Design the dosing interval τ from the steady-state peak/trough concentration ratio. For one-compartment linear kinetics at steady state, the peak-to-trough ratio over one interval is P = Cmax,ss / Cmin,ss = e^(kτ) where k = ln2 / t½. Mode A: given a target peak/trough ratio, solve for the dosing interval τ = ln(P) · t½ / ln2. Mode B: given a chosen interval τ, compute the resulting peak/trough ratio P = e^(kτ). Note: P reflects fluctuation WITHIN one interval and is NOT the accumulation index (R = 1/(1-e^(-kτ))). Valid only for linear one-compartment kinetics, steady state, fixed dose and interval. Not medical advice.
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Key facts
Category
Health
Input types
select, number
Output type
json
Sample coverage
4
API ready
Yes
Overview
Dosing Interval Designer calculates the dosing interval from a target steady-state peak/trough ratio or calculates the resulting ratio from a chosen interval. It uses linear one-compartment kinetics at steady state with a fixed dose and interval, and is not medical advice.
When to use
Estimate the dosing interval needed for a target peak/trough concentration ratio.
Calculate within-interval fluctuation for a proposed dosing interval.
Check pharmacokinetic assumptions using a known elimination half-life.
How it works
1Enter the elimination half-life in hours.
2Choose From peak/trough ratio → τ or From τ → peak/trough ratio.
3Enter either the target ratio or dosing interval, depending on the selected mode.
4The tool calculates the result using k = ln2 / t½ and returns JSON with the interval, ratio, elimination rate constant, method, and model details.
Use cases
Pharmacokinetic modeling of steady-state concentration fluctuation.
Comparing proposed dosing intervals using a known half-life.
Teaching or checking the relationship between half-life, interval, and peak/trough ratio.
Examples
1. Design a 12-hour interval from a target ratio
Pharmacokinetics student
Background
A one-compartment linear model uses a drug half-life of 6 hours and requires a steady-state peak/trough ratio of 4.
Problem
Find the dosing interval that produces the target ratio.
How to use
Select From peak/trough ratio → τ, enter a half-life of 6 hours and a ratio of 4, then calculate.