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# Drug dosing

calculation drug dosing drug dosage

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Newbie !!

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Posted 27 November 2018 - 04:59 PM

Hi,

I need to make drugs at 10 mM, 1 mM, 0.1 mM, 0.01 mM and 0.001 mM

The stock conc of drug A = 3.2 mg/ml which is dissolved in Methanol

Drug A = 387.5 g/mol

Drug B = 144.2 g/mol

Drug C =  546.7 g/mol

Drug D = 392.4 g/mol

Thank you.

Cheers,

### #2 bob1

bob1

Thelymitra pulchella

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Posted 27 November 2018 - 07:36 PM

I'll do A, you would need to have the w/v concentrations for the others too.

3.2 mg/ml = 3.2 g/l (so that your units for molarity are the same as concentration)

n=mass/molar mass

n= 3.2 g /387.5 g/mol

n=0.00826 mol

It just so happens that because the calculation is done on the per litre amount, you also have this as a concentration (i.e. 0.00826 mol/l)

0.00826 = 8.26 mmol/l or 8.26 mM. You don't have a high enough concentration to get your highest dose.

Newbie !!

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• 255 posts
15
Good

Posted 27 November 2018 - 07:39 PM

I'll do A, you would need to have the w/v concentrations for the others too.

3.2 mg/ml = 3.2 g/l (so that your units for molarity are the same as concentration)

n=mass/molar mass
n= 3.2 g /387.5 g/mol
n=0.00826 mol

It just so happens that because the calculation is done on the per litre amount, you also have this as a concentration (i.e. 0.00826 mol/l)

0.00826 = 8.26 mmol/l or 8.26 mM. You don't have a high enough concentration to get your highest dose.

Thanks. How do I make the lower points i.e 0.1 mM and so on?
Cheers,

### #4 bob1

bob1

Thelymitra pulchella

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Posted 27 November 2018 - 08:10 PM

There are a couple of options:

1) Dilute your stock using V1C1 = V2C2 to work out the amounts needed for each of the higher dilutions. This will probably only work feasibly for the 1, 0.1 and maybe 0.01 mM concentrations.

or the preferred method for these sorts of things - serial dilution:

2) Make your stock to something convenient (use formula above; 5 mM might work or 1 mM) then do the appropriate dilution series to get the final concentrations. Note that you have 1:10 dilutions at each step, so if you start with 1 mM then all you need to do is take 1 part stock and 9 parts  diluent for each of the subsequent dilutions.