First-Pass Bioavailability Estimate

Explicit F=FaFgFhserial absorbed/gut escape/hepatic escape fractions independently established; not portal extraction-only ledger or simultaneous unverified kinetics. All patient/product/route/units and applicable inputs independently clinically established; no dose, route, frequency, eligibility, titration, diagnosis or permission to administer is supplied.

Description

A serial bioavailability model separates absorption, gut escape and hepatic escape into independently established fractions.

A serial bioavailability model separates absorption, gut escape and hepatic escape into independently established fractions.^[1]

This tool multiplies those fractions to give the model's systemic availability, without estimating them from patient data.

When to use First-Pass Bioavailability Estimate

This tool multiplies those fractions to give the model's systemic availability, without estimating them from patient data.

How to use First-Pass Bioavailability Estimate and how it works

Prepare independently established absorbed fraction, independently established gut escape fraction, independently established hepatic escape fraction, using the input definitions and matching units below.
Enter the required fields and run First-Pass Bioavailability Estimate.
Read result.value using the units, signs and ordering explained below.
Correct any rejected inputs and rerun; interpret the result within the stated model and its assumptions.

Input field	Meaning	Value type	Requirement
callerIndependentlyEstablishedAbsorbedFraction	Caller Independently Established Absorbed Fraction. Use the units and matching context stated in the calculation below.	number	Required; fraction from 0 to 1; finite; other constraints below
callerIndependentlyEstablishedGutEscapeFraction	Caller Independently Established Gut Escape Fraction. Use the units and matching context stated in the calculation below.	number	Required; fraction from 0 to 1; finite; other constraints below
callerIndependentlyEstablishedHepaticEscapeFraction	Caller Independently Established Hepatic Escape Fraction. Use the units and matching context stated in the calculation below.	number	Required; fraction from 0 to 1; finite; other constraints below

Require each independently established absorbed fraction, gut escape fraction and hepatic escape fraction between 0 and 1 inclusive. Multiply all three and return the dimensionless serial-model systemic availability fraction. No fraction is fitted, and a hepatic extraction ratio alone does not supply the other terms.

F=Fa*Fg*Fh

Apply the input ordering, units and branch conditions stated above.

Output field	Meaning	Value type
result	Object containing the calculated or selected fields below.	object
result.value	Numeric model result on the ratio, score, constant or density basis explained above.	number

json

{
  "input": {
    "callerIndependentlyEstablishedAbsorbedFraction": 1,
    "callerIndependentlyEstablishedGutEscapeFraction": 0.5,
    "callerIndependentlyEstablishedHepaticEscapeFraction": 0.5
  },
  "output": {
    "result": {
      "value": 0.25
    }
  }
}

Limitations and assumptions

Patient context, drug formulation, route, sampling time, assay units and applicable clinician-verified protocol must be independently established. The output supplies no dosing, titration, switching or administration instruction.

The calculation uses the supplied observations and model inputs. It does not collect measurements, select a reference population or coefficient, or establish that the model applies to the actual case. The stated branch conditions and output units remain part of the result.

All fields require explicit values. Unexpected fields, wrong types, nonfinite numbers and sparse arrays are rejected. Alignment, bounds and supported-token rules are explained above; extremely large inputs or nonfinite results can also fail. Input errors differ from successful false comparisons, unavailable-domain flags and empty match lists.

Alternative or Complementary methods

Use Tmax Calculator for a complementary operation: Time to maximum concentration depends on both absorption and elimination in a one-compartment oral model.

Use Ke Rate Constant Calculator for a complementary operation: In a one-compartment first-order model, elimination rate constant relates clearance to distribution volume.

References

First-Pass Bioavailability Estimate — tool.io

Similar or alternative tools

Tmax Calculator
Time to maximum concentration depends on both absorption and elimination in a one-compartment oral model.
Ke Rate Constant Calculator
In a one-compartment first-order model, elimination rate constant relates clearance to distribution volume.