Reconstitution & handling

1. Subcutaneous vs. intramuscular

The vast majority of research peptides are administered subcutaneously (sub-Q) — into the fatty tissue just beneath the skin. A small number are given intramuscularly (IM).

2. Syringe vs insulin pen

For sub-Q peptide delivery you've got two main options: a traditional insulin syringe drawn from a vial, or an insulin pen (pre-filled or refillable). Pens are particularly common for GLP-1 protocols (Semaglutide, Tirzepatide, Liraglutide) because the commercial pharmaceutical formulations ship in pen format.

3. Site selection

For subcutaneous injections, you need a site with enough fat to pinch — approximately 1–2 cm of tissue between your fingers when pinched:

• Abdomen: 5 cm either side of the navel — the preferred site. Predictable fat depth, easy to see and reach, minimal nerve density.
• Outer thigh: The outer upper third. Good alternative, especially for sites with sufficient subcutaneous fat.
• Tricep / back of upper arm: Usable but harder to self-inject without practice.

4. Preparation checklist (syringe workflow)

1. Wash hands thoroughly with soap for at least 20 seconds.
2. Gather: alcohol swabs, reconstituted peptide vial, insulin syringe (correct size), sharps bin.
3. Check the vial — confirm it is clear, no particles, no unusual colour. If in doubt, discard.
4. Swab the rubber stopper of the vial with an alcohol swab. Allow to air dry for 30 seconds — do not blow on it or wipe dry.
5. Draw back the plunger to fill the syringe barrel with air equal to the volume you're drawing (e.g., draw 10 units of air if you plan to draw 10 units of peptide).
6. Insert the needle through the rubber stopper and inject the air — this creates positive pressure and makes drawing easier.
7. Invert the vial, draw slightly past your target volume, then push back to the exact unit mark.
8. Remove the needle, check for air bubbles. Tap and expel any bubbles.
9. Swab your injection site with an alcohol swab. Allow to dry — injecting through wet alcohol stings.

5. Step-by-step injection technique (syringe)

1. Pinch the skin.Using your non-dominant hand, pinch a fold of skin at the injection site — lift it slightly away from the underlying muscle. This ensures you're going into fat, not muscle.
2. Insert at 45°.Hold the syringe like a pen. With the bevel (the angled tip of the needle) facing up, insert at approximately 45° to the skin surface in a single smooth motion. Don't hesitate — a confident insertion is less painful than a tentative one.
3. Aspirate (optional).Some researchers pull back slightly on the plunger to check for blood — if blood appears, you've hit a vessel and should withdraw and try a new site. For sub-Q injections at these needle lengths, aspiration is generally considered unnecessary, but it does no harm.
4. Inject slowly. Depress the plunger steadily over 5–10 seconds. A slow injection minimises discomfort and bruising.
5. Withdraw cleanly. Remove the needle at the same angle it entered in a single smooth motion. Release the skin pinch.
6. Apply gentle pressure. Press a clean swab to the site for 10–15 seconds. Do not rub — rubbing spreads the peptide away from the intended site and can cause bruising.
7. Dispose of the needle immediately. Recap using the one-handed scoop method (lay cap on a flat surface, scoop with the needle). Place in your sharps bin. Never recap by holding the cap in your other hand.

6. Insulin pen technique

Insulin pens are the standard delivery device for GLP-1 and amylin-class peptides (Semaglutide, Tirzepatide, Retatrutide, Cagrilintide). Whether you're using a commercial pre-filled pen or refilling one with your own reconstituted peptide, the technique is essentially the same.

Anatomy of an insulin pen

• Pen body — houses the cartridge or refillable reservoir of peptide
• Dose dial — rotates to select dose in units (clicks audibly)
• Dose window — shows the currently dialled dose
• Push button — depressed to inject after dose is set
• Pen needle — separate disposable component, screws onto the front (4–8 mm length, 30–32G)
• Inner + outer caps — protect the pen needle, both removed before injection

Pen needle selection

Choose pen needle length based on body composition:

Common pen needle brands: NovoFine Plus, BD Ultra-Fine, Owen Mumford Unifine. Look for "universal fit" on the box — works with all standard pen brands.

Step-by-step pen injection

1. Inspect the pen. Take it out of the fridge 15–30 min before use so the peptide reaches room temperature (much less stinging). Check the solution through the cartridge window — should be clear, no particles, no discolouration.
2. Wash hands + swab. Wipe the pen needle attachment tip with an alcohol swab. Let it dry.
3. Attach a fresh pen needle. Peel back the paper tab on a new pen needle. Screw it firmly straight onto the pen tip. Pull off the OUTER cap and keep it (you'll use it for disposal). Pull off the INNER cap and discard.
4. Prime the pen (air shot). Dial the dose to 2 units. Hold pen with needle pointing up. Tap the cartridge to bring any air bubbles to the top. Press the button fully — a drop of peptide should appear at the needle tip. If nothing comes out, repeat with another 2 units. Priming clears air from the needle so your dose is accurate.
5. Dial your target dose. Turn the dose dial until your prescribed/research dose appears in the dose window. The dial clicks for each unit increment so you can confirm by feel. If you over-dial, simply rotate back — no peptide is wasted.
6. Choose injection site + swab. Same sites as syringe injection (abdomen, outer thigh, tricep). Swab with alcohol and let dry.
7. Insert needle at 90°. Unlike syringes, pens go in straight (90°), not 45°. With a 4–6 mm pen needle, no skin pinch is needed for most subjects. Press the needle firmly into the skin in one motion — fast and confident hurts less than slow and tentative.
8. Press the button slowly. Push the dose button down all the way. You'll feel resistance ease as the dose delivers. The dose window will count back down to 0.
9. Hold for 6–10 seconds. Keep the needle in place for at least 6 seconds (10 for larger doses) after the dial reads 0. This is critical — withdrawing too early causes peptide to leak back out of the injection site, reducing your effective dose.
10. Withdraw straight out. Pull the needle out at the same 90° angle. Light pressure with a swab if needed — no rubbing.
11. Recap + dispose. Use the OUTER cap you kept — scoop it over the needle one-handed, then unscrew the capped needle from the pen and drop it into your sharps bin. Never reuse pen needles — they dull immediately and increase injection pain + lipohypertrophy risk.
12. Cap the pen + store. Replace the pen cap. Store at 2–8°C between uses (most peptides). Pre-filled commercial pens often allow 28 days at room temperature once first used — check the specific product's data sheet.

Refilling an empty pen (research use)

A common practice in research-peptide circles is to refill an empty pen (e.g. an expired Ozempic/Wegovy pen, or purpose-built refillable pens) with reconstituted compounded peptide. Brief overview:

1. Reconstitute peptide vial with bacteriostatic water to your target concentration (e.g. 10 mg in 1 mL bac water = 10 mg/mL, where 1 unit on the pen ≈ 0.1 mg)
2. Draw the full reconstituted volume into a separate 1 mL or 3 mL Luer-lock syringe
3. With pen needle removed, slowly inject the peptide solution into the pen cartridge through the rubber septum (or through the rear plunger if your pen design allows)
4. Tap to remove air bubbles, replace pen needle, prime as normal
5. Label the pen clearly with peptide name, concentration, batch, and date — never share or mix up refilled pens

Pen-specific troubleshooting

7. Site rotation

Repeatedly injecting the same spot causes lipohypertrophy — hardened fatty tissue that forms under the skin and impairs absorption. Rotate sites systematically:

Any systematic rotation that prevents returning to the same spot within 4–5 days is adequate.

8. Troubleshooting common issues (syringe)