Free PK Calculators

The IVIVE clearance calculator uses the well-stirred model to predict hepatic clearance from in vitro data. It scales microsomal or hepatocyte CLint using physiological factors (MPPGL, HPGL, liver weight, hepatic blood flow) and plasma protein binding (fup). This hepatic clearance prediction is the foundation of every drug discovery DMPK workflow.

The fumic correction accounts for non-specific binding to microsomal membranes, which causes systematic underprediction of clearance for lipophilic compounds. Our calculator lets you toggle between microsomal and hepatocyte systems and edit all species parameters.

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The allometric scaling calculator uses log-log regression across species to predict human pharmacokinetics. The exponent for clearance is typically around 0.75 (Kleiber's law), meaning weight-normalised clearance decreases in larger species. Combined with Vdss scaling (exponent ~1.0), it predicts human half-life and enables human dose prediction.

The human equivalent dose (HED) calculator in the Unit Converter tab uses FDA body surface area correction factors (Km values) to convert animal doses to human-equivalent doses for first-in-human dose projection.

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The DDI risk calculator implements the FDA static model for CYP inhibition assessment. It computes the R1 value (1 + [I]/Ki) for both systemic and gut concentrations to determine whether a clinical drug-drug interaction study is needed. The gut [I]_gut = Dose / 250 mL is often the critical driver for intestinal CYPs.

For time-dependent inhibitors (mechanism-based), the calculator adds KI and k_inact parameters to compute R2. These irreversible inhibitors typically pose higher DDI risk and require careful clinical evaluation.

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