An overall view on medications containing digoxin
-THERAPEUTIC DRUG CONCENTRATION
• Therapeutic serum levels.
• serum levels range from 0.8 to 2 ng/mL.
• Toxic serum levels.
• 2 ng/mL or greater.
• signs of toxicity occur at serum levels excess of 3 ng/mL.
• CHF.(0.8-2 ug/L).
• Significant overlap between therapeutic and toxic level.
• Atrial fibillation.(0.8-2 ug/L).
• Patients may require conc. as high as 2.6 ug/L to control ventricular response.
• Falsely elevated serum digoxin concentration (SDC) can be caused by endogenous digoxin-like substances (EDLS) in patients with renal or liver impairment, pregnant, and neonates.
• Digoxin conc. in the presence of Digoxin immune fab is increased by 10-20 fold in total serum Digoxin.
• Digoxin Immune Fab (Ovine)
• is the generic name for an antidote for overdose of digitalis.
• It is made from immunoglobulin fragments from sheep who have already been immunized with a digoxin derivative, digoxin dicarboxy methoxyl amine (DDMA).
• Its brand names include Digibind and DigiFab, with the former manufactured by
GlaxoSmithKline.
• serum levels range from 0.8 to 2 ng/mL.
• Toxic serum levels.
• 2 ng/mL or greater.
• signs of toxicity occur at serum levels excess of 3 ng/mL.
• CHF.(0.8-2 ug/L).
• Significant overlap between therapeutic and toxic level.
• Atrial fibillation.(0.8-2 ug/L).
• Patients may require conc. as high as 2.6 ug/L to control ventricular response.
• Falsely elevated serum digoxin concentration (SDC) can be caused by endogenous digoxin-like substances (EDLS) in patients with renal or liver impairment, pregnant, and neonates.
• Digoxin conc. in the presence of Digoxin immune fab is increased by 10-20 fold in total serum Digoxin.
• Digoxin Immune Fab (Ovine)
• is the generic name for an antidote for overdose of digitalis.
• It is made from immunoglobulin fragments from sheep who have already been immunized with a digoxin derivative, digoxin dicarboxy methoxyl amine (DDMA).
• Its brand names include Digibind and DigiFab, with the former manufactured by
GlaxoSmithKline.
• It works by binding to the Digoxin, rendering them unable to bind to their action sites on target cells.
• The complexes accumulate in the blood and are expelled by the kidney.
• The complexes accumulate in the blood and are expelled by the kidney.
Sampling time
• Drug levels should be drawn during the 8 to 24 hour interval following the previous dose.
• It is better the samples to be taken at approximately the same time.
• Physical activity increase binding of Digoxin to skeletal muscle. So 2hr rest is required before sample time.
• It is better the samples to be taken at approximately the same time.
• Physical activity increase binding of Digoxin to skeletal muscle. So 2hr rest is required before sample time.
DOSING
• Usual Digoxin doses for adults are 250 μg/d(range: 125–500 μg/d) in patients with good
renal function (Creatinine clearance ≥80mL/min).
• 125 μg every 2–3 days in patients with renal dysfunction (Creatinine clearance ≤15mL/min).
• Divided daily dosing is presently recommended for:
– patients requiring a daily dose of 300 micrograms or greater;
– patients with a previous history of digitalis toxicity;
– patients considered likely to become toxic; and patients in whom compliance is not a problem.
renal function (Creatinine clearance ≥80mL/min).
• 125 μg every 2–3 days in patients with renal dysfunction (Creatinine clearance ≤15mL/min).
• Divided daily dosing is presently recommended for:
– patients requiring a daily dose of 300 micrograms or greater;
– patients with a previous history of digitalis toxicity;
– patients considered likely to become toxic; and patients in whom compliance is not a problem.
DOSING
• Vd equations
• Vd = (3.8 L/Kg) (wt in Kg) + (3.1 )(CrCI) (The resulting answer is in liters.).
Vd = 7.3 L/Kg
• Vd = approximately 4 L/Kg in the presence of HF and renal insufficiency.
• MD=((Cl)(Cpss ave)(ť))/F
• Cl, clearance of digoxin. Cpss, desired serum level. F, bioavailability and ť dosing interval (24hr).
• Vd = (3.8 L/Kg) (wt in Kg) + (3.1 )(CrCI) (The resulting answer is in liters.).
Vd = 7.3 L/Kg
• Vd = approximately 4 L/Kg in the presence of HF and renal insufficiency.
• MD=((Cl)(Cpss ave)(ť))/F
• Cl, clearance of digoxin. Cpss, desired serum level. F, bioavailability and ť dosing interval (24hr).
Monitoring parameters
1. The following patient parameters should be monitored during digoxin therapy:
– Digoxin serum level Obtain level within 24 hours of digitalization, weekly until stable, and at steady state.
– BUN and serum Creatinine Measure every two days, or every day in unstable renal function. – Weigh patient daily.
– Measure and monitor urine output daily
– Monitor apical pulse daily.
– Digoxin serum level Obtain level within 24 hours of digitalization, weekly until stable, and at steady state.
– BUN and serum Creatinine Measure every two days, or every day in unstable renal function. – Weigh patient daily.
– Measure and monitor urine output daily
– Monitor apical pulse daily.
2. Therapeutic serum concentrations The usual Digoxin therapeutic range is 0.8 to 2 ng/ml.
Adverse Effects
• Arrhythmias.
• Conduction defects.
• Thrombocytopenia.
• Hallucinations.
• Anorexia.
• Blurred vision.
• Disturbed color vision.
• Changes in visual acuity.
• Delirium.
• Conduction defects.
• Thrombocytopenia.
• Hallucinations.
• Anorexia.
• Blurred vision.
• Disturbed color vision.
• Changes in visual acuity.
• Delirium.
• Nausea.
• Vomiting.
• Abdominal pain.
• Vomiting.
• Abdominal pain.
• Hypokalemia.
• Hypomagnesemia.
• hypercalcemia.
• Hypomagnesemia.
• hypercalcemia.