The API Process Development System was designed to provide personnel and product protection when working with powder and liquid substances. The enclosure housed a Mettler Toledo Easy Max 102, vacuum oven, and IKA LR 1000. The unit required a stainless steel base to allow for intensive cleaning protocols with shelves underneath to assist in recirculating the chiller and vacuum pumps needed to operate the process equipment. Operators needed access from the rear of the enclosure for cleaning purposes and there would need to be enough space for movement of equipment inside the enclosure.

The initial task of the process required the weighing of Active Pharmaceutical Ingredient (API) powder utilizing a Mettler Toledo balance. Proper use of the balance required 12-14” of usable linear width within the enclosure. The powder was then to be placed into liquid suspension by way of a magnetic stirrer—this would preserve the structure of the API without any dissolution. A liquid suspension of powder API can also deliver a higher concentration of API than an equivalent volume of liquid solution. Solvents used were ethanol, acetonitrile, and esthers—some of which had flammable potential. Less than one liter of solution would be in a beaker at any given time. The suspension would then be transferred into a Mettler Toledo Easy Max 102 reactor, a unit that is 26” wide, 30” tall, and 30” deep. Additionally, the unit requires 25” of vertical operator access. The Easy Max 102 utilized a chiller unit connection so feed and return lines were integrated into the enclosure.

The process continued as the API solution was then filtered by vacuum filtration onto a filter paper disk that was to be dried in a vacuum oven. Oven dimensions were 15” width, 16” depth, and 21” height—a vacuum pump was needed so a connection for the pump exhaust line to the system exhaust was engineered. An N2 line connected to the oven for gas purge. Upon removal from the oven, the sample was manipulated by the IKA LR 1000—a 20” wide, 30” tall, and 20” deep unit. The LR 1000 uses a sealed glass reaction vessel to mix powders into a dry or wet cake.

A system was engineered since the sample would need to be contained throughout the process. The sample could only enter or exit the system clean. Given the length of physical travel that the sample would endure through the numerous process steps—and the material of construction requirements given the nature of the different substance manipulations—the design had a substantial number of considerations. Polypropylene was chosen for the superstructure.

The API powder entered via a pass-through into a Flow Sciences Hybrid Isolator as mobility inside the enclosure was as important to the operators as safe containment. However, in order for the sample to be removed, a glovebox workstation was designed for a secondary cleaning of the sample before exit via the final pass-through.

The resulting enclosure had a 252” exterior width, a 30” exterior depth, and a 101” exterior height—including the custom stainless steel table with shelves. A deflector shield was integrated into the table where the vacuum pump was positioned to minimize sound pollution in the lab. The system had inlet HEPA filtration, a black phenolic base, and acrylic viewing panels with a hinged door style. The draft shield with glove ports was removable for cleaning. Bag-In/Bag-Out filtration with dual HEPA filters and top mount fans were coupled with vent kits and five thimble connections for connection to house exhaust. A 6” solid waste port with continuous liner was ported into the base. LED lighting and acrylic viewing panels maximized lighting across the workspace, and iris ports and electrical outlets were installed where needed inside for the process equipment.

In general performance tests, the enclosure passed all requirements for ASHRAE and AIHA/ANSI standards and recommended practices and met the CPT of 1000 ng/m3. During surrogate powder testing, no samples from outside of the enclosure exhibited measurable amounts of naproxen sodium above 0.51 ng/m3 TWA. Additionally, task maximum concentrations did not exceed 5.42 ng/m3. These exposures were well below the CPT of 1000 ng/m3.

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