What's In That Medicine?

Digital imaging in the visible (400 to 700 nm) spectral region nowis commonplace with the availability of low-cost CCD and CMOScameras and powerful data processing hardware and software. Inmachine vision, for example, it is used for product inspection,quality control, quality assurance and manufacturing automation.
More recently, infrared cameras traditionally used for thermalimaging or night vision applications (3,000 to 5,000 nm) also havegained acceptance as valuable productivity tools in a number ofindustries and, in most cases, the data processing software iscommon to both imaging modalities. The two approaches mayreasonably be labeled as broadband imaging because the light inboth spectral intervals is integrated into a single image frametypically recorded at video frame rates. A less well-developed andcommercially exploited region lies between 1,000 and 2,500 nm. Inthis spectral interval, many molecular species absorb energy whichcan be utilized to generate image contrast that is chemicallyspecific. A variety of camera technologiescooled anduncooledoperates in this spectral interval and, when combined witha narrow-band wavelength selection device, provides high-speedchemical imaging capability. The approach was originally deployedfor remote sensing applications and termed hyperspectral imaging,but more recently has found its way into a variety of industrialapplications; in this capacity, it generally is referred to as nearinfrared chemical imaging (NIRCI). Indium Antimonide (InSb), IndiumGallium Arsenide (InGaAs) and Mercury Cadmium Telluride (MCT)cameras typically are used for chemical imaging in this spectralrange.
While NIRCI imaging is becoming more broadly utilized in industry,one of the more exciting application areas is the pharmaceuticalindustry1. Recent trends in the industry to improve manufacturingefficiency, reformulate existing products, combat counterfeitingand develop ever more complex drug delivery systems are making theindustry acutely aware of the need for increasingly sophisticatedanalytical instrumentation. In this regard, the pharmaceuticalindustry has adopted NIRCI as a technology that can provide suchinformation.
QUALITY ASSURANCE
The vast majority of pharmaceutical products are delivered in whatare called solid-dosage forms, or tablets. A typical productcontains one or more active ingredients as well as a number ofexcipients or non-active ingredients. In even the simplest product,there is a non-uniform distribution of these components that canexist at the micro (less than 100