Aggregated input data from the Science Cloud Excel file

The summary statistics used for the data were:

  • normally distributed, arithmetic mean (e.g. Hill coefficients, PRR);
  • log-normal, geometric mean (e.g. Blood to plasma ratio, clearance, IC50);
  • protein binding percentiles were first checked for =100% or operator '>' and such values were fixed to 99.9%. Then, geometric means of the resulting values were taken (e.g. Human Plasma Binding, Human microsome binding, Rat plasma binding, Albumax binding).
  • bounded, back-transformed means of logit transforms (e.g. protein binding, 0-100%).

In the absence of Science Cloud data, blanks or default values were used as follows:

  • Molecular Weight, Human Microsome Binding, Human Microsome CLint, TCGLS 3D7 72h IC50, Log10 in vitro PRR / 48h, Rat Plasma Vss, Relay-predicted Human Vss,u: blanks;
  • Albumax Binding: If human plasma protein binding (PPB) available, cacluated as 100*(1-14*Fu/(1+13*Fu)) where Fu=(100-PPB)/100, otherwise blank;
  • Human Plasma Binding, Rat Plasma Binding: if the value for the other species is specified use it as a default, otherwise if albumax binding (%) is available, default value equal to 100*(1-AlbumaxFu/(14 - 13*AlbumaxFu)) with AlbumaxFu=(100-Albumax binding)/100, otherwise blank;
  • in vitro Hill Slope: 6;
  • PRR Lag Time: 0;
  • Human Blood to Plasma Ratio, Rat Blood to Plasma Ratio: if the value for the other species is specified use it as a default, otherwise blank.

You can specify new values ovewriting the Science Cloud data. Enter a value in the header input field of a column to set this parameter value for all compounds at once.

Note: The background colour of input fields in the table indicates the source of the data:

  • azure: default value used if there is no Science Cloud or manual input
  • gold: Science Cloud Excel file,
  • white: manually entered value.

Unbound parameters and dose to achieve minimum inhibitory unbound concentration at required time point for a median 55 kg individual

Please enter a time point at which the minimum inhibitory concentration for the unbound compound (MICu) should be equal to or exceeded, a number of doses and a dosing regimen. Upload a Science Cloud MMVSola-format Excel file with the following data:

  • molecular weight, blood plasma ratio, human plasma, Albumax and microsomal % binding for the drug molecule;
  • smiles code of the molecule;
  • in silico prediction and/or in vivo (Rat) measurement of the plasma volume of distribution (Vss). If Rat Vss is available, plasma binding and blood to plasma ratio from rat would also be needed;
  • in vitro TCGLS 3D7 72h assay IC50;
  • in vitro parasite reduction ratio (PRR) and PRR lag time;
  • microsomal intrinsic clearance. If not available, a low value, e.g. 0.01 uL/min/mg, can be entered from the Input Data tab. Zero values cannot be log-transformed and will provoke an error.
Following the file upload, the Predicted parameters table will be populated and a graph showing the landscape of dose for t>MIC vs unbound volume of distribution vs clearance will be generated for every compound. If no results are displayed for some compounds in the dataset, please check the corresponding input values in the Input data tab and consider entering manually some of the parameter values.

Unbound parameters and dose

Dose landscapes

Details and references

Background

To provide a prediction for the concentration after the nth dose of a compound, accepting that a one compartment first order absorption model is appropriate, equation (392) from Gibaldi & Perrier (1975)

Cn = dose*ka/(Vss*(ka-ke))*(
(((1-exp(-n*ke*tau))/(1-exp(-ke*tau)))*exp(-ke*MICtime)) -
(((1-exp(-n*ka*tau))/(1-exp(-ka*tau)))*exp(-ka*MICtime)) )

can be rearranged for dose

dose = MICu/(ka/(Vssu*(ka-ke))*(
(((1-exp(-ndoses*ke*tau))/(1-exp(-ke*tau)))*exp(-ke*MICtime)) -
(((1-exp(-ndoses*ka*tau))/(1-exp(-ka*tau)))*exp(-ka*MICtime))))

where Cn is set as MIC (in consistent units, e.g. mg/L) and the other parameters are as defined below.

Parameters and descriptions

bit of descriptive text

MICu (nM), minimum unbound concentration to inhibit parasite growth.
ka (per hour), first order absorption rate, set as 0.5 per hour, a 2 hour mean absorption time
Vssu (L per kg), volume of distribution for unbound drug. Full human body weights are used for population calculation.
ke (per hour), first order elimination rate, calculated from CLu and Vssu.
CLintu and CLu (L/h per kg), taken to be the same assuming low hepatic extraction; intrinsic clearance of unbound drug.
n, number of administrations.
tau (hours), inter-dose interval.

Conversion factors

weight 55 kg,
human microsomal protein per g of liver, MPPGL, 39.8 mg protein/g liver (Simcyp v17_20191023)
human liver weight 20.48 g liver/kg body weight (Gastroplus)
(for later) human hepatocytes per g of liver (millions cells/g liver), HPGL, 117.5 10e6 cells/g liver Simcyp

References

[1] Author, Journal, year, etc., citation; DOI