Mechanism of Action

Question 0

Aspirin

Answer 0

1) acetylsalicylic acid
2) non-selective NSAIDs
3) Analgesic, anti-inflammatory, antipyretic and antiplatelet actions
4) preventing synthesis of prostaglandins by noncompetitively inhibiting both forms of cyclo-oxygenase (COX), COX-1 and COX-2

Question 1

Paracetamol

Answer 1

1) not fully determined
2) analgesic effect may include inhibition of central prostaglandin synthhesis and modulation of inhibitory descending serotonergic pathways
3) anti-pyretic effect is probably due to reduced production of prostaglandins in the hypothalamus
4) negligible anti-inflammatory effects

Question 2

Ibuprofen, Diclofenac, Naproxen

Answer 2

1) anti-inflammatory, antipyretic, analgesic
2) nonselective NSAIDs (COX-1 and COX-2)
3) Inhibit synthesis of prostaglandins by inhibiting cyclo-oxygenase (COX)

Question 3

Inhibition of Cyclo-oxygenase 1 (COX-1)

Answer 3

1) results in impaired gastric cytoprotection and antiplatelet effets
2) reduction to glomerular filtration rate and renal blood flow

Question 4

Inhibition of cyclo-oxygenase 2 (COX-2)

Answer 4

1) results in anti-inflammatory and analgesic action

2) reduction in glomerular filtration rate and renal blood flow

Question 5

Hydrocortisone

Answer 5

1) known as cortisol
2) binds to steroid receptors -> reduce inflammatory mediators in the area

2) anti-inflammatory, immunosuppressive and antimitotic activity against cutaneous fibroblasts and epidermal cells
3) vasoconstrictive

Question 6

Anti-fungal -azoles

Ketoconazole, Clotrimazole, Miconazole

Answer 6

1) impair biosynthesis of ergosterol for cytoplasmic membrane, inhibiting fungal growth (fungistatic)

Question 7

Aciclovir

Answer 7

1) prevent viral DNA synthesis

2) aciclovir metabolite inhibits and is a substrate for the HPV DNA polymerase -> prevent viral DNA synthesis

Question 8

Non-sedating antihistamines

Cetirizine, Loratadine, Fexofenadine

Answer 8

1) reduce the effects of histamine by binding to the H1 receptor and stabilising it in an inactive form

Question 9

Sedating antihistamine
(Dexchlorpheniramine = polaramine , Promethazine = phenergen, Doxylamine)

Answer 9

1) reduce the effects of histamine by binding to the H1 receptor and stabilising it in the inactive form
2) anti-cholinergic activity
3) Promethazine (Phenergen)- alpha-blocking activity
4) Cyproheptadine (Periactin) - antiserotonin activity

Question 10

Loperimide

Answer 10

1) activate opioid receptors in the gut wall, decreasing bowel motility and increasing fluid absorption

Question 11

Senna

Answer 11

1) direct simulation of nerve endings in colonic mucosa to increase intestinal motility
2) may also cause accumulation of water and electrolytes in the colonic lumen

Question 12

Celecoxib

Answer 12

1) anti-inflammatory and analgesic
2) COX-2 selective
3) inhibiting synthesis of prostagladins by inhibiting cyclo-oxygenase (COX)
4) inhibition of COX-2 results in anti-inflammatory and analgesic activity; as well as reduction in glomerular filtration rate and renal blood flow

Question 13

Opioid analgesics
(Morphine, Codeine, Oxycodone)

Answer 13

1) mimic endogenous opioids by activating opioid receptors in the central and peripheral nervous systems to produce analgesia, respiratory depression, sedation and constipation
2) reduce transmission of the pain impulse by acting pre- and post-synaptically in the spinal cord, and by modulating the descending inhibitory pathways from the brain
3) cough suppression occurs in the medullary centre of the brain

Question 14

Pure or partial agonists?

