Tablets & Capsules

TC0115A

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T 26 January 2015 Tablets & Capsules granulation analysis Density mapping of roller-compacted ribbons using terahertz spectroscopy Mark Sullivan, David Heaps, Richard McKay, Eiji Kato, and Xiao Hua Zhou Advantest America Chuan-Yu Wu, Chun-lei Pei, Jian-yi Zhang, and Serena Schiano University of Surrey Terahertz (THz) spectroscopy and imaging are non-destructive tools for measuring the chemical and physical attributes of pharmaceutical raw materials, intermediates, and finished products [1]. Examples include determining the crystallinity and polymorphism of drug substances, the 3D spatial uniformity of tablet coating thickness, and tablet hardness. Terahertz spectroscopy is also well suited to measure and control the density (solid fraction, porosity) of roller-compacted ribbons. In this article, we describe the principals of terahertz analysis and give examples of how it can help with formulation development and scale-up and commercialization of the roller compaction process. amount of energy for drying, roller compaction can operate as a continuous process and entails no drying. Figure 1 illustrates the major parts of the equipment: a feeder to introduce the powder blend, rollers to compact the powder into a ribbon, and a mill to reduce the ribbon to granules. The figure also shows the optical path of a terahertz beam. he terahertz range (0.1 to 10 THz) lies between the microwave and infrared regions of the electromagnetic spectrum and offers a unique combination of high material transparency and spectroscopic information. Terahertz spectroscopy uses extremely short pulses that yield a broadband response and provides a direct means to measure the bulk physical properties of materials, including refractive index, permittivity, and absorption coefficient. As a result, we can measure the density of roller-compacted ribbons—the most critical property of the process—quickly, non-destructively, and without contact in the lab and production settings. The design of the pulsed terahertz spectrometer was described previously [1], and its operation resembles that of other types of Fourier transform instruments that collect a background and analyze the intact solid sample using acquisition times of less than a second. Sampling can be done for at-line and in-line analyses, as detailed below. Roller compaction Roller compaction is a dry process that agglomerates powders into ribbons and mills them into granules for the manufacture of tablets and other solid dosage forms. Unlike traditional wet granulation, which operates in batch mode and requires a liquid binder and a large Figure 1 Roller compactor 1. Feeder introduces powder 2. Counter-rotating rollers compact powder into ribbon 3. Mill reduces ribbon to granules 4. Optical path of terahertz beam to ribbon

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