If I need to treat cell lines with drugs, that are (or are not) FDA approved, and I find the dosis used in human or mice....(I find it often on the FDA website), how can I calculate or where can I find how much would be the corresponding concentration I should use in vitro ? (the in vitro data I can't find on the FDA side)
I don't wanna do unnecessary experiments with to high concentration.....
thanks a lot in advance, I am happy for any help regarding somehow this issue....
Dear Vanessa,
Attached is a paper entitled "Correlation between in vitro and in vivo concentration–effect relationships of naproxen in rats and healthy volunteers " published in British Journal of Pharmacology (2006) 148, 396–404 that might shed light on the answer to your question.
Hoping this will be helpful,
Rafik
Hi Vanessa,
I guess you are starting a new Masters of PhD project. If this is the case, then it is good to read but you might want to bear in mind that you will not escape the "try and fail" rule. So I would advise you to integrate this to the first steps of your experiments. You can start by testing several different concentrations (crescendo/decrescendo) in order to find the one whose effects approaches what you want. This is the typical "experiment optimization phase" for every laboratory work.
I wish you good luck!
You can also use PBPK models to estimate concentrations (free or total) in various tissues. This may be overkill for your purposes however because a significant amount of work maybe required to parameterise tge model. Simcyp for example has the physiology built in and you are only required to find compound specific parameters. Simcyp is free for academics for teaching and/or research provided various criteria are met. Simcyp can also help estimate the range of concentrations you might get in different individuals due to interindividual variability in physiology, metabolic enzyme type and abundance etc
@ Joseph.... thanks, I know I have to try different concentration, but my aim is to not use concentrations that are anyway that high, that they might be toxic if transferred in mice or later in human.... so if certain drugs only work on certain cell lines at a tooo high concentration, I would not even start the experiment.....therefore I'd need to calculate backwards from concentrations used in humans or mice to in vitro conditions....
@ David : with PBPK you mean the website where you can calculatewith a tool ? Simcyp is an alternative tool ? never heard about these things....
@Paolo: what do you mean with convolution/deconvolution technique, same as Joseph said ? screening for best effect by varying concentrations?
Thanks to all for answers and help!
Hi Vanessa!
Please see the link enclosed. I guess this is the technique, which Paolo meant.
All the best!
http://www.drug-dissolution-testing.com/?p=187
Thomas gave the right interpretation of my suggestion. Go to the cited links and you will find the answer.
Two important factors to consider:
1. In humans and mice, the concentrations are changing with time. Researchers often try to simplify this for in vitro analyses and focus on static concentrations (e.g., the average concentration over a dosing interval or some arbitrary threshold concentration). This impacts the translational value of the in vitro data as the static system is not an accurate representation of the in vivo process. Ideally, you would want to vary the drug in your in vitro system to match the in vivo time-course of drug concentrations. Unfortunately, such a system is not currently viable for cancer cell lines.
2. Consider free-drug concentrations. In vivo, free-drug (i.e., that not bound to blood proteins) is most often the active form (assuming we are talking about a small molecule) but we usually measure total drug concentration. In vitro systems almost always utilize free-drug unless you are artificially supplementing your system with blood proteins. So you need to understand what the range of free-drug concentrations in vivo and try to match up to those in vitro.
Good luck!
hi
this depends upon the tissue that you work on e.g. adipose tissue
so you should know the concentration of drug at the interstitial fluid of the adipose tissue in vivo so that you can choose the proper dose in vitro
consequently this dose is tissue dependent
The following papers may answer your question, plz check out.
Warm Regards
https://www.researchgate.net/publication/279862617_Strategy_to_enhance_efficacy_of_doxorubicin_in_solid_tumor_cells_by_methyl--cyclodextrin_Involvement_of_p53_and_Fas_receptor_ligand_complex?ev=prf_pub
plz follow the link
Article Strategy to enhance efficacy of doxorubicin in solid tumor c...
In in vitro experiments in principle you should ALWAYS produce a full dose/response.
If this is even a pilot test, one concentration test may be misleading and should never be used. But if you want to do this anyway, because of some other reasons (very expensive agent or whatever?), here is what I think. I cannot develop the entire calculations here. But it is not very difficult to do. You must know the molecular weight of the drug anyway. In principle if you know the in vivo doses, you may roughly take that one such doses is initially dissolved in about 20L (5 L blood + some intercellular and intracellular distribution). What is its concentration then? Transform it in M per liter and use it in vitro. But again, full D/R is only way you should use to see what is happening.
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