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Anti-Ischaemic Medications

Learn about the pharmacological interventions for ischaemic heart disease, including the use of β-blockers and nitrates. Understand their actions, clinical uses, contraindications, and potential adverse effects.

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Anti-Ischaemic Medications

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  1. Anti-Ischaemic Medications β Blockers and Nitrates by: Mimoza Meholli 9/17/2003

  2. Case 1 • A 62 yr old male with a history of chronic Stable Angina since 1998 complains of chest pain radiating to the neck, left arm and back, occurring at rest. • Patient has DM-2, HTN, Duodenal ulcer and Hypothyroidism. • EKG shows evidence of previous inferior wall MI.

  3. Pharmacological Intervention in Ischaemic Heart Disease AIMS: • Increase coronary blood flow. • Reduce myocardial energy requirements. • To stop or reverse coronary artery occlusion in order to avoid or minimize myocardial cell death.

  4. β -Blockers • Competitively antagonize the action of catecholamines at β -adrenergic receptors. • Decrease heart rate, stroke volume, and cardiac output. • Normal sympathetic control of bp is maintained in HTN due to unopposed vasoconstriction by ά-receptors, thus avoiding orthostatic hypotension. • Carvediolol sensitizes down regulated β-receptors in CHF, making mayocytes responsive to catecholamines and improves ventricular function.

  5. Pharmacokinetics • Variable: depends on preparation, hepatic metabolism, renal elimination and lipid solubility. • Generally, β-Blockers have a short half-life (~4hrs), but long acting preparations are available.

  6. Clinical Use/Indications Hypertension Glaucoma Migraine Hyperthyroidism Angina Pectoris Myocardial Infarction Compensated CHF Contraindications Asthma/bronchospasm Uncompensated CHF Bradychardia Cardiogenic shock AV conduction abnormalities

  7. Adverse effects: • Bronchostriction • Arrhythmias • Sexual impairment/depression • Disturbances in metabolism • masks signs of acute hypoglycemia and hyperthyroidism; • abrupt withdrawal may exacerbate symptoms of hyperthyroidism, including thyroid storm. • Caution/monitor closely in: • Wolff-Parkinson-White syndrome and renal or hepatic dysfunction

  8. Drug Interactions • Aluminum salts • Barbiturates • NSAIDs • Penicillins • Calcium salts • Cholestyramine, and Rifampin may decrease effects • Calcium channel blockers, Cimetidine, Loop Diuretics, and MAOIs may increase toxicity • May increase toxicity of: Hydralazine, Haloperidol, Benzodiazepines, and Phenothiazines

  9. βBlocker Brand USA Brand ISRAEL PO Doze, mg T1/2 hrs Actions/ Selectivity Atenolol Tenormin Normitem 50-100 qd 6-9 β1 Metoprolol Lopressor Metopress Neobloc 50-100 Bid 3-4 β1 Acebutulol Sectral Sectral 200-600 Bid 3-4 β1 ,ISA Propanolol Inderal Deralin 20-80 qd 4-6 β1 β2 Nadolol Cogard N/A 40-160 qd 10-24 β1 β2 Timolol Blocarden N/A 10-20 bid 3-4 β1 β2 Pindolol Visken Pinden 5-20 tid 3-4 β1 β2 ISA Carvedilol Coreg Dimitone 25-50 bid 7-10 α1 β2 β1 Labetolol Normodyne Trandate 100-600 bid 6-8 α1 β2 β1

  10. Nitrates Mode of Action: • Smooth muscle relaxation • Nitric oxide stimulates guanylyl cyclase, which increases intracellular cGMP leading to relaxation. • Preload (venules) and Afterload (arterioles) are reducedbp and CO • Direct coronary artery dialation ischeamic pain

  11. Pharmacokinetics • Large first-pass effect • Short half-lives, 1-5 min (except isosorbide mononitrate, 5 hrs) • Large individual variations in blood concentrations • Preparations available: IV, sublingual, PO, transdermal

  12. Clinical use/Indications Acute Angina attacks: administered sublingually Prophylaxis: slow release preparations used as maintenance therapy to prevent angina IV used to control unstable angina, or threatened MI Contraindications Documented hypersensitivity Severe Anemia Closed-angle Glaucoma Orthostatic hypotension Head trauma Cerebral hemorrhage Constrictive Pericarditis Coronary Pulmonade and Arterial Hypoxemia Hypotensive Shock

  13. Adverse Effects • Doze related: • Orthostatic Hypotension • Flushing • Headache • Precautions: • Tolerance to vascular and antianginal effects of nitrates may develop • minimize tolerance by using smallest effective dose or pulse therapy (intermittent dosing), or by alternating with other coronary vasodilators • Caution when administering to patients with glaucoma

  14. Drug Interactions • Alcohol may cause severe hypotension and cardiovascular collapse • Aspirin may increase serum concentrations and actions • Calcium channel blockers may increase symptomatic orthostatic hypotension (adjust dose of either agent) • May decrease effects of Heparin

  15. Nitrate Brand USA Brand ISRAEL Doze, mg Onset min T1/2 Subl. Nitroglycerin Nitrostat Angised 0.3-0.6 2-5 10-30 min Aerosol Nitroglycerin. Nitrolingual Nitrolingual 0.4 2-5 10-30 min Sublingual Isosorbide dinitrate Isodril N/A 2.5-10 10-30 1-2 hr Oral Isosorbide Dinitrate Sorbitrate Isotard 5-40 30-60 4-6 hr Oral Isosorbide Mononitrate Monoket Monocord 10-20 30-60 6-8 hr Oral Sustained Release Nitroglycerin Nitroglyn, Nitro-Time N/A 2.5-9 30-60 3-8 hr Transdermal. Nitrog. Patch Nitro-Dur Trinipatch 5-15 >60 12-14 hr 2% Nitroglyc. Ointment Nitrol 2% N/A 0.5-2 inches 20-60 3-8 hr

  16. References • The Washington Manual of Medical Therapeutics, 30th ed. • Lippincott’s Review of Pharmacology, 2000. • Gibbson R, et al. Guidelines for the Management of Patients with Chronic Stable Angina:Treatment. Ann. Intern. Med. 2001;135:616-632.

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