1/9: Arrhythmia Drugs Flashcards
State the Anti-Arrhythmic Drugs Within Class 1 - 4
- Lidocaine + Flecanide
- Beta Blockers
- Amiodarone / Sotalol
- CCB (Verapamil)
True or False? “hyperkalaemia exposes people to digitalis toxicity”
False - HypoKalemia does
The Likelohood of toxicity increases progressively through what range of digoxin level?
1.3-3mcg/ litre of blood
What is the MHRA Warding with Sotalol
It May Prolong QT. Correct Hypomagnesium + Hypokalemia before initiaing.
Which two drug classes are first line for rate control in AF?
- . Beta Blocker
- . Rate Limiting Calcium Channel Blocker
Give 2 examples of Rate Limiting CCBs , and state their Class and MOA
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.
State the first-line diagnostic agent in Supraventricular Tachycardia, list its MOA and Interactions and Cautions
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
Can the GP initiate amiodarone
Nope, specialist care only within hospitals
What is the loading dose of amiodarone?
Week 1: 200mg TDS
Week 2: 200mg BD
Week 3 and thereafter 200mg OD
What are the 6 toxicities of Amiodarone
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)
What should happen when a patient is taking amiodarone gets thyrotoxicosis?
Withdraw amiodarone (at least temporarily) to help achieve control
What are the Main monitoring points for Amiodarone?
- Thyroid function before treatment then every 6 months (TSH, T4 and T3)
- LFTs before starting then every 6 months
- Chest X-ray before starting
- Serum potassium before starting
Councelling for Amiodarone?
- Shield skin from light during treatment and for several months after discontinuing
- Watch out for Weight Loss/ Gain
- Persistent cough / Breathlessness
- Do not drink grapefruit juice (can increase risk of side effects)
Which beta-blocker may prolong QT and cause potentially life-threatning arrhythmias?
Sotalol
Antidote to Digoxin?
Digoxin-Specific Antibiody. Digifab
When a Patient is on Digoxin, what must be the ventricular rate at rest ?
60BPM
“A Digoxin LD is needed for patients who have heart failure and are in sinus rhythm” True or False?
False – it is not needed here
What is the most important determinant of dosage for digoxin?
Renal Function
Give the MOA / Cautions/ Side Effects of Digoxin
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.
When digoxin is given concomitantly with amiodarone, dronedarone and quinine, what should be done to the dose?
half the dose
Important Interactions with Digoxin?
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
Dose of Digoxin in Heart Failure and Dose o f Digoxinin AF?
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.
Key Monitoring for Digoxin?
Symptoms and HR, Check ECG /Electrolytes and Renal Functionality espacially during illness.
What is the dose of Dabigatran / Apixaban / Edoxaban / Rivaroxaban in Non Valvular AF?
Dabigatran: 150mg twice daily
Apixaban: 5mg twice daily
Edoxaban: 60mg once daily
Give the Mechanism of Action of Amiodarone
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.
List all possible indications for Aspirin
Acute Coronary Syndrome (ACS), Acute Ischaemic Stroke. Cardiovascular, Cerebrovascular or Peripheral Arterial Disease.
