I have an undiluted drug in powder form. I need to give it to my 20 gram mouse at a dose of 10 mg/Kg. The drug is docetaxel and its MW is 807.87922.
The drug is Docetaxel and the product sheet says that it is soluble in 5 mg/ml DMSO and then can be diluted to 0.1 mg/ml in a 1:10 solution of DMSO;PBS. How can I do these two dilutions so that I can perform an i.p. injection into a mouse of up to 200 ul? Can you do i.p. injections of more than 200 ul?
Rachel - a 20 gram mouse is one-fiftieth of a kg (1000/20). Therefore to dose at 10 mg/kg, you need to divide your dose by 50 which means your 20 g mouse should receive 0.2 mg (10/50). The easiest way to dose mice at 10 mg/kg is to prepare a 1 mg/ml stock solution. Then a 20 g mouse would receive 200 uL, a 25 g mouse would receive 250 uL, etc. You don't even have to think about it. You don't say how you will be dosing, but I'm assuming you will be administering i.v. Thus you are restricted to smaller volues. So prepare your stock solution at 2 mg/ml. Then to dose at 10 mg/kg, you would need 100 uL which would contain 0.2 mg. A 25 g mouse would require 125 uL, etc. One additonal consideration: Is your drug pure or is it mixed with an excipient?. If the drug is 95% pure for example, then you will need to make your stock solution at 2.1 mg/ml to account for the reduced amount of active drug. Hope this helps.
Ah - the joy’s of working with water insoluble drugs. Below is the formulation for human IV dosing.
Weigh out 20 mg docetaxol (anhydrous) and add 0.395 g dehydrated ethanol. Once fully dissolved, add a magnetic stir bar and add 054 g polysorbate 80 (a detergent emulsifier). You may need to warm the solution slightly. This will give you a 20 mg/ml stock. This can now be diluted 1:20 with saline. Add the saline slowly at first (a few drops at a time) with stirring to avoid the drug crashing out of solution. Not too vigorously or the solution will foam. You can add the saline more rapidly once the volume increases. You will now have a 1 mg/ml solution which you can dose IP at 10 ml/kg or 200 uL for a 20 g mouse. Exceeding 10 ml/kg is not desired as you put the animal at risk of volume overload.
Alternatively, since you work at a Medical college, and depending on your college’s policy, you may be able to have a physician write a prescription for the IV solution or obtain it through your procurement office.
Need support for learning, How to prepare stock solution for 10, 100 and 1000 micro-gram/kg API drug for intravenous administration, sub-acute study in both rats and mice. Would appreciate if one can provide complete answer.
Article A simple practice guide for dose conversion between animals and human
Hope this paper will help.
Rachel - a 20 gram mouse is one-fiftieth of a kg (1000/20). Therefore to dose at 10 mg/kg, you need to divide your dose by 50 which means your 20 g mouse should receive 0.2 mg (10/50). The easiest way to dose mice at 10 mg/kg is to prepare a 1 mg/ml stock solution. Then a 20 g mouse would receive 200 uL, a 25 g mouse would receive 250 uL, etc. You don't even have to think about it. You don't say how you will be dosing, but I'm assuming you will be administering i.v. Thus you are restricted to smaller volues. So prepare your stock solution at 2 mg/ml. Then to dose at 10 mg/kg, you would need 100 uL which would contain 0.2 mg. A 25 g mouse would require 125 uL, etc. One additonal consideration: Is your drug pure or is it mixed with an excipient?. If the drug is 95% pure for example, then you will need to make your stock solution at 2.1 mg/ml to account for the reduced amount of active drug. Hope this helps.
Rachel Lieberman Technically,
Animal weight (kg) x dosage (mg/kg) / concentration of drug (mg/ml) = drug volume in ml or cc.
Sorry, I know this thread is pretty old, but maybe someone might look in here and be able to use it; I have made an online calculator that can help doing this type of calculations for both a drug in powder form and for stock solutions. You can find it here: https://littlelabhelper.com/working_solution_calc_powder.html. Hope it can be useful to others than me :)
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