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Pharmaceutical Manufacturing and Packing Sourcer

Creating Barriers

Once a tiny niche of the aerosol market, more and more companies are turning to Bag-on-Valve (BoV) aerosols to package their products. BoV is an ideal barrier package for liquids, gels, creams and lotions, keeping high product integrity and protection against oxygen exposure

In the pharma industry, there is an increased interest in giving old products new, more convenient applications, as well as finding niches for totally new products using Bag-on-Valve (BoV) technology for packaging and administration. Applications now cover saline/seawater nasal sprays, wound cleansing/irrigation sprays, eyewash sprays, dermal drug delivery products, disinfectant sprays and veterinary products, among others. There is a slow but growing consumer awareness regarding BoV products. Global volumes increase from year to year, replacing typical pump and dispensing sprays as well as traditional aerosols.

Diverse Range of Applications

With its many dispensing possibilities, BoV is suitable for direct dispensing, even in such sensitive areas as eyes or ears or with children. After an eye accident, for instance, it is very important to rinse the eye in the first seconds. BoV portable eye wash spray makes a good choice when a piped eye wash station is not available. With a 240ml can, equipped with a spray actuator giving a very soft spray, it is now possible to flush the eye constantly for more than 15 minutes.

Wound washing spray must be kept totally sterile during its entire shelf-life, which is possible for many BoV products. The spray works at any angle, reduces pathogens, removes foreign bodies as well as blood, clot and dead tissue, and moistens the tissue in the process.

Various nasal sprays are among the most popular BoV products on the over-the-counter market. Usually based on sterile saline solutions, they soothe and relieve stuffy noses and sinus pressure. No matter how long or how often they are used, they are safe for everyone. The saline nasal sprays are classified as medical devices in the EU and can either replace or complement the use of drug-classified nasal sprays.

Another upcoming area currently catching interest is that of throat sprays, with the aim of soothing and preventing sore throat symptoms during colds and allergies. It is possible that we will soon see a similar range of throat spray products on the market as is already available for nasal application. In the ear, nose and throat segment there are also BoV products on the market that help to prevent build-up of earwax.

Emollient sprays protect the skin from minor irritation and soreness and create a barrier that protects irritated skin from damage caused by urine and faeces, for instance. Unlike applying an emollient as a cream and rubbing it onto the skin, an emollient spray is contact-free, meaning it can be administered without risk of cross-contamination.

Gels can also be packaged using BoV, such as burn gel sprays for treating burns, scalds and sunburns. Creams and foams are also suitable solutions to be packaged in a BoV system, as are alcohol-based hand sanitisers.

Total Integrity and Sterility

Taking a look at some of the general benefits of BoV packaged products compared to alternative packaging solutions, there are a few particularly striking features. First of all, there is the obvious advantage of total integrity and sterility that BoV offers the product sealed inside the bag. The product will not only be kept sterile until it is used for the first time, but will remain sterile during the product’s entire shelf-life.

Then there are the many conveniences for the end users of the products, whether they are healthcare professionals or consumers purchasing the products over the counter. The fact that they can be used at any angle is a great advantage compared to hand-pumps or tubes, for instance, as is the continuous dispensing of the products, making them easy to use – even in emergency situations.

Contact-free dispensing gives advantages in hygiene and patient integrity. Since the products can be applied without actually touching the skin, avoiding the spread of contamination from the hands, they are ideal for sensitive product applications. For healthcare professionals and patients alike, it is less encumbering having someone spray rather than rub the content onto the skin.

If desired, a BoV aerosol can produce a smooth and even layer of a film-forming product or a protective barrier cream to the skin. Examples include siliconebased barrier films used for treating dry, sensitive skin. Oxygen-sensitive actives like probiotics and omega-3 oils are also suitable for packaging in BoV systems, even if the commercial products have yet to reach the consumer market.

Compared to traditional aerosol products where the propellant is part of the formula, products dispensed through BoV have no chilling effect. Product evacuation for a BoV product ranges between 95 and 99 per cent, and once the product is used up and empty, it does not contain any flammable residual of propellant.

Non-Flammable Propellants

The most common replacements for the chlorofluorocarbons, which were used as aerosol propellants before they were banned by the Montreal Protocol in 1989, are mixtures of volatile hydrocarbons, typically propane, n-butane and isobutane. Dimethyl ether and methyl ethyl ether are also used. All these have the disadvantage of being flammable.

Manual pump sprays can be used as an alternative to a stored propellant. However, these do have the disadvantages of requiring hand power, not providing an even, continuous dispensing, and normally the inability to use the product at any angle.

