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 Absorption Model

• ADAM, solid IR dosage form, permeability predicted by Caco-2 data, basolateral permeability scalar incorporated

Full model (method 3)

 Route of Elimination

• fm_CYP3A4 = 43.6, fm_CYP1A2 = 41.4, fm_CYP2C19 = 15.0

 Perpetrator DDI

• Not included

 Validation

• Model performance was verified in healthy adult volunteers and pediatric schistosomiasis patients. Eight clinical studies in adults (20 to 50 mg/kg PO) and one clinical study in children (20 to 60 mg/kg PO) were used for model verification. Across the adult healthy volunteer studies, eighteen of twenty-five simulated C_max values and twenty-one of twenty-five simulated AUC values were within 2-fold of the observed data. For the pediatric study in schistosomiasis patients, eleven of twelve simulated C_max and AUC values were within 2-fold of the observed data.
• The fm_CYP3A4 was verified through simulations of prazaquantel in the presence versus the absence of ketoconazole and rifampicin.

 Limitations

• Model was developed using 20 mg/kg and 40 mg/kg PO adult data. Use of 20 to 50 mg/kg PO (healthy adult volunteers) and 20 to 60 mg/kg PO (pediatric schistosomiasis patients) were verified. Utility of the model outside these dose ranges is not confirmed.
• Model assumes all CYP3A-dependent clearance is mediated by CYP3A4 (i.e., CYP3A5 is not included in the model)
• Model is not verified for use as victim of CYP1A2 and CYP2C19 interactions

  Absorption Model

First-Order

  Volume of Distribution

Full PBPK (Method 2)

  Route of Elimination

CYP2C8 = 72%; Additional HLM = 28%

  Perpetrator DDI

• CYP2D6 

  Validation

• Four clinical studies describing single and multiple dose exposure of amodiaquine were used to verify the PBPK model. In comparison of predicted vs. observed AUC, 75% of the studies were 2-fold and 50% were within 1.5-fold. A clinical DDI study where amodiaquine was the victim of a CYP2C8-mediated DDI was accurately recovered using the PBPK model.

  Limitations

• Clinical data has not been used to verify amodiaquine as a perpetrator of CYP2D6-mediated DDIs

  Updates in V19

• Updated in vitro­ data
  • fu: 0.033 -> 0.089
  • B:P: 1.3 -> 1.1
  • DEAQ Ki for CYP2D6 (µM) – 1.7 -> 1.6
• Converted from minimal PBPK model to full PBPK model
  • Recalculated retrograde clearance for CYP2C8 CL_int and additional HLM CL_int

 Publication

De Sousa Mendes, M., Hirt, D., Urien, S., Valade, E., Bouazza, N., Foissac, F., Blanche, S., Treluyer, J. M., & Benaboud, S. (2015). Physiologically-based pharmacokinetic modeling of renally excreted antiretroviral drugs in pregnant women. British journal of clinical pharmacology, 80(5), 1031–1041.

 Simcyp Version

V13

 Published Model Application

Prediction of exposure in pregnancy

 Absorption Model

First Order

Full PBPK

 Route of Elimination

• Renal Elimination
• Includes uptake by OCT2 and efflux by MRP4 in the kidney

 Perpetrator DDI

• None 

 Advantages and Limitations

• Model developed in healthy volunteers and verified in pregnant women.

 Model Compound Files

• v13_res_lamivudine_simcyp_mendex2015

 Publication

De Sousa Mendes M, Chetty M. Are Standard Doses of Renally-Excreted Antiretrovirals in Older Patients Appropriate: A PBPK Study Comparing Exposures in the Elderly Population With Those in Renal Impairment. Drugs R D. 2019 Dec;19(4):339-350.

 Simcyp Version

V17

 Published Model Application

Prediction of exposure in renal impairment

 Absorption Model

First Order

Full PBPK

 Route of Elimination

• Renal Elimination
• Additional non-specific clearance

 Perpetrator DDI

• None 

 Advantages and Limitations

• Model developed to extrapolate elderly populations and renally impaired populations.
• Model was verified in the elderly population

 Model Compound Files

• v17_res_ lamivudine_simcyp_mendex2019

 Publication

Shah, K., Fischetti, B., Cha, A., & Taft, D. R. (2020). Using PBPK Modeling to Predict Drug Exposure and Support Dosage Adjustments in Patients With Renal Impairment: An Example with Lamivudine. Current drug discovery technologies, 17(3), 387–396.

 Simcyp Version

V18

 Published Model Application

Prediction of exposure in renal impairment

 Absorption Model

First Order

Full (mechanistic kidney model)

 Route of Elimination

• Renal Elimination
• Includes uptake by OCT2 and efflux by MATE in the kidney

 Perpetrator DDI

• None 

 Advantages and Limitations

• Model developed to renally impaired populations.

 Model Compound Files

• v18_res_ lamivudine_simcyp_shah2020