Digoxin Flashcards
Digoxin - therapeutic levels
0.7-2 mcg/L
Cp = 6 hours after dose
Digoxin - MoA
HIGH RISK DRUG
Increases force of myocardial contraction (positive inotrope)
Reduces conductivity in the AV node (negative chronotrope)
Digoxin - monitoring
Regular monitoring NOT required during maintenance treatment unless suspect toxicity or renal impairment (renally cleared).
Dosing
Loading dose required due to long half-life.
Maintenance dose varies depending on indication.
Different formulations have different bioavailability.
Bioavailability
Elixir = 75%
Tablet = 90%
IV = 100%
Dose - AF/non-paroxysmal AF in sedentary patients
125-250 mcg
Dose - worsening or severe HF (in sinus rhythm)
62.5-125 mcg
Signs of toxicity
“Slow and sick” or BBLGCRMD
BBL Girls Crave Rich Mens Dick
- Bradycardia/heart block
- Blurred/yellow vision
- Lethargy, weakness
- GI disturbances
- Confusion/delirium
- Rash
- Mental confusion/psychosis, headache
- DIGOXIN
Toxicity - treatment
Range = 1.5-3 mcg/L
- Withdraw drug
- Correct electrolyte imbalances
- Digoxin specific antibody
Digoxin - monitoring
- Serum electrolytes
- Renal function
- Plasma-digoxin levels
- Heart rate
Monitoring - serum electrolytes
K+ (HYPO)
Mg2+ (HYPO)
Ca2+ (HYPER)
Increased risk of toxicity when there is electrolyte disturbances
Monitoring - renal function
Digoxin is renally excreted.
Reduce dose in renal impairment - accumulation of metabolite.
Monitoring - plasma/digoxin
Cp
Mainly in renal impairment
Blood taken at least 6 hours after dose
Monitoring - Heart rate
Maintained above 60 BPM
Interactions
CRASED
C = CCBs (verapamil)
R = Rifampicin
A = Amiodarone
S = St. Johns wort
E = Erythromycin
D = Diuretics
