Hypertension

Question 1

Alpha 2 agonists in the brain.

Answer 1

Clonidine and Alpha-methyl dopa

Question 2

The effect of α methyl dopa;

Answer 2

is due to its conversion to α methyl norepinephrine (α methyl dopa is a prodrug and converted to its active metabolite in the brain).

Clonidine acts directly.

Question 3

Sedation

Answer 3

Can be caused by Clonidine and Alpha-methyl dopa.

Question 4

Rebound hypertension

Answer 4

Abrupt discontinuation of clonidine therapy can lead to rebound hypertension.

(treated by phentolamine)

Question 5

Hemolytic anemia

Answer 5

Methyl dopa can cause hemolytic anemia as an adverse effect.

Question 6

Which alpha-2 agonist drug is preferred in pregnancy?

Answer 6

Alpha-methyl dopa.

Question 7

Clonidine and IV route.

Answer 7

Clonidine, if administered by i.v. route initially leads to rapid rise in blood pressure followed by prolonged fall. The initial rise is due to the activation of vascular post-synaptic α2 receptors by high concentration of clonidine.

Oral dose is slowly absorbed and such high concentrations are not attained, so orally it results only in antihypertensive effects.

Question 8

Congeners of clonidine with longer half lives.

Answer 8

New drugs like moxonidine and rilmenidine are congeners of clonidine with longer half lives.

These drugs are selective for imidazoline receptors that modulate the central α2 receptor activity.

Question 9

β1 receptor antagonists

Answer 9

Atenolol, Metoprolol and Propanolol

β1 receptor antagonists like atenolol, metoprolol and propanolol etc. can also produce reduction in the central sympathetic outflow by inhibiting the β1 receptors, which increase the central sympathetic outflow.

Question 10

Sympathoplegics; prolonged use.

Answer 10

All of these drugs can result in sodium and water retention on prolonged use. Diuretics can be added to these agents to restore the sensitivity.

Question 11

About Methyldopa side effects.

Answer 11

Methyldopa occasionally causes hematologic immunotoxicity, detected initially by test tube agglutination of red blood cells (positive Coombs’ test) and in some patients progressing to hemolytic anemia.

Question 12

Baroreceptor-Sensitizing Agents

Answer 12

A few natural products, such as veratrum alkaloids, appear to increase sensitivity of baroreceptor sensory nerves and reduce SANS outflow while increasing vagal tone to the heart.

These agents are toxic and no clinically available drugs act at this site.

Question 13

Ganglion blocking drugs; About

Answer 13

These drugs inhibit the Nn type of nicotinic receptors that are present on the autonomic ganglia (both sympathetic and parasympathetic).

The therapeutic effect (decrease in blood pressure) is due to the decrease in neurotransmission through sympathetic ganglia.

Question 14

Ganglion blockers

Answer 14

1. Hexamethonium
2. Trimethaphan
3. Mecamylamine

Question 15

Adverse effects of ganglion blockers.

Answer 15

Decreased transmission through parasympathetic ganglia is responsible for the adverse effects like urinary retention and dry mouth.

Question 16

Hexamethonium and trimethaphan

Answer 16

Hexamethonium and trimethaphan are the drugs in this group and are used rarely because of availability of drugs with lesser adverse effects.

Question 17

What is used along with trimethaphan?

Answer 17

Trimethapan, is used along with nitroprusside as a slow i.v. infusion for hypertensive emergencies in aortic dissection.

Question 18

Mecamylamine

Answer 18

Mecamylamine is a ganglion blocker used for smoking cessation.

Question 19

Adrenergic Neuron Blockers

Answer 19

Drugs of this group deplete the sympathetic neurotransmitter and thus decrease the sympathetic system activity.

Reserpine, Bretylium & Guanethidine

Rarely used now.

Question 20

Reserpine

Answer 20

Reserpine inhibits the vesicular uptake of neurotransmitters causing depletion of adrenaline, dopamine and serotonin in the synaptic vesicles.

Due to deficiency of serotonin in the brain, severe depression can result with use of reserpine sometimes leading to suicidal tendencies.

Question 21

Guanethidine & Bretylium

Answer 21

Guanethidine and bretylium is taken up inside the synaptic vesicles and displaces the stored noradrenaline (which is metabolized), resulting in the decreased neurotransmission.

Both of these drugs can be given orally.

These drugs can cause postural hypotension even if used for prolonged periods (unlike α blockers this is not first dose phenomenon).

Question 22

Adrenergic receptors are α and β receptors.

Answer 22

Alpha 1 is present on the smooth muscles of blood vessels (cause vasoconstriction)

β1 is present mainly in the myocardium (causing increased heart rate and cardiac output) and juxtaglomerular (JG) cells of the kidney (stimulate renin release)

Question 23

Alpha adrenergic blockers