Maintenance Dose Calculator
Steady-State Elimination Equilibrium Model
Understanding Maintenance Dosing and Elimination Equilibrium
The objective of maintenance dosing is to sustain a therapeutic steady-state drug concentration within the plasma where the rate of drug administration equals the rate of drug elimination. Unlike loading doses, which depend entirely on space and volume parameters, maintenance schedules are anchored heavily to body clearance mechanisms.
The Primary Role of Clearance (Cl)
Clearance is the functional volume of blood plasma completely cleared of a drug per unit of time (expressed in liters per hour or milliliters per minute). If a patient has impaired renal clearance (measurable via a reduction in glomerular filtration rate) or diminished hepatic metabolic function, the systemic elimination loop slows down.
If the maintenance dose is not proportionally down-titrated or the dosing interval lengthened, drug accumulation will trigger systemic toxicity profiles.
Balancing the Dosing Interval (Tau)
The interval choice represents a balance between clinical convenience and the mitigation of drug level fluctuations. Giving larger doses at extended intervals can lead to wide swings between peak levels and trough levels. Conversely, short intervals minimize fluctuations but demand frequent patient compliance or continuous clinical infusion monitoring.