Revision Drug Names, Functions and Facts

Question 1

Codeine:

Answer 1

Function: Opioid agonist painkiller.

Facts:
- Relatively low affinity for opioid receptors until metabolised by the CytP450 system.
- Metabolised into active form, morphine.

Mechanism of action:
- Mu opioid receptor agonist, see morphine.

Question 2

Clopidogrel:

Answer 2

Function: Anti-platelet medication used for heart attack and stroke victims.

Facts:
- Inactive until metabolised by the CytP450 system in liver.

Mechanism of action:
- Irreversibly inhibits the P2Y12 component of ADP receptors.
- Two ADP receptors on platelets, P2Y1 and P2Y12, P2Y12 activation causes downstream effects resulting in proliferation. One effect is inhibition of adenylyl cyclase, decreasing cAMP levels (GPCR).

Question 3

Morphine:

Answer 3

Function: Pain medication.

Facts:
- Comes from poppy seeds originally
- UGT system enzymes glucuronidate morphine into inactive form, and makes it polar, and thus hydrophilic allowing elimination via kidneys.

Mechanism of action:
- Mostly targets mu-opioid receptors.
- G protein-coupled receptor, ligand binding causes structural changes in receptor and G-protein, GDP swapped for GTP, alpha G portion dissociates from beta- and gamma- portions.
- alpha-G inhibits adenylyl cyclase, resulting in lower cAMP, thus PKA.
- Lower PKA results in the inhibition of Ca2+ voltage channels at presynaptic neuron, and opening of K+ channels, less action potential.
- Less excitatory neurotransmitters released (substance P and glutamate), less pain.

Question 4

Statins:

Answer 4

Function: Lowers LDL-C (low-density lipoprotein cholesterol) concentration in serum.

Mechanism of action:
- Inhibits HMG-CoA reductase, stopping cholesterol synthesis in the liver.
- As a result, liver cells upregulate LDL-C receptors, taking more from the blood, so less cholesterol and triglycerides.

Question 5

Grapefruit juice:

Answer 5

Mechanism of action:
- ‘Furanocoumarins’ present in juice inhibit CYP3A4 enzymes in small intestine, these can metabolise statins.

• Patients on statins required to refrain from drinking grapefruit juice, or limit consumption.

Question 6

Ritonavir:

Answer 6

Function: CYP3A4 inhibitor.

Facts:
- Original purpose was antiretroviral against HIV.

Mechanism of action:
- See function.

Question 7

Ibrutinib:

Answer 7

Function: Chemotherapy drug, useful against leukaemias and lymphomas.

Facts:
- Bruton’s tyrosine kinase facilitates proliferation of WBCs
- B-cell lymphomas commonly upregulate BTK.

Mechanism of action:
- Inhibits Bruton’s tyrosine kinase.
- Reduces cell proliferation.

Question 8

Warfarin:

Answer 8

Function: Anti-coagulant.

Facts:
- Can be displaced from plasma proteins by fluoxetine
- CYP2D6 enzyme also competitively inhibited by fluoxetine, affects metabolism
- Mainly metabolised by CYP2C9

Mechanism of action:
- Inhibits vitamin K epoxide reductase, vital in vitamin K synthesis. Vitamin K vital in blood clotting, used as cofactor for clotting factors (II (prothrombin)

Question 9

Fluoxetine:

Answer 9

Function: Anti-depressant

Facts:
- Inhibits CYP2D6 in liver, can interact with other drugs via this. Such as warfarin, though this is moreso from the plasma protein displacement effect.

Mechanism of action:
- Blocks serotonin reuptake channel proteins in presynaptic membrane.

Question 10

Aspirin:

Answer 10

Function: Painkiller/Anti Inflammatory

Facts:
- Prodrug
- Activated by esterases in the GI tract and liver (~80% in liver)
to form salicylic acid from acetylsalicylic acid.
- Inhibition of target is completely irreversible.
- Metabolised by UGT mainly, and CYP2C9.

Mechanism of action:
- Inhibits COX-1 and 2 enzymes.
- COX-1 and 2 responsible for arachidonic acid cascade to produce prostaglandins, which can be responsible for pain and fever, but also gastric protection in the case of COX-1.

Question 11

Celecoxib:

Answer 11

Function: Painkiller/ Anti Inflammatory

Mechanism of Action:
- Selectively inhibits COX-2, responsible more specifically for the prostaglandins responsible for fever and pain in arachidonic acid cascade. Avoids gastric side effects such as ulcers seen in continuous aspirin use.

