Standard issues

The question of whether blisterpacks are inherently child resistant has been hotly debated for several years. Stephen Wilkins, secretary of the Child-Safe Packaging Group, looks at the new British Standard that should level the playing field for reclosable and non-reclosable packs

Late December 2001 saw the publication of a new British Standard to test the child resistance of flexible packaging for pharmaceuticals, for example blister and strip packs. BS 8404 (2001) Packaging – Child Resistant Packaging – Requirements and Testing Procedures for Non-Reclosable Packages for Pharmaceutical Products, not only marks a sea change in the attitude to child safety of flexible pharmaceutical packs but represents an acknowledgement of an anomaly that has existed in child resistant packaging since the early 1970s – almost 30 years.

Child resistant (CR) packaging emerged in the US in the late 1960s and was adopted in the UK shortly thereafter, its use being codified in the 1974 Medicines (Child Safety) Regulations. Child resistance is achieved by creating a packaging system requiring two opposing actions to be undertaken simultaneously, e.g. 'push down & turn' and 'squeeze & turn' closures. Barriers of cognisance are also used, such as a 'line up the arrows' system. In the US barriers of cognisance have been successfully used for flexible strip and blister packs by requiring the user to expose a hidden tear start by, for example, folding it through 45°, or using a 'peel back and push' system.

test panel

Testing for child resistance has been undertaken both in the US and UK by asking panels of children to open a pack. In the case of reclosables – bottles with child resistant closures (CRCs) – the panel, split into pairs of children, is asked to open the pack and after five minutes shown a silent demonstration and then asked again to open the container.

Sequential testing is used and this means that a pack can pass or fail without being tested by the total sample, which under the current standard for reclosables BS EN 28317 – ISO 8317 (2000), can be up to 200 individuals. Sequential testing enables the test results to be achieved using a sample of only 40 individuals. To be child resistant a packaging system must be unopenable by 85% of the sample prior to demonstration or 80% post demonstration. Alternatively, it must fall on either side of the tolerance limits on the sequential system.

These procedures have applied since 1974 to rigid or reclosable packaging systems with mandatory use of CR packaging for aspirin and paracetamol, use as a practice direction from the Royal Pharmaceutical Society of Great Britain (RPSGB) for all prescription drugs, and retailer or brand owner driven use for other general sales and pharmacy items.

The Standards covering testing, BS 5321 (1975), BS 6652 (1985), BS EN 28317 (1989) and ISO 8317 (2000), have been improved and modernised to cover population trends, and in particular the needs of elderly users, because it was observed that if a child resistant pack is not openable by an elderly person then there is a danger of decanting by users with subsequent discovery and ingestion by children; in recorded cases visiting grandchildren.

Non-reclosables, i.e. blister and strip packs, have, during the last 25 years, escaped testing and have been considered inherently child resistant if, according to the 1974 code, they were 'opaque or dark tinted and selected with a view to resistance to opening by children'. This material specification was subsequently codified into BS 7236 (1989) and it was then that the untested but ascribed child resistance of blister packs became accepted by brand owners and packer/fillers in the pharmaceutical industry.

BS EN 862 (2001), entitled Packaging – child resistant packaging, requirements and testing procedures for non-reclosable packages for non-pharmaceutical products, was first published in 1997 and updated in 2001. At the time of its introduction BS EN 862 was wryly described as 'Hamlet without the Prince of Denmark' because of the exclusion of pharmaceuticals.

wide-ranging input

The new standard BS 8404 (2001) has been produced with substantial input from the Association of the British Pharmaceutical Industry (ABPI), Proprietary Association of Great Britain (PAGB) and the RPSGB who for the last 12 years had been happy to accept that blister and strip packs were inherently child resistant without the need for child panel testing.

These and all the other organisations involved in the preparation of BS 8404 are to be congratulated on achieving a workable standard that advances child safety in pharmaceutical packaging and certainly does not pay lip service to existing rules, procedures and practices. However, there are areas where the standard may be seen as falling short of the optimum level. Furthermore, there are certain anomalies when the new standard is compared with BS EN 862 (already referred to) and the German standard covering child panel testing for non-reclosables for pharmaceuticals – DIN 55 559 (1988).

front line of defence

The final paragraph of the introduction to BS 8404 continues to espouse the old nostrum that 'child resistant packaging is only the last in a series of protective measures and does not release parents or guardians from their duty to keep medicinal products out of the reach of children'. While this comment is laudable, it is totally ineffective. Parents manifestly do not keep medicines out of the reach of children and therefore CR packaging is a front line of defence.

