Originally Posted by Jerc
If swij had 10mg of 25c-nbome in salt form
First off it's important not to make assumptions about the mass of material one is working with. Based on the tone of this post I'm going to take a wild guess that the person in question does not own a suitably sensitive scale and is assuming that they have 10mg because this is what they ordered and/or what it says on the packaging.
Would this be the case? If so then it's essential not to take such assertions on good faith. Vendors routinely send out the wrong amount and in some cases the amount they send is way more than expected. It's impossible to discern 10mg by eye so it might be substantially more than 10mg. If this were the case then the calculations would be way off and the person would overdose. When working with a drug
that's active in the microgram range that overdose could easily be a fatal one.
what would be the best way to go about measuring a 400microgram dose out. Swij assumes dissolving it in water would be the way to go (not sure but since its hcl form would assume so) but wonders how long this solution would last?
Yes volumetric measurement is certainly the way to go for handling such small quantities but to do this accurately it is still essential to weigh out the substance on an accurate scale to begin with.
Water would seem like the most suitable solvent for intranasal
use. For longer term storage in water it is best to aliquot out individual doses, freeze them separately then thaw out the required doses as necessary. Freezing will slow the rate of degradation/spoiling. There are three reasons for aliquoting out individual doses rather than freezing the solution as one batch; (1) convenience, (2) it avoids repeated freeze/thaw cycles that may accelerate degradation of the drug, and (3) volumetric changes can occur even in frozen solutions (especially with small volumes) and this has a concentrating effect. By measuring out the individual doses prior to freezing one could never take more of the drug than they were expecting.
For sublingual use 40-50% ethanol
(e.g. vodka) might be a better choice as the alcohol
spoils less easily than water. For storage here it would be better to lay the solution onto blotter, though doing this consistently is quite an art in itself.
If swij wanted to dissolve all 10mg how much water would he use to get 1ml=400mics?
1) Weigh out the starting material on a suitably sensitive scale. One that is accurate to ±0.001g (±1mg) should be suitable in this case. In my example the person in question thought they'd been sent 10mg of 25C-NBOMe but in fact the substance weighed out as 0.030g (30mg or 30000µg).
2) They want a final solution of 400µg/mL 25C-NBOMe. 30000µg / 400µg = 75. They'd therefore need 75mL solvent to make a solution with a final concentration of 400µg/mL 25C-NBOMe.
3) Using suitably accurate glassware (an 100mL measuring cylinder with markings every 2mL) they measure out the appropriate volume of solvent and add it to the drug in a sealable container. They then mix thoroughly by inversion to ensure that the drug fully dissolves. It is absolutely critical that the drug dissolves completely and does not form a suspension. If the drug does not dissolve completely then the concentration of the solution will not be homogenous.
4) They measure out the volume of solvent again to check that mixing the drug into the solvent did not cause a change in volume. This would not be expected with most drugs
, but in some cases a cutting agent might elicit a volume change. Had the volume doubled to 150mL after adding the drug (highly unlikely!) then the effective drug concentration would've halved from the originally calculated 400µg/mL to 200µg/mL, so they would now need 2mL aliquots for a dose of 400µg. In this case we'll assume that there was no change in volume so they did not need to recalculate the concentration of the drug solution.
5) They aliquot out 1mL doses of the solution using a 1mL syringe and transfer them into individual containers for freezing. Each 1mL aliquot is a 400µg dose of the drug. Note that had they not bothered to weigh out the drug to begin with and assumed there to be 10mg then they would not have diluted the drug so far and each aliquot would contain 1200µg of the drug; much more than they anticipated and potentially dangerous if they were to take multiple doses of it.
Sorry if this is a simple math equation but swij would suppose it depends on what youre dissolving no?
No the calculation is not heavily dependent on the substance and solvent. The math involved is indeed quite straightforward. Without wanting to sound too patronizing if a person needs to ask how to do this calculation then they should not attempt to put it into practice unless there is another person on hand that is more comfortable with the math involved to check their working. If it's not something one does routinely then it's easy to make errors, especially when interconverting units from grams to milligrams to micrograms. These errors could make the end doses out by an order of magnitude or more and that is potentially lethal. Being 'terrible at math' isn't something that is worth dying for; get a second hand and watchful eye to ensure that nothing goes wrong.
Most importantly don't cut corners. It might be tempting to skip certain steps because if the necessary equipment is not immediately available, but this sloppy attitude has resulted in a number of RC-related injuries and deaths. The drug has to be weighed out on appropriately sensitive scales. The solutions have to be measured out with suitable gradiated equipment (measuring jugs/cylinders, graduated pipettes or syringes etc.).