Drug Of The Day

Question 1

Amlodopine

Answer 1

CLASS: dihydropyridine calcium-channel blocker
INDICATIONS: HTN, angina prophylaxis
MECHANISM OF ACTION: Interferes with the inwards displacement of calcium ions through slow channels of active membranes. Influence myocardial cells and cells of vascular smooth muscle. Reduces myocardial contractility and vascular tone.
ADRs: Headaches, flushing, palpitations, peripheral odema
IMPORTANT DRUG-DRUG INTERACTIONS: CYP3A4 inhibitors, SIMVASTATIN, cyclosporine

Question 2

Losartan

Answer 2

CLASS: Angiotensin II Receptor Antagonist
INDICATIONS: Diabetic neuropathy in T2DM, chronic HF when ACEi unsuitable or contraindicated, HTN
MECHANISM OF ACTION: Prevent binding of angiotensin II to AT1 receptors on muscles and surrounding blood vessels, causing vasodilation.
ADRs: Hypotension, hyperkalemia, can cause or worsen renal failure.
IMPORTANT DRUG-DRUG INTERACTIONS: NSAIDs, ^K+ drugs

Question 3

Indapamide

Answer 3

CLASS: Thiazide-like diuretic
INDICATIONS: Essentiel HTN
MECHANISM OF ACTION: At lower doses, vasodilatation is more prominent than diuresis; the diuretic effect becomes more apparent with higher doses. Blocks Na+ Cl- cotransporter at DCT. Increase Ca2+ reabsorption.
ADRs: Hypokalemia, hyponatremia, hyperuricemia (gout), arrythmia, increase glucose.
IMPORTANT DRUG-DRUG INTERACTIONS: NSAIDS, loop diuretics, (beta blockers (glucose)).

Question 4

Atorvastatin

Answer 4

CLASS: Statin
INDICATIONS: Primary hypercholestoralaemia, primary combined hyperlipidaemia, prevention of CV event.
MECHANISM OF ACTION: Competitively inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, an enzyme involved in cholesterol synthesis, especially in the liver.
ADRs: GI upset, headaches, myalgia, rhabdomyolysis
IMPORTANT DRUG-DRUG INTERACTIONS: CYP 3A4 (amiodarone, macrolides, diltiazem increase plasma [statin]). Amlodipine increases plasma [statin]
IMPORTANT DRUG-DRUG INTERACTIONS:

Question 5

Spironolactone

Answer 5

CLASS: Aldosterone recepotor antagonist.
INDICATIONS: Odema, acities, HF, nephrotic sydnromes, resistent HTN, patients with hyperaldosteronism awaiting surgery.
MECHANISM OF ACTION: Blocks action of aldosterone, blocks action of RAAS system.
ADRs: Hyperkalemia, gynaecomastia
IMPORTANT DRUG-DRUG INTERACTIONS: ^K+ drugs

Question 6

Metformin

Answer 6

CLASS: Biguanide
INDICATIONS: T2DM, PCOS, prevention of onset of T2DM
MECHANISM OF ACTION: Decreases gluconeogenesis and by increasing peripheral utilisation of glucose; since it acts only in the presence of endogenous insulin it is effective only if there are some residual functioning pancreatic islet cells.
ADRs: GI Upset
IMPORTANT DRUG-DRUG INTERACTIONS: ACEi, diuretics, NSAIDs

Question 7

Sitagliptin

Answer 7

CLASS: DPP-4 Inhibitors (gliptins)
INDICATIONS: T2DM (monotherapy or with metformin)
MECHANISM OF ACTION: Prevent incretin degradation, increasing plasma incretin. Glucose dependent so posprandial action, doesn’t stimulate insulin secretion at normal blood glucose so low hypo risk. Supress appetite, weight neutral.
ADRs: Headache, GI Upset, small risk of pancreatitis
IMPORTANT DRUG-DRUG INTERACTIONS: Thiazide like and loop diuretics, other hypoglycemic agents?