Morphine, Oxycodone, Codeine

and, what effect do partial agonists demonstrate in increasing dose?

Answer 14

Mophine = pure agonist
Oxycodone = pure agonist
Codeine = pure agonist

partial agonist = buprenorphine (Norspan)

Partial agonists demonstrate a ceiling response above which an increase in dose does not produce an additional increase in effect

Question 15

Meloxicam

Answer 15

1) anti-inflammatory and analgesic
2) selective COX-2 inhibitor
3) inhibits synthesis of prostaglandins by inhibiting cyclo-oxygenase (COX)
4) inhibiting COX-2 reduces inflammatory and provides analgesic effect
5) reduction in glomerular filtration rate and renal blood flow

Question 16

Ranitidine

Answer 16

1) H2 antagonists

2) competitively block H2 receptors on parietal cells, reducing gastric acid secretion

Question 17

Omeprazole, Esomeprazole

Answer 17

1) PPI
2) Irreversibly inactivate the hydrogen/potassium ATPase enzyme system (proton pump), suppressing both stimulated and basal acid secretion.
3) When PPIs are stopped, acid secretion is restored by synthesis of new hydrogen/potassium ATPase

Question 18

Allopurinol

Answer 18

1) reduces uric acid production by inhibiting xanthine oxidase, and lowers plasma and urinary urate concentrations.
2) allopurinol metabolised to oxypurinol, which also inhibits xanthine oxidase

Question 19

Colchicine

Answer 19

1) inhibits neutrophil migration, chemotaxis, adhesion and phagocytosis in the inflamed area
2) reduces the inflammatory reaction to urate crystals but has no effect on uric aid production or exretion

Question 20

Methotrexate

Answer 20

1) folic acid antagonist
2) inhibits DNA synthesis and cell replication by competitively inhibiting the conversion of folic acid to folinic acid, with cytotoxic, immunosuppressive and anti-inflammatory action

Question 21

Prednisolone, Prednisone

Answer 21

Corticosteroids regulate gene expression which results in:

1) glucocorticoid effects: gluconeogenesis, proteolysis, lipolysis, suppression of inflammation and immune responses
2) mineralocorticoid effects: hypertension, sodium and water retention, potassium loss
3) prednisone is converted to the phamacologically active prednisolone and vice versa

NB: corticosteroids may have predominantly gluco-corticoid effects (eg dexamethasone), mineralo-corticoid effects (fludrocortisone p444 AHM), or a combination of both (eg ydrocortisone)

Question 22

Oxymetazoline

Answer 22

1) produce vasoconstriction in nasal mucosa

2) decrease nasal blood flow and congestion

Question 23

Phenylepherine, Pseudoephedrine

Answer 23

1) act on alpha adrenoreceptors on vascular smooth muscle in the respiratory tract, producing vasoconstriction of dilated nasal vessels, reducing tissue swelling and nasal congestion

Question 24

Amytriptyline

Answer 24

1) TCA 2) inhibits reuptake of noradrenaline and serotonin into presynaptic terminals 2) unrelated to the therapeutic effects of the TCAs, they also block cholinergic, histaminergic, alpha1-adrenergic and serotonergic receptors

Question 25

Mirtazapine

Answer 25

1) tetracyclic antidepressant 2) acts by postsynaptic blockade of serotonin 5HT2 and 5HT3 receptors and presynaptic blockade of central alpha2-adrenergic inhibitory autoreceptors

Question 26

Sertraline

Answer 26

1) SSRI | 2) selectively inhibit the presynaptic reuptake of serotonin (5-hydroxytryptamine, 5-HT)

Question 27

Gliclazide

Answer 27

1) increase pancreatic insulin secretion | 2) may decrease insulin resistance

Question 28

Metformin

Answer 28

1) reduce hepatic glucose production | 2) increase peripheral utilisation of glucose

Question 29

Insulin

Answer 29

1) increase or restore ability to metabolise glucose by enhancing cellular glucose uptake 2) inhibit endogenous glucose output and lipolysis

