Pharmacology

Question 1

How do anti-coagulants work?

Answer 1

Work on different areas of clotting cascade:

—Heparin (UFH) - on Antithrombin III
—LMWH - inhibit Xa
—DOACs - inhibit Xa or direct thrombin inhibitors
—Warfarin - inhibits enzyme for Vit K dependent clotting factors

Anti-platelet agents too

Question 2

How do antibiotics work?

Answer 2

These are drugs that selectively kill or inhibit the growth of bacteria (bacteriocidal vs bacteriostatic) and are classified into:
—Inhibition of cell wall synthesis e.g. penicillins
—Inhibition of protein synthesis (ribosomes 30S and 50S) e.g. tetracyclines/aminoglycosides
—Inhibition of nucleic acid synthesis e.g. quinolones, metronidazole

Question 3

How do anti-hypertensives work?

Answer 3

Anti-hypertensives are drugs that work on the components of cardiac output and systemic vascular resistance to reduce BP.
They are classified into ACEi, Alphablockers, Betablockers, Calcium channel blockers, diuretics

Question 4

How do ACEi work?

Answer 4

ACEis work on the RAAS.
They prevent the conversion of Angiotensin I into Angiotensin II and reduce the metabolism of bradykinin

Angiotensin II:
— a potent vasoconstrictor (both slowly and rapidly)
— activates aldosterone and ADH secretion
— causes vascular hypertrophy/remodelling (hence why blocked post MI) by growth factors

Question 5

Describe calcium channel blockers

Answer 5

Act on L type calcium channels in vascular smooth muscle and in myocardial/nodal tissues

Rate limiting vs vascular type

3 drug types (Verapamil, Diltiazem, Amlodipine)

Question 6

How do alpha blockers work?

Answer 6

Treatment of hypertension
Target post-ganglionic alpha1 leading to peripheral vasodilatation and decreased SVR
Can be selective or non selective

Question 7

How do beta blockers work?

Answer 7

Selective or non selective effects on beta-1 and beta-2 adrenoceptors

Question 8

What is an isomer?

Answer 8

Same molecular formula, different structural arrangement
—Structural
-Chain
-Positional
-Functional
—Stereo
-Enantiomers
-Cis-trans

Question 9

What drugs act on the NMJ?

Answer 9

1. Inhibitors of vesicle exocytosis:
   —Mg
   —Aminoglycosides
2. Blockage of AChR:
   —NMBDs - depolarising and non-depolarising
3. AChE inhibitors:
   —Neostigmine

Muscarinic ACh receptors: metabotropic G protein couple receptor
Nicotinic ACh receptors: ligand gated ion channel

Question 10

How do anti-fungals work?

Answer 10

Azoles: fluconazole, ketoconazole
Echinocandins: caspofungin
Polyenes: Amphoteracin B
Other: Nystatin

MoA:
—Cell wall
—Cell membrane
—Cell nucleus - DNA/RNA synthesis

Question 11

What is the odds ratio?

Answer 11

Quantifies the strength of the association between 2 events, and identifies how likely an exposure is to lead to a specific event

The odds of the outcome of interest occuring after the first intervention divided by the odds of the outcome of interest occuring after the second intervention, where there are 2 mutually exclusive outcomes

(A/B)/(C/D)

Question 12

What is relative risk?

Answer 12

Relative probability of the event in the treatment group compared to the control group

Observed risk of the outcome after the first intervention
Divided by
Observed risk of the outcome after the second intervention

(A/(A+B)) / (C/(C+D))

Question 13

What are steroids?

Answer 13

A type of hormone made from cholesterol involved in the Hypothalamic-Pituitary-Axis
(CRH -> ACTH -> cortisol etc)

Can be endogenous or exogenous

Question 14

What is a hormone?

Answer 14

Chemical messengers secreted by glands that act on distant organs

• Peptides/protein (insulin, ADH, ACTH, TRH, GH, TSH)
• Steroids (cortisol, aldosterone)
• Monoamine derivatives (catecholamines, serotonin, thyroxine)
• Eicosanoids (prostaglandin)

Question 15

What types of hypersensitivity do you know?

Answer 15

1. IgE mediated - anaphylaxis
2. Cytotoxic (antibody mediated) - IgG/IgM - Haemolytic reactions/Goodpasture’s syndrome
3. Immune complex - SLE
4. T-cell mediated - nickel
5. Auto-antibodies (Grave’s)

Question 16

What are the Vaughan Williams Classification?

Answer 16

Class 1 act on cardiac myocyte itself
Classes 2-4 act on SA node action potential

Class 1:
—Na channel (Phase 0 of cardiac action potential)
-a - increase refractory period
-b - decrease refractory period
-c - no effect on refractory period

Class 2:
—Beta blockers
Pacemaker action potential - lengthens phase 4

Class 3:
—K channel
Prolong action potential of pacemaker cell

Class 4:
—Calcium channel
Reduce duration of phases 2 & 3 of pacemaker action potential

Question 17

What is a confounding factor in a study?

Answer 17

A third variable (not the one of interest) that distorts the observed relationship between the exposure and the outcome

Should be controlled for if possible
Age = very common source of confounding

Can try to control for it by stratification and multivariate analysis

Question 18

What is risk?

What is odds?

Answer 18

Risk
= chance of the outcome of interest/all possible outcomes

Odds
= probability of occurrence of an event/probability of event not occurring

E.g.
Risk of dying = death/all patients
Odds of dying = death/survivors

Question 19

What is delirium?

Answer 19

Acute onset fluctuating change in mental state, characterised by reduced awareness of the environment and disturbance of attention