In the current global market, prefilled syringes comprise more than two billion units per year in development and use. The rise of the prefilled syringe as the preferred container originated with an extremely successful market introduction of syringes for heparins by Sanofi and Rhone-Poulenc Rorer (Sanofi-Aventis) in Europe in the early 1980s. The prefilled syringe market has now exploded due to several factors: the growth of biopharmaceuticals, the need to eliminate overfills, precision of delivery volume, convenience of delivery, cost-effectiveness, reduction of dosage errors, or a combination of these factors (1-4).
Currently, glass dominates the prefilled syringe market. However, plastic prefilled syringes are making advances, particularly where glass has been unsuitable as a delivery system. In the last decade, pharmaceutical protein and peptide drug products have been approved for use with prefilled plastic syringes. More products using plastic prefilled syringes are currently in various phases of drug development.
COMBINATION DRUG DELIVERY SYSTEMS
Many chronic diseases, such as multiple sclerosis and rheumatoid arthritis, require home-based administration of injectable treatments. This need has spawned an increased interest in combination drug delivery systems that are safe and convenient, and that help to improve the administration process.
Pen injectors and multi-dose cartridges were created for those with frequent injection needs; however, they are limited to specific therapies such as diabetes and growth hormones, which often require weighed dosages or dose titration. While pen injectors were designed for frequent injections and for those who require variable dose capabilities, they are not ideal for chronic users of fixed-dose medications, including those suffering from dexterity issues. The need for a safe, reliable, easy-to-use, single-dose injection system was apparent.
Auto-injectors have been recognised as a convenient method for delivering drug products through an intuitive activation mechanism designed especially for patients who may have dexterity issues that affect their ability to inject a drug treatment effectively with a traditional syringe. As patients and caregivers become increasingly involved in determining the best treatment option, biopharmaceutical and pharmaceutical companies, with the help of device companies, are adapting to meet the needs of the consumer. Today’s auto-injectors represent a compelling, easy-to-use delivery solution rooted in simplicity, accuracy, durability, flexibility and quality.
TRADITIONAL SYSTEMS: PERFORMANCE ISSUES
Traditionally, auto-injector systems utilise 1ml-long glass prefilled syringes. While these systems have been successful, there are notable limitations, including autoinjector performance issues. Recent studies have shown that silicone oil, which is often used to increase lubricity in syringe systems, is often distributed nonuniformly, leaving certain areas of the prefilled syringe surface with insufficient lubrication (5). The low or inconsistent silicone oil coating can have a significant impact on the piston travel or glide forces, especially in the use of auto-injectors. In 2006, commercial lots of a drug product delivered by an auto-injector containing a glass prefilled syringe were recalled in a number of European countries because of problems with slow or incomplete delivery of the drug (6). Areas of non-uniformity may cause travel forces to increase, causing failure or incomplete injection.
