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

The label sets the concentration, not the vial size

Both current tesamorelin products are lyophilized powders that ship with their own diluent, and each label fixes three things: which diluent, how much of it, and what volume of the resulting solution is injected [1][2].

The Egrifta SV label reconstitutes the 2 mg vial with 0.5 mL of Sterile Water for Injection, written as 2 mg per 0.5 mL, and states the dose as 0.35 mL subcutaneously once daily [1]. The Egrifta WR label reconstitutes the 11.6 mg vial with 1.3 mL of Bacteriostatic Water for Injection, written as 8 mg per mL, and states the dose as 0.16 mL once daily [2]. The WR solution is therefore twice as concentrated as the SV solution, 8 mg per mL against 2 mg per 0.5 mL [1][2].

Egrifta SV and Egrifta WR are not substitutable

The Egrifta WR label states that Egrifta WR and Egrifta SV are not substitutable, and notes that the two formulations differ in dosage, in the number of vials required to prepare a dose, in reconstitution instructions and in storage requirements [2].

The math, run on the label's own numbers

Volume to inject (mL) = dose (mg) divided by concentration (mg/mL).

• Egrifta SV: 1.4 mg divided by 4 mg/mL = 0.35 mL [1].
• Egrifta WR: 1.28 mg divided by 8 mg/mL = 0.16 mL [2].

Both labels state the dose in milliliters, and neither states it in insulin-syringe units [1][2]. Where a syringe is marked in units rather than milliliters, turning 0.35 mL or 0.16 mL into marks on that barrel depends on that syringe's own scale, which the labels do not describe.

Egrifta SV: what the label specifies

The Egrifta SV label calls for only the diluent provided, Sterile Water for Injection, added to the 2 mg vial to give 2 mg per 0.5 mL [1]. It directs mixing by rolling the vial gently in the hands for 30 seconds, not shaking, then inspecting the solution and using it only if it is clear, colorless and free of particulate matter [1]. The 0.35 mL dose is given immediately after reconstitution, with unused solution and diluent thrown away; if the dose is not given immediately, the reconstituted solution is discarded, and it is not to be frozen or refrigerated [1]. That makes reconstituted Egrifta SV a single-dose solution rather than a stored multi-dose vial [1].

Egrifta WR: what the label specifies

The Egrifta WR label calls for 1.3 mL of the supplied Bacteriostatic Water for Injection, USP, added to the 11.6 mg vial for a concentration of 8 mg per mL [2]. It directs moving the vial in a circle to swirl the powder and liquid, not shaking, and inspecting the result; the solution is not to be used if solid particles appear or if it is cloudy or colored [2]. The dose is 0.16 mL, which is 1.28 mg, subcutaneously once daily [2]. One reconstituted vial provides 7 daily doses, and unused solution is discarded 7 days after mixing [2].

Where the 2 mg daily figure comes from

If you have read that tesamorelin is 2 mg once daily, that figure comes from the pivotal trials, which used 2 mg of the original 1 mg/vial formulation [1]. FDA accepted the Egrifta SV dose of 1.4 mg because its exposure, both peak concentration and total exposure, is similar to that 2 mg dose [1]. The Egrifta SV label covers only the 2 mg/vial formulation and points readers to the separate Egrifta prescribing information for the 1 mg/vial product, which has a different dosage, a different number of vials per dose, and different reconstitution and storage instructions [1]. The 2 mg figure is not a mixing or measuring instruction for either current product, and it does not substitute for 1.4 mg or 1.28 mg in the arithmetic above.

Compounded tesamorelin is a separate matter

The concentrations and volumes above come from the Egrifta SV and Egrifta WR labels and apply to those products. Compounded tesamorelin is not an FDA-approved drug, and FDA does not review the safety, effectiveness or quality of compounded drugs before they are marketed [3]. Tesamorelin does not appear among the bulk drug substances FDA lists as presenting significant safety risks, and it appears in no category of FDA's lists for state-licensed pharmacies and physicians or for outsourcing facilities, so FDA has made no category-based statement about compounding it [4][5][6]. It is also not one of the six peptides named in HHS's draft enforcement-discretion policy for compounding [7][3].

Two arithmetic errors the numbers invite

Using the Egrifta SV volume with Egrifta WR solution. At 8 mg per mL, 0.35 mL contains 2.8 mg, twice the 1.4 mg Egrifta SV dose [1][2].

Reading a mark on a syringe as a milligram amount. A mark on a syringe is a volume. What that volume delivers depends on the concentration in the vial: the same 0.35 mL is 1.4 mg at 4 mg/mL and 2.8 mg at 8 mg per mL [1][2].

What both labels say about the injection itself

Both labels direct the injection into the abdomen, rotating sites, and say not to inject into scar tissue, bruises or the navel [1][2]. Injection site reactions were reported in 25% of tesamorelin-treated patients and 14% of placebo-treated patients during the first 26 weeks of the trials [1][2]. The labels also describe hypersensitivity reactions in 4% of patients in the trials, including itching, redness, flushing, hives and rash, and direct patients to seek prompt medical attention and stop treatment if such a reaction is suspected [1][2].