How to reconstitute a lyophilized peptide vial

Materials

• The sealed peptide vial, with its batch number readable.
• Bacteriostatic water, the preserved diluent made for vials that are drawn from more than once^[4]. Why it and not plain sterile water is covered in bacteriostatic water vs sterile water.
• A new, sealed sterile syringe for each time a needle goes into a vial.
• Alcohol prep pads, a clean flat surface, and a pen or label for the vial.

Every order ships with bacteriostatic water, insulin syringes, alcohol pads and a reconstitution syringe, included rather than sold separately.

Clean technique

Wash and dry your hands and clear the work surface. CDC's safe injection guidance says to disinfect the rubber stopper of a medication vial with alcohol before piercing it, and to enter a vial with a new needle and a new syringe every time^[1]. Wipe the stopper of the peptide vial and of the water vial, let the alcohol dry, and do not touch the stoppers afterwards.

Choose the volume

The volume of water sets the concentration and nothing else: milligrams in the vial divided by millilitres of water gives milligrams per millilitre. 5 mg in 2 mL gives 2.5 mg/mL. The same 5 mg in 1 mL gives 5 mg/mL. More water makes a weaker solution that is spread across more syringe marks, which makes small volumes easier to measure. The reconstitution calculator does this arithmetic for any vial and water volume you enter and shows it on a syringe scale.

Add the water down the wall

Draw the chosen volume of bacteriostatic water into the syringe. Push the needle through the centre of the peptide vial's stopper, tilt the vial, and aim the stream at the inside of the glass rather than at the powder. Press the plunger slowly so the water runs down the wall and settles over the cake instead of blasting it. Withdraw the needle and discard the syringe.

Swirl, do not shake

Swirl the vial gently or roll it between your palms until the powder has dissolved. The US instructions for tesamorelin, a lyophilized peptide medicine, say to move the vial in a circle to mix and not to shake it, and not to use the solution if it is cloudy, coloured or has particles in it^[2]. Shaking whips air into the solution and can damage the peptide. If a haze or undissolved cake remains after gentle swirling, see the in-depth guide to cloudy vials before deciding what to do.

Label and store

Write two things on the vial: the date you added the water and the concentration you made, for example "24 Sep, 2.5 mg/mL". CDC guidance, citing USP chapter 797, is that a multi-dose vial is dated when it is first opened and discarded within 28 days unless the manufacturer states another date^[3]. How long a particular reconstituted peptide stays stable is compound-specific: follow the lab report or product label. Then put the vial in the refrigerator; the storage guide covers temperatures, light and freezing.