GlaxoSmithKline (GSK) appointed 42 Technology (42T) to evaluate existing powder dispensing approaches that could be scaled for highspeed manufacturing.
42T suggested an innovative precision powder dispensing technology, now known as Sticky Web, which can accurately 'print' powdered APIs onto edible or inert adhesive surfaces to create a novel dosage form.GSK has now granted 42T worldwide pharmaceutical rights to the technology.
According to Keith Smith, Manager of GSK's strategic technologies department, the core technology was first proposed as a result of some "shrewd research" by 42T. "GSK first appointed 42T to conduct an independent strategic technology review and to evaluate existing, credible powder dispensing approaches that could potentially be scaled for high-speed manufacturing. We already knew of some commercial systems claiming speeds of up to 15000 doses/h, but these typically involved check weighing or volumetric techniques, which are often unsuitable for some pure APIs that require careful handling," said Smith. "The consultancy team responded not only with a detailed review of the options, but with some great new ideas of their own — including the approach we now call Sticky Web."
Developing the technology
Sticky Web takes its name from a simple discovery by one of 42T's engineers, based on the following theory: when a piece of adhesive parcel tape is dipped into powder and the excess shaken off, the quantity left adhering is directly proportional to the surface area of the tape. The exact quantity depends on the combined properties of the specific adhesive and powder, but even the very first tests conducted by 42T showed consistent coverage rates of approximately 1.5 mg/cm2 with accuracies greater than ±10%.
The development programme progressed quickly to deliver the core approach, as well as several adhesives and designs for a prototype production machine. A number of key patent applications were also secured.
Dispensing the powder
The powder dispensing head and process are critical to the Sticky Web approach. The web, which is preprinted with adhesive further up the production line, passes around a drum where powder from a vibrating hopper is applied through drum apertures or masks to the sticky areas; any excess is tapped off using a vibrating paddle. The technique delivers uniform coverage for freeflowing powders, as well as powders that have dry clumping behaviours. It is also gentle enough for powders that require very careful handling to prevent degradation or any loss of activity.