OSPE - Drug mechanisms of action

Question 1

Salbutamol

Answer 1

Agonist which causes adenylyl cyclase to increase cAMP resulting in decreased intracellular calcium ion concentration. Resulting in smooth muscle vasodilation and bronchodilation

Question 2

Nifedipine

Answer 2

Channel Blocker

Inhibits the influx of Ca2+ in smooth muscle cells, decreasing vasoconstriction

Question 3

Enalapril

Answer 3

Competitively inhibits ACE which prevents Angiotensin I conversion to Angiotensin II and lowers levels of angiotensin II which lowers vasoconstriction.

Question 4

Simvastatin

Answer 4

Competitive inhibitor of HMG-CoA reductase, the enzyme catalysing the rate-limiting step of cholesterol synthesis, which decreases hepatic cholesterol concentrations.

Question 5

Aspirin

Answer 5

Analgesic, antipyretic, and anti-inflammatory effects due to direct and irreversible inhibition of COX-1 and COX-2 leading to decreased formation of the precursors of prostaglandins and thromboxanes from arachidonic acid.

Inhibition of platelet aggregation caused by irreversible acetylation and inactivation of platelet COX, which blocks the formation of the aggregating agent thromboxane A2.

Question 6

Fluoxetine

Answer 6

Inhibitor

Increase serotonin stimulation of somatodendritic and terminal 5HT receptors

Question 7

Metoprolol

Answer 7

Prevents binding of norepinephrine to beta 1-adrenergic receptors in cardiac myocytes

Question 8

Imatinib

Answer 8

Protein-tyrosine kinase inhibitor that inhibits proliferation and induces apoptosis in Bcr-Abl leukemic cells from Philadelphia chromosome positive chronic myeloid leukemia (CML) and as such is an antineoplastic agent.

Question 9

Fentanyl

Answer 9

mu opioid receptor agonist causing decreased Ca2+ influx which results in decreased repolarization time and thus decreased action potential duration.

Question 10

Rituximab

Answer 10

Monoclonal antibody

Binds to the antigen on B lymphocytes, recruits antibodies and complements to mediate cell killing

Question 11

Diazepam

Answer 11

Increases chloride ion influx across the chloride ion channel pore at the centre of the GABAa subunit which hyperpolarizes the neuron’s membrane potential leading to a greater difference between resting potential and threshold.

Question 12

Sildenafil

Answer 12

Blocks the degredation of cGMP which leads to vasodilation of smooth muscle

Question 13

Clopidogrel

Answer 13

Inhibits ADP-induced platelet aggregation via irreversible inhibition of the P2Y12 subtype of ADP receptors.

Question 14

Ranitidine

Answer 14

Competitive inhibition of H2 receptors on parietal cells leads to supression of gastric acid secretion.

Question 15

Vancomycin

Answer 15

Prevents incorporation of NAM and NAG peptides into the peptidoglycan matrix, inhibiting cell wall synthesis

Question 16

Metformin

Answer 16

Induces activation of AMPK and decreases Glc production and absorbtion and increases insulin mediated glucose uptake

Question 17

Furosemide

Answer 17

Competitively binds the Cl- binding site resulting in the inhibition of reabsorption of sodium, potassium and chlorine.

Question 18

Prednisolone

Answer 18

GR homodimers bind to glucocorticoid response elements in the promoter region of steroid-sensitive genes causing the up-regulation of anti-inflammatory proteins.