First-Pass Metabolism Calculator

Actual portal-delivered minus independently resolved first-pass-escaping fraction, not oral absorption fraction, AUCavailability or hepatic-flow clearance.

Description

First-pass extraction compares portal-delivered mass with mass independently established as escaping that process.

First-pass extraction compares portal-delivered mass with mass independently established as escaping that process.^[1]

It is different from the fraction absorbed or overall oral bioavailability.

When to use First-Pass Metabolism Calculator

Use this tool to calculate or review the supplied observations under the stated rules. Establish the chemical, exposure route, endpoint, measurement basis and independently applicable assay or assessment reference.

How to use First-Pass Metabolism Calculator and understand its results

Establish the chemical, exposure route, endpoint, measurement basis and independently applicable assay or assessment reference.
Enter actualPortalDeliveredMass, independentlyMeasuredMassEscapingFirstPass, using the field meanings and rules below, then run the tool.
Read result.observedFirstPassExtractionFraction. Use the units and subtraction order below to interpret each value; retain negative differences where returned.
Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.

Input field	Meaning	Value type	Requirement
actualPortalDeliveredMass	Actual portal delivered mass	number	Required
independentlyMeasuredMassEscapingFirstPass	Independently measured mass escaping first pass	number	Required

Require a positive portal-delivered amount and a nonnegative escaping amount no larger than the portal amount. Subtract the escaped fraction from one. Both amounts must describe the same independently established interval and basis.

conditionalFirstPassExtraction=1−escapingAmount/portalDeliveredAmount

Use the matching field units and the exact boundary, ordering and reference rules above.

Output field	Meaning	Value type
result	Qualified observed calculation or explicit reference	object
result.observedFirstPassExtractionFraction	One minus escaping amount divided by portal-delivered amount; dimensionless fraction.	number

json

{
  "input": {
    "actualPortalDeliveredMass": 10,
    "independentlyMeasuredMassEscapingFirstPass": 6
  },
  "output": {
    "result": {
      "observedFirstPassExtractionFraction": 0.4
    }
  }
}

Limitations and assumptions

Chemical identity, route, assay, exposure basis and reference applicability are caller-established. The output supplies no causal conclusion, universal toxicity threshold or authoritative regulatory determination.

Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Extremely large composite outputs are rejected.

Alternative or Complementary methods

For a related step, use Enterohepatic Circulation Calculator: Enterohepatic circulation concerns recirculation involving the liver and intestine under a specified substance model. For a complementary comparison, use Metabolism Clearance Calculator: Metabolic clearance relates independently attributed metabolized mass per time to substrate concentration.

References

First-Pass Metabolism Calculator — tool.io

Similar or alternative tools

Enterohepatic Circulation Calculator
Enterohepatic circulation concerns recirculation involving the liver and intestine under a specified substance model.
Metabolism Clearance Calculator
Metabolic clearance relates independently attributed metabolized mass per time to substrate concentration.