Question 12

L-DOPA + Carbidopa:

Answer 12

Function: Dopamine treatment for Parkinson’s.

Mechanism of Action:
- L-DOPA is a precursor to dopamine and is converted by DOPA decarboxylase.
- Don’t want excess dopamine metabolism outside of the brain, so Carbidopa (designed to not cross BBB) inhibits DOPA decarboxylase.

Question 13

Ethanol:

Answer 13

Function: シ

Facts:
- Zero-order kinetic drug.
- 10mg/hour metabolised by alcohol dehydrogenase to acetaldehyde, a toxic compound that is responsible for hangovers.

Mechanism of Action:
- Acts as an agonist for GABA receptors, and weakly for glycine receptors. Inhibitory on brain.
- Inhibitor of NMDA receptors in higher concentrations, responsible for brain plasticity and memory making, drinking too much can cause blackout.

Question 14

Disulfiram (Antabuse):

Answer 14

Function: Management of alcohol abuse.

Mechanism of Action:
- Inhibits aldehyde dehydrogenase, which normally quickly converts acetaldehyde into acetic acid.
- Higher levels of acetaldehyde cause extremely unpleasant, hangover-like effects.

Question 15

Benzodiazepines:

Answer 15

Function: Anxiolytic/Sedative drug

Facts:
- The target, GABA receptors, are ion channel-linked receptors. Binding of ligand opens these and Cl- ions flow into neuron,

Mechanism of Action:
- Enhances the binding of GABA to its receptor, prevents inhibition by this neurotransmitter.
- Inhibition results in less release of neurotransmitters such as glutamate, norepinephrine, dopamine, serotonin.

Question 16

Propranolol:

Answer 16

Function: Decrease heart rate and contractility.

Facts:
- The class of drugs are called ‘Beta-blockers’, because the target is beta-adrenergic receptors.

Mechanism of Action:
- Non-selective beta-blocker, targets beta-1 and beta-2 adrenergic receptors.
- These receptors are GPCRs that when stimulated by norepinephrine and epinephrine in the sympathetic nervous response to increase heart rate and contractility.
- Stops binding of these neurotransmitters.

Question 17

Amlodipine:

Answer 17

Function: Increased systemic vasodilation of arteries, lowering blood pressure. Heart doesn’t work as hard and pain in chest is reduced.

Facts:
- It is a ‘dihydropyridine

Mechanism of Action:
- Calcium channel blocker, blocks L-type voltage-gated calcium channels (in the vasculature mostly).
- These channels predominantly found in smooth muscle of blood vessels and in the heart muscle.
- Blocks influx of calcium into smooth muscle, necessary for contraction.

Question 18

Digoxin:

Answer 18

Function: Increases contractility of the heart muscle, and steadies the heart rate (vagus nerve effects). Used in heart failure and arrhythmia.

Facts:
- Derived from the Digitalis plant

Mechanism of Action:
- Inhibits sodium-potassium pump, and in cardiac muscle cells, this causes build-up of Na+.
- Sodium-calcium exchange protein relies on export of 1 Ca2+ ion for 3 Na+ ions, when many Na+ in cell, pump is less efficient.
- Increase in Ca2+ causes positive inotropic effect (more actin/myosin interactions).
- Increased Ca2+ in baroreceptors (pressure receptors in heart), leads to stimulation of the vagus nerve, and a steadying of heart rate.

Question 19

Verapamil:

Answer 19

Function: Negative inotropic effect, and negative chronotropic effect.

Facts:
- Belongs to group ‘non-dihydropyridines’.

Mechanism of action:
- Blocks L-type calcium channels (in the heart mostly)
- Decreases levels of Ca2+ in cardiac muscle cells
- Less interaction of actin and myosin, negative inotropic effect.
- Lower calcium leads to reduced firing of the sinoatrial node, negative chronotropic effect.
- Lower calcium causes negative dromotropic effect on AV node, leading to a steadier heart rate.

Question 20

Heroin:

Answer 20

Function: Narcotic

Facts:
- Most heroin deacetylated in the liver to 6-monoacetylmorphine, then to morphine.
- ‘Diacetylmorphine’ can cross the blood-brain barrier
- Also deacetylated in the brain to intermediate 6-MAM, which is also more potent than morphine.

Mechanism of Action:
- Same as morphine.

Question 21

Fosinopril:

Answer 21

Function: Lowers blood pressure and increases blood flow to the heart. Used to treat hypertension.