Question 8

Gliclazide

Answer 8

CLASS: Sulfonylureas
INDICATIONS: T2DM, in combination with other agents or first line if metformin contraindicated.
MECHANISM OF ACTION: Stimulate beta-cell pancreatic insulin secretion, blocking ATP-dependent K+ channels. Works at low glucose levels, needs residual pancreatic function.
ADRs: Mild GI upset, hypos
IMPORTANT DRUG-DRUG INTERACTIONS: loop and thiazide like diuretics, other hypoglycemic agents

Question 9

Clopidogrel

Answer 9

CLASS: ADP receptor antagonist
INDICATIONS: Prevention of atherothrombotic and thromboembolic events
MECHANISM OF ACTION: Irrevesably inhibits PY212, inhibits acitvation of GPIIb/IIIa receptors. Independent of COX pathway.
ADRs: Diarrhoea; gastrointestinal discomfort; haemorrhage; skin reactions
IMPORTANT DRUG-DRUG INTERACTIONS: Requires CYPS for activation. CYP inhibitors: omeprazole, ciprofloxacin, erythomycin, SSRIs. Caution when copescribed with antiplatelets or anticouagulants or NSAIDs (bleeding risk)

Question 10

Amiodarone

Answer 10

CLASS: Class III antiarrhythmic
INDICATIONS: Treatment of arrhythmias, particularly when other drugs are ineffective or contra-indicated, VT
MECHANISM OF ACTION: Prolongs repolarization.
ADRs: Pulmonary fibrosis, hepatic injury, increase ldl cholesterol, thyroid disease, photsensitivity, opic neuritis.
IMPORTANT DRUG-DRUG INTERACTIONS: Reduce dose of digoxin, monitor warfarin (^INR).

Question 11

Verapamil

Answer 11

CLASS: Calcium chanel blocker, phenylalkylamines.
INDICATIONS: Treatment of supraventricular arrhythmias, paroxysmal tachyarrhythmias, prophylaxis of cluster headache, HTN, angina, prophylaxis after myocardial infarction where beta-blockers not appropriate
MECHANISM OF ACTION: Interfere with the inward displacement of calcium ions through the slow channels of active cell membranes. They influence the myocardial cells, the cells within the specialised conducting system of the heart, and the cells of vascular smooth muscle. Thus, myocardial contractility may be reduced, the formation and propagation of electrical impulses within the heart may be depressed, and coronary or systemic vascular tone may be diminished.
ADRs: Abdominal pain; dizziness; drowsiness; flushing; headache; nausea; palpitations; peripheral oedema; skin reactions; tachycardia; vomiting
IMPORTANT DRUG-DRUG INTERACTIONS: Beta blockers, other antihypertensives and antiarrythmatic agents

Question 12

Aspirin

Answer 12

CLASS: Salicylates
INDICATIONS: CVS secondary prevention, analgesia, suspected TIA, pyrexia, pre-eclampsia prevention, pyrexia
MECHANISM OF ACTION: Irreversably inhibits COX-1 mediated pathway of TXA2 and reduces platelet aggregation.
ADRs: haemorrhage, bronchospasam, hypersensitivity, GI irritation
IMPORTANT DRUG-DRUG INTERACTIONS: Other antiplatelets or anticoagulants
DOSAGE: 75mg in CVS event prevention, 300mg for loading dose or analgesic

Question 13

Flecainide

Answer 13

CLASS: Class 1C
INDICATIONS: Wide spectrum, SV arrhythmias, premature ventricular contractions, WPW syndrome
MECHANISM OF ACTION: Increases APD, refractory periods, AP threshold, substancially reduces phase 0
ADRs: CNS, GI, pro-arrythmia and sudden deatth
IMPORTANT DRUG-DRUG INTERACTIONS: Digoxin. Flecainide will increase the levels of digoxin in the body, anti HTN agents, amiodarone, phenytoin
NOTE: Give AV nodal blocking drug to stop fleccanide flutter in atrial flutter

