DISSOLUTION TESTER MODEL DIS-EMC
THE ULTIMATE
If you require the ultimate in a dissolution tester then the DIS-EMC is the dissolution tester for you. The Copley Dissolution Tester Series DIS-EMC includes all of the features of the standard DIS 6000 and 8000 units described on Pages 10 to 23 of our 2009 brochure titled ‘Quality Solutions for the
Testing of Pharmaceuticals’ including:
- Sturdy, robust construction specifically designed to reduce clutter and maximise visibility and access in the critical sampling area above the water bath.
- Simple, easy-to-use operation ensures that the number of operations required to perform a test are kept to a minimum.
- Full supporting documentation (including full IQ/OQ/PQ qualification documentation if required).
It goes without saying that the standard DIS 6000 and 8000 units already comply with the new EMC specifications as laid down by FDA. Where the DIS-EMC differs from the standard units is in the application of the latest state-of-the-art technologies to the manufacture of the Test Station, bringing you a new level of standard in terms of dimensions and tolerances and hence the ultimate in dissolution tester technology. It is the Test Station in which the dosage form resides during testing and which consequently has the most potential to contribute variability. The undoubted key to overcoming instrument induced variability lay in the development of the EMC Dissolution Vessel. The superior dimensions of the new vessel not only provided quantifiable improvements to the hemispherical bottom but also provided a platform for a new design of dissolution vessel lid and stirring element.
The inside diameter of the vessel ( /- 0.13 mm) and flange perpendicularity tolerance of 0.50 mm TIR facilitated the design of a lid to specifically fit the vessel and simultaneously provide a bottom bearing for the stirring element shaft. By using Rulon friction free bearings in the lid and a precision ground shaft as the basis for the stirring element, it was then possible to reduce all of the tolerances relating to wobble, verticality and centering by 50%. The table below provides a comparison between the standard DIS 6000 and 8000 series based on the specifications of the new FDA Mechanical Qualification Document No. DPA-LOP.002 currently recommended by the FDA Guidance of January 2010 and the new Dissolution Tester DIS-EMC, illustrating a bettering of the dimensional tolerances specified in the FDA’s Enhanced Mechanical Calibration by a factor of 2.
The DIS-EMC Series come complete with all the relevant documentation so that you can start using the dissolution tester immediately. All parts of the Test Stations employed are individually serialised as standard.
ENHANCED MECHANICAL CALIBRATION – IN PRACTICE
Such enhancements as suggested would not have been possible in the 1970s when the dissolution tester was first introduced. Fortunately, improvements in the precision of the machine tools and metrology techniques used to manufacture and qualify modernday dissolution testers means that, today, enhanced mechanical calibration is not only a possibility but a reality. One of our goals in the design brief was to create an ‘audit-proof’ Dissolution Tester by bettering the dimensional tolerances specified in the FDA’s Enhanced Mechanical Calibration by a minimum factor of 2. Improvements in instrument technology have enabled us to meet this goal in all respects. In the design brief, we quickly recognised that the critical elements of the Dissolution Tester and therefore those most likely to affect the accuracy of the results were those making up the actual test station, namely (a) the dissolution vessel (b) the dissolution vessel lid and (c) the stirring element. It followed that if we could control the dimensions of these critical elements and their spatial relationship with each other and then ensure that (d) the speed of the stirring element and (e) composition and temperature of the dissolution media were maintained within equally tight limits then any instrument contribution to test method variability would be minimised. The dissolution community have long recognised that one of the major problems relating to results variability relates to vessel dimensions and irregularities. A comprehensive article on this subject by Mark R.Liddell, Gang Deng, Walter W.Hauck, William E.Brown, Samir Z.Wahab and Ronald G.Manning entitled “Evaluation of Glass Dissolution Vessel Dimensions and Irregularities” can be found on Page 28 of the February 2007 edition of Dissolution Technologies. In their dissertation, the writers of the article found large variations in a sample of vessels purchased from five different suppliers between individual manufacturers and even between individual vessels from the same manufacturer. Whilst the inside diameter of all of the 30 vessels that they examined conformed to the USP requirements of 98-106 mm, the i.d. of vessels from different sources varied between 99.9 mm and 104.5 mm and from the same source by up to 2.0 mm. Similar variations were reported for height (up to 4 mm) and radius of hemisphere with variations in volume in the hemispheric region reported of up to 18% (from 260 to 370 mL). We determined from the outset that were we able to resolve the problems arising from the vessel then the problems emanating from the other elements of the test station, the stirring element and the vessel lid, could be easily solved.
Traditionally, dissolution vessels have been made individually using manual glass blowing techniques from extruded glass tubing having a nominal tolerance of /- 2 mm. Unfortunately, even using ‘specially sjelected’ tubing, it is simply not possible to obtain the tolerances (twice as tight as those specified) desired using this technique.
The solution, the EMC Dissolution Vessel was to vacuum form the vessel as opposed to extrude it. In this method, the glass blank employed to produce the EMC Dissolution Vessel is first heated to 2000 degrees C before being vacuum formed by shrinking it on to a precision ground stainless steel mandrel. This method guarantees an inside diameter tolerance and blemish free spherical radius of /- 0.13 mm (compared with /- 2 mm on the traditional unit) together with a flange perpendicularity tolerance of 0.50 mm Total Indicated Runout (TIR). Having resolved the problems relating to the dissolution vessel, it was then a relatively simple matter to design a dissolution vessel lid and stirring element to match it. The result is a Test Station having a centering tolerance, basket wobble tolerance and paddle/basket height tolerance of 0.50 mm max and a shaft wobble tolerance of 0.25 mm max. All three parts of the Test Station are serialised and come complete with a Certificate of Conformity (CoC) to ASTM.
It is this EMC Test Station that forms the basis of the our Tablet Dissolution Tester DIS-EMC described in the above section
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