In: Biology
a drug is given at an infusion rate of 50 mg/h. The drug concentration value determined that at 3 hours after the start of the infusion is 8mg/L. Assuming the patient has 5L of blood, estimate the half-life of this drug
Vd = amount of drug in body/ (concentration of drug in plasma)
Clearance = rate at which you eliminate the drug = elimination rate/remaining drug or
Cl (clearance) = (Dose / interval) / Cpss ave
Half-life = Vd/ clearance X 0.7
Calculation for Vd
Infusion rate: 50 mg/h
Vd = 50 mg/h x 3 = 150 mg
150mg body/8mg plasma/L = 18.75
Calculation for clearance
50 mg/h/8mg/L
= 6.25
Calculation for half life
= 18.75/6.25 x 0.7
= 2.1 hr