1/9: Arrhythmia Drugs

Question 1

State the Anti-Arrhythmic Drugs Within Class 1 - 4

Answer 1

1. Lidocaine + Flecanide
2. Beta Blockers
3. Amiodarone / Sotalol
4. CCB (Verapamil)

Question 2

True or False? “hyperkalaemia exposes people to digitalis toxicity”

Answer 2

False - HypoKalemia does

Question 3

The Likelohood of toxicity increases progressively through what range of digoxin level?

Answer 3

1.3-3mcg/ litre of blood

Question 4

What is the MHRA Warding with Sotalol

Answer 4

It May Prolong QT. Correct Hypomagnesium + Hypokalemia before initiaing.

Question 5

Which two drug classes are first line for rate control in AF?

Answer 5

1. . Beta Blocker
2. . Rate Limiting Calcium Channel Blocker

Question 6

Give 2 examples of Rate Limiting CCBs , and state their Class and MOA

Answer 6

Verapamil and Diltiazem. They are Non-Dihydroprydines and thus are more selective for the calcium channel blockers in the heart. Between the two, Verapamil is the most cardioselective, so its okay in athsma.

Question 7

State the first-line diagnostic agent in Supraventricular Tachycardia, list its MOA and Interactions and Cautions

Answer 7

Drug: Adenosine

MOA: It is an Agonist of the G protein coupled receptors and slows the heart muscle down, increasing the refractoryness of the AV node and breaking re-entry circuits.

Cautions: By interfering with AV and SA nodes, can cause bradycardia. It can also cause bronchospasm so avoid in Asthma or COPD. Avoid in Decompensated HF

Interactions: Dipyriamidole blocks cellular updake of Adenosine, This increases its effects. Caffine can reduce its effect, so patients may need higher doses

Question 8

Can the GP initiate amiodarone

Answer 8

Nope, specialist care only within hospitals

Question 9

What is the loading dose of amiodarone?

Answer 9

Week 1: 200mg TDS

Week 2: 200mg BD

Week 3 and thereafter 200mg OD

Question 10

What are the 6 toxicities of Amiodarone

Answer 10

Amiodarone can precipitate:

1 Corneal Microdeposits (Drivers may be dazzled by lights)

2 Thyroid (AmIODarone) So both Hypo or Hyperthyroidism

3 Pulmonary Toxicity or Pneumonitis

4 Liver Toxicity (Hepatocellulatr)

5 Peripheral Neuropathy (Numbness or Tingling)

6 Phototoxicity (Grey discolouration of skin)

Question 11

What should happen when a patient is taking amiodarone gets thyrotoxicosis?

Answer 11

Withdraw amiodarone (at least temporarily) to help achieve control

Question 12

What are the Main monitoring points for Amiodarone?

Answer 12

1. Thyroid function before treatment then every 6 months (TSH, T4 and T3)
2. LFTs before starting then every 6 months
3. Chest X-ray before starting
4. Serum potassium before starting

Question 13

Councelling for Amiodarone?

Answer 13

1. Shield skin from light during treatment and for several months after discontinuing
2. Watch out for Weight Loss/ Gain
3. Persistent cough / Breathlessness
4. Do not drink grapefruit juice (can increase risk of side effects)

Question 14

Which beta-blocker may prolong QT and cause potentially life-threatning arrhythmias?

Answer 14

Sotalol

Question 15

Antidote to Digoxin?

Answer 15

Digoxin-Specific Antibiody. Digifab

Question 16

When a Patient is on Digoxin, what must be the ventricular rate at rest ?

Answer 16

60BPM

Question 17

“A Digoxin LD is needed for patients who have heart failure and are in sinus rhythm” True or False?

Answer 17

False – it is not needed here

Question 18

What is the most important determinant of dosage for digoxin?

Answer 18

Renal Function

Question 19

Give the MOA / Cautions/ Side Effects of Digoxin

Answer 19

Digoxin is Negatively Chronotropic and Positively Inotropic. In AF it increases Parasympathetic Vagal Tone.

In HF it blocks Ca²⁺ escape, so it accumulates within the myocyte. Na⁺ accumulates also because the Ca/K/NA channel is blocked. This explains its reduction of rate.

Side effects: Digoxin can cause Blurred or Yellow vision, Bradycardia, Rash, GI disturbance & Dizziness

Cautions: Reduce dose in renal failure, heart block. Hypokalaemia / Hypomagnamesia and Hypercalcaemia predispose the risk of digoxin toxicity.

Question 20

When digoxin is given concomitantly with amiodarone, dronedarone and quinine, what should be done to the dose?

Answer 20

half the dose

Question 21

Important Interactions with Digoxin?

Answer 21

Digoxin Interacts with loop + thiazide diuretics, which INCREASE the risk of digoxin toxicity by causing hypokalaemia.

Amiodarone / CCB / Quinine / Spironolactone can all increase the [digoxin] so reduce or half the dose of digoxin

Question 22

Dose of Digoxin in Heart Failure and Dose o f Digoxinin AF?

Answer 22

AF: Maintenance 125–250 micrograms daily, dose according to renal function and initial loading dose, reduce dose in the elderly.

HF for adults in sinus rhythm: 62.5–125 micrograms once daily, reduce dose in the elderly.

Question 23

Key Monitoring for Digoxin?

Answer 23

Symptoms and HR, Check ECG /Electrolytes and Renal Functionality espacially during illness.

Question 24

What is the dose of Dabigatran / Apixaban / Edoxaban / Rivaroxaban in Non Valvular AF?

Answer 24

Dabigatran: 150mg twice daily

Apixaban: 5mg twice daily

Edoxaban: 60mg once daily

Question 25

Give the Mechanism of Action of Amiodarone

Answer 25

Amiodarone causes Blockade of Sodium, Calcium and Potassium channels, and antagonism of σ and ß adrenergic receptors. These effects reduce spontaneous depolarisation (automaticity) and increase resistance depolarisation (refractoriness). It also increases the chance of conversion to Sinus rhythm.

Question 27

List all possible indications for Aspirin

Answer 27

Acute Coronary Syndrome (ACS), Acute Ischaemic Stroke. Cardiovascular, Cerebrovascular or Peripheral Arterial Disease.