A compounded GLP-1 vial with an additive has two numbers on its label where an ordinary vial has one: "5/0.5 mg/mL" means 5 mg of semaglutide and 0.5 mg of cyanocobalamin in every millilitre. The searches around these products — how many units, how much B12, what a dosage chart means — all come down to reading that pair correctly. This page does the arithmetic for the combinations pharmacies list, states what is known about the additions, and quotes pharmacy dosing only to show what its numbers mean. It recommends nothing.
The single-drug figures are on the semaglutide dosage page and the tirzepatide dosage page; the approved and compounded GLP-1 ladders are side by side on the GLP-1 dosage chart.
What is on the market, and what is not
No combination is approved. DailyMed returned zero labels on 2026-10-01 for semaglutide or tirzepatide paired with cyanocobalamin, glycine, niacinamide or pyridoxine. The products exist only as compounded preparations, which FDA does not review.
What pharmacies list, from one 503A pharmacy's product pages read on 2026-10-01:
| Product | Strengths listed | Vials |
|---|---|---|
| Semaglutide / cyanocobalamin | 1/0.5 mg/mL · 5/0.5 mg/mL | 1 mL, 2.5 mL |
| Tirzepatide / niacinamide | 8/2 mg/mL · 17/2 mg/mL | 2 mL, 2.5 mL, 4 mL |
A 2026 study in the Annals of Pharmacotherapy (PMID 41689811) searched compounders' websites between February and March 2025 and found 33 semaglutide or tirzepatide products that differed from the approved drugs; 48% combined the drug with some mix of cyanocobalamin, glycine, niacinamide, docusate or ondansetron. Its conclusion on the nutrient additions: "little justification". The study's framing explains the timing — once the shortages ended, compounders could only lawfully sell products that differ from the approved ones.
Semaglutide with B12: units and B12 per dose
Units on a U-100 syringe = mg of semaglutide ÷ semaglutide mg/mL × 100. The B12 delivered = volume drawn × 500 mcg/mL. The doses below are the label's steps (0.25 to 2.4 mg, from the Wegovy label).
| Semaglutide | 1/0.5 mg/mL: units | B12 in that dose | 5/0.5 mg/mL: units | B12 in that dose |
|---|---|---|---|---|
| 0.25 mg | 25 units | 125 mcg | 5 units | 25 mcg |
| 0.5 mg | 50 units | 250 mcg | 10 units | 50 mcg |
| 1 mg | 100 units | 500 mcg | 20 units | 100 mcg |
| 1.7 mg | 170 units | 850 mcg | 34 units | 170 mcg |
| 2.4 mg | 240 units | 1,200 mcg | 48 units | 240 mcg |
The same weekly semaglutide dose carries five times as much B12 from the weaker vial, because the weaker vial means five times the volume. At 1 mg/mL the upper steps are also more than one 1 mL syringe. For scale only: a cyanocobalamin injection label (1,000 mcg/mL) gives 100 mcg per injection for pernicious anaemia, a dose the 5/0.5 vial reaches at 1 mg of semaglutide and the 1/0.5 vial reaches at 0.2 mg.
Tirzepatide with niacinamide: units and niacinamide per dose
Same formula, with niacinamide at 2 mg/mL.
| Tirzepatide | 8/2 mg/mL: units | Niacinamide | 17/2 mg/mL: units | Niacinamide |
|---|---|---|---|---|
| 2.5 mg | 31.3 units | 0.63 mg | 14.7 units | 0.29 mg |
| 5 mg | 62.5 units | 1.25 mg | 29.4 units | 0.59 mg |
| 7.5 mg | 93.8 units | 1.88 mg | 44.1 units | 0.88 mg |
| 10 mg | 125 units | 2.5 mg | 58.8 units | 1.18 mg |
| 15 mg | 187.5 units | 3.75 mg | 88.2 units | 1.76 mg |
17 mg/mL is not a round divisor of any label step, so every step lands between syringe marks — 14.7 units, 29.4 units. That is the practical hazard of these strengths, and it is the one FDA names: its page on unapproved GLP-1 drugs (current as of 2026-09-01) reports hospitalisations that "may be related to dosing errors", from patients measuring incorrect doses and professionals miscalculating them. The units formula and its tenfold slips are set out separately.
A schedule in units without a concentration
One pharmacy's semaglutide/glycine/B12 page, read on 2026-10-01, lists a titration entirely in units: 4, 8, 18, 30 and then 44 units (0.04 to 0.44 mL) once weekly, with no drug concentration stated on the page. Quoted here only to show why a unit count is incomplete: 44 units is 0.44 mL, which is 0.44 mg of semaglutide at 1 mg/mL, 1.1 mg at 2.5 mg/mL and 2.2 mg at 5 mg/mL. The label that goes with the vial is what turns units into milligrams. The same gap between a fixed-volume label dose and a unit count on a pharmacy vial, step by step for tirzepatide, is on compounded tirzepatide vs Zepbound.
Glycine and pyridoxine
Glycine is an amino acid with no drug label of its own as an injection; no study of it in a GLP-1 injection turned up beyond the 2026 product survey above. Pyridoxine (vitamin B6) injection has a label — 100 mg/mL, 10 to 20 mg daily for dietary deficiency (openFDA version 2024-01-28) — but no GLP-1 combination product with a stated pyridoxine strength was opened for this page, so no per-dose table is given for it.
What is not established
No randomised trial has tested semaglutide or tirzepatide combined with B12, glycine, niacinamide or pyridoxine in one injection: PubMed returned 16 records and no randomised trial on 2026-10-01, and the three ClinicalTrials.gov records naming the words test surgery, diet or exercise, not a combined vial. Nothing is known from trials about stability, absorption or effect of the combinations. Pharmacy schedules quoted here are the pharmacies' own and are not adopted by this site. FDA also warns that salt forms (semaglutide sodium, semaglutide acetate) are different active ingredients. Dose and product decisions belong with the prescriber. The calculator's semaglutide and tirzepatide settings work any single-drug concentration; the compounds are covered in Medibact's Semaglutide guide and Tirzepatide guide.
Sources and dates
Opened 2026-10-01: DailyMed SPL search (five combination queries); Empower Pharmacy product pages for semaglutide/cyanocobalamin and tirzepatide/niacinamide; Strive Pharmacy's semaglutide/glycine/B12 page; FDA, "FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss" (content current 2026-09-01); PubMed abstract PMID 41689811 and the PubMed and ClinicalTrials.gov searches described above; openFDA labels for cyanocobalamin injection (Meitheal, 2025-06-12) and pyridoxine hydrochloride injection (2024-01-28). The Wegovy dose steps from its label (openFDA copy, read 2026-10-01). Units and additive amounts are arithmetic by this site. Corrections go to the contact page.