nca.analytes¶

Several analytes in one analysis: the metabolite to parent ratio.

A study of a parent drug and its metabolite (or of two enantiomers) is one batch with a substance coordinate along a sample dimension, analyte by default, and is analysed in one call of pkpdutils.nca.nca: every row keeps its own substance and the result carries the coordinate. metabolite_ratio then divides the exposure of the metabolite by the exposure of the parent, subject by subject, which is the metabolite to parent ratio ICH M13A asks for when a metabolite contributes to the effect.

metabolite_ratio ¶

metabolite_ratio(
    result,
    *,
    parent,
    metabolite,
    parameters=DEFAULT_RATIO_PARAMETERS,
    molar=None,
)

The metabolite to parent ratio of every subject.

For every parameter the ratio of the metabolite to the parent of the same subject,

\[\mathrm{MPR} = \frac{X_\mathrm{metabolite}}{X_\mathrm{parent}},\]

of the two analytes of the result, which are two positions of the sample dimension the substance coordinate lies along. With the molar masses (molar, in the same unit for both, usually g/mol) the ratio is on a molar basis,

\[\mathrm{MPR}_\mathrm{molar} = \frac{X_\mathrm{metabolite} / M_\mathrm{metabolite}} {X_\mathrm{parent} / M_\mathrm{parent}} = \mathrm{MPR}\, \frac{M_\mathrm{parent}}{M_\mathrm{metabolite}},\]

which is what a metabolite to parent ratio of two substances measured in mass concentrations means (ICH M13A 2024, 2.2.3). The parameters must have the same unit for both analytes, which they do when the two curves were measured in the same unit; the ratio is dimensionless.

Parameters:

Name	Type	Description	Default
`result`	`ParameterResult`	the result of the analysis of both analytes, which carries the `substance` coordinate	required

Other Parameters:

Name	Type	Description
`parent`	`str`	the substance of the parent, a value of the coordinate
`metabolite`	`str`	the substance of the metabolite, a value of the coordinate
`parameters`	`Sequence[str]`	the parameters to divide, `auc_inf_obs` and `cmax` by default
`molar`	`Mapping[str, float] \| None`	molar mass per substance, `{"parent": 300.4, "metabolite": 316.4}`; `None` reports the ratio of the values as they are

Returns:

Type	Description
`DataFrame`	One row per subject: the labels of the remaining sample dimensions and
`DataFrame`	one column per parameter with the ratio. `attrs` name the two
`DataFrame`	substances and the correction factor.

Raises:

Type	Description
`ValueError`	if the result does not carry the two analytes (`_analyte_position`), if a parameter is not a variable of the result or does not lie along the analyte dimension, or if a molar mass is missing for one of the two substances.