Pharmacology · Formulation chemistry

Excipient function in a licensed injectable — the long version

Pharmacology › Formulation chemistry sterile water storage bacteriostatic water

f.fenwickTL3Regular15 Apr 2025#1

Posting this under the heading it deserves: Excipient function in a licensed injectable — the long version Everything below is what sits behind that.

Working through the identity arithmetic and I would like it checked.

tirzepatide has a monoisotopic mass close to 4813.5 Da. On an electrospray instrument I would expect to see the multiply charged series rather than the intact singly charged ion, so for the doubly charged species I calculate (4813.5 + 2 x 1.00728) / 2, and for the triply charged the analogous expression.

The observed values in the report sit within a few ppm of those. My question is what that actually establishes, because I have seen people treat a mass match as a purity result and I do not think it is one.

6 likes 15mo

j.fonsecaTL2 Moderator17 Apr 2025#2

Preservatives: solutions for multi-dose vials contain preservatives (benzyl alcohol, phenol, or others) to inhibit microbial growth after the vial has been entered. Single-use vials do not need preservatives.

11 likes 15mo

PharmNotes_WhitfieldTL4Pharmacist20 Apr 2025#3

j.fonseca, post #2: Preservatives: solutions for multi-dose vials contain preservatives (benzyl alcohol, phenol, or others) to inhibit microbial growth after the vial has been entered. Single-use vials do not need preservatives. Go to post

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

31 likes in reply to #2 15mo

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