IV trastuzumab exposure with parallel elimination

Breast-cancer context: every three weeks

How does the conditional three-weekly exposure profile behave at fixed reference covariates? Absolute-mg dose events and non-albumin covariates remain fixed; no clinical recommendation.

Readouts

Conditional central intravenous concentration · mg/L

Central amount divided by the selected apparent central volume; mg/L equals micrograms/mL. Provisional fixed-effect exposure, not a source observation, individual estimate or clinical endpoint.

Study purpose

• How does the conditional three-weekly exposure profile behave at fixed reference covariates?

Assumptions

• Conditional fixed-effect innovator IV trastuzumab exposure; no original population, patient prediction, clinical dosing, efficacy or safety claim.
• Albumin exploration at 30–47 g/L uses the reported 5th–95th percentile anchors (3.0–4.7 g/dL). These bounds are not a confidence interval or clinical limit.
• Editing albumin changes clearance with fixed absolute-mg dose events. Weight, AST, liver-metastasis status and tumor class remain preset context; weight editing would require coordinated dose rescaling.
• The AST clearance exponent is the final Table 1 estimate 0.205; final estimates and bootstrap means are distinct.
• Albumin normalization is 4 g/dL = 40 g/L. Source per-day clearance and rate constants are converted to per hour.
• Initial 90-minute and subsequent 30-minute infusions follow a common study protocol. The 30-minute reloading diagnostics are authored administration contexts; trial-specific and reloading durations are not fully identified.
• Peripheral concentration is an apparent model coordinate. Loss states are accounting coordinates, not measured excretion. Continuous integrated AUC is not a population AUC over a dosing interval.
• Changing the simulation start uses the supplied initial state at that time, without reconstructing earlier doses.
• No original legacy population-modeling workflow fit, variability or residual likelihood, patient observations, prediction interval, population exposure summary or full paper-panel reproduction. Fitting and normal server scans are unavailable.
• No subcutaneous formulation, biosimilar, explicit receptor binding, tumor response, missed-dose, washout or pregnancy recommendation.