Short, plain definitions of the words used on Vialwise, from IU to dead space. Each one links to the guide that goes into more detail.
A measure of how much of a drug there is, based on its biological effect. Each substance has its own definition, so 1 IU of one drug is not the same weight as 1 IU of another. HGH and HCG are usually labeled in IU.
IU is not the same as the units on a syringe. Syringe units measure liquid. How many IU one syringe unit holds depends on how much water you mixed in.
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One mark on an insulin syringe. On every U-100 syringe, 1 unit is 0.01 mL, so 10 units is 0.1 mL and 100 units is 1 mL. A unit measures liquid, not drug: what it holds depends on the strength of the vial.
A vial mixed to 5 mg/mL holds 0.05 mg (50 mcg) in each unit.
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The standard insulin strength: 100 units per mL. U-100 syringes are marked to match, and they’re the syringes the Vialwise calculator draws.
Don’t use U-40 syringes instead. They’re made for some pet insulins (40 units per mL) and often have a red cap, where U-100 caps are usually orange. Their numbers don’t match: 10 units on a U-40 syringe is 0.25 mL, which is 25 units on a U-100 syringe.
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The three barrel sizes of insulin syringes: 0.3 mL holds 30 units, 0.5 mL holds 50 and 1 mL holds 100. All three use the same scale. A smaller barrel spreads the marks out, so small doses are easier to read.
0.3 and 0.5 mL syringes usually have a line every unit; 1 mL syringes usually every 2 units.
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Two names for the same amount of liquid: 1 mL (milliliter) is exactly 1 cc (cubic centimeter). Syringe boxes use either one.
Milligram and microgram, both measures of weight. 1 mg is 1,000 mcg, and mcg is also written µg. Vial labels usually give mg while doses are often given in mcg, so check which one you’re reading.
0.25 mg is 250 mcg.
The liquid left in the needle and hub after the plunger is pushed all the way in. It leaves the vial with every draw but is never injected, so a vial gives a few doses fewer than the arithmetic says. Syringes with a built-in needle leave almost nothing; detachable needles leave more.
Low dead space detachable needles have been measured at about 17 µL per draw, and conventional ones at up to 84 µL.
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Adding liquid to a freeze-dried powder so it becomes a solution you can draw into a syringe. For peptides the liquid is usually BAC water. The amount of water doesn’t change how much peptide is in the vial, only how much each unit holds.
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Freeze-dried powder. Many peptides are sold this way because a dry powder is more stable than a liquid. It can look like a small white cake or a thin layer at the bottom of the vial, and it has to be reconstituted before use.
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Sterile water with a little benzyl alcohol added, usually 0.9%. The benzyl alcohol stops bacteria from growing, so the same vial can be punctured again and again. It’s the usual liquid for mixing peptides.
Healthcare guidance is to date a multi-dose vial when it’s first punctured and throw it away within 28 days, unless the maker gives a different date.
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Sterile water for injection with nothing added. It has no preservative, so it comes in single-use containers, and the label says to throw away what’s left. That makes it a poor fit for a vial you’ll draw from for days or weeks. Some products name sterile water as their diluent; follow the product’s instructions.
How much drug is in each mL of liquid. To work it out, divide the amount in the vial by the amount of water you added.
10 mg + 2 mL of water = 5 mg/mL. One unit (0.01 mL) then holds 0.05 mg.
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The rubber top of a vial, under the flip-off cap. Wipe it with an alcohol swab and let it dry before every puncture. A pen cartridge has a stopper too: the plunger at the back that the pen pushes forward.
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Two or three compounds mixed in one vial. In the calculator, enter each compound and its amount, and it shows how much of each is in every unit or click.
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One step on a pen’s dose dial. Each click pushes the cartridge stopper forward by a fixed volume. Most peptide pens move 0.01 mL per click, the same as 1 unit on an insulin syringe, but some use other steps, so check yours.
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The glass tube of liquid that goes into a reusable pen. Peptide pens take a standard 3 mL cartridge, filled from your mixed vial. At 0.01 mL per click, a full cartridge holds 300 clicks.
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Subcutaneous (subQ) means into the layer of fat under the skin; intramuscular (IM) means into a muscle. Insulin syringes and pen needles are made for subcutaneous injection, which is what the Vialwise guides cover. Intramuscular injections need longer needles and different sites.
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Gauge is the thickness of the needle, and the scale runs backwards: the higher the number, the thinner the needle, so 31G is finer than 29G. Insulin needles are usually 28G to 31G. Length is given in mm or inches; for adults, injection-technique experts recommend 4 mm pen needles and 6 mm syringe needles.
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Moving each injection to a new spot instead of reusing the same one. A common way is to split each area into parts, use one part for a week, and keep each injection at least 1 cm from the last. The dose log on the shelf suggests the next site.
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Lumps of hardened fat under the skin from injecting into the same spot again and again. Lumpy areas absorb unevenly and can hurt. Rotating sites helps prevent it; if you find a lump, stop using that spot.
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