Safety Guides New Syringe Designs

Global efforts driving safer syringes for developing nations are spurring interest in new single-use, auto-disable syringes. Parenterals manufacturers should be prepared and evaluate the new designs with new products.

By Don Gerson, President, Axenic, Inc.

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The World Health Organization (WHO), the Red Cross and the Safe Injection Global Network (SIGN) are supporting programs to improve injection safety worldwide. In developing nations, 10 billion syringes are used each year, but unfortunately, unsafe injection practices are common and cause at least 1.3 million deaths and 10 million cases of hepatitis annually.

WHO recommends single-use, auto-disable (AD) syringes and is attempting to eliminate the use of traditional syringes as soon as possible. A worldwide effort to improve injection safety is being coordinated by SIGN with the guiding principle that a safe injection should not harm the recipient, the healthcare worker administering the injection, or the community at large.

Abandoning traditional barrel-plunger-needle syringes in favor of auto-disable technologies offers an effective way to solve a major problem that is difficult to control procedurally. However, the new designs will require efficient device manufacturing technologies, effective sterile filling equipment and extensive testing.

Although new designs have not yet penetrated the market, purchasing contract requirements by large organizations like UNICEF or PAHO may force parenterals suppliers to adopt new technologies. A proactive approach, and close evaluation of alternatives, can pay off.

This article will review hollow-needle type AD injection devices, and discuss the manufacturing issues and challenges they pose.

Scoping the problem

In developed nations, disposable plastic syringes have been in widespread use for 30 years, virtually eliminating re-use in a professional medical setting.

In developing nations, however, the cost of a new, sterile syringe and needle is often enough to prevent the use of vaccines and legitimate therapeutic drugs. When the vaccine or drug is available in a multidose form, economic realities mean that all too often unclean and unsterilized syringes and needles will be reused, and spread disease.

Some solutions to this problem are procedural. However, technical solutions, such as the following, promise to be much more effective:

  • Alternative injector design and methodology

  • Syringe plungers that lock once used

  • Plastic liquid compartments that collapse on use

  • Needles that can be used only once

  • Needle-free injectors based on high-velocity sprays — these can be extremely cost-effective, but permit aerosolization of the recipient’s bodily fluids, creating the possibility of cross-contamination [3].

  • Oral, inhaled or skin administration, via patches or inhalers — an approach that, other than its notable success with the oral polio vaccine, hasn’t worked with many vaccines.
Global standards

International standards also promise to help drive new technologies. The International Standards Organization, ISO, has addressed auto-disable injection devices through consultation with WHO, industry and other interested parties.

Its most current standard, ISO-7886-3-2005, provides specifications for syringe-like injection devices that deliver a known fixed dose, are of plastic and stainless steel construction and become non-functional once used. ISO-7883-4 deals with general purpose syringes with automatic re-use prevention. Injection devices meeting these standards can be used with multidose vials and, by their nature, will prevent re-use and the spread of blood-borne diseases.

Mandating specifications for bulk purchases based on internationally accepted standards will allow organizations such as UNICEF to meet their goal and encourage innovation and market development. The Global Alliance for Vaccines and Immunization (GAVI) has promoted the use of AD syringes, and from 2001 to 2004 has catalyzed the use of almost 1 billion AD syringes [5].

Injectables article: B-D Uniject syringe
The BD Uniject Prefill Injection Device. Courtesy of Becton, Dickinson and Co.

Filling and packaging of sterile injectable products requires specifically engineered facilities and highly specialized equipment. Sterile injectables are subject to high levels of regulatory scrutiny and are always a costly activity utilizing a highly trained workforce and considerable QA and QC support. Up to half of the cost of manufacturing traditional vaccines occurs during filling and packaging, as a combination of operational, container and packaging materials expenses.

Manufacturers have approached cost challenges by making multidose vials for use in developing nations. However, these designs pass on syringe costs to the user, and fail to address safety issues.

The amount of losses in use, important in the efficiency of mass vaccination programs, is moderate, and balanced between low overfills per dose and losses due to partially used vials. Providing AD syringes for each dose taken from a multidose vial should bring the actual cost to approximately the same as was intended. However, there may be operational issues related to matching the supply of AD syringes to the expected number of delivered doses.

Single-dose approaches using a vial and a separate syringe, whether the syringe is traditional or AD, add filling, packaging and shipping costs and may add to losses in use due to a higher overfill per dose. However, they reduce the possibility of vial contamination. Single-dose approaches using a pre-filled injector provide individual application, the least losses, and the greatest safety.

However, not all single-dose syringes are created equal. Prefilled traditional syringes are costly, create a waste-disposal problem and present opportunities for intentional re-use. Prefilled AD syringes of traditional design but with locking devices greatly reduce re-use, but do not offer any cost advantages. However, prefilled specialized AD injection devices such as Becton, Dickinson and Co.’s Uniject (photo) offer the possibility of high safety and a relatively reduced cost [4].
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