For sensitive, expensive drugs, however, the expense could be justifiable. At least one other alternative is available to drug makers not quite ready to make that investment: surface inspection of the formable web before filling and sealing. This imaging-based system potentially could eliminate some leakers by detecting visually imperceptible cracks, pinholes, and other defects as small as 10 μm at 3.75 m/s. Especially suitable for foil, the unit also can check nontransparent film and laminated paper. Multiple zone inspection prevents rejection of good blisters ("VisioScan," inspection system Uhlmann VisioTec, Towaco, NJ, http://www.uhlmann-visiotec.com/).

Meanwhile, when implementing a leak-testing program, quality specifications for incoming materials must be considered. When looking at in-house quality control, a product's sensitivity and cost will determine whether leak testing is needed, whether it's off- or on-line, and how sensitive the equipment must be. Although it may technically be possible to locate defects measuring just a few micrometers, it's only necessary to do so if a hole that size will affect the product negatively. Other considerations in equipment selection include data-collection and networking capabilities, ease of calibration and validation, material limitations, tooling costs, cycle time, and changeover.

Hallie Forcinio is Pharmaceutical Technology's Packaging Forum editor, 4708 Morningside Drive, Cleveland, OH 44109, tel. 216.351.5824, fax 216.351.5684, editorhal@cs.com
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