ANTIHYPERTENSIVES 1.0 Flashcards by yvonne muiru

Give the classification of antihypertensive drugs

Diuretics
Sympatholytic drugs
Calcium channel blockers
Drugs acting on RAAS
Vasodilators

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Give the Sympatholytic agents for hypertension

1) Alpha receptor antagonists
2) Beta receptor antagonists
3) Mixed beta and alpha receptor antagonists
4) Centrally acting adrenergic receptor agents
5) Adrenergic neuron blocking agents

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Give the centrally acting receptor agonists

Methyldopa
Clonidine
Guanabenz
Guanfacine

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Give the mechanism of action of the centrally acting antihypertensive agents

They act on a2 receptors in the brainstem for sympathetic inhibition by inhibiting release of NE

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What is the function of the a2 receptors

When stimulated they inhibit NE release through feedback mechanism

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What type of G protein coupled receptor is a2 receptor

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Methyldopa is termed as a prodrug , explain

Methyldopa is converted to its active form methylnorepinephrine that works to stimulate the a2 receptors in the brainstem thus inhibiting NE release

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Give five PK of methyldopa

1) Taken orally
2) Rapidly absorbed
3) Metabolized in the brain
4) Half life of two hours
5) Excreted in urine as sulfate conjugate(50-70%) and parent drug (25%)

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Give uses of Methyldopa

Used as a hypertensive drug in pregnancy

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Give the A/E of methyldopa

Dry mouth , Sedation , Hemolytic anemia (discontinue) , Positive Coombs test , Thrombocytopenia , Leukopenia , Red cell Aplasia , Prolactinemia , Parkinsonism

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Clonidine is said to have two a2 receptor effects , give them

A2a stimulation in brainstem to reduce NE release
A2b stimulation in bloodvessels to bring vasoconstriction (high doses)

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Clonidine reduces blood pressure by reducing the CO and PVR ,Explain

BP = CO X PVR
Clonidine reduces the CO in supine by
Reducing the HR , Stroke volume and myocardial contractility
It reduces the PVR in postural position

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Reduction in the Myocardial contractility of Clonidine can predispose a patient to

Congestive Heart failure

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Give atleast 10 A/E of Clonidine

sedation , dry mouth, nose and eyes , Erectile dysfunction , vivid dreams , depression , restlessness , sinus arrest , postural hypotension

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To treat the withdrawl that comes fro sudden discontinuation , three things can be done?

1) Restore the drugs
2) Give sodium nitroprusside
3) Hive mixed alpha and beta blockers

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Sudden discontinuation of Clonidine can lead to withdrawl effects such as

Headaches , Tremors , Apprehension , Abdominal pain , Tachycardia , Rebound hypertension

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Clonidine is rarely used for hypertension. Give an important use of Clonidine.

Diagnosis of Phaeochromocytoma

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Give two main Adrenergic blocking agents

Reserpine and Guanethidine

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Give the mechanism of action of Guanethidine

Transported into the presynaptic membrane by NET transporters and stored in the NE vesicles thus deplets NE stores

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Give the mechanism of action of Guanethidine

Transported into the presynaptic membrane by NET transporters and stored in the NE vesicles thus deplets NE stores

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NET is inhibited by

Cocaine , Amphetamine, Tricyclic antidepressants , Phenoxybenzamine

Give the PK of Guanethidine

Has a long half life of 5 days
Gradual onset of sympathoplegia with maximal effect in 2 weeks
Persisiting sympathoplegia even after cessation
Titrate dose of drug in 2week interval

Give four A/E of Guanethidine

1) Postural hypotension
2) Retrograde ejaculation
3) Diarrhea
4) Hypertensive crisis in pheochromocytoma

Give two main DDI in Guanethidine

Sympathomimetic agents - worsen hypertension
Tricyclic antidepressants

Give the MOA of reserpine

Irreversibly Blocks the vessicle associated membrane transporter thus depletion of NE, serotonin and dopamine stores

Give A/E of Reserpine

Severe depression ( discontinue) Sedation Nightmares Parkinsonism Postural hypotension GIT problems

Alpha receptor antagonists may be grouped into 3

1) Non selective 2) Selective 3) Ergot alkaloids

Give the non-selective alpha receptor antagonists.

PPUTY Phenoxybenzamine Phentolamine Urapidil Tolazoline Yohimbine

Give the non-selective alpha receptor antagonists preferrentials

Phenoxybenzamine - a1 more than a2 Phentolamine - a1=a2 Urapidil - a1 more than a2 Tolazoline and Yohimbine - a2 more than a1

Give the selective alpha receptor antagonists

PTTD Prazosin , Terazosin , Trimazosin , Doxasozin TA Tamsulosin and Alfuzosin

Give the types of beta receptor antagonists

1) Non-selective 2) Selective 3) Combined

Give the none selective beta blockers

Propranolol Pindolol Timolol

Give examples of selective beta blockers

b1 - Metoprolol, Betaxolol ,bisprolol ,atenolol, acebutolol, Tolamolol b2 - butoxamine

Give the mixed alpha and beta receptor antagonists

Labetolol Carvedilol

Give the MOA of Phenoxybenzamine

Irreversibly blocks alpha adrenoreceptors and thus reduce vasoconstriction cause by norepinehrine and epinenphrine

What is the main clinical use of phenoxybenzamine

Pre and intra operative management of pheochromocytoma

Give the A/E of phenoxybenzamine

Postural hypotension Dry mouth Inhibiton of ejaculation Nasal stuffiness Miosis

Give three absolute C/I of Phenoxybenzamine

Porphyria Hypovolemic states History of cerebrovascular accidents

Give relative C/I of phenoxybenzamine

Elderly patients Pregnancy Renal imparement Marked arterioscleorsis

ACE inhibitors have 2 main types of moa

1) Prevent conversion of Angiotensin I to II which is a potent vasocntrictor 2) Inhibits breakdown of bradykinin thus causes its accumulation and an increase in nitric oxide and prostacyclin which are potent vasodilator

ACE inhibitors have 2 main types of moa

ACE inhibitors are used in which type of hypertensive pateints

Patients with co morbidities such as diabetes ,

All ACE inhibitors are guven orally except

Enalaprilat

All ACE inhibitors are eliminated by the kidneys except

Fosinopril

All ACEIs undego hepatic metabolism to active metabolites except

Captopril and Lisinopril

ACEIs adverse effects include

Dry cough , rash , fever , altered taste , hypotension and hyperkalemia

What rare but life threatening A/E may be associated with ACEIs

Angioedemea

Which two things must be monitored in patients using ACE inhibitors

1) Potassium 2) Serum creatinie

Give two examples of ARBs

Losartan and irbersartan

ARBs are similar to ACE inhibitors but differ in one of the mechanisms

ARBs do not increase bradykinin levels

Give a C/I for ACE inhibitors and ARBs

Pregnancy - teratogenic

Give the three main classes of drug sas RAAS modulators and examples

1) ACE inhibitors - Lisinopril , Etanapril 2) ARBs - Losartan , 3) Direct Renin inhibitors - Aliskerin