Pharmacology

Question 1

Adrenaline (1 in 1,000 and 1 in 10,000)

Answer 1

A sympathomimetic hormone that stimulates alpha and beta adrenergic receptors. This increases myocardial and cerebral blood flow, increases peripheral resistance and systemic vasoconstriction, improving perfusion pressures and therefore CPR quality. It also increases strength of ventricular contraction

Relieves bronchospasm in asthma, and relieves allergic manifestations in anaphylaxis. It causes vasoconstriction to reduce inflammation and swelling in anaphylaxis. It increases blood pressure and heart rate, as well as working as a bronchodilator in the lungs. It also prevents the release of histamine, so prevents further progression of anaphylaxis

Question 2

Amiodarone

Answer 2

A non competitive alpha and beta adrenergic inhibitor. It works as an anti-arrhythmic that lengthens the cardiac action potential, and therefore the effective refractory period. It works by blocking both sodium and potassium channels in the heart, which lengthens the QT interval. This decreases both the heart rate and vascular resistance, as well as relaxing the vascular smooth muscle w

Question 3

Aspirin

Answer 3

Has an antiplatelet action that reduces clot formation. It relieves pain by inhibiting cyclooxygenase, which inhibits the formation of prostaglandins. It also produces analgesia in the hypothalamus, but mode of action here is unknown

It inactivates cyclooxygenase by acting as an acetyl donor. This prevents the aggregating agent of thromboxane being formed in platelets

Question 4

Atropine

Answer 4

An anticholinergic that reverses the effect of vagal overdrive by blocking vagal activity and enhancing AV conduction. It works by inhibiting acetylcholine receptors

When used in an MI it increases oxygen demand, therefore worsening ischaemia. Therefore should only be used when bradycardia is causing problems with perfusion

Question 5

Benzylpenicillin (Penicillin G)

Answer 5

Works by interfering with the synthesis of the bacterial cell wall, peptidoglycan. It does this by inhibiting the enzyme that forms cross links in the cell wall. This makes the cell wall osmotically unstable, leading to lysis of the bacteriumw

Question 6

Chlorphenamine

Answer 6

It is an antihistamine, or a histamine antagonist. It competes with histamine for the receptor sites on the effector cells of the GI tract, blood vessels and respiratory tract. This relieves all of the negative symptoms caused by histamine

Question 7

Clopidogrel

Answer 7

It inhibits platelet aggregation by inhibiting ADP from binding to its platelet receptor, which prevents the activation of the glycoprotein complex, therefore inhibiting platelet aggregation. It also prevents fibrinogen binding to platelets, further reducing platelet aggregation

Question 8

Dexamethasone

Answer 8

A corticosteroid that reduces subglottic inflammation. It is a glucocorticoid agonist, and works by crossing the cell membrane, binding to glucocorticoid receptors. This alters the DNA, inhibiting leukocyte infiltration at the site of inflammation. This consequently reduces subglottic inflammation

Question 9

Diazepam

Answer 9

It is a central nervous system depressant, that acts on the limbic system, the thalamus and the hypothalamus, inducing calming effects. It binds to benzodiazepine receptors, causing muscle relaxation. It also binds to GABA receptors, opening the chloride channel. This causes a hyperpolarised cell membrane, preventing further excitation of the cell

Question 10

Entonox

Answer 10

Induces opioid peptide release in the brain stem, which leads to the activation of descending noradrenergic neurones. This modulates the nociceptive process in the spinal cord, acting as an analgesic. The specific mode of action however is unknown

Question 11

Furosemide

Answer 11

It is a loop diuretic that inhibits water reabsorption in the nephron by blocking the sodium potassium chloride cotransporter in the loop of Henle. The lumen becomes hypertonic, reducing the osmotic gradient for water reabsorption throughout the nephron

Question 12

Glucagon (Glucagen)

Answer 12

Acts only on liver glycogen, converting it to glucose through the release of insulin. It activates adenylate cyclase, which manufactures cyclic AMP. This cyclic AMP activates glycogen phorphorylase, converting it into phosphorylase A. This is the enzyme responsible for the release of glucose from glycogen

Question 13

Glucose 10%

Answer 13

Glucose supplies the body with energy by generating ATP and NADH during glycolysis. Glucose is phosphorylated initially. Glucose (6 carbons) is converted into two 3 carbon sugar molecules, which then enter the energy releasing phase, where 4 ATP and 2 NADH are generated. Aerobic metabolism of glucose can produce 36 ATP

Question 14

Glucose 40% Oral Gel

Answer 14

Glucose supplies the body with energy by generating ATP and NADH during glycolysis. Glucose is phosphorylated initially. Glucose (6 carbons) is converted into two 3 carbon sugar molecules, which then enter the energy releasing phase, where 4 ATP and 2 NADH are generated. Aerobic metabolism of glucose can produce 36 ATP

Question 15

Glyceryl Trinitrate (GTN)

Answer 15

A vasodilator that dilates the coronary arteries, and relieves coronary spasm. It also lowers preload by dilating the systemic veins, which also lowers blood pressure. It is converted to nitric oxide, which activates guanylate cyclase. This stimulates cyclic GMP, which then activates a series of reactions in the smooth muscle cells that causes the dephosphorylation of the myosin smooth muscle fibre. This releases calcium ions, and causes the relaxation of smooth muscle cells, and vasodilation

Question 16

Heparin

Answer 16

An anticoagulant with antithrombotic properties. It inhibits the reactions that lead to blood clotting, and the formation of fibrin. It works by inactivating thrombin, and preventing the conversion of fibrinogen to fibrin. Heparin prevents the formation of further clots, but does not break down existing ones

