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Pharmaceutical Manufacturing and Packing Sourcer

Material Choice

There is nothing random about the growth of polyolefins in medical devices and pharmaceutical packaging, and understanding rigorous supply and development demands is key to success when choosing them as a production medium

We all know that plastics in general are probably the most versatile materials known to mankind, thanks to their extreme range of physical, chemical and mechanical properties. Within this very large family, polyolefins are the most multi-faceted, with applications that range from automobile air intake manifolds to numerous medical equipment components. In this article, the focus will be on the use of random polypropylene (PP) in a specific medical application, the syringe. The use of high density polyethylene (HDPE) in syringes will also be explained briefly.

Background

The use of PE and PP in medical devices applications has been increasing for some 40 years, and growth remains strong to this day. Worldwide, the growth of polyolefins in healthcare applications remains in high single-digits. Polypropylene possesses a combination of properties that makes it very useful for a wide variety of medical applications. It has extremely high chemical resistance, can be sterilised by all commonly-used methods, can be formulated to have high impact resistance, and compared with alternatives, it is a relatively low cost material.

Impact resistance is of particular importance in the medical device field. Polypropylene’s very high resistance to breakage confers a considerable advantage over glass. Syringes and other thin-walled containers made of glass are at risk of breakage, both in transit and while being administered. Handling glass containers always involves a certain level of risk of lacerations and splinters.

In recent years, developments in polypropylene chemistry and in additive formulations have made it possible to deliver improved clarity – approaching that of polycarbonate, PET and even glass. This is achieved with a combination of random copolymers and next-generation clarifying agents that affect the way the polymer crystallises, significantly reducing the dispersion of light through a product. Polypropylene random copolymers contain short segments of polyethylene that are dispersed randomly along the PP chain. This distinguishes them from so-called block copolymers, which have higher impact properties (hence their use in car body panels for example), but which are opaque.

Disposable syringes account for the largest amount of PP used in injection-moulded medical devices. Much of this is homopolymer, but this has a milky appearance that is not always ideal for the application. Highly transparent syringes are advantageous for medical staff because good visibility of the active ingredient in the syringe enhances the safe administration of the medicine. This goes a long way to explaining the increasing attraction of clarified randoms, and the increasing attention given to them by leading polymer suppliers.

The latest developments on show at Pharmapack 2011 in Paris in February included new high-purity PP random copolymers developed specifically for healthcare applications. Two new grades were showcased, one for a wide range of blow moulding applications, such as small bottles and ampoules; and the other, a clarified grade, for injection moulded parts – syringes in particular. The latter featured not only high clarity but also good antistatic properties necessary for injection moulded housings of disposable syringes.

At the same time, a high flow HDPE injection molding grade has also been developed, intended amongst other things to be used in syringe plungers (in two-part syringes). The high fluidity of this HDPE helps to reduce cycle time and so increase production efficiency and reduce production costs.

Clarifiers in polypropylene are multifunctional. They work by creating multiple nuclei around which the polymer crystals can form. Because there is only a finite space in which to grow, the crystals end up being smaller than in a non-nucleated PP. In this case, small is beautiful, because the smaller crystals disrupt the passage of light through the material less than larger ones, hence the improved clarity. But in addition, the total crystalisation process takes less time, which means that the part can be ejected from the mould earlier, and the cycle time is reduced.

Moreover, these new random PP copolymers can be processed at a lower temperature than their predecessors, so the syringe maker is rewarded with lower electricity bills. So in all, converters can operate with significantly shorter cycle times and achieve substantial energy savings.

Of course, producing polymers for the medical market is not for everybody. Supplying to this sector has many rewards, but it also has many responsibilities. It is certainly not one that a company can dip in and out of at will. Polymer suppliers need to commit themselves long-term to continuously investing in new product developments, in order to support customers in developing safe and eco-responsible products while meeting stringent healthcare regulations. What customers want is product stability, reliability, traceability and consistency, together with security of long term supply.

