What Are 1.0 mL and 2.25 mL PFS Injection Pens Used For?

A Complete Guide to Their Applications & Key Differences

Pre-filled syringe (PFS) injection pens have become one of the most popular delivery systems in modern biopharmaceuticals. With simple operation, high precision, and excellent compatibility with peptide and biologic formulations, they are widely used in weight-management therapies, chronic-disease treatment, and specialty medications.

Among all formats, the 1.0 mL PFS injection pen and 2.25 mL PFS injection pen are the two most commonly used specifications.
But what medications does each size support?
And what are the functional differences between them?

This article provides a clear, professional comparison to help pharmaceutical companies, clinics, and distributors choose the right device.

1. What Is a PFS Injection Pen?

A PFS (Pre-Filled Syringe) Injection Pen is a reusable or disposable pen designed to deliver medication that is pre-filled inside a glass or plastic syringe.
It allows:

• Accurate dosage delivery

• Stable injection force

• Convenient self-administration

• High medication compatibility (especially for peptides, GLP-1 drugs, hormones, and biologics)

PFS pens are commonly used with 1 mL or 2.25 mL pre-filled syringes—these two sizes cover most of today's popular injectable drugs.

2. Applications: What Drugs Use 1 mL PFS Pens?

The 1.0 mL PFS injection pen is the standard and most widely used specification.
It is suitable for medications requiring low to medium dosage and frequent injections.

Common drug types for 1 mL PFS pens:

✔ GLP-1 Peptides (Weight Loss & Diabetes)

• Semaglutide (Ozempic)

• Liraglutide (Saxenda)

• Dulaglutide low-dose formulations

✔ Hormone Therapies

• Growth hormones (GH)

• Fertility medications (FSH, HCG)

• Testosterone or estrogen micro-dose therapies

✔ Chronic Disease Management

• Insulin

• Multiple sclerosis drugs

• Osteoporosis injections (daily use)

✔ Cosmetic & Dermatology Solutions

• Skin-boosting peptides

• Aesthetic clinic formulations

Why 1 mL?
1 mL syringes support smaller, more frequent dosages and shorter pen strokes, which make injections smoother and easier.

3. Applications: What Drugs Use 2.25 mL PFS Pens?

The 2.25 mL PFS injection pen is a newer specification designed to meet the growing demand for higher-dose, longer-interval medications, especially in the GLP-1 market.

Common drug types for 2.25 mL PFS pens:

✔ High-Dose GLP-1 Medication (Weight Loss & Diabetes)

• Semaglutide high-dose

• Tirzepatide (Mounjaro / Zepbound)

• New dual/triple agonists in pipeline

✔ Long-Acting Biologics

• Once-weekly or once-monthly peptide treatments

• Anti-inflammatory biologics

✔ High-volume specialty drugs

• Monoclonal antibodies

• Immunology drugs

Why 2.25 mL?
Manufacturers are increasing drug concentration and volume to reduce injection frequency.
A larger syringe volume allows a single injection to deliver more active substance while maintaining patient comfort.

4. Key Differences Between 1 mL and 2.25 mL PFS Injection Pens

Simply put:

➤ 1 mL = precision + frequent injections

➤ 2.25 mL = high dosage + fewer injections

5. How to Choose the Right PFS Injection Pen?

When choosing a PFS injection pen, manufacturers and clinics should consider:

• ✔ The viscosity and stability of the drug

• ✔ Dosage volume per injection

• ✔ Frequency of patient usage

• ✔ Required dosage increments

• ✔ Compatibility with 1 mL or 2.25 mL syringes

• ✔ Certification & regulatory requirements

Our PFS pen solutions support both 1.0 mL and 2.25 mL syringes, customizable for:

• Drug viscosity

• Patient force threshold

• Dosage scale

• Housing color

• OEM branding

• Clinical trial batches

6. Conclusion

1 mL and 2.25 mL PFS injection pens each serve a distinct purpose in modern drug delivery.
As the pharmaceutical industry shifts toward high-dose weekly or monthly injections—especially in the booming weight-management sector—the demand for 2.25 mL pens is rapidly increasing.

Meanwhile, 1 mL pens remain the gold standard for precision dosing, daily use, and hormone therapy.

Choosing the right device ensures medication safety, consistent injection performance, and a better patient experience.