Question 17

Hydrocortisone

Answer 17

A glucocorticoid that reduces inflammation and suppresses the immune response. It produced phospholipase inhibitory proteins, which control the synthesis of prostaglandins and leukotrienes. It inhibits COX 1 and 2, and so the two main products in inflammation (prostaglandins and leukotrienes) are inhibited. It also binds to the leukocyte membrane receptors, and inhibits inflammatory events, and releases inflammatory mediators. It also suppresses the immune system by decreasing the function of the lymphatic system

Question 18

Ibuprofen

Answer 18

An NSAID that inhibits COX 1 and 2, which decreases the synthesis of prostaglandins involved in inflammation, pain, fever and swelling. Antipyretic effects are caused by acting on the hypothalamus to increase peripheral blood flow and vasodilation

Question 19

Ipatropium Bromide (Atrovent)

Answer 19

A muscarinic antagonist that works as a bronchodilator, and relieves bronchospasm. It is an anticholinergic, that inhibits muscarinic cholinergic receptors. This decreases the formation of cyclic GMP, which decreases the contractility of the smooth muscle

Question 20

Metoclopramide (Maxolon)

Answer 20

It inhibits gastric smooth muscle, increasing the cholinergic response. It accelerates gastric emptying and relaxes the upper small intestine. It decreases reflux by increasing the resting pressure of the oesophageal sphincter, and increasing amplitude of peristalsis

Question 21

Midazolam

Answer 21

A short acting benzodiazepine CNS depressant that increases GABA activity by binding to GABA receptors, increasing the frequency of chloride channel opening

Question 22

Misoprostol

Answer 22

Increases the amplitude and frequency of uterine contractions by binding to EP 2 and 3 prostanoid receptors

Question 23

Morphine Sulphate

Answer 23

It interacts with the opioid mu receptor. It also inhibits GABA inhibitory interneurons, which usually inhibit the pain inhibition pathway.

It causes respiratory depression by reducing the responsiveness of the brain stem respiratory centres to carbon dioxide and electrical stimulation

Question 24

Naloxone Hydrochloride (Narcan)

Answer 24

An opiate antagonist that competes for the same receptor sites as opiates, especially mu receptor

Question 25

Ondansetron

Answer 25

A 5HT receptor antagonist, which inhibits 5HT receptors. This results in the inhibition of the visceral afferent stimulation of the vomiting centre, and also inhibits serotonin activity within the chemoreceptor trigger zone and the area postrema

Question 26

Oxygen

Answer 26

Improves cellular oxygenation. Adjusts hypoxic ventilatory drive by acting on chemoreceptors that relay sensory information to the brainstem

Increases arterial pressure of oxygen and improves gas exchange to tissues. It plays a critical role as an electron acceptor during oxidative phosphorylation, which achieves aerobic respiration to generate ATP. Also reduces metabolic acidosis

Reverses hypoxia by increasing the concentration of inspired oxygen

Question 27

Paracetamol

Answer 27

It inhibits COX 1 , 2 and 3, which are involved in prostaglandin production. This increases the pain threshold

Its antipyretic effects are due to peripheral vasodilation and sweating caused by effects on the hypothalamus heat regulation centre

Question 28

Reteplase

Answer 28

Works by activating the fibrinolytic system, inducing the break up of thrombi and emboli. It breaks a bond in plasminogen, to form plasmin. Plasmin degrades the fibrin matrix of the thrombus, breaking it down. It therefore binds to fibrin rich clots

Question 29

Salbutamol

Answer 29

It is a beta 2 adrenergic receptor agonist. It is made up of R and S isomers. The R isomer is responsible for bronchodilation, and the S reduces bronchial reactivity. It binds to beta 2 receptors in the lungs, which relaxes smooth muscles of bronchi. It increases cyclic AMP, which inhibits the phosphorylation of myosin and lowers intracellular calcium concentration. This lower calcium levels is what causes the bronchodilation and muscle relaxation. Salbutamol also inhibits bronchoconstricting agents from mast cells, inhibits microvascular leakage and enhances mucociliary clearance

Question 30

0.9% Sodium Chloride

Answer 30

It increases vascular fluid volume which raises cardiac output and improves perfusion. The sodium and chloride are major electrolytes of extracellular fluid, so work together to control volume and blood pressure

Question 31

Sodium Lactate Compound (Hartmann’s/Ringer’s Lactate)

Answer 31

It increases vascular fluid volume, which raises cardiac output and improves perfusion. The lactate is metabolised into bicarbonate by the liver, which can help to correct metabolic acidosis. It maintains electrical neutrality by having a lower level of sodium than in blood plasma or normal saline. It is an alkalising solution, due to proton consumption caused by the ion difference in the solution

Question 32

Syntometrine

Answer 32

Stimulates the contractions of the uterus by increasing the sodium permeability of uterine myofibrils. Increases both the amplitude and the frequency, which impedes uterine blood flow through dilation and reduced activity of the cervix. It increases contractions by increasing intracellular Ca2+

Question 33

Tenecteplase

Answer 33

Activates the fibrinolytic system, inducing the break up of thrombi and emboli. It is a fibrin tissue-plasminogen activator. IT binds to fibrin rich clots, and breaks a bond in plasminogen to form plasmin. Plasmin degrades the fibrin matrix in a thrombus

Question 34

Tetracaine 4%

Answer 34

Local anaesthetic agent that works by blocking sodium ion channels involved in the initiation and conduction or neuronal impulses

Question 35

Tranexamic Acid (TXA)

Answer 35

An anti fibrinolytic that reduces the breakdown of a clot by competitively inhibiting the activation of plasminogen, and so reducing the conversion of plasminogen to plasmin (plasmin degrades clots). It also inhibits plasmin activity at higher doses