drugs affecting the cardiovascular system.ppt

7/28/2019 Drugs affecting the Cardiovascular system.ppt

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ObjectivesName the main classes of Anti anginal and antihypertensive drugs

Describe the principles of drug action in the treatmentof Angina and HypertensionDescribe the mechanism of action of the above drugsName the adverse effects of each of the drugs


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Angina Pectoris


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Main anti anginal drug classesOrganic Nitrates

Beta blockers

Calcium Channel blockers

(Antiplatelet drugs)


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Angina PectorisDEMAND

SUPPLY


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Principals of drug Action in AnginaSUPPLY Dilates Coronaries

Slows Heart Rate

DEMAND Reduces Preload

Reduces AfterloadReduces contractility Slows heart rate


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The NitratesCause Vasodilatation

Dilates Venules >> Arterioles

Veno dilatation Preload O 2 Demand

Coronary dilatation ImprovesCoronary Flow


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Mechanism of actionReleases NO intracellulary Activates Guanylate cyclase

cyclic GMP

free intracellular Ca

vascular smooth muscle relaxation


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The NitratesOral / Sublingual / Transdermal / IV GTN Sublingual spray usually

Short half life- few minutesImmediate relief of angina

ISMN/ISDN TabletsLonger half lifeContinuous cover


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The NitratesNitrate Tolerance Nitrate free periodneeded

Adverse EffectsHeadache

HypotensionCollapse


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Calcium Channel blockers Vasodilators, arterioles >> venulesDepress myocardium, slow cardiac conduction

Varying selectivity to the above Arteriolar dilatation Afterload

cardiac conduction Heart ratecardiac contractility


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Mechanism of actionBlock L type voltage gated Calcium channels in

arterioles

Reduced Intracellular Calcium

Smooth muscle relaxationDepress cardiac pacemaker cells Negative inotropicand chronotropic action


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Calcium Channel blockersDihydropyridines Less effects on myocardium

nifedipine, amlodipine

Non- dihydropyridines More effects onmyocardium

verapamil, diltiazem


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Adverse effects of Ca ch. blockers Ankle oedemaFlushingHeadache

HypotensionPalpitations


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The Beta Adrenoreceptor blockersBlock cardiac 1adrenoreceptor Heart

rate

cardiac contractility cardiac O 2demand

Also reduces renin secretion from the kidney


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Adverse drug effects of Beta blockers

Bronchoconstriction Caution in asthmaCold extremities

FatigueBradycardiaHypoglycaemia

Precipitation of cardiacfailureBad dreams


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A bad dream..??


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Drugs used in Hypertension


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Factors affecting blood pressure

BLOOD = CARDIAC PERIPHERAL

PRESSURE OUTPUT RESISTANCE(vascular tone)

Heart Rate Stroke Volume


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Renin Angiotensin-Aldosterone

SystemLow renal bloof flowrenin

Angiotensinogen Angiotensin I ACE

Angiotensin I Angiotensin II

Angiotensin II is a powerful vasoconstrictor

Stimulates Aldosterone release Na retension


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ACE Inhibitors- mechanism

Inhibit synthesis of Angiotensin II

vascular resistance

Blood PressureReduced aldosterone

Na/H 2O retension Stroke Vol

BP


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ACE InhibitorsACE I s

captopril, ramipril, lisinoprilAngiotensin Receptor blockers

losartan, candesartan

Particularly useful in diabetic nephropathy

Adverse effects?? find out!


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drugs affecting the cardiovascular system.ppt

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