Peptifact

How Peptides Are Reconstituted: The Procedure, the Math, and the Doses Sources Actually Cite

How a lyophilized peptide is turned into a solution, taken from an FDA label that describes it; the arithmetic that turns milligrams and millilitres into syringe units, with worked tables; and the dosages that labels, trials, clinics and vendor pages state for the compounds people ask about, each attributed and dated.

Peptifact Editorial · Published 2026-09-05

Reconstitution is arithmetic wrapped in a procedure, and both halves are described in public documents. The procedure is on the labels of approved lyophilized peptides, which come with step-by-step instructions written for patients. The arithmetic is the same for every vial: mass divided by volume gives concentration, and a U-100 syringe reads that concentration in hundredths of a millilitre. This page sets out both, with worked tables, and then reports the dosages that labels, trials, clinics and vendor pages state for the compounds people ask about, each with its source and date. It reports; it does not prescribe. What a given laboratory does with a vial is a matter for its own protocol, and how brands appear on this site is set out on our disclosure page.

The procedure, as an FDA label describes it

The most authoritative description of reconstituting a lyophilized peptide is a prescribing-information document, because approved products must include one. EGRIFTA WR (tesamorelin), a growth-hormone-releasing peptide sold as a lyophilized powder with a 30 mL vial of Bacteriostatic Water for Injection, USP, in the kit, describes the process in section 2.2 of its label, revised March 2025 (FDA label):

  • "Use only the diluent provided, Bacteriostatic Water for Injection, to reconstitute EGRIFTA WR."
  • "Reconstitute 1 vial of EGRIFTA WR lyophilized powder with 1.3 mL of diluent (8 mg per mL). Move the vial in a circle (swirl) to mix all the powder and liquid. Do not shake."
  • "Parenteral drug products should be inspected visually for particulate matter and discoloration prior" to use.
  • "One reconstituted EGRIFTA WR vial provides daily doses for 7 consecutive days. One dose of EGRIFTA WR is 1.28 mg in 0.16 mL of the reconstituted solution."
  • "Store reconstituted EGRIFTA WR at room temperature at 20 °C to 25 °C (68 °F to 77 °F). Discard unused solution of EGRIFTA WR 7 days after mixing. Do not freeze."

The earlier single-vial formulation, EGRIFTA SV, uses Sterile Water for Injection instead: 0.5 mL per 2 mg vial, rolled gently for 30 seconds, not shaken, with 0.35 mL (1.4 mg) drawn immediately and the remainder discarded (2019 label). The contrast between the two is instructive: with a preserved diluent the label allows seven days at room temperature; with an unpreserved one it allows no storage at all.

The sequence is the same in every reconstitution guide, clinical or otherwise: a measured volume of diluent introduced through the stopper, gentle mixing without shaking (shaking foams and can denature a peptide), a visual check for particles or colour, and dated storage. What the label supplies and a research-peptide vial does not is the volume, the concentration, the storage condition and the discard date, all of which a manufacturer has validated for the approved product and nobody has validated for the research one.

CDC's injection-safety guidance adds the aseptic rules the labels assume: "Always use aseptic technique when preparing and administering injections"; "Use a new sterile syringe and needle for each patient. Once used, the syringe and needle are both contaminated and must be discarded"; "Do not enter a medication vial, bag, or bottle with a syringe or needle used on another patient"; and draw up medications "in a designated clean medication preparation area" away from sinks and water sources (CDC). Our syringe page covers the device, and our bacteriostatic-water guide the diluent's label.

The arithmetic

Three quantities, one relationship:

Concentration (mg/mL) = peptide in the vial (mg) ÷ diluent added (mL).

Everything else follows. Multiply by 1,000 for mcg/mL. A U-100 insulin syringe is graduated so that 100 units is 1 mL, so one unit is 0.01 mL and the peptide in one unit is the concentration in mcg/mL divided by 100. The number of units for a given quantity is that quantity in mcg divided by the mcg per unit. The number of such quantities in the vial is the vial's total mcg divided by the quantity.

