Community drug MOA, use and handy tips

Question 1

Aspirin

Answer 1

MOA:
COX-1 inhibitor => decreased production thromboxane A2 => decreased platelet activation and stabilisation of clots

Use:
- Risk profiles for cardiovascular protection.
- Analgesia

Note:
- Metabolism of arachidonic acid is blocked resulting in Lukatrine formation => asthma

Question 2

Paracetamol:

Answer 2

MOA:
- Non-selective COX inhibition, including COX-3
This confers some of the analgesic properties
- Inhibition of central prostaglandin synthesis
This confers the antipyretic effect by inhibiting prostaglandin E synthesis in the anterior hypothalamus in response to pyrogens
- Serotonergic inhibition
Provides some additional analgesic action
- Cannabinoid inhibition
Provides some additional analgesic action via endocannabinoid reuptake inhibition.
Use:
- Analgesia

Note:
- Toxic dose = 75mg/kg over 24hours
- Septic patients are more likely to see a BP drop of up to 15mmHg.
- Antidote = NAC (N-acetylcysteine)
- Glutathione deficiencies are responsible for cytotoxicity of paracetamol OD.

Question 3

Benzodiazepines:

Answer 3

MOA:
Potentiates GABA hyper polarising neurone for CNS depression via Cl- influx

Use:
- Anxiety
- Sleeping disorders

Notes:
- Antidote = Flumazenil

Question 4

Amitriptyline

Answer 4

MOA: Tricyclic Antidepressant
- Competitively inhibit reuptake of NA and 5-HT
- Muscarinic antagonism (Leads to anticholinergic side effects.
- H1 and H2 antagonism
- α1 antagonism
- NMDA antagonism

Use:
- anxiety
- depression
- pain management

Note:
- Na channel blockage may result in toxicity with really wide QRS.
- Symptomatic toxic dose >10mg/kg
- serious toxic dose >30mg/kg

Question 5

Fluoxetine

Answer 5

MOA:
- SSRI

Use:
depression
anxiety

Note:
- Serotonin syndrome (altered mental status, motor changes, autonomic instability)

Question 6

Pregabalin:

Answer 6

MOA:
- Are both structural analogues of GABA
Have no direct action on the GABAA receptor
- Act on the α2δ subunit of voltage gated Ca2+ channels in the CNS, inhibiting neurotransmitter release
- May have some NMDA receptor activity

Use:
- anti-epileptic
- nerve pain

Note:
- comes with a lot of side effects (sedation, weight gain, poor quality of sleep)

Question 7

Gabapentin:

Answer 7

MOA:
- Are both structural analogues of GABA
Have no direct action on the GABAA receptor
- Act on the α2δ subunit of voltage gated Ca2+ channels in the CNS, inhibiting neurotransmitter release
- May have some NMDA receptor activity

Use:
- anti-epileptic
- nerve pain

Note:
- comes with a lot of side effects (sedation, weight gain, poor quality of sleep)

Question 8

Ondansetron:

Answer 8

MOA:
peripheral 5-HT3 receptor antagonist => decreased afferent stimulation of vagus nerve to the CTZ.

Use:
antiemetic

Note:
potential QT prolongation

Question 9

Metoclopramide:

Answer 9

MOA:
D2 receptor antagonist

Use:
antiemetic

Note:
contraindicated in
- parkinsons
- previous dystonic reactions
- bowel obstruction (due to gastric emptying)

Question 10

Prochlorperazine

Answer 10

MOA:
Prochlorperazine blocks the D2 dopamine receptors in the brain, which are somatodendritic autoreceptors.

Use:
Vertigo
Antiemetic

Note:
contraindicated in
- parkinsons
- previous dystonic reactions

Question 11

Atorvastatin:

Answer 11

MOA:
competitive inhibitor of the enzyme HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase, which catalyzes the conversion of HMG-CoA to mevalonate, an early rate-limiting step in cholesterol biosynthesis

Use:
Hyperlipidemia
cardio-protective

Notes:
- increased risk of diabetes, arthralgia, dyspepsia, diarrhea, nausea, nasopharyngitis, insomnia, urinary tract infection, and pain in the extremities.

