Thymosin Alpha-1 Reconstitution — Dose Schedule Calculator

Published 2026-08-13 · Lyophile Editorial

Bacteriostatic water calculator — 1.5 mg Thymosin Alpha-1 vial

Add 1.5 mL bacteriostatic water → 1 mg/mL (1000 mcg/mL)

| Diluent | Concentration | Per U-100 unit | 100 mcg dose | |---------|--------------|----------------|--------------| | 1.5 mL | 1000 mcg/mL | 10 mcg | 10 units | | 0.75 mL | 2000 mcg/mL | 20 mcg | 5 units | | 0.5 mL | 3000 mcg/mL | 30 mcg | 3.3 units |

Math: 1.5 mg ÷ 1.5 mL = 1 mg/mL. Each 0.01 mL (1 unit on a U-100) = 10 mcg.

How to reconstitute:

1. Inject 1.5 mL bacteriostatic water into the vial, aiming down the side wall
2. Roll gently — do not shake
3. Let sit 5 minutes before drawing

USP <797> permits sterile water for injection as diluent for lyophilized peptides; bacteriostatic water (0.9% benzyl alcohol) is standard for multi-dose research use. The benzyl alcohol acts as a bacteriostatic preservative, but it also carries a critical limitation: it can denature peptides over extended storage. Thymosin Alpha-1 is a 28-amino-acid acetylated peptide with a molecular weight of 3108 Da; it is relatively stable, but prolonged contact with 0.9% benzyl alcohol at room temperature accelerates deamidation and oxidation. Keep reconstituted vials at 2–8°C and never freeze — ice crystal formation disrupts the peptide's secondary structure and can cause precipitation upon thawing.

A common failure mode is injecting diluent directly onto the lyophilized cake. The forceful stream creates localized supersaturation, which can cause aggregation and visible fibril formation. Aiming down the side wall mitigates this. Another failure is shaking — this introduces air bubbles and shears the peptide, reducing measurable recovery by HPLC. Gentle rolling for 30–60 seconds is sufficient; the 5-minute rest allows complete dissolution without mechanical stress.

Biweekly 1.5 mg dosing — 4-week supply math

Eight injections total (2×/week × 4 weeks). At 1.5 mg/dose = 12 mg peptide required.

Option A — single-dose vials: Eight 1.5 mg vials, each reconstituted with 1.5 mL.

Option B — 5 mg vials: Three 5 mg vials = 15 mg total (3 mg overage for dead-space and draw loss). Reconstitute each with 5 mL BAC water → 1000 mcg/mL. Draw 1.5 mL per injection.

| Vial | Diluent | Concentration | Dose | Injection volume | U-100 units | |------|---------|---------------|------|------------------|-------------| | 1.5 mg | 1.5 mL | 1000 mcg/mL | 1500 mcg | 1.5 mL | 150 | | 1.5 mg | 3.0 mL | 500 mcg/mL | 1500 mcg | 3.0 mL | 300 | | 5 mg | 5.0 mL | 1000 mcg/mL | 1500 mcg | 1.5 mL | 150 |

Note: 1.5 mL exceeds typical sub-Q single-site tolerance (~1 mL). Split into two 0.75 mL injections at separate sites, or reconstitute at 2000 mcg/mL (see below). Subcutaneous tissue absorbs approximately 0.5–1.0 mL comfortably; larger volumes cause pain, induration, and inconsistent absorption kinetics. Splitting into two sites also doubles the injection surface area, which slightly accelerates uptake but introduces twice the contamination risk — use alcohol swabs on both sites and fresh needles for each puncture.

Total bacteriostatic water for 4-week protocol

Eight injections × 1.5 mL = 12 mL minimum. Add 20% overage for draw loss, hub dead-space, and vial retention → ~15 mL. A 30 mL multi-dose vial covers this with margin.

Preservative window: 0.9% benzyl alcohol remains effective 28 days after first puncture per USP <797>, stored per label. Your protocol fits inside that window. The 28-day clock starts at first vial puncture, not at reconstitution — mark the date on the vial immediately. Beyond 28 days, benzyl alcohol concentration can drop below 0.5% due to evaporation and dilution, allowing microbial proliferation. A 30 mL vial punctured eight times retains adequate preservative, but each puncture introduces a 30-gauge hole that never fully reseals; the rubber stopper self-heals, yet micro-channels remain.

Dead-space math: Standard U-100 syringe holds 0.02–0.03 mL in hub + needle after plunger bottoms out. Eight injections = 0.16–0.24 mL lost — 160–240 mcg peptide at 1000 mcg/mL. Low dead-space syringes cut this to ~0.01 mL per injection. The difference matters more at higher concentrations: at 3000 mcg/mL, 0.03 mL dead-space equals 90 mcg lost per injection — nearly 6% of a 1500 mcg dose. Low dead-space syringes (often labeled "LDS") achieve 0.01 mL by shortening the hub and integrating the needle directly into the barrel. They cost slightly more but pay for themselves across an eight-injection protocol.

U-100 syringe reading — 1.5 mg dose

U-100 = 100 units/mL. Each unit mark = 0.01 mL.

