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Although the source of spots and specks on tablets is sometimes difficult to identify, following good maintenance and manufacturing practices can help solve or even prevent the problem.
Manufacturers of tablets have long battled a host of occasional but common issues, one of which is spots or specks, which are undesirable visual flaws that can be superficial and/or embedded within a tablet. Commonly referred to by the over-generalizing term “black spots,” these unsightly blemishes or foreign substances should more appropriately be categorized as any spots or specks that are not supposed to appear in the first place, but that in most cases are easily (and visually) detectable. Spots are generally those imperfections that reside on the surface of the tablet only, while specks can be present throughout a tablet. Specks are sometimes visible on the surface, sometimes hidden inside, or both. It is important to note that undesirable spots or specks can be gray, black, or almost any other color, even white.
Possible causes of spots and specks
Although it often proves true that an oil-based issue on the tablet press is the culprit, the following are other potential sources:
The best possible solution for an issue with spots on tablets is to consistently employ methods for avoiding them in the first place. This may appear obvious, but in reality, tablet press operators often deviate from GMP methodology, especially in terms of following recommended guidelines for cleaning and set-up as provided by original equipment manufacturers (OEMs). If not already in possession of such procedures, every company should poll their suppliers for them and implement their contents into a cohesive and all-encompassing set of standard operating procedures (SOPs).
Having stated the above as a best line of first defense, strict adherence to good SOPs cannot supersede all potential issues. Some suggested guidelines for eliminating spots when they do appear, or for helping to prevent their occurrence at all, include:
If, indeed, raw material issues are ruled out and a press manufacturer is asked to recommend a first place to look, most will generally suggest the bottom of the barrels on the upper punches, where the punches protrude from the upper punch ring. A quick visual inspection can detect any unusual build-up of material and excessive lubricant that may be contributing to a problem. If present, it should then prove easier to put a stop to the offense.
Depending on the severity of the issue and the company experiencing it, some will seek independent analysis from a third-party laboratory in an effort to determine the source and composition of the spots. It is, however, important to note that the success of such an investigation can vary considerably. Certainly there are times where the lab can shine the brightest light on a shadowy issue, while just as frequently the offending contaminant is identified and confirmed locally, at the floor level.
For further suggestions and to read how a mysterious problem of blue spots was solved, read the full article in the December issue of Pharmaceutical Technology.
Matt Bundenthal is direct sales and communications manager at Fette Compacting America.