Question 12

Rosvustatin

Answer 12

MOA:
competitive inhibitor of the enzyme HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase, which catalyzes the conversion of HMG-CoA to mevalonate, an early rate-limiting step in cholesterol biosynthesis

Use:
Hyperlipidemia
cardio-protective

Notes:
- increased risk of diabetes, arthralgia, dyspepsia, diarrhea, nausea, nasopharyngitis, insomnia, urinary tract infection, and pain in the extremities.

Question 13

Perindopril

Answer 13

MOA:
Ace inhibitor => inhibits vasoactive mechanism of the drug.

Use:
Hypertension
Heart failure

Notes:
- bradykinin mediated angioedema possible. nebuliser adrenaline is likely not effective. (TXA may be useful).

Ref:
Hasara S, Wilson K, Amatea J, Anderson J. Tranexamic Acid for the Emergency Treatment of Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema. Cureus. 2021;13(9):e18116. Published 2021 Sep 20. doi:10.7759/cureus.18116

Question 14

Amlodipine

Answer 14

MOA:
calcium channel blocker

Use:
heart failure
hypertension

Notes:
- longest lasting Ca+ channel blocker 30-50hrs.
-

Question 15

Candesartan

Answer 15

MOA:
Candesartan selectively blocks the binding of angiotensin II to AT1 in many tissues including vascular smooth muscle and the adrenal glands. This inhibits the AT1-mediated vasoconstrictive and aldosterone-secreting effects of angiotensin II and results in an overall decrease in blood pressure.

Use:
heart failure
hypertension

Notes:

Question 16

Telmisartan

Answer 16

MOA:
interferes with the binding of angiotensin II to the angiotensin II AT1-receptor by binding reversibly and selectively to the receptors in vascular smooth muscle and the adrenal gland.

Use:
Heart failure
Hypertension

Note:

Question 17

Isbesartan

Answer 17

MOA:
Irbesartan prevents angiotensin II binding to the AT1 receptor in tissues like vascular smooth muscle and the adrenal gland.

Use:
Heart failure
Hypertension

Notes:

Question 18

Sertraline

Answer 18

MOA:
Sertraline is a selective serotonin reuptake inhibitor (SSRI)

Use:
major depressive disorder,
social anxiety disorder and many other psychiatric conditions.

Notes:
- may take a long time to reach therapeutic effect.
- risk of Serotonin syndrome.

Question 19

Metformin

Answer 19

MOA:
anti-hyperglycaemic through multimodal effects
- decreases blood glucose levels by decreasing hepatic glucose production (also called gluconeogenesis),
- decreasing the intestinal absorption of glucose, and
- increasing insulin sensitivity by increasing peripheral glucose uptake and utilisation.

Use:
Diabetes mellitus

Notes:
- often pharmacological initial treatment.
- Metformin-associated lactic acidosis can occur acutely in an overdose but typically has a more gradual onset in patients with hepatic or renal dysfunction due to decreased excretion. This is through decreased liver uptake of lactate.

Question 20

Escitalopram

Answer 20

MOA: (SSRI)
Sertraline is a selective serotonin reuptake inhibitor (SSRI)

Use:
major depressive disorder,
social anxiety disorder and many other psychiatric conditions.

Notes:
- may take a long time to reach therapeutic effect.
- risk of Serotonin syndrome.

Question 21

Apixaban

Answer 21

MOA: (anticoagulant)
Apixaban selectively inhibits factor Xa in its free and bound forms, independent of antithrombin III.

Use:
Cardio-protective
Deep vein thrombosis

Notes:

Question 22

Caffine:

Answer 22

MOA:
- Adenosine receptor antagonist.
- cAPM breakdown inhibitor

Use:
helps clinicians treat more effectively

Note:
significantly reduces the effectiveness of adenosine.

Question 23

Quetiapine:

Answer 23

MOA:
Quetiapine antagonises the mesolimbic dopamine (D2), serotonin, histamine the muscarninic M1 and peripheral alpha 1 receptors.

Use:
antidepressants.

Notes:
- OD may see pt’s with hypotension. Importantly these patients have paradoxical hypotension to adrenaline.