At 1000 mcg/mL: 1500 mcg = 150 units — exceeds a single 1 mL syringe. You'd need two full syringes plus a 0.5 mL.

Fix: reconstitute at 2000 mcg/mL. Add 0.75 mL BAC to the 1.5 mg vial.

• 1.5 mg ÷ 0.75 mL = 2 mg/mL
• 1500 mcg ÷ 2000 mcg/mL = 0.75 mL = 75 units — one syringe, one site

| Concentration | Dose | Volume | U-100 units | |---------------|------|--------|-------------| | 1000 mcg/mL | 1500 mcg | 1.50 mL | 150 | | 2000 mcg/mL | 1500 mcg | 0.75 mL | 75 | | 3000 mcg/mL | 1500 mcg | 0.50 mL | 50 |

2000 mcg/mL is the practical sweet spot — single syringe, single site, 0.75 mL within sub-Q tolerance. At 3000 mcg/mL, the 0.5 mL volume is even more comfortable, but concentration errors amplify: a 1-unit misread at 3000 mcg/mL equals 30 mcg, versus 20 mcg at 2000 mcg/mL. For research protocols requiring precise dose titration, lower concentration reduces relative error.

Draw steps:

1. Draw 0.75 mL air into syringe, inject into vial
2. Withdraw 0.75 mL peptide solution
3. Tap syringe to settle bubbles, push to 75-unit mark

Air bubble management is the most common source of under-dosing. A 0.05 mL bubble in a 0.75 mL draw represents 6.7% of the dose — 100 mcg at 2000 mcg/mL. Tap the syringe barrel firmly with a fingernail to dislodge bubbles adhering to the plunger shaft. Never push air back into the vial after drawing; this introduces moisture and contaminates the remaining solution.

What is the maximum safe injection volume for subcutaneous research use?

Subcutaneous injection volume in research settings is generally capped at 1.0 mL per site. Volumes above 1.5 mL cause tissue distension, localized pain, and erratic absorption. For a 1.5 mg Thymosin Alpha-1 dose, reconstitute at 2000 mcg/mL to keep the injection at 0.75 mL — comfortably within the 1.0 mL ceiling. Alternatively, split the dose into two 0.75 mL injections at separate sites (left and right abdomen, or abdomen and thigh). Rotating sites reduces lipohypertrophy risk and maintains consistent absorption kinetics across the protocol.

Vial and filter dead-space loss

Vial dead-space after reconstitution: 0.05–0.1 mL unreachable. At 2000 mcg/mL = 100–200 mcg lost per vial. Over eight vials = 0.8–1.6 mg — 7–13% of total protocol.

Recovery tactics:

• Low dead-space syringe + 1-inch needle angled to vial's lowest point
• 30-gauge needle for precise bottom-corner access (slower draw)
• Skip filter needles (0.22 µm) — they add ~0.1 mL hold-up volume. With USP-grade BAC water, filtration is unnecessary and increases loss.

Vial geometry matters more than most researchers expect. Standard 2 mL serum vials have a concave bottom that traps solution in a ring around the edge. Tilt the vial to 45° and insert the needle at the lowest visible point — this recovers an additional 0.02–0.03 mL. Some researchers use a 1 mL syringe with a 27-gauge, 1.5-inch needle to reach the bottom corner; the longer needle allows better angle control. Never invert the vial and draw from the neck — the rubber stopper's inner surface retains solution via surface tension, and you risk drawing air.

Storage stability after reconstitution

Reconstituted Thymosin Alpha-1 retains >95% purity for 14 days at 2–8°C, per manufacturer stability data typical of lyophilized peptides. The 28-day USP <797> window is a preservative limit, not a peptide stability guarantee. For research protocols exceeding 14 days, consider aliquoting: reconstitute at 2000 mcg/mL, draw 0.75 mL into sterile low-retention microcentrifuge tubes, and freeze at −20°C. Thaw one aliquot per injection. This avoids repeated punctures and preserves peptide integrity. However, freezing introduces its own risk — cryoprotectants like mannitol or trehalose are often present in the lyophilized cake, but repeated freeze-thaw cycles still degrade the peptide. Freeze once, thaw once, use once.

Supply sources

Bacteriostatic water:

• BAC Water Depot — 30 mL multi-dose vials, 0.9% benzyl alcohol
• Hopkins Medical Products — sterile, hospital supply channel
• Cascade Biologics — lab-grade WFI, bulk packaging

Research peptides:

• Alpha Amino USA — per-lot HPLC/MS COA, US-shipped
• PurePeptides Research — third-party tested, lyophilized in sterile vials
• ResearchChem Supply — synthesis specialists, purity docs included

Verify each supplier's COA against the peptide's theoretical mass (3108 Da for Thymosin Alpha-1). A COA should report HPLC purity ≥98% and mass spectrometry confirmation. Any supplier unwilling to provide batch-specific documentation should be excluded. Also confirm the lyophilized cake's appearance: it should be a white to off-white powder or plug. Discoloration, clumping, or partial collapse indicates moisture ingress during storage — reject the vial.

For research use only — not clinical guidance. Verify purity certificates, use USP-grade diluent, store reconstituted peptide at 2–8°C, and discard after 28 days per USP <797>.