angiotensin II receptor antagonists β-antagonists β- antagonists CNS-directed sympatholytics ACE inhibitors Angiotensin II receptor antagonists diuretics 2
Potassium-Sparing Diuretics -mild diuretic and antihypertensive effect -Minimize renal-k + loss thus preventing hypokalemia -If the patient can t tolerate these drugs then use thiazide and take KCl tablets Drug Classification Diuretics Thiazide and loop diuretics Common Adverse Effects Blood cell deficiencies, hyperlipidemia, hyperuricemia, hypokalemia, and other electrolyte changes Aggravation of diabetes Common Drug Interactions Increase serum levels of lithium. Hypotensive effect decreased by NSAIDs and augmented by ACE inhibitors Potassium-sparing diuretics Hyperkalemia Hyperkalemic effect increased by ACE inhibitors and potassium supplements 3
Sympatholytics Drug Classification Adrenergic receptor antagonists α-adrenergic receptor antagonists β-adrenergic receptor antagonists Centrally acting drugs Clonidine Guanabenz Guanfacine Methyldopa Common Adverse Effects Dizziness, first-dose syncope, fluid retention, and orthostatic hypotension Bradycardia, bronchoconstriction, depression, fatigue, impaired glycogenolysis, and vivid dreams Dry mouth, fatigue, rebound hypertension, and sedation Same as clonidine Same as clonidine but milder Autoimmune hemolytic anemia, hepatitis, and lupuslike syndrome. Other adverse effects same as those of clonidine Common Drug Interactions Hypotensive effect increased by β-adrenergic receptor antagonists and diuretics Cardiac depression increased by diltiazem and verapamil. Hypotensive effect decreased by NSAIDs Hypotensive effect decreased by tricyclic antidepressants Sedative effect increased by CNS depressants Same as clonidine Same as clonidine Hypotensive effect increased by levodopa. Other interactions same as those of clonidine 4
vasodilators β-antagonists α-antagonists Angiotensin II receptor antagonists β-antagonists β- antagonists CNS-directed sympatholytics ACE inhibitors Angiotensin II receptor antagonists diuretics 5
Angiotensin Inhibitors Drug Oral Bioavailabili ty Absorption Reduced by Food Active Metabolite Duration of Action (Hours) Angiotensin-converting enzyme inhibitors Benazepril 37% No Benazeprilat Captopril 75% 30-40% None 12-Jun Enalapril 60% No Enalaprilat* Fosinopril 36% No Fosinoprilat Lisinopril 25% No None Quinapril 60% 25-30% Quinaprilat Ramipril 55% No Ramiprilat Angiotensin receptor antagonists Losartan 33% 10% Carboxylic acid metabolite Valsartan 25% 40% None Candesartan 15% No None 6
Angiotensin inhibitors 1. ACE inhibitors 2. Angiotensin receptor inhibitors Renin secretion induced by: 1-Symp. Outflow 2-reduction in BP and wall tension in renal arterioles 3-reduced NaCl reabsorbtion AT 1 AT 1 G-proteins IP3 7
ACE inhibitors Adverse effects Increase fetal morbidity and mortality, especially during 2 nd and 3th trimesters Renal failure in patients with bilateral renal artery stenosis 8
Drug Classification Angiotensin inhibitors Common Adverse Effects Common Drug Interactions Angiotensin-converting enzyme (ACE) inhibitors Angiotensin receptor antagonists Acute renal failure, angioedema, cough, hyperkalemia, loss of taste, neutropenia, and rash Hyperkalemia Increase serum levels of lithium. Hyperkalemic effect increased by potassiumsparing diuretics and potassium supplements. Hypotensive effect decreased by NSAIDs Serum levels of drug increased by cimetidine and decreased by phenobarbital 9
Vasodilators Organic nitrites and nitrates Amyl nitrites; (nitrites), administered by inhalation Nitroglycerin (glyceryl trinitrate); sublingual, oral or transdermal administration Calcium channel blockers Amlodipine, felodipine Diltiazem, verapamil 10
Tolerance Aldehyde dehydrogenase releases NO from nitroglycerin, and this process is accompanied with formation of superoxide anion free radical (O 2 - ) that in turn, deactivate aldehyde dehydrogenase -to avoid periodically interrupt the administration of the drugs Pills sublingual Sustained release- patches, skin ointments, IV Adverse effects- headaches, hypotension, dizziness, reflex tachycardia, use β-blocker in combination 11
Ca 2+ - channel blockers (CCBs) Suppress cardiac activity and relax smooth muscles-in combination increase coronary blood flow Side effects: fatigue, headache, dizziness, flushing, peripheral edema Occasionally cause gingival hyperplasia 12
Selection of Antihypertensive Drugs for Patients with Specific Traits or Concurrent Diseases Patient Characteristic Age over 65 years African heritage Pregnant Angina pectoris Myocardial infarction Congestive heart failure Recurrent stroke prevention Chronic kidney disease Diabetes Asthma Benign prostatic hyperplasia Migraine headache Osteoporosis Most Preferred Drugs Diuretic, ACEI, CCB Diuretic, CCB Methyldopa, labetalol β-blocker, CCB β-blocker, ACEI, aldosterone antagonist Diuretic, ACEI, ARB, β-blocker Diuretic, ACEI, ARB ACEI, ARB Diuretic, ACEI, ARB, β-blocker, CCB CCB, ACEI α-blocker β-blocker, CCB Diuretic Least Preferred Drugs Centrally acting α2 agonist β-blocker ACEI, ARB Hydralazine, minoxidil β-blocker 13