Question 30

Carbamazepine

Answer 30

1) prevents repetitive neuronal discharges by blocking voltage-dependent and use-dependent sodium channels

Question 31

Phenytoin

Answer 31

1) prevents repetitive neuronal discharge by blocking voltage-voltage and use-dependent sodium channels

Question 32

Valproate

Answer 32

1) prevent repetitive neuronal discharge by blocking voltage-dependent and use-dependent sodium channels

Question 33

Metoclopramide, Domperidone

Answer 33

1) stimulates upper GI tract 2) dopamine antagonist activity with antiemetic properties 2) EPSE (usually acute dystonic reactions), due to central dopamine antagonist activity, may occur and are more common in the elderly and in people <20 years. 3) EPSE are rare with domperidone as it does not readily cross BBB 4) prokinetic activity

Question 34

Haloperidol, Risperidone

Answer 34

1) mediated by blockade of dopaminergic transmission in various parts of the brain (in particular the limbic system) Evidence suggest: 2) all effective antipsychotics block D2 receptors 3) differential blockade of other dopamine receptors (eg D1) may influence therapeutic and adverse effects 4) antagonism of other receptors may influence antipsychotic activity

Question 35

Lithium carbonate

Answer 35

1) unknown 2) inhibition of dopamine release 3) enhancement of serotonin release and decreased formation of intracellular second messengers 4) little or no psychotropic effect in normal individuals

Question 36

Ethinyloestradiol (oestrogen) Levonorgestrel (progestogen) Norethisterone (progestogen)

Answer 36

1) all COCs contain an oestrogen and progestogen 2) inhibit ovulation 3) reduce receptivity of endometrium to implantation 4) thicken cervical mucus to form a barrier to sperm

Question 37

Alendronate

Answer 37

1) decrease bone resorption by inhibiting osteoclasts

Question 38

Thyroxine

Answer 38

1) known as T4 or levothyroxine 2) thyroid replacement therapy 3) best ingested in a fasting state, food impairs absorption

Question 39

Levodopa + benserazide/carbidopa

Answer 39

1) levodopa is converted to dopamine in the brain and peripheral tissues, and replenishes depleted striatal dopamine 2) benserazide/carbidopa is a peripheral dopa decarboxylase inhibitor which reduces peripheral dopamine production and also reduce adverse effects (eg nausea, vomiting, hypotension)

Question 40

Diazepam

Answer 40

1) benzodiazepines potentiate the inhibitory effects of GABA throughout the CNS, resulting in anxiolytic, sedative, hypnotic, muscle relaxant and antiepileptic effects

Question 41

Digoxin

Answer 41

1) slows heart rate and reduces AV nodal conduction by an increase in vagal tone and a reduction in sympathetic activity 2) increase the force of myocardial contraction by increasing the release and availability of stored intracellular calcium

Question 42

Atenolol, Metroprolol Antihypertensive effect CNS effect Anti-anginal effect Anti-arrhythmic

Answer 42

1) beta-blocker 2) competitively block beta receptors in heart, peripheral vasculature, bronchi, pancreas, uterus, kidney, brain and liver 3) antihypertensive effect: due to reduction in cardiac output without reflex increase in peripheral vascular resistance 4) CNS effect: and reduced renin secretion may also contribute 5) anti-anginal effect: due to reduction in left ventricular work and oxygen use, resulting from decrease in heart rate and contractility 6) anti-arrhythmic properties: antisympathetic effect -> depress sinus node function and atrioventricular node conduction, and prolong atrial refractory periods Atenolol - beta 1 Metroprolol - beta 1 beta1-selectivity: higher affinity for beta1 receptors in the heart, with less effect on beta2 receptors in bronchi and peripheral vasculature. beta1-selectivity diminishes with higher doses

