Codeine half-life calculator

Overview

Codeine is listed here as opioid. Opioids are analgesics that act primarily on opioid receptors. Reported half-life depends on formulation, route, metabolism, and whether metabolites meaningfully contribute to measured concentrations.

This page provides an educational visualization of exponential decay based on a single half-life estimate. It is not medical advice.

Half-life used on this page

HalfLifeDB uses a mean half-life of 3.0 hours to generate the curve below. The curve shows a relative amount remaining in a simplified model.

Half-life note: Mean terminal half-life reported in published pharmacokinetic studies. Values vary by population, dose, route, and analytic method.

What the curve represents

The calculator assumes a one-compartment, first-order elimination model after a single starting amount. In that model, the remaining amount halves every half-life interval. The curve is best used to understand the shape of exponential decline.

Why published half-life values differ

Even when a study reports a single half-life number, values can differ across studies and people. Common drivers include:

• Route and formulation: immediate vs extended release, oral vs inhaled vs injected, and co-administered ingredients.
• Study design: sampling window, analytic sensitivity, and how the terminal phase is defined.
• Individual biology: age, genetics, body composition, and liver and kidney function.
• Interactions: other medications and substances can inhibit or induce metabolism.

How to use this page

• Use the calculator to visualize how quickly a half-life process decays over time.
• Use the source links to see the context for the half-life estimate.
• Treat this curve as a conceptual model, not a personal prediction.

What this page does not do

• It does not provide dosing guidance or treatment advice.
• It does not estimate impairment or functional safety.
• It does not predict laboratory outcomes.

If you have questions about medication use or health decisions, consult a licensed clinician. In an emergency, contact local emergency services.