Dissolution Solutions Network

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Let’s talk about Fiber Optics

Let’s talk about Fiber Optics

Vivian Gray

About the Author: With over 25 years of experience in the dissolution field, Vivian has lectured frequently, especially in the areas of calibration, dissolution equipment, gelatin crosslinking, and regulatory topics. She is a proactive participant in the field as demonstrated by many publications, writing and revising USP Chapters, initiating change in USP methods, in-depth work with calibration, organizing workshops, serving on the USP Expert Biopharmaceutics Committee, the FIP (International Pharmacy Federation) Dissolution Working Group, and the Editorial Board for Dissolution Technologies.  vagray@rcn.com

The promise of Fiber Optics

About 20 years ago, in the USP lab we started to hear about the promise of fiber optics for dissolution analysis. It seemed almost too good to be true and we waited to hear more, and waited and waited. Well, it seems the time has finally come. There are several vendors selling equipment that apply the fiber optics technology. The vendors that I know of are Leap Technologies, Ctechnologies, and Delphian/Purdue (this vendor may have changed hands by now according to rumor). My experience with all of these vendors was very positive. They are very responsive to the customer or potential customer and are willing to either loan or provide testing services on your products. We are very lucky in dissolution to have such willing and cooperative vendors when it come to the nitty gritty of how does the equipment work in your hands or with your product.

Evaluating Fiber Optics

In the dissolution lab at DuPont Pharmaceuticals, we evaluated the several brands of fiber optics instrumentation using a large tablet with a huge amount of excipient (during dissolution the vessel contents became completely milky), and yet generated data equivalent to the UV method. We also evaluated a product that used an HPLC procedure and with using the second derivative, obtained comparable results to the HPLC method. One product did have a placebo background that was too high even with the baseline correction with one brand but with the other brand of fiber optics instrumentation it worked out fine. I would suggest that if you are serious about purchasing the equipment, which is with management approval, you bring the equipment in house for a loan. Be sure you use it on several typical formulations and have someone devote full time energy to the evaluation. Some formulators tend to use the same excipients over and over again. If this is the case, be sure those products are used for evaluation. Transdermal testing and intrinsic dissolution will be ideal for fiber optics, as there are no excipients to interfere with the analysis.

Differences in Design

There are different designs of probes: arch, in shaft, in resident, in resident but partially out during sampling. The probe design does appear to be stabilizing although it looks like the vendors are constantly revisiting it in response to customers. Some designs have each probe as a different spectrophotometer and others are sequentially related to one central spectrophotometer. There is are issues of sample bracketing, cell size availability, bubbles, cleaning of cell, software, and many others –so there are many aspects of the fiber optics to cover. So why don’t you send an email to the website and get the dialogue going.
-Vivian Gray

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