---
title: "Calculate PK parameters"
method: POST
path: "/api/pk/parameters"
tags: ["pk"]
---

# Calculate PK parameters

`POST /api/pk/parameters`

## Request

- Base URL: `https://api.ivive.app`
- URL: `https://api.ivive.app/api/pk/parameters`
- Auth: OAuth 2 (password, token URL `/api/auth/login`)

Calculate volume of distribution (Vd), elimination half-life (t½), oral bioavailability (F), and steady-state concentration (Css) from hepatic clearance (CLhep) and plasma unbound fraction (fu,p). Vd is Schmitt 2008 Vss from fu,p, logP and pKa. t½ and Css use plasma CL = CLhep × rb. F accounts for hepatic first-pass only.

## Request body

- PKRequest
  - `clhep` number, required: Hepatic blood clearance CLb (mL/min/kg). From IVIVE calculation or manual input.
  - `fu_p` number, required: Unbound fraction in plasma (0–1). Plasma protein binding correction.
  - `logp` number, required: Octanol:water logP. Drives tissue lipid partitioning in Vss.
  - `pka_acid` number, nullable: Most acidic pKa (proton donor). Omit if the compound has no acidic group.
  - `pka_base` number, nullable: Most basic pKa (conjugate acid of the base). Omit if no basic group.
  - `rb` number: Blood-to-plasma ratio. CLhep is blood clearance; plasma CL = CLhep × Rb is used for t½ and Css.
  - `dose` number, nullable: Dose (mg/kg). Optional — required for Css calculation.
  - `tau` number, nullable: Dosing interval (hours). Optional — required for Css calculation.
  - `species` 'human' | 'rat' | 'dog': Species for physiological parameters (Qh used to derive EH).

## Response `200`

Successful Response

- PKResponse
  - `vd` number, required: Volume of distribution at steady state (L/kg, plasma-referenced). Schmitt 2008 tissue partitioning with Pearce 2017 calibration.
  - `half_life` number, required: Elimination half-life (hours). t½ = ln2×Vd×1000/(CLp×60), CLp = CLhep×Rb
  - `f_oral` number, required: Oral bioavailability (fraction). F = 1−EH, hepatic first-pass only
  - `css` number, nullable: Steady-state plasma concentration (µg/L, plasma-referenced), Css = F×Dose/(CLp×τ). Only present when dose and dosing_interval provided
  - `eh` number, required: Hepatic extraction ratio. EH = CLb / Qh
  - `species` string, required: Species used for calculation

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/ivive/apis/ivive-app-api.md) · [All operations](https://skmtc.dev/ivive/apis/ivive-app-api/llms.txt) · [OpenAPI document](https://skmtc.dev/ivive/apis/ivive-app-api/revisions/a67615eaf584?raw)