medical history

Question 1

what is propranolol’s mechanism of action

Answer 1

blocks B1 and B2 receptors
stops arrhythmias that could lead to cardiac arrest (ventricular fibrillation) by stopping heart muscle excitation

prevents increase in heart rate so can cause postural hypotension and worsen heart failure or asthma (there are B2 receptors in the lungs)

Question 2

what is ramipril’s mechanism of action

Answer 2

angiotensin converting enzyme inhibitor that prevents the conversion of angiotensin I into angiotensin II, and prevents the aldosterone dependent resorption of salt and water
used to lower blood pressure

can have side effects of cough, hypotension, lichenoid reactions, angio-oedema

losartan is an angiotensin II blocker that inhibits the same system but by a different mechanism

Question 3

what is clopidogrel’s mechanism of action

Answer 3

anti platelet drug that inhibits platelet aggregation for the lifetime of the platelet (7-10 days)
often used in conjunction with aspirin to reduce the risk of MI or stroke
inhibits ADP induced platelet aggregation

aspirin increases prostacyclin and reduces thromboxane A2

prolongs bleeding time following extraction

Question 4

give examples of new oral anti coagulants and the mechanism of each

Answer 4

rivaroxaban - activated factor X inhibitor; taken once a day

apixaban - activated factor X inhibitor; taken twice a day

dabigatran - direct thrombin inhibitor; taken twice a day

all have a short half life so their effect is rapidly lost
no anticoagulant test is used as they have predictable bioavailability
patients may only been on them for a short course (eg deep vein thrombosis) so postpone extraction until stopped

interact with erythromycin and clarithromycin (macrolide antibiotics); and NSAIDs will prolong their action

Question 5

what is warfarin’s mechanism of action

Answer 5

coumarin based vitamin K antagonist inhibits the formation of clotting factors 2, 7, 9, 10
initial hypercoagulation (first 2-3 days) then bleeding risk
monitored with INR (should be <4 within 24h pre op)
patient may be on heparin initially to prevent hyper coagulation
always use local haemostasis measures for patients on warfarin
all drugs interact

Question 6

what is the mechanism of action of frusemide

Answer 6

loop diuretic that treats hypertension and heart failure
increases salt and water loss to reduce plasma volume and reduce cardiac workload
can lead to Na/K imbalance, or dry mouth in the elderly

Question 7

what is the mechanism of action of simvastatin

Answer 7

inhibits cholesterol synthesis in the liver to reduce total and LDL cholesterol levels
inhibits the enzyme in the liver that produces cholesterol
can cause thrombocytopenia and anaemia
can lead to myositis (interacts with anti fungals like fluconazole)
it is a prodrug so ingested in its inactive form then metabolised to become activated

Question 8

what is the mechanism of action of amlodipine

Answer 8

Ca channel blocker that relaxes smooth muscle (cause vasodilation) to reduce hypertension
can lead to gingival hyperplasia (so can cyclosporin and phenytoin)

Question 9

what is the mechanism of action of salbutamol

Answer 9

blue inhaler
short acting beta agonist used to treat acute asthma by achieving bronchodilation
emergency use to treat bronchial constriction (2-3m onset; 4-6h half life)
can cause erosion as contains sulphuric acid

Question 10

what is the mechanism of action of salmeterol

Answer 10

green inhaler
long acting beta agonist that is used to prevent bronchial constriction
always used with an inhaled steroid
slow onset 1-2h; lasts 12-15h

Question 11

what is the mechanism of action of ipratropium

Answer 11

grey inhaler
anticholinergic that inhibits muscarinic nerve transmission in autonomic nerves
additive effect in bronchial dilation and reducing mucous secretion

Question 12

what is the mechanism of action of betamethasone when used to treat respiratory disease

Answer 12

brown inhaler
reduces inflammation in the bronchial walls
effective topically or systemically
can cause dry mouth and risks fungal infections in the mouth

Question 13

what is the mechanism of action of seretide

Answer 13

compound preparation of inhaled steroid (fluticasone) and a long acting beta agonist (salmeterol)

Question 14

what is the mechanism of action of chromoglycate

Answer 14

mast cell stabiliser prevents degranulation

Question 15

what is the mechanism of action of metformin

Answer 15

insulin sensitiser (biguanide)
enhance cell insulin sensitivity
reduce hepatic gluconeogensis (glucose being produce in the liver)
preferred in the obese
can cause wit B12 deficiency if taken for a long time

Question 16

what is the mechanism of action of amitriptyline

Answer 16

tricyclic antidepressant that increases norepinephrine and serotonin neurotransmitters
block acetylcholine action
cause xerostomia, agranulocytosis (low WBC count leading to infection risk), bone marrow suppression (low platelet and RBC count so bleeding risk)

Question 17

what is the mechanism of action of aledronic acid

Answer 17

bisphosphonate drug that inhibits osteoclast action to reduce bone turnover in osteoporosis patients
can cause MRONJ (review all extraction patients after 8 weeks)

Question 18

what is the mechanism of action of denosumab

Answer 18

a fully human monoclonal antibody that inhibits osteoclast function and associated bone resorption by binding to RANKL
administered subcutaneously every 6 months in osteoporosis patients
its effects on bone turnover diminish 9 months after treatment completion

Question 19

what is the mechanism of action of citalopram

Answer 19

selective serotonin reuptake inhibitor that is used to treat depression or panic disorder
can cause dry mouth, altered taste, arrythmias

Question 20

what is the mechanism of action of omeprazole

Answer 20

proton pump inhibitor that inhibits stomach acid secretion by parietal cells
if taking for more than a year the patient can be at risk of vital B12 deficiency (mouth ulcers) and bone fractures

Question 21

what is the mechanism of action of allopurinol

Answer 21

used to treat gout by lowering uric acid levels
can cause agranulocytosis

Question 22

what is the mechanism of action of gabapentin

Answer 22

reduces excitability of nerve cells in the brain to treat seizures and chronic pain
can cause xerostomia or leucopenia

Question 23

what is the mechanism of action of isosorbide mononitrate

Answer 23

long acting nitrate that prevents angina pectoris

short acting glyceryl trinitrate is used in an emergency to treat angina pectoris by dilating veins, dilating resistance arteries, and dilating collateral coronary artery supply

nitrates are inactivated by first pass metabolism and have side effects of headache