A worked example, the one Medibact's calculator page uses: a 5 mg vial plus 2 mL gives 2.5 mg/mL, which is 2,500 mcg/mL and 25 mcg per unit; 250 mcg is therefore 0.1 mL, or 10 units, and the vial holds 20 such portions (Medibact reconstitution calculator). The calculator takes vial mass, diluent volume, a target quantity and a syringe size, and returns concentration, mcg per unit, volume, the unit reading and portions per vial; it is the quickest way to check any row below.

Concentration and mcg per unit by vial size and diluent volume

Vial 1 mL diluent 2 mL 3 mL 5 mL
2 mg 2 mg/mL · 20 mcg/unit 1 mg/mL · 10 mcg/unit 0.67 mg/mL · 6.7 mcg/unit 0.4 mg/mL · 4 mcg/unit
5 mg 5 mg/mL · 50 mcg/unit 2.5 mg/mL · 25 mcg/unit 1.67 mg/mL · 16.7 mcg/unit 1 mg/mL · 10 mcg/unit
10 mg 10 mg/mL · 100 mcg/unit 5 mg/mL · 50 mcg/unit 3.33 mg/mL · 33.3 mcg/unit 2 mg/mL · 20 mcg/unit
15 mg 15 mg/mL · 150 mcg/unit 7.5 mg/mL · 75 mcg/unit 5 mg/mL · 50 mcg/unit 3 mg/mL · 30 mcg/unit
30 mg 30 mg/mL · 300 mcg/unit 15 mg/mL · 150 mcg/unit 10 mg/mL · 100 mcg/unit 6 mg/mL · 60 mcg/unit

Units on a U-100 syringe for common quantities

Quantity at 25 mcg/unit (5 mg in 2 mL) at 50 mcg/unit (5 mg in 1 mL or 10 mg in 2 mL) at 100 mcg/unit (10 mg in 1 mL) at 150 mcg/unit (15 mg in 1 mL)
100 mcg 4 units (0.04 mL) 2 units 1 unit 0.67 unit, not readable
250 mcg 10 units (0.10 mL) 5 units 2.5 units 1.67 units
500 mcg 20 units (0.20 mL) 10 units 5 units 3.3 units
1 mg 40 units (0.40 mL) 20 units 10 units 6.7 units
2.5 mg 100 units (1.0 mL) 50 units 25 units 16.7 units
5 mg exceeds a 1 mL syringe 100 units (1.0 mL) 50 units 33.3 units

Two things the tables show. First, why guides describe adding enough diluent to put a typical quantity in the middle of the syringe scale: at 150 mcg per unit, 100 mcg is two-thirds of one unit and cannot be read; at 25 mcg per unit it is 4 units. Second, why the vial size and the diluent volume are the two numbers that matter and the product name is not: the same 250 mcg is 10 units, 5 units or 2.5 units depending only on those two choices. A quantity stated in units without the concentration behind it is meaningless, and a surprising number of forum posts state one.

Syringe barrel sizes bound the useful range: a 0.3 mL syringe reads to 30 units, often in half-unit steps; a 0.5 mL to 50; a 1 mL to 100 in two-unit steps. Our syringe page has the cleared ranges.

The doses sources state

This section reports figures, each with its source and date. The sources are of very different weight, and the table says which kind each is: an FDA-approved label is a validated schedule; a trial protocol is what a company tested; a clinic guide is what one practice publishes; a vendor page is marketing. None of it is a recommendation from this site.

