GSK Montrose is a 45 acre site located on the coast in Angus, Scotland. The site performs primary manufacture of active pharmaceutical ingredients and specialises in respiratory, steroid and anti viral products that are shipped to customers worldwide.

In the summer of 2009, GSK had an immediate and urgent requirement to rapidly increase its production of the anti-flu drug Relenza in response to a potential global health crisis, a flu pandemic.

In order to facilitate this requirement, the refurbishment and upgrade of an existing installation was agreed for the GSK Montrose plant. The Dec Group’s technology, the Powder Transfer System (PTS), was already well established on the site and used in many production areas for the safe charging of potent powders to reaction vessels. So it came as no surprise that the PTS would be used on this project. There was also now, however, a specific and urgent challenge for GSK Montrose to rapidly increase the production of Relenza, namely to charge up to 20 10kg bags in less than 20 minutes whilst protecting the operator. So something new was required.

Stewart Doyle, engineering director at GSK Montrose, says: “The site had successfully used Dec systems for charging powders to reaction vessels in a safe manner for a number of years. The Dec systems are easy to use and provide both process safety and eliminate occupational hygiene risks for the process operator. The Dec team had always provided good technical support and responded to manufacture systems in a short lead time, so it was automatic that we turned to Dec to meet our requirements.”

During 2008 some development had already been completed on Dec’s new bag discharge station, the Dec Isocharge, between Dec UK staff and another GSK site. In the latter development stages independent powder trials were conducted and containment levels of <1microg/m³ (8hrTWA) were achieved with an open system. It was this open system that was so vital to GSK Montrose because of the limited amount of time available to charge the full load of powder to the vessels.

The Dec Isocharge is best described as a hybrid design, crossing laminar flow technology with a glove box isolator. This means that the operator has the protection that a gloved visor provides and also the flexibility of an open laminar flow booth. The ‘bullet’ shape of the main chamber is designed so that a minimum air velocity of 0.7m/s is achieved over the open bag entrance at all times but as the air moves through the chamber it slows to less than half this speed.

In conjunction with the operator’s controlled pouring of powders in to the suction cone, there is little dust generation within the chamber.

The operator can load the chamber through the open end and then use the gloves to open the bags and pour the contents into the discharge hopper located in the base of the chamber. The powder is then discharged from the hopper by means of the PTS (attached to a nozzle on the receiving vessel) whose controls are linked to the Isocharge control panel. This also has the added advantage that only one Isocharge is needed for a number of reactors. In this case two stations were supplied to feed three reactors with different powders. A door is provided on the Dec Isocharge, but is only used to prevent splashes during cleaning with the inclusive wash gun (an optional Dec spray ball was not deemed necessary). The washing fluids from the station are then removed either by sucking with the PTS or via a drain.

Chris Broadbent of Dec UK says, “GSK were delighted with the performance of the Dec products in helping the site to meet the challenge to produce Relenza on such a huge scale and tight timescale with the safety of their operators maintained.”

Stewart Doyle says, “The Dec systems were delivered on time and have performed to our exact specification. Using the Dec systems, more specifically the Dec Isocharge, Montrose was able to start up the expanded process on time and provide Relenza for customers across the globe. The systems have operated safely and provided occupational hygiene protection for process operators who can work without the need for protective air suits.

“GSK Montrose has continued to use Dec products since this plant expansion, and is eliminating air suit operations across the site by using Dec systems for both powder and liquids charging to reactors.”