Nitrogen Dioxide Enables In-House Gas Sterilization without Facility Modifications

The advantages of nitrogen dioxide (NO2) sterilization, a relatively new technology, will spur changes in the pharmaceutical and medical device industries, says David Opie, Senior Vice President, Research and Development at Noxilizer, which sells NO2 sterilization equipment. More medical device manufacturers will move sterilization in-house, and engineers will replace packaging and device materials incompatible with NO2 with other options.

Noxilizer will be exhibiting in Booth #2074 at MD&M East June 10-12 in New York City.

NO2 sterilization is a room-temperature process that can be used instead of other gas sterilization methods or gamma radiation in some cases. The equipment is less expensive than EtO or gamma radiation and doesn’t require extensive facility modifications. While NO2 is toxic, it is non-explosive and non-carcinogenic and can be used at much lower concentrations than EtO. This enables MDMs who previously have used contract sterilization services to move the process in-house.


Camilla Andersson

“When we look at the relative cost of using this process versus using the traditional way of using contract sterilization, we can save medical device manufacturers between 40 and 60 percent of the sterilization cost, because we are saving them the inventory carrying cost, the transportation cost and the cost of sterilization at the contract sterilization facility,” says Opie.

Noxilizer provides NO2 sterilization equipment to the pharmaceutical, medical device, and biotech industries and also offers contract services. It is one of the few companies specializing in this technology, which Opie attributes to the patent portfolio the company has developed.

NO2 sterilization is compatible with many medical device and packaging materials. For incompatible materials, the company encourages engineers to switch to alternative options. For example, designers can use polyester or polyolefins instead of nylon, or thermoplastic elastomers instead of polyurethane.

“I really think that once NO2 is accepted in the industry, medical device designers and people who develop packaging will design with NO2 in mind and those materials will be replaced by readily available materials,” says Opie.

As with other types of gas sterilization, devices are sterilized in a breathable packaging, typically Tyvek-based packages with a pouch, or a tray with a Tyvek lid.

“Coated Tyvek can be less predictable in its response because the coating on the Tyvek ends up affecting the total permeability or the porosity of the Tyvek,” says Opie. “For some processes, like EtO, the coating is not that significant, but for our process, which is a fairly rapid process, the coating can hinder the gas. It’s important that permeability is reproducible with the package so that we know that the gas gets into the package.”

The technology can be used at a wide range of temperatures, but is especially advantageous for temperature-sensitive products. The process is much faster at high humidity settings, but can be used at 0% humidity.

In pharmaceutical applications, NO2 sterilization can offer advantages in pre-filled syringes and other drug-delivery products, since it is less likely to penetrate and damage the closure system or drug than EtO, says Opie. It also is unique among room-temperature gas sterilization processes because it can be used for depyrogenation.

The company recently announced an exclusive agreement with Weiler Engineering, where it will supply the NOX FLEX Rapid Biodecontamination units for Weiler’s blow/fill/seal systems. The units provide a sterilization and depyrogenation process for the shroud area of Weiler’s machines.

“In the future we have a broad pipeline of opportunities that we are going to introduce on the market,” says Opie.” We have in-line continuous sterilizers, we have larger chambers, such as two and four pallet chambers. We also have some unique sterile generation technology that we will introduce into the system where the NO2 is generated on demand by the sterilizer, so we don’t have to deliver the NO2 containers to the users. Finally we will be moving into the hospital market and make sterilizers for clinical use.”

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By Camilla Andersson
Freelance Journalist

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