Compound Figure as stated Kind of source Source and date
Semaglutide (Wegovy injection) "Initiate at 0.25 mg once weekly for 4 weeks. Then follow the dosage escalation schedule ... titrating every 4 weeks to achieve the maintenance dosage"; "The usual recommended maintenance dosage of WEGOVY injection is 2.4 mg once weekly"; a 7.2 mg strength exists FDA-approved label Wegovy label, revised 06/2026
Tirzepatide (Zepbound) "The recommended starting dosage of ZEPBOUND for all indications is 2.5 mg injected subcutaneously once weekly" for 4 weeks, then 5 mg, increasing in "2.5 mg increments, after at least 4 weeks on the current dose"; "The maximum dosage of ZEPBOUND for all indications is 15 mg injected subcutaneously once weekly" FDA-approved label Zepbound label, revised 02/2026
Tesamorelin (EGRIFTA WR) 1.28 mg once daily, as 0.16 mL of an 8 mg/mL reconstituted solution FDA-approved label EGRIFTA WR label, 03/2025
Retatrutide (investigational) 4 mg, 9 mg and 12 mg once weekly, with escalation, in TRIUMPH-1 (2,339 adults, 80 weeks) and the other Phase 3 trials; not approved anywhere Trial protocol, company release Lilly, 2026-05-21
Retatrutide, tirzepatide, semaglutide as sold by a research vendor Schedules "up to 12mg weekly", "15mg weekly" and "2.5mg weekly", quoted by FDA from the seller's site as evidence the products were intended as human drugs Vendor page, as quoted in a warning letter FDA letter to Mile High Compounds, 2026-03-31
BPC-157, the one human study A single intra-articular knee injection of "2 cc of 2000 mcg/mL solution", 4 mg, in 12 patients, 7 reporting relief beyond 6 months; no control group Retrospective series, via a systematic review HSS Journal 2025
BPC-157, animal studies "6 μg/kg to 20 mg/kg" by intramuscular, intravenous, intraperitoneal and oral routes Preclinical, via the same review Same
BPC-157, clinic and vendor pages "Commonly discussed BPC-157 dosages range from 250 to 500 mcg per day" subcutaneously, with the note that "there is no universally accepted human dosage" (clinic, 2025-10-30); "doses in research typically range from 200 to 800 mcg per day" with "250 mcg twice daily" described as the most common protocol and 5 mg in 2 mL as the reconstitution (vendor, updated 2026-08-30) Clinic guide; vendor guide Tucson Wellness MD; FormBlends
TB-500, clinic page "TB-500 2–5 mg weekly" in a combination protocol with BPC-157 Clinic guide Tucson Wellness MD, as above
CJC-1295 (no DAC) with ipamorelin, clinic page "100 mcg of each peptide per dose, injected subcutaneously once daily at bedtime on an empty stomach, five days per week", titrated to "200–300 mcg of each per dose", in "8–12 weeks" cycles; a 5 mg/5 mg blended vial in 2 mL gives 25 mcg of each per unit, so 100 mcg is 4 units; CJC-1295 with DAC "1–2 mg once or twice weekly" Clinic guide Beverly Hills Rejuvenation Center, 2026-07-24

Three things to hold alongside the table. The approved-label rows are the only ones with dose-finding trials behind them; the schedules were set by studies designed to find them. The retatrutide row is a trial protocol for a drug that is not yet approved; the trial doses are what Lilly will ask FDA to approve, not what anyone can lawfully be prescribed today. The BPC-157, TB-500 and CJC-1295/ipamorelin rows have no human dose-finding study behind them at all, which both the clinic and the vendor pages acknowledge in their own words; their figures are conventions that circulate between clinics, vendors and forums, and a convention is not evidence. The animal range for BPC-157, 6 mcg/kg to 20 mg/kg, spans more than three orders of magnitude, which is what "no established dose" looks like in numbers. Our wolverine-stack page on MuscleLedger counts the human evidence for BPC-157 and TB-500; our warning-letter tracker shows what FDA has done with vendor dosing schedules.

Storage after reconstitution

For an approved product the label answers this: EGRIFTA WR, seven days at room temperature, then discard; EGRIFTA SV, immediately, no storage. For a research peptide nobody has validated an answer. The peptide-synthesis houses' guides say that solutions have a very limited shelf-life, recommend −20 °C single-use aliquots, and prefer not storing solutions at all; Medibact's calculator page reports a "commonly reported usable window ~2–4 weeks" refrigerated, and labels it as commonly reported rather than as a manufacturer figure. The 28-day figure that vendor pages attach to reconstituted peptides is CDC's discard rule for the opened multi-dose vial of bacteriostatic water, not a stability measurement of any peptide. Our storage page lays out what each source says and where each is silent.

What this page is and is not

It is a description of a procedure as an FDA label states it, the arithmetic that any vial obeys, and a sourced record of the doses that labels, trials, clinics and vendors state. It is not a protocol. It does not tell any reader what to reconstitute, at what concentration, or what quantity to draw. Where a figure has a trial behind it the table says so; where it has only a clinic's page or a vendor's blog behind it the table says that too.

