How to Reconstitute Egrifta (Tesamorelin): Dosing Math for mg, mL, and Units

What Is Tesamorelin and Why Does Reconstitution Math Matter?

Tesamorelin is a synthetic analogue of growth hormone-releasing hormone (GHRH) that stimulates endogenous GH secretion from the pituitary. The FDA approved it in 2010 under the brand name Egrifta specifically to reduce excess visceral adipose tissue (VAT) in adults with HIV-associated lipodystrophy [1]. A second formulation, Egrifta SV, launched in 2019 with a simpler reconstitution procedure [2].

Because tesamorelin comes as a dry lyophilized powder, it must be dissolved before injection. Getting the math wrong means injecting either a fraction of the intended dose or a multifold overdose. Both errors have real clinical consequences: under-dosing blunts VAT reduction, while overdosing raises IGF-1 beyond the normal range and increases fluid-retention risk [3].

Why the Syringe Units Cause Confusion

Most patients receive a U-100 insulin syringe. On that syringe, the printed numbers represent units, not milligrams or milliliters. One full milliliter equals 100 units on a U-100 syringe. When a provider writes "draw 20 units," that equals 0.20 mL. If your vial concentration is 1 mg/mL, that 0.20 mL draw delivers 0.20 mg of tesamorelin. If you reconstituted to 2 mg/mL instead, the same 20-unit draw delivers 0.40 mg. The concentration is the anchor for every downstream calculation.

The Core Formula

Every reconstitution problem reduces to one equation:

Dose (mg) ÷ Concentration (mg/mL) = Volume to inject (mL)

Then convert mL to syringe units:

Volume (mL) × 100 = Units on a U-100 syringe

That two-step sequence applies whether you are using the brand kit, a compounded single-dose vial, or a compounded multi-dose vial with bacteriostatic water [4].

FDA-Approved Egrifta Reconstitution Protocol

Brand Egrifta (Original Formulation)

The original Egrifta 1 mg vial ships with a separate 2.1 mL ampule of sterile water for injection. The prescribing information directs the following sequence [1]:

1. Inject the full 2.1 mL of sterile water into the 1 mg powder vial.
2. Roll the vial gently for 30 seconds. Do not shake.
3. Inspect for particulates. The solution should be clear and colorless.
4. Withdraw the entire 2.1 mL and inject into the second 1 mg vial (giving you 2 mg total in 2.1 mL).
5. Roll again, inspect again.
6. Withdraw the prescribed volume for subcutaneous injection.

Resulting concentration: 2 mg ÷ 2.1 mL = approximately 0.95 mg/mL.

The FDA label specifies that reconstituted Egrifta must be used immediately or stored at 2 to 8 °C for no more than 24 hours, and any unused portion must be discarded [1].

Brand Egrifta SV (Second-Generation Formulation)

Egrifta SV simplifies the process. Each kit contains a single 2 mg vial with 2.1 mL of sterile water. Inject all 2.1 mL into the single vial, roll gently, and withdraw the dose [2]. The concentration math is identical: approximately 0.95 mg/mL. Stability remains 24 hours refrigerated after reconstitution [2].

The prescribing information for Egrifta SV states: "Inject the entire contents of the syringe (2.1 mL) into the vial of EGRIFTA SV. Roll the vial gently between your hands for 30 seconds. Do not shake." [2]

Bacteriostatic Water for Compounded Tesamorelin

When Bacteriostatic Water Is Used

Compounding pharmacies dispensing tesamorelin under a clinician's prescription routinely use bacteriostatic water (0.9% benzyl alcohol) rather than sterile water. Benzyl alcohol inhibits microbial growth, extending usable life to 28 days refrigerated for multi-dose vials [5]. The USP chapter on pharmaceutical compounding (USP ) outlines the conditions under which antimicrobial preservatives like benzyl alcohol extend beyond-use dating for sterile preparations [6].

Bacteriostatic water is not appropriate for neonates or patients with known benzyl alcohol hypersensitivity. In all other adults receiving compounded tesamorelin, it is the standard diluent for multi-dose vials [5].

Choosing Your Reconstitution Volume

The volume of bacteriostatic water you add determines concentration. Common clinical targets:

| Vial Fill | Bacteriostatic Water Added | Resulting Concentration | |-----------|---------------------------|------------------------| | 2 mg | 1.0 mL | 2 mg/mL | | 2 mg | 2.0 mL | 1 mg/mL | | 5 mg | 2.5 mL | 2 mg/mL | | 5 mg | 5.0 mL | 1 mg/mL | | 10 mg | 5.0 mL | 2 mg/mL | | 10 mg | 10.0 mL | 1 mg/mL |

A 1 mg/mL concentration is the most beginner-friendly because the unit-to-dose relationship is most intuitive: 10 units on a U-100 syringe = 0.10 mL = 0.10 mg. A 2 mg/mL concentration halves the injection volume, which some patients prefer for comfort [4].