Question 14

Celecox

Answer 14

CLASS: NSAID - selective COX-2 inhibitor
INDICATIONS: Pain and inflammation
MECHANISM OF ACTION: Inhibit PGI2
ADRs: GI, pectoris angina, increased risk of MI, headache, HTN, decreased GFR and renal blood flow
IMPORTANT DRUG-DRUG INTERACTIONS: aspirin, glucocorticosteroids, anticoagulants
NOTE: Consider PPIs

Question 15

Azathioprine

Answer 15

CLASS: Immunosupressant
INDICATIONS: SLE, vasculitis (maintainence), IBD, atopic dermatitis
MECHANISM OF ACTION: Cleaved to 6-MP, anti-metabolite decreases DNA and RNA synthesis
ADRs: Bone marrow supression, increase risk of mallignancy, increased risk of infection, hepatitis
IMPORTANT DRUG-DRUG INTERACTIONS: Other immunosupressent drugs, corticosteriods,
NOTE: TPMT is highly polymorphic, test activity before pescribing

Question 16

Salbutomol

Answer 16

CLASS: Short acting B2 agonist
INDICATIONS: Asthma, COPD, Prophylaxis of allergen- or exercise-induced bronchospasm
MECHANISM OF ACTION: Major action on airway smooth muscle, also aid airway clearance
ADRs: Adenergic, tachycardia, palpitations, anxiety, tremor. Increase renin and glycoenolysis.
IMPORTANT DRUG-DRUG INTERACTIONS: Beta blockers

Question 17

Morphine

Answer 17

CLASS: Opiod
INDICATIONS: Analgesic, cough/dysponea in palliation, acute PE
MECHANISM OF ACTION: Complete activation of meu receptor.
ADRs: Resp depression, emisis, constipations, CVS, miosis, histamine release (caution in asthmatics)
IMPORTANT DRUG-DRUG INTERACTIONS: Buprenorphine is predicted to increase the risk of opiate withdrawal when given with morphine. Alcohol. Slows down GI system so slowed absoprtion of PO drugs.

Question 18

Fluticasone

Answer 18

CLASS: Corticosteriod
INDICATIONS: Asthma, prophylaxis and treatment of allergic rhinitis and perennial rhinitis, nasal polyps.
MECHANISM OF ACTION: INcrease B2 receptor activity, anti-inflamatory mediatiors, inhibit relesase of arachidonic acid.
ADRs: Local immunosupressive action, candidiasis, horse voice.
IMPORTANT DRUG-DRUG INTERACTIONS: NSAIDS

Question 19

Omeprazole

Answer 19

CLASS: PPI
INDICATIONS: Helicobacter pylori eradication [in combination with other drugs]. Ulcers (+/- NSAID associated.)
MECHANISM OF ACTION: Proton pump inhibitors inhibit gastric acid secretion by blocking the hydrogen-potassium adenosine triphosphatase enzyme system (the ‘proton pump’) of the gastric parietal cell.
ADRs: GI distrubance, headache, dizzieness, dowsieness/confusion.
IMPORTANT DRUG-DRUG INTERACTIONS: Reduced clopidogrel action. Can increase effects of warfarin and phenytoin - close monitoring required.

Question 20

Cyclizine

Answer 20

CLASS: H1 receptor antagonist
INDICATIONS: Nausea, Vomiting, Vertigo, Motion sickness, Labyrinthine disorders
MECHANISM OF ACTION: Acts on vestibular nucleio, inhibits histamenergic signals from the vestibular system to the CTZ in medulla.
ADRs: dont use in elderly or children Sedation, excitation, dry mouth, constipation, urinary retention, long QT interval.
IMPORTANT DRUG-DRUG INTERACTIONS: Opiods, increased side effects.

