Drugs like digoxin and warfarin with a long half life will take longer to reach a steady state than drugs with a shorter half life
As digoxin is now the only cardiac glycoside available in most countries, the method of initiating therapy with digoxin for patients with atrial fibrillation is
Digoxin Monitoring - When monitoring digoxin therapy, drug levels should be drawn when the patient is at steady-state (ie: 4-5 half lives have passed since the last dose change
5-2 days (36-44 hours) although this becomes prolonged in renal dysfunction [4, 20-23, 25, 26]
Therefore, in the absence of a loading dose, the time required to reach steady state, after the initiation of a repeated administration
Rapid digoxin loading —
We can show this using a bucket to represent the
The time taken to reach the steady state is about five times the half life of a drug
Digoxin is the primary cardiac glycoside in clinical use
Once a steady-state digoxin concentration has been obtained, repeated measurements are not necessary After oral administration of digoxin, half-life and time to steady state vary significantly between individuals, and are also dependent on renal function (Ehle et al
, 2011), and steady state is reached in 5–7 days (Ehle et al
Cpss = (MD x F) / (Cl x tau) where MD = Maintenance dose (mcg) F = bioavailability factor
S
were 1 to 2 mcg/L and probably today doses of approximately one-half would be more common in patients with heart failure (see Therapeutic Plasma Concentrations, this chapter)
As discussed above, average steady-state levels are defined by CL and dose/time, but not by Therefore, the half-life of digoxin may not change in the aged, but most often the half-life increases, as does the risk of toxicity
As a general rule the steady state takes four or five half lives to reach
20-40% HEPATIC
Digoxin dosing advice in 'Drugs for atrial fibrillation' section refers to loading doses and initial maintenance doses in Collect specimen just before dose if steady-state estimate is needed
Patients with renal failure may have an endogenous digoxin-like material in their serum which makes digoxin measurements The time to reach steady state is determined by the half-life (3-5 half-lives, see Article 3 'Half-life' Aust Prescr 1988; 11:57-9)
18% to 7
Digoxin is extensively distributed in the tissues, as reflected by the large volume of distribution
24 Renal insufficiency caused by aging-related impairment, coexisting diseases (eg, HF, hypertension, diabetes mellitus) and use of medications M D =(Concentration Steady State X Clearance X Dosing Interval)/Bioavailability
5 to 5 days] Children: 18 to 36 hours
Post-dose levels are recommended no sooner than 6 hours for an IV dose and 12 hours for an oral dose
The half-life in anuric patients is prolonged to 3
Kidway took her digoxin at 8:00am on a Monday then the medication would be 75% cleared around 8:00am on Thursday in an elderly woman because of the prolonged half-life, in a regular adult it would be around 2:00pm on Wednesday