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AMD - TMDD#

Will develop the best TMDD model based on an input model or dataset.

Running#

The code to initiate the AMD tool for a tmdd model:

from pharmpy.modeling import read_model
from pharmpy.tools read_modelfit_results, run_structsearch

start_model = read_model('path/to/model')

res = run_amd(
            modeltype='tmdd',
            input=start_model,
            cl_init=2.0,
            vc_init=5.0,
            mat_init=3.0,
            search_space='PERIPHERALS([1,2]);ELIMINATION([FO,ZO])',
            dv_types={'drug': 1, 'target': 2, 'complex': 3}
)

Arguments#

The AMD arguments used for TMDD models can be seen below. Some are mandatory for this type of model building while others are optional, and some AMD arguments are not used for this model type. If any of the mandatory arguments is missing, the program till raise an error.

Note

The name of the DVID column must be “DVID”.

Mandatory#

Argument

Description

input

Path to a dataset or start model object. See input in amd

modeltype

Set to ‘tmdd’ for this model type.

cl_init

Initial estimate for the population clearance

vc_init

Initial estimate for the central compartment population volume

mat_init

Initial estimate for the mean absorption time (only for oral models)

Optional#

Argument

Description

dv_types

Dictionary of DV types for multiple DVs (e.g. dv_types = {‘target’: 2}). Allowed keys are: ‘drug’, ‘target’, ‘complex’, ‘drug_tot’ and ‘target_tot’. (For TMDD models only) For more information see here. Default is None which means that all observations are treated as drug observations.

Note

In addition to these arguments, common arguments can be added.

Strategy components#

For a description about the different model building strategies in AMD, see Strategy. This section will cover the aspects that are specific to TMDD models.

Structural#

digraph BST { node [fontname="Arial",shape="rect"]; rankdir="LR"; base [label="Input", shape="oval"] s0 [label="add structural covariates"] s1 [label="modelsearch"] s2 [label="structsearch"] base -> s0 s0 -> s1 s1 -> s2 }

Structural covariates

The structural covariates are added directly to the starting model. If these cannot be added here (due to missing parameters for instance) they will be added at the start of the next covsearch run. Note that all structural covariates are added all at once without any test or search.

If no structural covariates are specified, no default is used.

Modelsearch

In this step the best structural PK model is found. The settings that the AMD tool uses for the modelsearch subtool can be seen in the table below.

Argument

Setting

search_space

'search_space' (As defined in AMD options)

algorithm

‘reduced_stepwise’

iiv_strategy

‘absorption_delay’

rank_type

‘bic’ (type: mixed)

cutoff

None

If no search space is given by the user, the default search space is dependent on the administration argument.

ABSORPTION([FO,ZO,SEQ-ZO-FO])
ELIMINATION([MM, MIX-FO-MM])
LAGTIME([OFF,ON])
TRANSITS([0,1,3,10],*)
PERIPHERALS([0,1])

Note

Before modelsearch is run, the dataset of the model is filtered so that it only contains PK data (i.e. DVIDs smaller than 2). Before running structsearch the dataset is replaced again with the original dataset containing all DVIDs.

Structsearch

The input model to the structsearch tool is the highest ranking (PK) model from modelsearch that has mixed-mm-fo elimination (note that this model might not be the highest ranking overall). If no such model exists then the final model from modelsearch will be used regardless of the elimination type. The dataset of the input model is replaced with the original dataset containing all DVIDs.

The extra model is the highest-ranking model that has the same structural features as the input model but with one less peripheral compartment. If no such model exists the extra model is set to None.

For a TMDD model, structsearch is run to determine the best structural model. All input arguments are specified by the user when initializing AMD.

Argument

Setting

modeltype

‘tmdd’

dv_types

'dv_types' (As defined in AMD input)

strictness

strictness (As defined in AMD input)

extra_model

The same model as the inputted model with one less peripheral compartment, if such a model exists in the modelsearch results and passed the strictness criteria. Otherwise None.

extra_model_reults

The connected modelfit results object for the extra model, if any. Otherwise None.

IIVSearch#

The settings that the AMD tool uses for this subtool can be seen in the table below.

Argument

Setting

Setting (rerun)

algorithm

‘top_down_exhaustive’

‘top_down_exhaustive’

iiv_strategy

‘fullblock’

‘no_add’

rank_type

‘mbic’ (type: iiv)

‘mbic’ (type: iiv)

cutoff

None

None

keep

Clearance parameters from input model

Clearance parameters from input model

Residual#

The settings that the AMD tool uses for this subtool can be seen in the table below. When re-running the tool, the settings remain the same.

Argument

Setting

groups

4

p_value

0.05

skip

None

IOVSearch#

The settings that the AMD tool uses for this subtool can be seen in the table below.

Argument

Setting

column

occasion (As defined in AMD options)

list_of_parameters

None

rank_type

‘bic’ (type: random)

cutoff

None

distribution

‘same-as-iiv’

Allometry#

The settings that the AMD tool uses for this subtool can be seen in the table below.

Argument

Setting

allometric_variable

allometric_variable (As defined in AMD options)

reference_value

70

parameters

None

initials

None

lower_bounds

None

upper_bounds

None

fixed

None

covsearch#

digraph BST { node [fontname="Arial",shape="rect"]; rankdir="LR"; base [label="Input", shape="oval"] s0 [label="mechanistic covariates"] s1 [label="exploratory covariates"] base -> s0 s0 -> s1 }

The settings that the AMD tool uses for this subtool can be seen in the table below.

Argument

Setting

search_space

search_space (As defined in AMD options)

p_forward

0.05

p_backward

0.01

max_steps

-1

algorithm

‘scm-forward-then-backward’

If no search space for this tool is given, the following default will be used:

COVARIATE?(@IIV, @CONTINUOUS, exp, *)
COVARIATE?(@IIV, @CATEGORICAL, cat, *)

Here, both statements are defined with a ‘?’, meaning that these are covariate effect(s) to be explored rather than structural covariate effects, which are added during the earlier “structural” step.

Mechanisitic covariates

If any mechanistic covariates have been given as input to the AMD tool, the specified covariate effects for these covariates is run in a separate initial covsearch run when adding covariates. These covariate effects are extracted from the given search space

Exploratory covariates

The remaining covariate effects from the search space are now run in an exploratory search.

Examples#

Minimal#

A minimal example for running AMD with model type PK:

from pharmpy.tools import run_amd

dataset_path = 'path/to/dataset'

res = run_amd(
            dataset_path,
            modeltype="tmdd",
            administration="iv",
            cl_init=2.0,
            vc_init=5.0
)

Model input and search space#

Specifying input model and search space:

from pharmpy.modeling import read_model
from pharmpy.tools read_modelfit_results, run_structsearch

start_model = read_model('path/to/model')

res = run_amd(
            modeltype='tmdd',
            input=start_model,
            search_space='PERIPHERALS([1,2]);ELIMINATION([FO,ZO])',
            dv_types={'drug': 1, 'target': 2, 'complex': 3}
            cl_init=2.0,
            vc_init=5.0,
            mat_init=3.0
)
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