EAST AND NORTH HERTS NHS TRUST ADULT DRUG GUIDE Digoxin

EAST AND NORTH HERTS NHS TRUST

Digoxin

ADULT DRUG GUIDE

DOSE Loading Dose ? Only if cardiac glycosides not given in last

2 weeks 1,2,3 IV: 500?1000micrograms Give 50% loading dose immediately then 25% at 6 hours and 12 hours1,3,4 PO: 750?1500micrograms as a single dose or in divided doses 6 hours apart2,3,4 Maintenance dose PO: Usual maintenance dose is 125?250micrograms daily, but higher or lower doses may be required1,2,3,4

Switching Route PO to IV: reduce dose by a third1,2,5

Blood levels Take 6 hours or more after last dose1,3. Steady state plasma digoxin concentrations of 0.5?2 nanograms/ml acceptable1,3 Toxicity commonly associated with serum concentrations of 0 2nanogram/ml but may occur at therapeutic levels1,3

METHOD OF PREPARATION

ROUTE Single IV Infusion

Over 2 hours5

PREPARATIONS AVAILABLE

IV: 500micrograms in 2ml ampoules

COMMENTS

Digoxin has a low therapeutic index, therefore tailor dose to each individual patient according to age, lean body weight and renal function1,2,3,4

Multiple IV Doses IV infusion over 10? 20 minutes1,3,5

Rapid IV injection can cause vasoconstriction producing hypertension and may reduce coronary blood flow1.

PO: 250 microgram tablets

125microgram tablets 62.5microgram tablets 50microgram/ml liquid

HR, BP and ECG monitoring required for IV administration5.

Effects of digoxin enhanced by hypokalaemia, hypomagnesaemia, hypercalcaemia, hypoxia and hypothyroidism and doses may need to be reduced1,2,3,4

Resistance to the effects of digoxin may occur in hyperthyroidism1,2,3,4

Volume of distribution and elimination half life increase with age1,2,3,4

IV dose produces appreciable pharmacological effect within 5?30 minutes reaching max after 1-5 hours1,2,3,4

PO dose produces a detectable effect in 0.5?2 hours with a maximal effect in 2?6 hours1,2,3,4

Dilute 1 part digoxin with at least 4 parts of sodium chloride 0.9% or glucose 5%. Volume 50 ? 100ml (maximum 500ml)1,4,5,6 NB Use of more concentrated solution could lead to precipitation of digoxin.

USUAL TOTAL RISK FACTORS: 45 OVERALL RISK RATING: Amber5 Risk factors: Therapeutic risk; Use of concentrate; Part/multiple container; Use of infusion pump/driver5 COMPATIBILITY AND pH

Compatible ? bivalirudin6, midazolam5,6, morphine5,6, potassium chloride6

Incompatible ? amiodarone5,6, propofol5,6 , insulin5,6

pH = 6.8 ? 7.2 5 STORAGE AFTER DILUTION/RECONSTITUTION

Please contact Pharmacy for further information

Dilution should be carried out immediately before use and any unused solutions discarded1

Review date: October 2013

Compiled by ................................. Checked by................................... Approved by.................................

References

1. Summary of Product Characteristics. Lanoxin injection. Last updated 08/03/2010. Accessed via .uk/EMC on 13/10/2011 2. Summary of Product Characteristics. Lanoxin tablets. Last updated 08/03/2010. Accessed via .uk/EMC on 13/10/2011 3 .Martindale "The Complete Drug Reference". Digoxin monograph. Accessed via on 14/10/2011 4. American Hospital Formulary Service Drug Information. Digoxin monograph. Accessed via on 14/10/2011 5. Medusa "Injectable Medicines Guide". Digoxin monograph. Published 02/06/2010. Accessed via on 15/09/2011 6. Trissel "Handbook of Inlectable Drugs. Digoxin monograph. Accessed via on 14/10/2011

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