Prefilled Syringes and Autoinjectors: Device Selection for Biologic Drug Delivery

Subcutaneous administration of biologics has expanded rapidly as therapies move from hospital infusion to self-administration at home. Prefilled syringes (PFS), autoinjectors and on-body devices make injections simpler and more convenient, supporting adherence and reducing healthcare costs. Yet choosing the right device for a biologic is a complex decision involving container closure compatibility, formulation properties, human factors and regulatory requirements. This white paper guides developers through the key considerations in selecting and developing drug delivery devices for biologic therapies.

Trends Driving Device Adoption

Patients with chronic conditions such as autoimmune disease, diabetes, migraine and osteoporosis benefit from therapies they can administer themselves. Payers favor lower-cost settings of care. Pharmaceutical companies see devices as a way to differentiate products and extend lifecycle. High-concentration formulations enabling smaller volumes and less frequent dosing further support subcutaneous delivery.

Device Categories

• •Prefilled syringes, with or without needle safety systems
• •Autoinjectors, single-use or reusable, spring or motor driven
• •Pen injectors for multi-dose products
• •On-body injectors for larger volumes delivered over minutes
• •Needle-free and novel delivery technologies

Container Closure Choices

Glass and Polymer Syringes

Borosilicate glass has a long history and good barrier properties, but may release alkali ions, tungsten residues from needle forming, and require silicone oil lubrication. Cyclic olefin polymer syringes offer lower breakage risk, reduced extractables for some applications and siloxane-free options, but have different permeability and compatibility profiles.

Silicone Oil and Protein Interaction

Silicone oil lubricates the plunger, but droplets can induce protein aggregation and subvisible particles. Baked-on silicone, reduced silicone levels and alternative coatings mitigate risk. Particle characterization methods that distinguish silicone droplets from protein aggregates are important.

Elastomers and Needles

Plunger stoppers and needle shields must be compatible with the formulation, with extractables and leachables evaluated. Needle gauge and length affect injection comfort and force.

High-Concentration and High-Viscosity Formulations

Many monoclonal antibodies are formulated at 100 mg/mL or more to allow small injection volumes. Increased concentration raises viscosity, which affects syringeability, injection force and time. Strategies include excipient screening to reduce viscosity, larger-bore needles, thin-wall designs and device mechanisms providing sufficient force. Formulation and device teams must collaborate early, since viscosity-lowering excipients may alter stability.

Large-Volume Delivery

For volumes above a few milliliters, on-body injectors deliver doses slowly with patient-friendly adhesion, enabling therapies that would otherwise require intravenous administration. Considerations include wear time, adhesive performance, needle insertion and alarms.

Human Factors Engineering

Designing for Real Users

Devices are used by patients of varying age, dexterity and training, sometimes under stress. Human factors engineering identifies use-related risks and designs mitigations. Formative studies refine the design; a summative validation study with representative users confirms that critical tasks can be performed safely and effectively.

Instructions for Use

Clear, illustrated instructions, intuitive device cues and training resources reduce errors. Nurse-led training, digital apps and connected devices can further support adherence.

• •Identify critical tasks such as removing the cap, positioning and holding time
• •Test with intended users including those with limited dexterity
• •Evaluate usability for caregivers as well as patients

Regulatory Pathway for Combination Products

Integrated Requirements

A biologic in a device is a combination product, regulated under both drug and device requirements. In the United States, design controls, risk management and current good manufacturing practice requirements for combination products apply. In the EU, the device component may require conformity assessment or notified body opinion in marketing applications.

Documentation

Design history, verification and validation testing such as dose accuracy, injection time, activation force and drop testing, and risk management files under ISO 14971 are expected. Alignment between the drug filing and device documentation is essential.

Platform Devices

Using established platform devices can streamline development and regulatory review, since much of the device data can be leveraged. Customization should be limited to what is truly needed.

Manufacturing and Assembly

Fill-finish of syringes requires specialized equipment and sterile processing. Assembly and labeling of autoinjectors can be performed in-house or by partners. Process validation, container closure integrity, and inspection for particulates and cosmetic defects ensure quality. Supply chain security of device components is a key risk.

Connected Devices and Digital Health

Smart autoinjectors can record dose time, remind patients and transmit data to caregivers, supporting adherence and real-world evidence generation. Data privacy, cybersecurity and software regulation must be addressed.

Selecting the Right Device Strategy

Early dialogue between formulation, device, clinical and commercial teams ensures that the device aligns with the target product profile. Key questions include dose volume, viscosity, dosing frequency, patient population, setting of use and market expectations. Evaluating total cost, manufacturing capacity and supplier reliability completes the decision.

Conclusion

Choosing and developing the right delivery device is integral to the success of a subcutaneous biologic. By aligning container closure selection, formulation, human factors and regulatory strategy from the start, developers can create therapies that patients can use confidently and that stand out in a competitive market.