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Maintenance Dose
Maintenance Dose
Purpose
- The maintenance dose is the dose required to maintain a target plasma concentration.
Equation
Overview
- Maintenance dose is the dosing rate multiplied by the dosing interval.
Equation
Maintenance dose = (TCCL)/F x tau
- TC*CL = Dosing rate
- CL = Clearance
- tau = Dosing interval
Meaning
- Maintenance dose is calculated by multiplying the Target Plasma Concentration by the Clearance Rate, dividing that number by the Bioavailability, and multiplying by the Dosing Interval.
Units
Dose Rate= [CL (Blood (L)/Time (h)) x TC (Mass (mg)/Blood (L))] / F* Percentage (%)
- The liter units cancel each other.
- We are left with Mass (mg)/ Time (h) for the maintenance dose.
- Dosing Interval
- We multiply this by time interval, which is the time interval (h) in which we are actually giving the drug.
Example
- As an example, we calculate the following loading dose (Mass(mg)/Time(h)):
- Clearance = 2 L/h
- Target concentration = 5 mg/L
- Bioavailability = 50%
- Dosing Interval = 12 h
- Dosing Rate = 2 (L/h) x 5 (mg/L) / 0.50 = 20 mg/h
- The liter units cancel
- Drug needs to be given at 20 mg/h
- We are giving drug every 12 hours
- Maintenance dose = 20 mg/h x 12 h = 240 mg every 12 hours