Reconstituting my first peptide, bac water amount is doing my head in

Posted by fasted_scientist in Beginner Questions - 5 points, 3 comments.

Right so I've finally bitten the bullet and got hold of a vial (10mg) and some bacteriostatic water. Watched about four youtube videos and now I'm more confused than when I started, so hopefully someone can talk me off the ledge.

If I'm using insulin syringes (those 1ml ones with the orange cap, 100 unit markings), and my vial is 10mg of lyophilised peptide, how do I actually work out how many units equals a sensible starting dose?

I keep seeing people say things like "draw to the 10 mark" but I don't actually understand what maths gets me there. Do I just add 1ml of bac water and then 1 unit = 0.1mg? Or does it depend on how much water I push in first?

This is probably the dumbest question on here but I'd rather ask it now than waste the whole vial messing it up. Also cheers in advance, I know it's a basic one.

Comments

• brooke81: Not a dumb question at all, this stuff is confusing until it clicks. The amount of water you add changes everything, thats the bit nobody explained to me at first either. If you add 1ml of bac water to a 10mg vial, then yes, 10 units on your insulin syringe would give you 0.1mg (or 100mcg). The general rule I use in my head is: total mg in the vial divided by the ml of water added, then multiply by 100 to get units per mg. So 10mg in 2ml of water works out to 0.05mg per 10 units, or 50mcg. Add
• fasted_scientist: (they got cut off at the end btw) Cheers, that actually makes sense now. The "pick your water amount first" bit is what clicked for me, I was trying to work backwards from the dose. So if I'm aiming for 250mcg twice a day, adding 2ml gives me 5 units per dose on the syringe which is way easier to eyeball than faffing with 1ml. Going to go with 2ml I reckon, gives me a bit more wiggle room if my hands are shaky.
• fasted_scientist: The trick is just pick your water amount first and then read the concentration back off it, that's the bit that finally made it click for me. I went with 2ml on my first vial just so the numbers felt less fiddly on the insulin pin.

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