Is Dilution of Pharmaceuticals Necessary for Accurate Dosage?

[bmlevac]

I have a question regarding the dilution of a pharmaceutical. I need to provide subjects in a study with a certain amount of drug (1200 mg), and there is 3.3 g in 5 mL of the preformed solution. Since I will require about 1.82 mL to achieve the necessary amount of drug (1200 mg), should I just give 1.82 mL dissolved in 250 mL of water or would I be better off to dilute the concentrated standard solution and dissolve a larger volume of diluted standard in a smaller amount of water? Basically, I am wondering: (1) will a small volume of 1.82 mL be delivered to the subject without significant loss to remnants in the bottle?
(2) does diluting the concentrated standard by a factor of 10 and then transferring 18.2 mL of standard to a water bottle for administration improve the chance of the subject receiving the required amount of drug (1200 mg)?
(3) does dilution have no effect and the risks of loss to transfer error and remnants in containers (water bottle) exist equally no matter what?

Thank you in advance to anyone willing to provide some insight. Also, feel free to ask for more information if I have left anything out.

 

[gravenewworld]

This is not an easy question and depends on a lot of things. What is the design of your experiment? Is it a 1 Shot bolus or a continual IV? Ideally it is optimal to minimize your vehicle as much as possible. There's no way you could give a 250 ml one shot administration to a rat without causing toxicity because you are adding too much volume to the rats systemic system. There's only so much a living organism's circulatory system can hold in terms of volume. It also depends on your drug as well. Drug formulation is a complex and totally separate field of science on its own. Many drugs are specially formulated to control for things like pH and the amount of zwitter ions and salt forms that may be present and that may affect optimal efficacy. Diluting with just water could ruin the efficacy of your drug. If you're doing simple study though (nothing clinical) it might not matter as much.

 

[bmlevac]

It is a single orally administered dose that will be taken as ~250 ml solution.

This is not a study in rats, although I see how it could be easily confused based on how I presented the information (i.e.. water bottle for dispensing).

To my knowledge, dilution would not affect the efficacy of the active ingredient since it is normally followed by fluids.