Sources and dates

Opened 2026-09-05: FDA labels for EGRIFTA WR (revised 03/2025) and EGRIFTA SV (2019), Wegovy (revised 06/2026) and Zepbound (revised 02/2026); CDC injection-safety guidance (2024-03-26); Medibact's reconstitution calculator page; the HSS Journal 2025 BPC-157 systematic review (PMC12313605); Lilly's TRIUMPH-1 release (2026-05-21); FDA's warning letter to Mile High Compounds (2026-03-31); Tucson Wellness MD's BPC-157 guide (2025-10-30); FormBlends' BPC-157 guide (updated 2026-08-30); Beverly Hills Rejuvenation Center's CJC-1295/ipamorelin guide (2026-07-24). Corrections, and better-sourced dose data than a clinic page, go to the contact page. Who we are is on the about page.

Frequently asked questions

How is a lyophilized peptide reconstituted?

The clearest public description is an FDA label, because approved lyophilized peptides come with instructions. For EGRIFTA WR (tesamorelin), the label says: use only the supplied diluent, Bacteriostatic Water for Injection; reconstitute one vial of powder with 1.3 mL of diluent; move the vial in a circle to mix all the powder and liquid, do not shake; inspect the solution for particulate matter and discoloration before use; store the reconstituted vial at 20 to 25 °C and discard unused solution 7 days after mixing. The same sequence, diluent through the stopper, gentle swirling, visual inspection, dated storage, is what every reconstitution guide describes; the volumes and the discard window are what differ, and for a research peptide no manufacturer states them.

How much bacteriostatic water is added to a 5 mg vial?

There is no correct amount; the volume sets the concentration, and the concentration sets how many syringe units correspond to a given quantity. With 1 mL the vial is 5 mg/mL (50 mcg per unit); with 2 mL it is 2.5 mg/mL (25 mcg per unit); with 3 mL it is about 1.67 mg/mL (16.7 mcg per unit). Vendor and clinic guides most often describe 1 to 3 mL for a 5 mg vial, on the reasoning that a typical quantity should fall in the middle of the syringe's scale rather than at 1 or 2 units, where reading error is largest. The table on this page shows the arithmetic for common vial sizes.

How many units is 250 mcg on an insulin syringe?

It depends entirely on the concentration. At 2.5 mg/mL (a 5 mg vial in 2 mL), 250 mcg is 0.1 mL, which is 10 units on a U-100 syringe. At 5 mg/mL (5 mg in 1 mL), it is 5 units. At 1.67 mg/mL (5 mg in 3 mL), it is 15 units. The formula is units = quantity in mcg divided by mcg per unit, where mcg per unit = (vial mcg ÷ diluent mL) ÷ 100. Medibact's calculator does this arithmetic for any combination.

What are commonly used peptide doses?

For approved peptides, the label states the schedule: Wegovy 0.25 mg weekly escalating every 4 weeks to 2.4 mg; Zepbound 2.5 mg weekly for 4 weeks, then 5 mg, rising in 2.5 mg steps to a maximum of 15 mg; EGRIFTA WR 1.28 mg daily. For investigational retatrutide, Lilly's trials used 4, 9 and 12 mg weekly. For research compounds with no approval, the figures come from clinics and vendors, not trials: BPC-157 pages commonly cite 250 to 500 mcg per day, CJC-1295/ipamorelin pages 100 to 300 mcg of each per injection. The one human BPC-157 study used a single 4 mg injection into the knee. This page reports those figures with their sources; it does not recommend any of them.

How long does a reconstituted peptide last?

For an approved product, the label says: EGRIFTA WR's reconstituted vial is discarded 7 days after mixing, kept at room temperature; EGRIFTA SV is used immediately. For research peptides, no manufacturer states a refrigerated shelf-life; the peptide-synthesis houses' guides say solutions have a very limited shelf-life and recommend −20 °C aliquots or not storing solutions at all. Vendor pages commonly report 2 to 4 weeks refrigerated, and the 28-day figure many cite is CDC's rule for the opened multi-dose vial of diluent, not a peptide stability figure. Our storage page sets this out.

Does this page tell me what dose to use?

No. It reports what labels, trial protocols, clinic guides and vendor pages state, with a link and a date on each, so the reader can see where a number comes from and how solid it is. What any laboratory or clinician does with a vial is their protocol, not ours.