Facts:
- Angiotensin II is the main effector molecule in renin-angiotensin-aldosterone system, playing a critical role in the blood pressure, fluid and electrolyte balance.
- When blood pressure falls, decrease in NaCl in kidneys, renin cleaves angiotensinogen to become angiotensin I, ACE primarily in lungs converts to angiotensin II.
- Angiotensin II vasoconstrictor, stimulates release of aldosterone (promotes sodium and water retention in kidneys) and also triggers release of antidiuretic hormone.

Mechanism of Action:
- Inhibits ACE in lungs.
- Less angiotensin II
- Blood pressure drop, blood volume drop, and promotes diuresis.

Question 22

Angiotensin II type 1 receptor blockers:

Answer 22

Function: Lower blood pressure and volume

Facts:
- Avoids inhibiting angiotensin II action on potentially protective effects from type 2 receptors, such as vasodilation and anti-inflammatory effects.

Mechanism of Action:
- Inhibits the GPCR Angiotensin II type 1.
- Angiotensin II cannot exert vasoconstrictive, fluid retention effects.

Question 23

Nitrates:
(Nitroglycerine)

Answer 23

Function: Relieves chest pain associated with coronary heart disease. Protect heart by decreasing work done by heart and increasing blood flow to heart (coronary arteries).

Mechanism of Action:
- Converted to nitric oxide in the body
- Nitric oxide stimulates guanylate cyclase, increased cGMP.
- Higher cGMP leads to increase in protein kinase G.
- Higher PKG leads to vasodilation of smooth muscle.

Question 24

Loop diuretics:

Answer 24

Function: Management of fluid overload syndromes (e.g. in heart failure), and edema.

Facts:
- Called so because it affects ‘Loop of Henle’

Mechanism of Action:
- Inhibits the Na/K/2Cl cotransporter in Loop of Henle.
- No ion movement out of Loop of Henle to blood.
- No reabsorption of water into blood at this point.

Question 25

Trastuzumab:

Answer 25

Function: Chemotherapy drug.

Facts:
- Significantly has increased survival in patients with HER2-positive breast cancer (20-30% express it).
- HER2

Function:
- Blocks the binding of ligands to HER2.
- HER2 is a RTK upregulated in some breast cancers.
- HER2 can involve Ras-MAPK pathway or PIK3-AKT pathway.
- Upregulation leads to increased cell survival, proliferation.

Question 26

Rituximab:

Answer 26

Function: Monoclonal antibody for Hodgkin’s Lymphoma subtype (Nodular Lymphocyte-Predominant HL).

Mechanism of Action:
- Binds to CD20, highly expressed in NLPHL.
- Stimulates immune system to attack it.

Question 27

Prednisone:

Answer 27

Function: Corticosteroid Immunosuppressant.

Facts:
- Prodrug
- Metabolised by 11-beta-hydroxysteroid dehydrogenase (11B-HSD) to form Prednisolone.

Mechanism of Action:
- Prednisolone binds to glucocorticoid receptors on various cells around the body, and receptor-prednisolone complex is endocytosed.
- Once at the nucleus, it binds to glucocorticoid response elements (GREs) in the DNA.
- This binding to GREs influences the gene expression of various genes.
- Up-regulation of anti-inflammatory genes, down-regulation of pro-inflammatory cytokines, reduces activity of COX.
- Also down-regulates some genes associated with NO2 production, a vasodilator, resulting in vasoconstriction.

Question 28

Vincristine:

Answer 28

Function: Useful for treating several cancers (ALL, AML, Hodgkin’s Lymphoma).

Facts:
- Isolated from Madagascar Periwinkle.
- 0.0003% yield from plant
- Causes side effects such as hair loss, neuropathic pain, and low white cell numbers.

Mechanism of Action:
- Binds to tubulin dimers in cells, prevents microtubule formation in mitosis, preventing it. Useful for cancers as these divide frequently.

Question 29

St John’s Wort:

Answer 29

Function: SSRI-like

Facts:
- Cannot be taken with SSRIs

Mechanism of Action:
- Binds to TRPC6 receptors, causing an influx of Ca2+ and Na+ ions in neuron.
- Not fully understood, but leads to reuptake of serotonin, norepinephrine, dopamine.

Question 30

Artemisinin:

Answer 30

Function: Antimalarial drug

Facts:
- Project 523 started to aid Vietnam in their war, by producing an antimalarial medicine.
- Isolated from the Artemisia annua plant by Dr. Tu Youyou and her team in 1972.
- First clinical trials published in 1979.

Mechanism of Action:
- Artemisinin is a prodrug, metabolised to

Question 31

Psilocybin:

Answer 31

Function: Potential depression, PTSD, anxiety, OCD treatment.