Dead volume across syringe and needle combinations

On the subject in the title: Dead volume across syringe and needle combinations Working notes rather than a conclusion.

Practical question with the units stated, because I have seen how quickly these go wrong without them.

I have a 15 mg vial of semaglutide and I am working to a 1.0 mg step. My syringes are U-100 insulin syringes, 1.0 mL barrel.

I can do the arithmetic and I have done it twice, getting the same answer both times, but I would like someone to check the reasoning rather than the number — specifically whether I have thought about the residual volume correctly, and whether the graduation I am landing on is one a person can actually read.

Picking up post #2: that is the part I would want checked first.

Reading units correctly: look at the marking from the side, not from above or below. The bottom of the plunger tip is the reading. Parallax error (wrong angle) is a source of dosing error.

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

Sharps disposal: needles and syringes should be disposed in a sharps container (a rigid, puncture-resistant container). Do not put them in regular trash. Many pharmacies accept filled sharps containers.

Insulin syringe graduations: U-100 syringes are marked in units where 100 units = 1 mL. Always confirm your syringe is U-100. Confusion between insulin units and milligrams is the most common syringe error.

Picking up post #38: that is the part I would want checked first.

Fixed versus detachable needles: insulin syringes usually have fixed needles (no dead volume loss to the hub). Luer-lock syringes use detachable needles (more dead volume). Fixed needles are preferred for small doses.

Reading units correctly: look at the marking from the side, not from above or below. The bottom of the plunger tip is the reading. Parallax error (wrong angle) is a source of dosing error.

Coming back to post #51, because the follow-up matters more than the original answer.

Aspirating before injection: for subcutaneous injection, aspirating (pulling back on the plunger to check for blood) is not necessary and is sometimes discouraged because it is associated with more discomfort. Subcutaneous injection without aspiration is standard practice.

Coming back to post #66, because the follow-up matters more than the original answer.

Insulin syringe graduations: U-100 syringes are marked in units where 100 units = 1 mL. Always confirm your syringe is U-100. Confusion between insulin units and milligrams is the most common syringe error.