Is 5 mg in 1.5 mL of bacteriostatic water a sensible presentation for liraglutide?

Setup, so nobody has to ask: 5 mg · 1.5 mL · bacteriostatic water · liraglutide.

I would like to set this up properly once, rather than adjust it repeatedly.

My budget is real but not tight, and my tolerance for uncertainty is low.

How would you structure this, and what thresholds would you set in advance?

Answering this needs the syringe you actually own, because the barrel graduations decide what "readable" means.

Vial headspace is the hard constraint. A nominal 2 mL vial typically holds a little over 2 mL to the shoulder; adding 3 mL is not an option and attempting it wastes the lot.

Dead-space loss scales with the number of draws, not with the concentration, so a lower concentration spread over more draws loses proportionally less of the total peptide.

Concentration equals content over volume, and content is not label claim.

Total vial volume is a physical constraint: most 2 mL vials will not take 3 mL of anything.

Content matters. If the same 10 mg vial assays at 94 per cent content, you have 9.4 mg. In 2 mL that is 4.7 mg/mL, and a nominal 0.5 mg draw of 10 units actually delivers 0.47 mg — a six per cent shortfall that no amount of careful drawing will fix.

Write the concentration and the resulting units-per-dose on the vial label at reconstitution. The arithmetic that is obvious now will not be obvious at six in the morning three weeks from now.

Nominal vial volumes in the standard 2R and 3R glass sizes have published brimful capacities well above the nominal fill, but the usable volume is bounded by the stopper displacement.

Write the concentration on the label at reconstitution, in units per dose.

Worth being precise here: this is the one decision in the whole preparation sequence that cannot be revised later, which is why it is worth thirty seconds of arithmetic.

Worked example. A 10 mg vial reconstituted with 2 mL gives 5 mg/mL. A 0.5 mg dose is 0.5 ÷ 5 = 0.1 mL, which on a U-100 syringe is 10 units. Reconstitute the same vial with 1 mL and the concentration doubles to 10 mg/mL, the same dose becomes 0.05 mL, and you are now reading 5 units instead of 10 — the same dose at half the resolution.

Choose the volume that puts your largest intended dose between 10 and 30 units. Everything else follows.