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Calcium antagonists PowerPoint Presentation

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Description : Check out this medical presentation on Pharmacology, which is titled "Calcium antagonists", to know about the calcium channel blockers. They block calcium influx through voltage-dependant calcium channels in the smooth muscles. They dilate coronaries and peripheral arteries and reduce heart afterload.

Tags : Pharmacology, Calcium antagonists, calcium channel blockers, block calcium influx, voltage-dependant calcium channels, smooth muscles

Published on : Jul 18, 2021 | Views : 1940 | Downloads : 2

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Slide 1-

Calcium antagonists (Summary) Dr Ivan Lambev (itlambev@mail.bg)
Slide 2-

Calcium antagonists (calcium channel blockers) They block calcium influx through voltage- dependant calcium channels in the smooth muscles. They dilate coronaries and peripheral arteries and reduce heart afterload.
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VDCC ROCC Receptor AP Ca2+ Ca2+ Sarcoplasmatic reticulum Cell wall NA (–) Calcium antagonists AP – action potential, NA – noradrenaline VDCC – voltage-dependent calcium channels ROCC – receptor operating calcium channels
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ppt slide no 4 content not found
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Regulation of intracellular calcium
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In the cell membranes there are three types of calcium channels: Voltage-dependent (L, N, O, P, Q, R, T)  Receptor operating  Stretch activated
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Calcium antagonists block predominantly L-type calcium channels, localized in the myocardium and myocytes of blood vessels. L-type channels are connected to the plateau of the AP. Plateau phase of AP
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Calcium antagonists reduce coronary and peripheral vascular resistance, decrease blood pressure and myocardial oxygen consumption. Dihydropyridines (nifedipine, amlodipine, etc) don’t have cardionegative inotropic, chronotropic, and dromotropic effect in comparison with verapamil and diltiazem.
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 Dihydropyridines ● Norm frequent (with normal heart rate) and 24-hours long effect: Amlodipine, Felodipine ● Other dihydropyridines produce tachycardia (increase baroreflex sensibility): Isradipine, Lacidipine, Nicardipine, Nifedipine, Nisoldipine, Nitrendipine ● cerebral vasodilators (Nimodipine)  Phenylalkylamines: Verapamil  Benzotiazepines: Diltiazem  Flunarizine type (cerebral vasodilators) Cinnarizine, Flunarizine
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 Arterial hypertension a) Dihydropyridines b) Verapamil and Diltiazem  Coronary heart disease a) Dihydropyridines b) Verapamil and Diltiazem  Ischemic cerebral stroke Cinnarizine, Flunarizine, Nimodipine  SV tachyarrhythmias: Verapamil, Diltiazem (i.v.)  Migraine (in remission periods) Flunarizine, Verapamil Beta-blockers + dihydropyridines: YES (OK) Beta-blockers + Verapamil or Diltiazem = NO Main indications
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Calcium antagonists Amlodipine norm frequent dihydropyridine t1/2 31–47 h, 55–91% p.o. bioavailability 5–10 mg/24 h p.o. (once daily) Nifedipine (tachycardia!) – effective in vasospastic angina Diltiazem (in SR dosage forms) Verapamil (Isoptin SR® – tabl. 240 mg) (22% p.o. bioаvailability, first pass effect – extensive liver metabolism)
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Class IV antiarrhythmic drugs Indications: SV tachyar- rhythmias ARs: headache, ankle swelling, bradycardia, AV block, negative inotropic effect (decreasing cardiac contractility) Mainly verapamil (p. o./i. v.) and diltiazem (only i.v.) has specific action on ..the… SA and AV node (they shorten AP)
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Atrial flutter with a 4:1 conduction ratio.
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ARs of calcium antagonists Arterial dilation: headache, flush, dizziness, ankle swelling (resistant to treatment with diuretics but not with ACE inhibitors). Bradycardia and AV block (verapamil). Verapamil + beta-blockers: potentiate cardiodepression. Tachycardia (nifedipine, nisoldipine). Constipation (verapamil 8%; nifedipine 3%) Haemorrhagic gingivitis