I am trying to determine the concentration/dose of a drug that was effective on mouse primary neurons at 100-500nanoMolar. I'm planning to inject intracerebroventricularly (ICV), is there a standard/empirical way to determine the concentration/dose to start with?
Not that I know. In fact, converting in vitro concentrations to in vivo doses (and vice versa) is a tough issue.
I had similar problems when trying to convert in vivo doses reaching the kidney to in vitro concentrations based on pharmacokinetic parameters. We decided to consider that the compound's concentration in the kidney tubules was similar to the one reported in the plasma.
Your case seems a bit more complicated. You could consider the brain as a volume consituted of water that will dilute your stock solution, and try to reach your 100-500 nM range after injection.
Alternatively, you may try to compare the amounts of neurons in a mouse brain and in your plastic dishes, and adapt the dose consequently.
I am pretty sure that both approaches will give you rather different values.
However, if your compound has something to do with drugs that are used in humans, you may simply convert the dose : have a look here : http://www.ncbi.nlm.nih.gov/pubmed/?term=Dose+translation+from+animal+to+human+studies+revisited
(but I believe this is not the case...)
If the mode of action of your compound is well known, you may consider doses that are reported in PK studies of similar drugs, which will allow you to compare their efficacy.
This is perhaps the best you to proceed.
Good luck !
Please guide me regarding :
I have a similar situation wherein the effective inhibitory conc of the compound in vitro was 0.04% v/v and 0.08%v/v. i want to test the compound it in mice (weighing 30-35mg) thru oral feeding. what conc (ie %) should i use. My LD50 studies using oral route is 10ml/kg ie greater than 9257.50 mg/kg.
I agree with Valérian Bunel it's quite complicated to convert from in vitro to in vivo! Many many obstacles and you need to have in mind that your component/s can be easily modified in animal. This modification can drastically change the activity of compound that you are testing. I dont have experience with ICV injection but what Anju asked for oral I have...especialy you can be dealing with pharmacodynamics and pharmacokinetics here! You can't know for sure what dose you need to apply, do the experiments in several doses so you can observe the effects and explain the obtained results in those doses (wide ranges from 0.1 nM - 0.1M). That is my suggestion...
Dear Can you translation of concentration through calculation the culture cells numbers and the dilution factors in media that can converted in to blood volume of animal model and organ cell counts per millimeters can estimated the effect .... further if you LD50 and ED50 could set you dose on the range of therapeutic index that I work on this system and suggested to you on piolet study
It's quite complicated to convert from in vitro to in vivo or vice versa. Many many modifications and ADME-properties can drastically change the activity of compound that you are testing. Still following methods can be used for an approximation of the drug dosages!
Say you`re working with a drug - DRUG X with clinical dosage of 100 mg/m2.
Method 1:
Clinical dosage of DRUG X is 100 mg/m2.
Assuming that we`re doing viability assay in 96 well plates. The surface area of a single well in 96 well plate is 0.32 cm2, which means that we will need the following equivalent in vitro dose in each well = 100*3.2e-5 = 0.0032 mg.
Now, in order to calculate the concentration of 0.0032 mg of DRUG X for in vitro experiment, we can use the molarity formula (M = m/MW * 1/V where m = mass in grams, MW = molecular weight of the substance and V = volume of the diluent in litres).
We need 0.0032 mg of DRUG X in 100 µL or 0.0001 L (V) for our in vitro experiments (96-well plate) and knowing that MW of DRUG X = 588.72 g/mol and m = 0.0000032 g.
The resultant concentration (molarity) will be: 0.00005435 M or 54.35 µM.
Method 2:
Clinical dosage of DRUG X is 100 mg/m2.
Mice dosage in mg/kg = Human Equivalent Dosage in mg/m2 / Mice Km = 100 / 3 = 33.3 mg/kg
Assuming that average mouse weight is 25 gms, amount of DRUG X administered to each mouse = (33.3/1000)*25 = 0.8325 mg
Now, in order to calculate the concentration of 0.8325 mg of DRUG X in our in vitro experiment, we can use the molarity formula (M = m/MW * 1/V where m = mass in grams, MW = molecular weight of the substance and V = volume of the diluent in litres).
Assuming that we would like to make 25 ml or 0.025 L (V) of DRUG X solution for our in vitro experiments (assumption is 25g mice as 25ml volume) and knowing that MW of DRUG X = 588.72 g/mol and m = 0.0008325 g.
The resultant concentration (molarity) will be: 0.00005656 M or 56.56 µM.
As mentioned earlier, these calculations are just approximations!
I know this is an old thread, but I find your responses beneficial as I get my in vivo work for my thesis started. Thank you for everyone for your contributions!
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