Question 43

Clopidogrel

Answer 43

1) thienopyridines 2) active metabolite irreversibly binds to platelet P2Y12 receptor and inhibits platelet aggregation for the life of the platelet

Question 44

Heparin

Answer 44

1) inactivate clotting factors IIa (thrombin) and Xa by binding to antithrombin III

Question 45

Warfarin

Answer 45

1) Vit K antagonist 2) inhibits synthesis of vitamin K-dependent clotting factors (II, VII, IX, X) and the anti-thrombotic factors protein C and protein S

Question 46

Dabigatran

Answer 46

1) direct thrombin inhibitors 2) reversibly inhibit both free and fibrin- bound thrombin, preventing conversion of fibrinogen to fibrin, preventing thrombus formation 3) inhibition of thrombin-induced platelet aggregation

Question 47

Frusemide

Answer 47

1) loop diuretics (potent diuretics) 2) inhibit reabsorption of sodium and chloride in the ascending limb of the loop of Henle (this site accounts for retention of approx. 20% of filtered sodium)

Question 48

Spironolactone

Answer 48

1) aldosterone antagonist (weak diuretic) 2) inhibit sodium absorption in the distal tubule by antagonising aldosterone -> increasing sodium and water excretion and reducing potassium excretion 3) aldosterone may contribute to the pathophysiology of heart failure; by reducing aldosterone activity, aldosterone antagonists improve outcome

Question 49

Hydrochlorothiazide

Answer 49

1) moderately potent diuretics 2) inhibit reabsorption of sodium and chloride in the proximal (diluting) segment of the distal convoluted tubule and produce a corresponding increase in potassium excretion 3) used in recommended low doses for hypertension, thiazides lower BP mostly by a vasodilator effect

Question 50

Captopril, Perindopril

Answer 50

1) ACE-I = angiotensin converting enzyme inhibitor 2) block conversion of angiotensin I to angiotensin II 3) inhibit breakdown of bradykinin 4) reduces the effect of angiotensin II-induced vasoconstriction, sodium retention and aldosterone release 5) reduce the effect of angiotensin on sympathetic nervous activity as a growth factor

Question 51

Atorvastatin, Simvastatin

Answer 51

1) lipid-lowering 2) competitively inhibit 3-hydroxy-3methylgglutaryl coenzyme A (HMG-CoA) reductase (a rate limiting enzyme in cholesterol synthesis) 3) increase hepatic cholesterol uptake from blood 4) reduce concentrations of total cholesterol, LDL and triglyceride (modest) and produce a small increase in HDL concentration

Question 52

Irbersartan

Answer 52

1) known as angiotensin II antagonists, angiotensin receptor antagonist or angiotensin receptor blocker 2) competitively block binding of angiotensin II to type I angiotensin (AT1) receptors 3) reduce angiotensin-induced vasoconstriction, sodium reabsorption and aldosterone release

Question 53

Amlodipine

Answer 53

1) dihydropyridines calcium channel blocker 2) block inward current of calcium into cells in vascular smooth muscle, myocardium and cardiac conducting system via L-type calcium channels 3) act on coronary arteriolar smooth muscle to reduce vascular resistance and myocardial oxygen requirements, relieving angina symptoms 4) dihydropyridines - act mainly on arteriolar smooth muscle to reduce peripheral vascular resistance and BP. Have minimal effect on myocardial cells

Question 54

Verapamil

Answer 54

1) non-dihydropyridine calcium channel blocker 2) block inward current of calcium into cells in vascular smooth muscle, myocardium and cardiac conducting system via L-type calcium channels 3) act on coronary arteriolar smooth muscle to reduce vascular resistance and myocardial oxygen requirements, relieving angina symptoms 4) non-dihydropyridines - act on cardiac and arteriolar smooth muscle. they reduce cardiac contractility, heart rate and conduction, with verapamil having the greater effect. (Diltiazem has a greater effect on arteriolar smooth muscle than verapamil)

