DO NOT USE FOR CLINICAL PRACTICE
Please use current guidelines available on the UHNM intranet for patient treatment
Please use current guidelines available on the UHNM intranet for patient treatment
INDICATIONS
ADMINISTRATION
- Give orally, no advantage to IV
Younger and fitter
- Normal renal function, normal weight, no interacting medicines, not frail / elderly
Loading dose
- Give in 500 micrograms or 250 micrograms doses with a 6 hr interval between each dose
- reassess HR response before next dose
- if HR <100bpm no need for further loading dose, jump directly to maintenance
- Maximum allowed total loading dose: 1mg, occasionally 1.25mg
Maintenance dose
- Initially 125 micrograms once daily
- assess HR response and consider adjusting dose
- levels only useful in context of suspected toxicity e.g. nausea, bradycardia
Older, frail or reduced renal function
- CKD or CrCl <60ml/min, reduced weight <60kg, interacting medicines, frail/elderly
Loading dose
- Give in 250 micrograms doses with a 6 hr interval between each dose
- reassess HR response before next dose
- if HR <100bpm no need for further loading dose, jump directly to maintenance
- Maximum allowed total loading dose: 750 micrograms
Maintenance dose
- Initially 62.5 micrograms once daily
- assess HR response and consider adjusting dose
- levels only useful in context of suspected toxicity e.g. nausea, bradycardia
MONITORING
Patients taking digoxin alone for rate control in AF
- Once treatment is established, ventricular rate is the best guide to the appropriate dosage
Care with concurrent medication
- e.g. if amiodarone added, reduce usual dose by half
Digoxin levels
Indications
- To question need for continued treatment in patients with sinus rhythm
- To monitor effect of concurrent disease or drug treatment
- To confirm diagnosis of suspected toxicity (nausea, visual disturbances, bradycardia) and to aid dose reduction
- To investigate suspected treatment failure or non-compliance
Sampling
- Steady state is not achieved until 1-3 weeks after starting therapy or changing the dosage, depending on patient's renal function
- Take samples at least 6 hr post-dose
- often easier to sample immediately before a dose is due
Target range
- 0.8-2.0 microgram/L
- concentrations <0.8 microgram/L have no useful inotropic effect
Interpretation
- Consider the clinical effect of the drug as well as the serum concentration in dosage adjustment
- Sensitivity to digoxin is affected by thyroid function, oxygen saturation, and serum concentrations of potassium and calcium
- increased sensitivity to digoxin if hypothyroidism, hypoxia, hypomagnesaemia, hypokalaemia and hypercalcaemia
- decreased sensitivity to digoxin if hyperthyroidism and hyperkalaemia
- take into account when interpreting individual serum digoxin concentrations in relation to the target range