Receptor Target and Mode Of Action

Question 1

Furosemide

Answer 1

Competitive inhibition of sodium-potassium-chloride cotransporters (NKCC2).

MOA: Inhibits reabsorption of sodium and chloride ions at the loop of Henle, increasing excretion of these ions = increased urine output and decreased BP.

Question 2

Codeine

Answer 2

Mu opioid receptor agonist.

When bound to Mu opioid receptors, inhibits transmission of pain signals.

Question 3

NSAID’s

Answer 3

Inhibits COX enzyme.

Inhibition of COX enzyme leads to decrease in production of prostaglandin.

Question 4

Metoprolol and Atenolol

Answer 4

Blocks adrenaline and noradrenaline at the Beta 1 adrenergic receptors.

Reduces the sympathetic response = lower HR and decreased cardiac output.

Question 5

Cilazapril

Answer 5

Inhibits angiotensin-converting enzyme (ACE) so that angiotensin I cannot be converted to angiotensin II.

Less angiotensin II = decrease in BP.

Question 6

Cyclizine

Answer 6

Antagonist at H1 histamine receptors.

Affects gut motility, reducing N+V. Also has anticholinergic effects.

Question 7

Ondansetron

Answer 7

Antagonist at the serotonin 5-HT3 receptor.

Blocks the action of serotonin at this receptor, which reduces N+V.

Question 8

Morphine

Answer 8

Agonist at Mu opioid receptor.

When bound to opioid receptors, inhibits transmission of pain signals.

Question 9

Naloxone

Answer 9

Antagonist at Mu opioid receptor.

Blocks opioids from binding to opioid receptors, reversing opioid effects and overdose.

Question 10

Digoxin

Answer 10

Binds to the extracellular domain of the sodium-potassium ATPase enzyme in the cell membrane of cardiac myocytes.

Inhibits the action of the sodium-potassium ATPase enzyme, increasing intracellular sodium and calcium in the myocardial cells, causing increased contractile force of the heart and decrease in HR.

Question 11

Diltiazem, Amlodipine, Verapamil

Answer 11

Blocks L-type calcium channels in the smooth muscle cells of blood vessels and cardiac myocytes.

Prevents calcium from entering cells = relaxation of smooth muscle cells and vasodilation = decreased oxygen demand of the heart.

Question 12

Tramadol

Answer 12

Mu opioid receptor agonist and weak SNRI.

When bound to opioid receptors, inhibits transmission of pain signals. Weakly inhibits reuptake of serotonin and norepinephrine.

Question 13

Paracetamol

Answer 13

Inhibits COX enzyme.

COX inhibition leads to decrease in prostaglandin production.

Question 14

Salbutamol

Answer 14

Agonist at the beta 2 adrenergic receptors in the lungs.

When bound to the beta 2 adrenergic receptors, it relaxes the smooth muscle cells in the lungs which causes bronchodilation. Short acting.

Question 15

Beclomethasone

Answer 15

Suppresses the actions of inflammatory cells, such as mast cells, eosinophils, basophils, lymphocytes, macrophages, and neutrophils. It also inhibits the release of inflammatory mediators, such as histamine, eicosanoids, leukotrienes, and cytokines.

Inhibiting the inflammatory response leads to decreased airway hyper-reactivity, improved lung function and decrease in asthma symptoms.

Question 16

Warfarin

Answer 16

Competitive vitamin K antagonist. Inhibits production of vitamin K by vitamin K epoxide reductase.

With less vitamin K availability, synthesis of active clotting factors is also reduced, thereby reducing clot formation.

Question 17

Carvedilol

Answer 17

Antagonist at beta 1, beta 2 and alpha 1 adrenergic receptors.

Blocking at beta receptors reduces sympathetic response, decreasing HR, BP and cardiac output. Blocking at alpha 1 receptor relaxes smooth muscle cells in vessels, increasing blood flow to the heart and reducing peripheral resistance.

Question 18

Ketamine

Answer 18

N-methyl-D-aspartate (NMDA) receptor antagonist.