Companies need to fully understand the challenges of the healthcare industry, and should provide the security of a strong logistical network capable of holding and handling a sufficient level of supplies, enabling continuous availability for customers worldwide. Current developments within the healthcare industry demand a strong and responsive partner. Multinational medical device producers expect their suppliers to have a broad network of sales offices and manufacturing sites to provide them with local expertise and a reliable supply of material.

Customers should look out for companies that can supply grades with a drug master file (DMF) number and which comply with the relevant monographs of the European Pharmacopoeia (EP) and the US Pharmacopoeia (USP VI).

Compliance

What all players in the medical field have to do, particularly those in the most innovative areas, is match the speed of their developments with the need for compliance. There is little point in a polymer supplier bringing out new and improved grades every year if there is a good chance that they will fail to gain compliance with the pharmacopoeia in a key target market, and when it takes at least 18 months – and sometimes many years more – for them to be validated by target customers. Companies all along the supply chain need to be extremely careful in their materials selection.

An important point of consideration is the difference between the European Pharmacopoeia (EP) and US Pharmacopoeia (USP). The aim of both systems – and indeed the numerous pharmacopoeias around the world, all with their own particularities – is the same: to prevent errors in the supply chain and to protect the health of the patient. In this, all parties are pulling in the same direction. However, the European Pharmacopoeia works with a positive list of ingredients that can be used, and also applies compliance testing. The USP, on the other hand, does not operate with a positive list, but with approvals depending on an evaluation of the material. The latest clarified random PP copolymers are in compliance with USP VI only, although not all the ingredients they contain appear on the positive list of the EP. But in the end, it is the compliance of the finished article, the syringe, that is needed, and as long as the syringe producer can show compliance according to their own monograph, the new material can be used.

And all the while, the major drug producers are carrying out their own validations. If the polymer supplier introduces a new grade that, for example, delivers cycle time reductions and important energy savings while also yielding a superior syringe, the drug makers will carry out validations on that material hand in hand with validations of their own new products. When they file for approval, they file for approval of a complete package – drug, delivery system and packaging. If anything changes, the approval process starts all over again.

There are several implications of this process. Polymer producers are only likely to have the opportunity of supplying an upgraded product when the drug maker introduces a new drug or changes the delivery system or packaging – something that obviously does not happen frequently. The polymer supplier also needs to make firm commitments to long term supply of the material, which will remain unchanged throughout the lifetime of the contract. No changes to the raw material, the catalyst system used to make the polymer, any of the additives, nothing. Few suppliers are in a position to make that sort of commitment.

But those who do, think it is worth the effort. In a sense, it is rather like the NASA story. It is possible that PTFE would not have been invented were it not for the special needs of the US space effort. Now, as the last Space Shuttle touches down for the final time, maybe it is the medical industry that is working in a similar way. If you can do it here, you can do it anywhere.

Conclusion

What is certain, inasmuch as anything is certain for the future, is that the use of polyolefins in medical and pharmaceutical applications will continue to grow. With their low environmental footprint and absence of toxicological concerns, these materials are well suited to displace less attractive and more expensive materials in existing applications, and to compete strongly for inclusion in new areas. As the area of self-medication, for example, increases in importance, such products as insulin pens and the like will take advantage of the polymer’s ability to create products that are aesthetically pleasing as well as functionally efficient. The prognosis for polyolefins is positive.


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Peter Tackx is Business Development Manager, Healthcare at SABIC. Before moving to his current position, he was active as Business Development Manager Ultra High Molecular Weight Polyethylene (UHMWPE). From 2004 to 2007, Peter was Senior Technical Account Manager Automotive. Prior to the sale of the Petrochemical Division of DSM to SABIC, he held several positions within DSM. He began his career as scientist at DSM Research. Peter studied Physical Chemistry at the Catholic University of Leuven (Belgium) and obtained a PhD in nonlinear optics. Email: solange.schlosser@sabic-europe.com
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