Digoxin & Amiodarone HRDs

Question 1

Amiodarone

Answer 1

DOSE:
Arrhythmias
200mg TDS for 1 week THEN
200mg BD another week THEN
200mg OD - Maintenance dose

AEs
Amiodarone is a photogenic bitch
P- Photosensitivity
B- Bradycardia
I- interstitial lung disease
T- Thyroid (hypo/hyper)
C- Corneal (ocular) - microdeposits can dazzle u if driving at night by headlights.
H- Hepatic (liver issues)

T- Ami has iodine which will affect thyroid glands.
H- STOP if shows signs of liver disease (NV, Jaundice, abdo pain, 3 raised liver enzymes)
I - Pulmonary toxicity (sus if SOB or dry cough)
C - Opti neuropathy (blindness) STOP if vision impaired.
Peripheral neuropathy - Tingling/Numbness in hands and feet.
Phototoxicity- Skin reactions so AVOID sunlight use sunscreen

Contraindication
Thyroid disorder, Iodine sensitivity.

Monitor
- TFTs B4 and every 6 months.
- LFTs B4, Every 6 months (Monitor liver transaminases closely)
- Serum K+ conc. - Ami causes hypokalaemia
- Chest X-ray
- Annually Eye test
- ECG (with IV use) & BP

Patient and carer advice
Shield skin from sunlight during and several months after treatment
Use wide spectrum sunscreen (at least SPF30)
Seek medical attention if ANY of these symptoms develop:
- SOB,
- Light headedness
- Palpitations
- Fainting
- Unusual tiredness
- Chest pain

Interactions
Ami is a enzyme inhibitor
AMI has a long half life so interaction can happen over time after AMI stopped.
- Increases plasma conc. (Warfarin, Digoxin, Ciclosporin & Phenytoin)
- Lithium (increases risk of arrhythmias)
- Statin (increases risk of myopathy)
- QT prolongation drugs (Ami also prolongs QT so greatens its affect)- CAUTION with Antidepressants, antipsychotics, Lithium, Macrolides, Quinolones

Question 2

Random note

Answer 2

Drugs that prolong QT with drugs that can cause hypokalaemia
eg Furosemide + antipsychotic = Higher risk of causing QT interval prolongation

Question 3

Digoxin (Cardiac glycoside) OVERVIEW

Answer 3

Memory trick: 2 kidneys

2 = Plasma conc. of digoxin keep within <2. (RANGE - 1-2)
K = Potassium - Most important electrolyte to monitor in pts taking digoxin
I = Positive inotrope - Increases forces of contraction of heart.
D = Decrease Digitalis toxicity - Happen if you have hypokalaemia and Higher conc. of digoxin.
N = Nausea (sign of digitalis toxicity)
E = Emesis (Vomiting) SIGN
Y = Yellow vision (SIGN)
S = Sparing - K+ Sparing diuretic - prevents hypokalaemia prevent digoxin toxicity.

• MUST MONITOR RENAL function when on digoxin.
• Digitalis toxicity = digoxin toxicity
  Signs of Digitalis toxicity: (EXAM Q)
  N onwards in acronym. Signs are also AEs of digoxin.

Question 4

Digoxin extra details

Answer 4

Increases force and decreases HR - Reduces conductivity in AV node.

Useful in AF, A flutter - esp sedentary Pts. can be used in HF (sinus rhythm)

In AF maintenance dose is calculated when at rest ie VR cant be <60BPM

-Takes longer to work due to long half life even as IV. So not used for rapid heart control.
- IM not recommended

Loading dose NOT needed in Pts with HF (sinus r) - right dose can be found in a week.
- Narrow therapeutic drug
Maintenance
AF/ A flutter:
- 125-250mcg OD - LOADING dose needed
Severe HF (in sinus rhythm):
- 62.5-125mcg OD - NO LOADING DOSE needed. Reduce in elderly.
IF have both condition cam give 125

Higher doses can be BD.
- Dose based on renal function.

RANGES
Therapeutic - 1-2mcg/L
Toxic - 1.5-3 mcg/L
- Hypokalaemia can = Digoxin toxicity.
Give K+ sparing diuretic.

TOXICITY OCCURS:
Withdraw digoxin, Serious issues = URGENT specialist care.
Life threatening overdose - REVERSE with digoxin specific antibody fragments (Digifab)

Question 5

Signs of digoxin toxicity (EXAM Q)

Answer 5

Arrhythmias
Cardiac conduction disorders
Diarrhoea
Dizziness
Nausea
Vomiting
Skin reactions
Vision disorders (Yellow)
Hypoxia
NOTE: they will make it obvs in Q.

Question 6

Monitoring

Answer 6

Plasma conc. of digoxin - At least 6 hrs after dose

Serum electrolytes - Toxicity increases if imbalance

Renal function - Reduce dose in impairment or not use at all

Question 7

Interactions

Answer 7

Drugs which:
Reduce renal secretions (NSAIDs, ACEi/ARBs)
Decrease digoxin conc (enzyme inducers) (CRAP GPs Shout BS)
Increase digoxin conc. (Enzyme inhibitors) (SICKFACES.COMGF)
Decrease K+ (diuretics loop/thiazide, theophylline, steroids)

Memory trick: CRASED
C CCBs (Verapamil)
R Rifampicin
A Amiodarone
S St johns
E Erythromycin
D Diuretics