Researchers Test Green Drug Manufacture July 21, 2010
Rowan Univ. faculty and students have teamed with Pfizer Global Engineering and Manufacturing personnel to investigate green approaches to drug manufacture. This is the second time Rowan has partnered with Pfizer to investigate methods to reduce the carbon footprint of pharmaceutical plant operations.
This year, the Rowan team has worked with scientists and engineers from plants where drugs such as the widely prescribed Solu-Medrol are made, along with other highly specialized medicines.
The team has collaborated to analyze the economic viability and to quantify the environmental benefits of investing in a small solvent recovery system as an alternative to incineration to address smaller-volume waste streams. Solvents often represent the primary component of waste from the production of active pharmaceutical ingredients (APIs) used in medicinal formulations.
According to Frank J. Urbanski, director of Pfizer Global Engineering: “There are economic and environmental benefits when Pfizer recovers solvent for re-use, especially when expensive solvents and large volumes are involved. Pfizer has been recovering solvents for many decades at its various manufacturing facilities. As we seek to improve our conservation efforts and reduce our carbon footprint, one challenge faced is how best to deal with numerous small-volume waste streams from multi-product facilities when existing solvent recovery equipment may be too large to be practical.”
Solvent recovery is a routine practice in the pharmaceutical industry when it is technically and economically viable for the particular waste stream. Capital investment in the required piping, tank farms and recovery equipment is more easily justified when dealing with large volumes, high-cost solvents and high equipment-utilization rates, and when solvents from multiple products can be pooled together.
The use of recovered solvents and the pooling of solvents must be appropriately qualified to assure product quality and avoid cross contamination. Economic justification to recover small-volume, “non-poolable,” and intermittently generated waste streams remains challenging, but a potential recovery opportunity.
Mariano J. Savelski and C. Stewart Slater, both Rowan chemical engineering professors, are leading this research effort with a team of chemical engineering students.
The Rowan team performed a case study on several waste streams being generated at an API synthesis building at the Pfizer Kalamazoo plant. The goal was to investigate those streams that could be most easily recovered with traditional separation and purification processes.
As a first step in that analysis, the recovery of acetonitrile solvent from a waste stream in the selamectin synthesis was considered. Selamectin is the active ingredient in the veterinary drug Revolution. This stream was initially chosen because of the relative high cost (and value) of acetonitrile, and the ability to separate acetonitrile from acetone.
Rowan designed a small-scale distillation, solvent-recovery system, and compared the proposed operation with the current waste-disposal practice. To increase the economic feasibility and improve the environmental footprint further, the Rowan team evaluated the proposed design for use with the other waste streams in the facility.
The simulation included isopropanol solvent recovery from the manufacture of nelfinavir, the active ingredient in the antiretroviral drug Viracept, used in the treatment of HIV. The study also examined toluene recovery from hydrocortisone manufacture (used in several drug products for relief of inflammation).
“The case study estimates the environmental impacts and economics, using life-cycle assessment, associated with the proposed improvement using various computer routines,” Savelski says.
“From a plant perspective, the Rowan team has given us some valuable estimates to use in evaluating our solvent use and disposal practices,” says Donald J. Knoechel, principal scientist for Pfizer. “The team’s unique life-cycle assessment capability helps us understand where we can have the most impact on reducing our greenhouse gas emissions.”
The case study for the three drugs showed that 732,000 kg/yr of life cycle emissions, of which 677,000 kg/yr are CO2, could be reduced by using the solvent recovery system. This results from not having to manufacture the virgin solvent as well as from a reduction in waste disposal.
The study also projects significant operating cost benefit. The CO2 reductions are equivalent to the amount of emissions saved by not driving cars 1.4 million miles in a year.
Pfizer and Rowan continue to discuss further green engineering partnerships.
Source: Rowan Univ.
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