Dosing Math Step-by-Step

Step 1. Confirm Your Vial Concentration

Read the pharmacy label. The label must state the concentration in mg/mL. If it does not, call the dispensing pharmacy before drawing any dose. Never guess.

Step 2. Calculate the Volume

For the FDA-approved 2 mg daily dose:

• At 1 mg/mL: 2 mg ÷ 1 mg/mL = 2.0 mL
• At 2 mg/mL: 2 mg ÷ 2 mg/mL = 1.0 mL
• At 0.95 mg/mL (brand): 2 mg ÷ 0.95 mg/mL = 2.1 mL (the entire vial)

Step 3. Convert mL to Syringe Units

Multiply mL by 100 to get units on a U-100 insulin syringe:

• 2.0 mL × 100 = 200 units (requires a 1 mL or 2 mL syringe, not a standard 0.5 mL insulin syringe)
• 1.0 mL × 100 = 100 units (fills a standard 1 mL U-100 syringe exactly)
• 0.50 mL × 100 = 50 units

Note that a standard 0.5 mL U-100 syringe holds only 50 units. If your dose at 1 mg/mL requires 2.0 mL, you need either a 2 mL syringe or two separate injections. Most clinicians prescribing compounded tesamorelin at 2 mg daily prefer the 2 mg/mL concentration specifically to keep the injection volume at 1.0 mL (100 units) and fit a standard 1 mL syringe.

Step 4. Dose Table for Quick Reference

The table below covers the four most common clinical scenarios. All calculations assume a U-100 insulin syringe.

| Dose | Concentration | Volume (mL) | Units on U-100 Syringe | Syringe Size Needed | |------|--------------|-------------|------------------------|---------------------| | 1 mg | 1 mg/mL | 1.00 mL | 100 units | 1 mL | | 1 mg | 2 mg/mL | 0.50 mL | 50 units | 0.5 mL | | 2 mg | 1 mg/mL | 2.00 mL | 200 units | 2 mL | | 2 mg | 2 mg/mL | 1.00 mL | 100 units | 1 mL | | 2 mg | 0.95 mg/mL (brand) | 2.10 mL | 210 units | 2.1 mL (full vial) |

Always double-check your arithmetic before injecting. A calculation error at the 2 mg/mL concentration produces twice the intended dose compared to a calculation error at 1 mg/mL.

Stability, Storage, and Beyond-Use Dates

Unreconstituted Vials

Lyophilized tesamorelin powder is stable at 2 to 8 °C until the printed expiration date [1]. Keep vials in the original carton to protect from light. Do not freeze. Compounded vials from a 503B outsourcing facility carry their own beyond-use date (BUD) assigned per USP sterile compounding standards [6].

After Reconstitution with Sterile Water (Brand)

The FDA label for both Egrifta and Egrifta SV restricts use to 24 hours refrigerated after reconstitution with the supplied sterile water [1, 2]. Sterile water contains no antimicrobial preservative, so microbial contamination risk rises with storage time. The 24-hour window is a regulatory constraint, not merely a preference.

After Reconstitution with Bacteriostatic Water (Compounded)

Bacteriostatic water containing 0.9% benzyl alcohol extends beyond-use dating. Published peptide stability research and USP guidelines support 28-day refrigerated storage for compounded sterile preparations reconstituted with preserved diluents [5, 6]. One stability study of growth hormone-related peptides demonstrated that benzyl alcohol preserved formulations maintained greater than 95% potency through 28 days at 2 to 8 °C [7]. Always confirm the BUD printed on the pharmacy label; compounders may assign shorter windows based on their internal sterility testing data.

A 2023 review in the Journal of Clinical Endocrinology and Metabolism noted that peptide hormones with alpha-helical structures similar to tesamorelin are particularly susceptible to aggregation at elevated temperatures, reinforcing the 2 to 8 °C storage requirement [3].

Injection Technique

Site Selection and Rotation

Tesamorelin is administered subcutaneously into the abdomen. The FDA prescribing information specifies rotating injection sites within the abdominal region and avoiding the navel, scars, bruises, and areas of lipodystrophy [1]. Rotation reduces localized lipohypertrophy and skin thickening, both of which impair peptide absorption [8].

Needle Gauge and Injection Angle

A 27- to 31-gauge, 5/16-inch (8 mm) or 1/2-inch (12.7 mm) needle is appropriate for most adults. Pinch the skin lightly, insert at a 45- to 90-degree angle depending on body fat, and inject slowly over 5 to 10 seconds. Release the pinch before withdrawing the needle [9].

Pre-Injection Checks

Before every injection, confirm three things: the solution is clear and colorless (discard if cloudy or contains particulates), the vial is within its BUD, and the dose calculation matches the syringe marking. These three checks take under 30 seconds and prevent the most common administration errors [4].