Inhibits excitatory signals in the brain.

Question 19

Omeprazole

Answer 19

Inhibits hydrogen potassium ATPase enzyme in the parietal cells of the stomach lining.

Inhibiting this enzyme decreases the amount of stomach acid secreted by it.

Question 20

Metoclopramide

Answer 20

Antagonist at D2 dopamine receptors in the gut.

This increases gut motility, decreasing N+V.

Question 21

Atropine

Answer 21

Antagonist at muscarinic acetylcholine receptors.

Decreases parasympathetic activity and can raise HR in bradycardia.

Question 22

Adrenaline

Answer 22

Agonist at adrenergic receptors throughout the body.

Stimulates sympathetic nervous system, leading to increased HR, BP and bronchodilation.

Question 23

Acetylcysteine

Answer 23

Precursor of the amino acid L-cysteine.

L-cysteine is converted into glutathione - a powerful antioxidant which helps protect cells from oxidative stress.

Paracetamol antidote.

Question 24

Propofol

Answer 24

Stops GABA from disassociating from GABA receptors.

Increases GABA-mediated inhibitory action in the brain.

Question 25

Lignocaine

Answer 25

Inhibits voltage-gated sodium channels.

This prevents propagation of nerve fibre signals.

Question 26

Midazolam

Answer 26

Binds to benzodiazapine site on GABA receptors.

Increases the action of GABA in the brain.

Question 27

Lactulose

Answer 27

Draws water into the colon.

Question 28

Biscodyl

Answer 28

Stimulates nerve endings in the lining of the intestine.

This leads to increased movement and contractions of intestinal wall muscles.

Question 29

Docusate + Senna

Answer 29

Docusate breaks up surface tension of stool, allowing water and lipids to penetrate. Senna increases contractions in the intestines.

Question 30

Atorvastatin

Answer 30

Inhibits HMG-CoA reductase enzyme.

This enzyme produces cholesterol.

Question 31

Bezafibrate

Answer 31

PPAR-alpha receptor agonist.

Leads to increase in the expression of genes that control lipid metabolism.

Question 32

Salmeterol

Answer 32

Agonist at the Beta 2 adrenergic receptors in the lungs.

Relaxes smooth muscle, leading to bronchodilation.

Same as salbutamol, but long acting.

Question 33

Ipratropium

Answer 33

Antagonist at the M3 muscarinic acetylcholine receptors in the smooth muscle of the airways.

Relaxation of smooth muscle, improved airflow and bronchodilation.

Question 34

Theophylline

Answer 34

Inhibits adrenoreceptors in the lungs.

Smooth muscle relaxation - bronchodilation.

Question 35

Montelukast

Answer 35

Leukotriene receptor antagonist.

Reduces inflammation in the lungs.

Question 36

Prednisone, fluticasone

Answer 36

Glucocorticoid receptor agonist (synthetic cortisol)

Activates genes that trigger suppression of inflammation.

Question 37

Fludrocortisone

Answer 37

Mineralcorticoid receptor agonist in the kidneys (synthetic aldosterone)

Increases reabsorption of sodium and water, which increases BP.

Question 38

Dopamine

Answer 38

Agonist at beta-adrenoceptors.

Produces positive chronotropic and inotropic effects on the myocardium, resulting in increased heart rate and cardiac contractility.

Question 39

Bendroflumethiazide

Answer 39

Inhibits sodium-chloride cotransporters.

Inhibits chloride reabsorption from the tubules, resulting in increased excretion of sodium, chloride and water. Increases urine output - decreases BP.

Question 40

Spironolactone

Answer 40

Mineralcorticoid (aldosterone) receptor antagonist.

Competitively inhibits mineralcorticoid receptors in the distal convoluted tubule to increase sodium and water excretion and potassium retention.

Question 41

Hyoscine

Answer 41

Muscarinic acetylcholine receptor antagonist.

Blocks effects of acetylcholine at muscarinic receptors, decreasing N+V.