"Peptide pen" names two different objects, and the difference matters more than any feature comparison. An approved pen is a drug and a device reviewed together; its dial is labelled in the dose. A refillable pen is a device alone; its dial measures volume, and the dose is whatever the cartridge was filled with. This page sets out what FDA's labels and files say about each, with dates. It describes and reports; it does not tell anyone how to use either, and anything involving a dose belongs with a clinician. How brands appear on this site is on our disclosure page.
The approved pen: one product, not two
Most approved peptide drugs that patients inject themselves come in a pen, and FDA does not treat that pen as a separate item. In its NDC directory, read on 2026-09-25, the approved peptide injectables are packaged like this:
| Product | Peptide | Container as FDA lists it |
|---|---|---|
| Ozempic, Wegovy | semaglutide | Syringe, plastic (the pen) |
| Saxenda, Victoza | liraglutide | Syringe, plastic (the pen) |
| Mounjaro, Zepbound | tirzepatide | Syringe (single-dose pen), KwikPen, and vials |
| Trulicity | dulaglutide | Syringe (the pen) |
| Forteo, Bonsity | teriparatide | Syringe (the pen) |
| Vyleesi | bremelanotide | Syringe (autoinjector) |
| Byetta | exenatide | Cartridge (the pen) |
| Tymlos | abaloparatide | Cartridge (the pen) |
| SymlinPen | pramlintide | Cartridge (the pen) |
| Imcivree | setmelanotide | Multi-dose vial — no pen |
| Egrifta SV / WR | tesamorelin | Bottle (powder) — no pen |
The labels describe fixed, counted doses. Zepbound's current label (Lilly, effective 2026-08-28) lists a single-patient-use KwikPen containing four doses; Byetta's (2025-09-02) states that each prefilled pen delivers 60 doses, thirty days of twice-daily use. The number on the dial is the labelled dose in milligrams or micrograms, set at the factory by the drug's concentration. Nobody does arithmetic.
Both labels carry the same warning: "Never share a ZEPBOUND KwikPen between patients, even if the pen needle is changed." Byetta's says the same of its pen. Zepbound's label gives the reason: sharing "poses a risk for transmission of blood-borne pathogens." That follows from the mechanism — one cartridge, many injections — not from the drug, so it applies to any multi-dose pen, approved or not.
The approved presentations also change, and a figure that is correct for one pen can be wrong for its successor. The Ozempic pen's concentration changed between label versions, so a circulating "clicks" chart made for the old pen delivers half the intended amount in the current one; Medibact Guides' Ozempic pen clicks page sets out the two labels side by side. Ozempic's own instructions for use say: "Do not set the dose by counting the number of clicks you hear."
The refillable pen: a device, and a cartridge someone else filled
The second object is a reusable pen body sold alongside research peptides, with empty 3 mL glass cartridges. Seller and clinic guides read on 2026-09-25 (Optimised Lifestyle, Chia) describe the same arrangement: a cartridge filled by syringe from a reconstituted vial, and a dial on which one line is 1 unit, or 0.01 mL, up to 60 units per fill. Some sellers also offer cartridges already filled with a research compound.
FDA's classification for a stand-alone pen injector is class II, 21 CFR 880.5860, product code NSC. openFDA returned one 510(k) clearance under that code on 2026-09-25 — Eli Lilly's HumaPen Luxura HD, an insulin pen, in 2007. Whatever its regulatory status, a device clearance covers the device; it says nothing about what is put into it, and the research compounds loaded into these cartridges have no approval.
The arithmetic the refillable pen hides
Because the dial measures volume, what one unit contains is set entirely by how the cartridge was filled. The calculation is ours, from the guides' own figures:
| Vial dissolved into a 3 mL cartridge | Per unit (0.01 mL) | 10 units | 60 units (a full dial) |
|---|---|---|---|
| 5 mg | ≈16.7 mcg | ≈167 mcg | 1 mg |
| 10 mg | ≈33.3 mcg | ≈333 mcg | 2 mg |
| 15 mg | 50 mcg | 500 mcg | 3 mg |
The same dial setting delivers two or three times as much drug depending on a number the pen does not display. On an approved pen the concentration is printed on the label and fixed at manufacture; on a refillable pen it lives in whoever filled it — and in the vial's true content, which is the seller's claim until a lab says otherwise. A vial stated as 10 mg that assays at 7 mg makes every unit in the table 30% lighter. That is why what a certificate of analysis does and does not show matters more to a pen user than the pen does. The general arithmetic for any vial and volume is on our reconstitution page; the syringe-based equivalent, with the same unit trap, is on our syringes page.
What else changes when a vial goes into a pen
- Time in solution. A cartridge holding 60 units is designed to last many doses, so the peptide spends longer dissolved than in a syringe drawn fresh each time. How long reconstituted peptides are reported to stay stable, and where those figures come from, is on our peptide storage page and peptide fridge page.
- A second transfer. Filling a cartridge from a vial adds a puncture and a transfer step beyond drawing into a syringe; approved pens are filled and sealed at the factory.
- Sterility. Approved pens are sterile products released under manufacturing controls; a cartridge filled outside a pharmacy is exactly as sterile as the process that filled it. What endotoxin and sterility tests cover is on our peptide testing page.
What this page does not establish
It does not compare the dose accuracy of any refillable pen with an approved one — we found no published test of the pen bodies sold for research peptides. It does not rate any pen or seller. And it does not describe how to use either kind: the approved pens come with instructions for use written into their labels, which are the document to read, and the decision to use any injectable belongs with a clinician. Where the approved peptide drugs sit relative to the research market is on our peptide therapy explainer, and the route these pens deliver by is on our subcutaneous injection page.
Sources and dates
Read 2026-09-25: openFDA NDC directory packaging records for semaglutide, tirzepatide, liraglutide, dulaglutide, teriparatide, bremelanotide, exenatide, abaloparatide, pramlintide, setmelanotide and tesamorelin; openFDA drug labels for ZEPBOUND (Eli Lilly, effective 2026-08-28), BYETTA (effective 2025-09-02) and the Ozempic pen's instructions for use (repackager copy effective 2026-07-30); openFDA device classification (21 CFR 880.5860, NSC) and 510(k) records for product code NSC; refillable-pen guides from Optimised Lifestyle and Chia. The per-unit figures are our arithmetic from the guides' stated unit volume. Corrections go to the contact page.