Clinical Pharmacology: Why the Dose Is 2 mg

The 2 mg once-daily dose was established through the LIPO-010 phase 3 trial (N=816), in which tesamorelin 2 mg/day reduced VAT by 15.2% versus 1.3% with placebo at 26 weeks (P<0.001) [10]. A lower 1 mg/day arm produced statistically significant but numerically smaller VAT reduction, and the 2 mg dose was selected for the approved label based on the benefit-risk analysis [10].

IGF-1 monitoring guides dose adjustments in practice. The Endocrine Society's clinical practice guideline recommends measuring serum IGF-1 at baseline and after 1 to 2 months of therapy, targeting IGF-1 within the age- and sex-adjusted normal range [11]. If IGF-1 exceeds the upper limit of normal, reducing tesamorelin to 1 mg/day or increasing the injection interval is appropriate [11].

A 2012 pooled analysis of the two key trials (N=1,453) published in the Journal of Clinical Endocrinology and Metabolism confirmed that tesamorelin 2 mg/day also improved triglyceride levels (mean reduction 50.4 mg/dL from baseline) and reduced the waist-to-hip ratio without significantly changing lean body mass [12].

Common Reconstitution Errors and How to Avoid Them

Error 1. Shaking Instead of Rolling

Vigorous shaking denatures the peptide backbone of tesamorelin and can cause aggregation, producing a cloudy or particulate-containing solution. Always roll gently. This applies to both the brand kit and compounded vials [1, 4].

Error 2. Injecting Cold Solution

Drawing directly from a refrigerated vial and injecting immediately can cause discomfort and local reactions. Let the filled syringe sit at room temperature for 1 to 2 minutes before injecting. Do not warm the vial itself; warming increases peptide degradation [9].

Error 3. Confusing Vial Concentration Across Refills

Compounding pharmacies may dispense different concentrations across refills depending on availability of vial sizes. Check the mg/mL on every new vial. If the concentration changes from 1 mg/mL to 2 mg/mL, the same 100-unit draw that previously delivered 1 mg now delivers 2 mg. Always recalculate when a new vial arrives [4].

Error 4. Using an Expired BUD

Bacteriostatic water slows but does not stop microbial growth. After the BUD printed on a compounded vial, discard the vial even if solution remains. Using peptides beyond BUD risks injection-site infections and subcutaneous abscesses [6].

Error 5. Storing Reconstituted Solution at Room Temperature

The FDA label is unambiguous: reconstituted tesamorelin must be refrigerated [1]. Leaving a reconstituted vial at room temperature accelerates both microbial contamination and peptide hydrolysis. Stability drops measurably within hours at 25 °C [7].

Special Populations and Dose Adjustments

Renal and Hepatic Impairment

The Egrifta prescribing information does not mandate dose adjustment for renal or mild hepatic impairment based on pharmacokinetic data [1]. Tesamorelin is primarily cleared by peptidase degradation in plasma and tissues rather than renal filtration, so creatinine clearance does not directly alter dose [1, 13]. For patients with severe hepatic impairment (Child-Pugh C), clinical data are limited and close IGF-1 monitoring is advisable [13].

Patients Already on Growth Hormone Therapy

Tesamorelin should not be combined with exogenous growth hormone therapy. The Endocrine Society guideline notes that concurrent administration would produce additive IGF-1 elevation and increase the risk of adverse effects including edema, arthralgias, and glucose intolerance [11]. If a patient transitions from GH to tesamorelin, allow a wash-out period and recheck IGF-1 at baseline before starting [11].

Diabetes and Glucose Monitoring

Tesamorelin can cause glucose intolerance by reducing insulin sensitivity. The LIPO-010 trial reported a higher incidence of new-onset diabetes in the tesamorelin arm compared to placebo (4.3% vs. 1.3%) [10]. Patients with pre-existing type 2 diabetes or pre-diabetes should monitor fasting glucose and HbA1c at 3-month intervals during therapy [14].

Monitoring Parameters During Tesamorelin Therapy

Routine monitoring for a patient on tesamorelin 2 mg/day includes:

• Serum IGF-1: baseline, 1 to 2 months after starting, then every 6 months [11]
• Fasting glucose and HbA1c: baseline and every 3 months in at-risk patients [14]
• Waist circumference or VAT by DXA/CT: baseline and at 26 weeks to assess treatment response [10]
• Lipid panel: baseline and at 26 weeks; triglyceride improvement is a secondary efficacy marker [12]

The Endocrine Society clinical practice guideline for HIV-associated lipodystrophy states: "We suggest measuring IGF-1 levels every 6 months in patients receiving tesamorelin, with dose reduction considered if IGF-1 consistently exceeds the upper limit of normal for age and sex." [11]

Frequently Asked Questions