Question 21

Metoclopramide

Answer 21

CLASS: D2 receptor antagonists
INDICATIONS: Anti emetic, good for GORD, illeus.
MECHANISM OF ACTION: Acts of visceral afferents of the gut. Increases Ach at muscarinic receptors in the gut. Promotes gastric emptying, increases tone at LOS, increases tone and amplitutde of gastric contractions, decreased tone of pylorus. Increased peristalsis.
ADRs: Galactorrhoea via prolactin release, extra pyramidal effects - dystonia, parkinsonism.
IMPORTANT DRUG-DRUG INTERACTIONS: Dopamine agonists, antipsychotics.

Question 22

LMWH

Answer 22

CLASS: Heparin
INDICATIONS: VTE - DVT and PE. ACS.
MECHANISM OF ACTION: Inhibition of Xa, by enhancing ATIII acitivity.
ADRs: Pain and skin hematoma at the injection site, less ADRs than UFH
IMPORTANT DRUG-DRUG INTERACTIONS: NSAIDs, platelet inhibitors.

Question 23

Apixaban

Answer 23

CLASS: DOACs
INDICATIONS: Phrophalaxis: DVT, PE, stroke, treatment of thromboembolism.
MECHANISM OF ACTION: Inhibit both free Xa and that bound with ATIII
ADRs: Bleeding, caution in GI bleed risk groups
IMPORTANT DRUG-DRUG INTERACTIONS: Less frequent interactions than warfarin but affecred by the CYP inhibitors and inducers [plasma} reduced by carbamazepine, phenytoin and barbiturates.

Question 24

Co-amoxiclav

Answer 24

CLASS: Penicillin
INDICATIONS: Respiratory tract infections, bone and joint infections, genito-urinary and abdominal infections, actue diverticulitis, cellulitis, bite phrophalaxis, diabetic foot infection, CAP, surgical phrophalaxis.
MECHANISM OF ACTION: Clavulanic acid: beta lactamase inhibitor. This enzyme is used by certain bacteria to break down Beta-lactam antibiotic molecular structure, so this overcomes this issue. Amoxicillin: binds to penicillin-binding protein on bacteria. Inhibits transpeptidation enzyme (responsible for linking the peptidoglycan chains to for rigid cell walls). Disruption of cell wall structure.
ADRs: Diarrhoea; hypersensitivity; nausea; skin reactions; thrombocytopenia; vomiting
IMPORTANT DRUG-DRUG INTERACTIONS: Doxycycline, warfarin, some live vaccines

Question 25

Carbamazepine

Answer 25

CLASS: Sodium channel blocker
INDICATIONS: Focal and secondary generalised tonic-clonic seizures, bipolar disorder, chronic pain, acute alcohol withdrawal, diabetic neuropathy.
MECHANISM OF ACTION: Blocks Na+ channels, reducing cell membrane depolarization, reduced APs, reduced seizures.
ADRs: Suicidal thoughts, bone marrow failure, joint pain, HLA ALLELES
IMPORTANT DRUG-DRUG INTERACTIONS: DOACs, MAIOs, CYP3A4 substrate and INDUCER, reduces oral contraceptive efficacy.

Question 26

Co-careldopa

Answer 26

CLASS: Dopamine precursor
INDICATIONS: Parkinsons Disease
MECHANISM OF ACTION: Levodopa: Dopamine precursor, can cross blood brain barrier. Carbidopa: peripheral DOPA decarboxylase inhibition
ADRs: Impulse control disorders, drowsieness.
IMPORTANT DRUG-DRUG INTERACTIONS: MAOi, antipsychotics

Question 27

Sodium valproate

Answer 27

CLASS: Anticonvulsant
INDICATIONS: All forms of epilipsey, bipolar, migraine prophylaxis.
MECHANISM OF ACTION: GABAa effects, sodium channel blockade.
ADRs: TETRAGENIC. Liver failure, panceratitis, lethargy.
IMPORTANT DRUG-DRUG INTERACTIONS: Antidepressants, antibiotics.