Question 55

Glyceryl trinitrate

Answer 55

1) provide exogenous source of nitric oxide, which mediates vasodilator effects 2) predominantly venodilators 3) reduce venous return and preload to the heart 3) reducing myocardial oxygen requirement

Question 56

NRT (nicotine replacement therapy)

Answer 56

1) reduce the severity of tobacco withdrawal symptoms and increases the likelihood of smoking cessation 2) eMIMS

Question 57

Amoxycillin | Amoxycillin/ clavulanic acid

Answer 57

1) bactericidal - mainly gram+ and anaerobes, some gram- (more with clavulanic acid) 2) interfere with bacterial cell wall peptidoglycan synthesis by binding to penicillin-binding proteins -> leads to cell lysis and death 3) clavulanic acid -> bacteria that secretes beta-lactamase 4) amoxycillin - moderate spectrum 4) amoxycillin/clavulanic acid - broad spectrum

Question 58

Flucloxacillin

Answer 58

1) bactericidal - narrow spectrum gram+ 2) interfere with bacterial cell wall peptidoglycan synthesis by binding to penicillin-binding proteins -> leads to cell lysis and death

Question 59

Phenoxymethylpenicillin

Answer 59

1) bactericidal - narrow spectrum mainly gram+ and anaerobes, 2 gram- 2) interfere with bacterial cell wall peptidoglycan synthesis by binding to penicillin-binding proteins -> leads to cell lysis and death

Question 60

Cephalexin

Answer 60

1) cephalosporin family 2) bactericidal - some gram-, gram+ and anaerobes 3) interfere with bacterial cell wall peptidoglycan synthesis by binding to penicillin-binding proteins -> leads to cell lysis and death 4) moderate spectrum for cephalexin

Question 61

Clarithromycin

Answer 61

1) macrolides (broad spectrum) 2) bacteriostatic - some gram-, gram+, most anaerobes, and miscellaneous ones (like chlamydia and legionella) 3) inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit 4) also have immunomodulatory and anti-inflammatory effect

Question 62

Metronidazole

Answer 62

1) nitroimidazole family 2) bactericidal - gram+, gram- anaerobic, protozoal infections 3) metabolised to active metabolites that are thought to interfere with DNA synthesis

Question 63

Ciprofloxacin

Answer 63

1) quinolone family 2) bactericidal - mainly gram- 3) inhibit bacterial DNA synthesis by blocking DNA gyrase and topiosomerase IV NB: there is increasing worldwide resistance to quinolones. Judicious use may extend their clinical life

Question 64

Doxycycline

Answer 64

1) tetracycline family 2) bacteriostatic - some gram+, gram-, protozoa 3) inhibit bacterial protein synthesis by reversibly binding to 30S subunit of the ribosome 4) effect of tetracyclines in acne vulgaris also involves mechanisms other than their antimicrobial activity

Question 65

Trimethoprim | Trimethoprim/ sulfamethoxazole

Answer 65

1) other antibacterials 2) bacteriostatic - gram-, and some gram+, no data for anaerobes 3) competitively inhibits bacterial folate production essential for bacterial growth

Question 66

Fluconazole

Answer 66

1) azole family 2) fungistatic - candidiasis, alternative choice for cryptococcal 3) impair the synthesis of ergosterol in fungal cell membranes leading to their breakdown 4) cell leakage and death occur by lytic activity of the host defense system

Question 67

Salbutamol, Terbutaline | Salmeterol

Answer 67

1) salbutamol/terbutaline - SABA (short-acting beta2-agonist) 2) salmeterol - LABA (long-acting beta2-agonist) 3) relax bronchial smooth muscle by stimulating beta2-adrenoceptors

Question 68

Fluticasone

Answer 68

1) reduce airway inflammation and bronchial hyper-reactivity

Question 69

Tiotropium

Answer 69

1) anticholinergic | 2) promote bronchodilation by inhibiting cholinergic bronchomotor tone