BS 8404 goes on to state that as a standard it is intended for type approval and not for QA purposes; this is in accordance with ISO 8317 and BS EN 862 (2001).

The crux of BS 8404 revolves around eight units or tablets, which is one below the dangerous dose for adult aspirin. According to the standard: 'The package is deemed child resistant if the trail of results on the test charts passes into the acceptance zone or if at least 80% of the children are unable to access more than eight units within 10 minutes and at least 85% of the children are unable to access more than eight units within the first five minutes.

But no specific number of units is referred to in BS EN 862 – merely whether the pack is opened or not; and in the case of DIN 55 559 'tests shall be considered failed if within 10 minutes a child is able to gain access to sufficient unit doses to cause severe injury or damage or to remove more than eight units from, for example, a blister package'. Similarly, in the US a pack passes or fails on the basis not of a fixed number of units extracted but on a variable number depending upon the toxicity of the pharmaceutical concerned.

BS EN 862 stipulates two periods each of three minutes as opposed to five minutes. This test period should be standardised: why should there be a shorter opportunity to open a blister pack containing, for example, hearing aid circular batteries than one containing aspirin?

Brand owners and packer/fillers should think carefully about the test period and the number of units extracted, particularly where products with a dangerous dose below eight units are involved.

The relevant legislation is the Consumer Protection Act 1987 and the EU Directive on General Product Safety, and while compliance with available standards is a defence against any action under this legislation or any civil action, it is not an absolute defence, particularly where it can be shown that the standard itself does not make good sense.

As with the standard concerning reclosable rigid packaging systems, an adult test is an integral part of BS 8404. The adult sample consists of 100 individuals evenly spread over the age range 50-70 but weighted 70:30 in favour of female participants.

The test procedure for adults is different from that for children. Each adult is given a package together with any associated opening tools that would be provided with the package at the point of sale. No demonstration is given as to how to open the package and a period of five minutes is allowed for the test participants to familiarise themselves with the package. Participants who successfully open the test package within the five-minute period are then given a new identical package and are requested to open this as quickly as possible. A one-minute test period is allowed for the participants to open the new pack.

For the pack to pass, at least 90% of the adults have to be able to access at least one unit dose within the one-minute test period without a demonstration.

Despite the reservations expressed above and the anomalies between BS 8404 and BS EN 862, DIN 55 559 and the American procedures, the emergence of the new standard will represent a real opportunity in the UK to improve pharmaceutical flexible packaging systems.

It is easy enough to make blister packs child resistant – a 'peel back and push' system achieves that – but such packs are not elderly friendly and there is doubt as to whether they will pass the adult test section of the standard. Certainly this has been the experience in the US, where blisterpacks have required panel testing since the early 1970s and enjoy less than 20% market penetration.

expensive systems

It is the blister itself, of course, that is tested and thus selling or dispensing a standard blister pack in a child resistant box does not comply with BS 8404, although it will comply, as a child resistant reclosable, with ISO 8317.

The Child-Safe Packaging Group (CSPG) has undertaken development work using security strips with high burst but low tear strength, and in Germany, Algroup Wheaton has worked on systems involving barriers of cognisance. The CSPG has also designed systems where a unit can be observed on a blister in a storage chamber and needs to be encouraged along a passage to an expulsion chamber.

A number of sophisticated systems are presently emerging from the US packaging supply chain, where individuals clearly perceive a competitive advantage in designing a truly CR blisterpack. However, all those seen by the CSPG are considered to be extremely expensive – for example, a system packing 16 units cost US$8 (€8.97).

Clearly, the industry needs a mid- or end-of-line system if standard blister packs are to be made child resistant. But a substantial and arguable case could be made for reverting to rigid systems, i.e. bottle and CRC, particularly for dispensed prescription-only medicines, which under NHS guidelines should tend towards generics where possible.

This decision – reclosable or non-reclosable – also revolves around the unique qualities of a blisterpack. A blister or strip pack delivers high quality protection by shielding each unit dose from the atmosphere and from other unit doses. But where this protection is not required, particularly in the case of many analgesics and high volume prescription medicines, old-fashioned tried and tested reclosables could enjoy a resurgence.