The propellants of BoV products, on the other hand, are compressed air or nitrogen, neither of which are flammable or hazardous to the environment. Since they are contained between the bag and the can, and they never come into contact with the product, they guarantee its integrity and are not released into the atmosphere.

As the BoV does not use any flammable propellant, it can be classified as a non-flammable aerosol, providing the solution itself does not contain flammable ingredients. The non-flammable classification offers obvious advantages regarding safety, transportation and storage.

The foil-based packaging used in a BoV system typically consists of four-layer aluminium film laminates, for instance polyester, aluminium, polyamide and polpypropylen (PET/ALU/OPA/PP), which guarantee impermeability. The film laminate bag is welded to the aerosol valve, which is crimped to the aerosol can in the filling process. BoV typically uses standard aerosol cans with one-inch can openings

When the valve is crimped to the can, the compressed gas is also filled into the area between the bag and the can. This pressurising process is called under the cup gassing. The process creates an initial pressure of a few bars in the can.

The final pressure, when the product has been filled through the valve, is normally between six and nine bars, depending on product configuration. The product in the bag encompasses 60 per cent of the can’s brim capacity, while the compressed gas occupies the remaining 40 per cent.

When pressure-filling the product through the valve stem, BoV fillers need to be aware of the difference in stem stroke between the various BoV systems on the market.

When choosing a BoV system, the first step should be to source both the BoV system and the spray actuator from the same supplier to guarantee that the total configuration is compatible. This is to avoid micro-leakage and secure the correct performance of the product. Another important factor when using compressed gases is to select a good quality aluminium can.

Due to the low permeability rate, BoV is compatible with commercially available liquefied propellants. These propellants make good choices for products that call for a steady dispensing rate over the life of the can, such as post-foaming gels and creams.

Almost all fluids and many viscous products can be filled into a BoV system as long as the product’s viscosity is low enough to get it through the valve stem. However, the system does not work well with products that need to be shaken before use, since the bag is fully filled and does not allow mixing when shaken.

Low Bioburden

The BoV system can provide microbiological safety to the product as it will only come into contact with the inside barrier film of the bag, and as a one-way valve system no contamination will come from outside the bag. With pre-sterilised bags and cleanroom production, the bioburden of the product can be minimised.

For the pharmaceutical market, the cans are most often made of aluminium, even if tinplate BoV systems are also available. Since gamma rays are able to penetrate aluminium, the most convenient sterilisation method for BoV products is gamma irradiation, although aseptic filling is also sometimes used. For gamma irradiation of products that can be classified as sterile, the most common irradiation dose is a minimum of 25kGy, even if lower doses are also used. Minimum and maximum irradiation doses will need to be validated for each product. The gamma irradiation process is carried out by sterilisation contractors. Some gamma irradiation providers offer full pallet sterilisation, while sterilisation in ‘tote boxes’ is most common. In the tote box irradiator, the product is loaded into tote boxes, which are conveyed around the irradiation source.

Although the gases used in BoV products are totally harmless, the products are still classified as aerosols (UN 1950). Depending on the local regulations for aerosols, recycling of BoV products are handled differently in different states or countries. However, they usually fit into the recycling programmes of most countries. Aluminium has a high recycling value and can be recycled many times without loss of quality. Still, aerosol cans are currently always made of virgin aluminium even though they could potentially be manufactured from recycled aluminium instead.

What the Future Holds

Ongoing developments of BoV include valves where two different mediums may be filled, separated from each other into a three-chamber-system. Mixing is effected while spraying or by the user after application. Another new feature under development, which will be appreciated by the pharma industry, is metering dosage BoV where dosages like 100μl or 1ml guarantee a certain number of uses for the end consumer, as well as the same product quality from the first dosage to the last.

In the near future, we can expect new innovative ways to manufacture BoV with higher speed manufacturing, laminate developments for more compatibility and decreasing the number of laminate layers, as well as many other steps in developing the next generation of BoV systems.

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Magnus Hedman is the Co-Founder, Partner, Marketing Director and Business Development Manager of Aurena Laboratories AB. He is a seasoned entrepreneur and business development specialist who has been involved in the medical device and pharma industry for over 20 years. International Sales and Marketing Manager for Swedish respiratory care company Aiolos Medical, 1990 to 2000, he co-founded Aurena Laboratories in 2000 and has developed a range of medical devices in BoV packaging for the pharma industry.
Magnus Hedman
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