SimBiology

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Dear all, I am trying to build a PBPK model of a radioactive probe, and the proposed drug dose unit is Bq (becquerel), but the becquerel unit in current simbiology is not a drug dose category. The error is as follows：Quantity named Dose_Central references a unit that dose not exist or is not a valid unit. In addition, do you have any experience in building PBPK models of radioactive probes? If so, can you share it? Thanks！ Miya

I am tyring to build a model using irreversible and reversible mass action kinetics (Matlab R2023a). My species units are all in molarity and I follow the reaction rate constant units of paper.However, Simbiology repeatedly fails dimensional analysis and give me those two error meeage: 'Quantities of different dimensions cannot be added or subtracted' 'Reaction rate units should result in dimensions of either concentration/time or substance/time' for the first one error message My reactions are all quite straight forward: A + 5 B <-> AB ( kf : 1/molarity*second , kr : 1/second) for second error message the reaction is like this: FGUvsXcD + 9 ATP -> 9 FD + 9 UvsX + 9 AMP + 9 PPi ( kf :1/second) I had tried to adject the units and follow instruction from the manual but still the same error. so I don't understand why this is causing such problems.

Hello, I have a Simbiology PK model and the unit of all species (drug) is in microgram/milliliter. However, I would like to include a new reaction considering the drug and receptor binding behavior. The equation for this reaction is reversible as below. Drug + Receptor <-> Complex: k_on*Drug*Receptor - k_off*Ccomplex However, the unit of the k_on is 1/Molarity/Second and the unit of the k_off is 1/second and the unit for the Drug, Receptor and Complex should be in molarity. Is there any way I could keep my species unit still in microgram/milliliter but only have their unit become in molarity when they participate in this reaction? or is there any trick I could apply to achieve this thought? Thank you very much. Jesse

Hi, all I want to calculate the intestinal solubility of drug according to intestinal cyclodextrin concentration in a SimBiology model, so I compile a function like: function [IntestinalAGSolubility] = calculateSolubilityCD(CDConcentration,CDMW,AGMW) % This is a function to calculate solubility of a drug,AG, according to concentration % of cyclodextrin (CD). Equation is transformed from phase solubility test. % AGMW: AG molecular weight (g/mol); CDMW: CD molecular weight (g/mol); % CDConcentration (mg/mL); IntestinalAGSolubility (mg/mL) % 0.4653: slope; 0.4409: intercept (mmol/L) if (0.4653*CDConcentration*1000/CDMW+0.4409)*AGMW>2990.1 IntestinalAGSolubility=2990.1*1000; elseif (0.4653*CDConcentration*1000/CDMW+0.4409)*AGMW<=2990.1 IntestinalAGSolubility=(0.4653*CDConcentration*1000/CDMW+0.4409)*AGMW*1000; end This function is due to the fact that the solubility of AG and CD concentraion is consistent with a equation: S (mmol/L) =0.4653*CD (mmol/L)+0.4409, and maximum solubility is 2990.1 mg/L. Variables in function with their dimension are used in my SimBiology model, which is modified from "generic PBPK model". I have turned on the UnitConversion in program and I call this function in SimBiology APP like ColonSolubility=calculateSolubilityCD(Colon.CD,CDMW,AGMW). The line: IntestinalAGSolubility=2990.1*1000; and IntestinalAGSolubility=(0.4653*CDConcentration*1000/CDMW+0.4409)*AGMW*1000 are coded like this because only by this way I can get the exepexted result that presented in figure. However, value of 2990.1*1000 is not what I want to use in AG solubility (2.990 mg/mL). I am confused why I can not use IntestinalAGSolubility=2.990 in function (which will result in 1000-fold decrease in simulated solubility). Can anyone explain why this happens and do I make it right in other part of this function? Thanks a lot.