frequently asked questions
about the Chewing Apparatus, chewing machine, dissolution rate tester, DRT
How can we perform IQ / OQ (Instrument Qualification & Operation Qualification)?
Will we get any further support with method development etc. ?
How can we arrange supply of compressed air?
What is the use of Support Nets?
How many pair of jaws do we need?
Where can we get Dissolution Calibrator Gums?
How can you find out the correct gap between the jaws?
When jaws are stuck or difficult to remove, any tricks or tools?
Which importance does has the Warming up Period have?
What about Service on Jaws; do we need it?
Before buying:
Question:
Will FDA (Food and Drug Administration) or other authorities accept a file with data from this instrument?
Answer:
Yes, they will, it is adopted by the European Pharmacopeia 7.4, § 2.9.25. The text will come into force in April 2012. Apart from that, Nicorette and Rugby Nicotine gums are registered in all countries with dissolution data from this very Chewing Apparatus. It is spread throughout the world is now to be adopted by the US Pharmacopeia. In EP another machine is also described with poor specifications, no default settings or details. It is not commercially available. It has some similarities to the FIA / Erweka Chewing Apparatus, but many points differ.
Advantages with the FIA / Erweka Chewing Apparatus are:
It is well known by FDA and other authorities worldwide
It gives reproducible results with low standard deviations
It is sized to fit the analytical laboratory and is silent
It has transparent dissolution cells for good visibility
Operating height in positions to achieve a comfortable working environment
Easy to prepare and fast to reload and warm up for effective handling and use
It has well documented examples of use
Easy to change settings of the Chewing parameters
Good support is given for method development
Question:
May we see the manual?
Answer:
Manuals may be obtained on the download page.
Question:
How can we perform IQ / OQ (Instrument Qualification & Operation Qualification)?
Answer:
Normally this is done by the customer with minor support from the distributor. IQ / OQ documents for the Chewing Apparatus may be supplied by the distributor that also may help you with the tests.
After unpacking:
Question:
Will we get any further support with method development etc. ?
Answer:
You will get free expert support via e-mail ( Bo Wennergren ) as far as possible. You may also get support with method development including chemical analysis from our training and method development centers against payment. Please ask via e-mail for advice.
Questions about technical details:
(Some of the questions below are discussed in the Manual. A good advice is to read the manual carefully before starting with any experiments).
Question:
How can we arrange supply of compressed air?
Answer:
In the manual you will find the demands. Many labs have compressed air connections in the building or in each lab-room. For a 6-cell Chewing Apparatus, compressed air of 6 bar (84 psi) and minimum 100 liter per minute is needed. Normally a standard compressor is placed in a room, separated from the lab and preferably sound insulated (the cellar). In the lab a permanent installation is made on the wall with a reduction valve and a manometer where the pressure may be read. A water trap is mounted at the reduction valve. All the items mentioned are standard and may be found in a machine or hardware store.
For a 1-cell Apparatus a large tube with compressed air may be used or a compressor of "Silent Air"-type installed in the laboratory. All models from 2007 and on have a suitable reduction valve with manometer and water trap mounted on the carrier.
Question:
What is the use of Support Nets?
Answer:
Support Nets are more or less compulsory to use. It may be worth a try to make chewing without nets but it is likely that the gum or pieces of it will try to creep out from the jaws during mastication if no nets are used to keep it together in a unit between the jaws. The nets are cheap and quite inert (from Nylon, PA).
Question:
How many pair of jaws do we need?
Answer:
It depends from how much you use the Chewing Apparatus. The idéa is that the operator simply put the used jaws to the side and replace them with a clean and qualified pair. This is a cost effective use of the Chewing Apparatus and the trained operators. This means that cleaning and qualification of the jaws has to be made batchwise. A batch should be of minimum two weeks use. One batch is cleaned and qulified while another batch is being used. So the need will be at least two batches. We recommend for a 6-cell Chewing Apparatus 120 pair of jaws and 60 pair for a 1- or 2-cell apparatus. For a start, of course a smaller amount may be tried.
Question:
Where can we get Dissolution Calibrator Gums?
Answer:
We are optimistic about a calibrator to appear in the near future. So far we may only use samples of well known medical gums as reference material. On request we will suggest a suitable gum that is available in your own country.
Question:
How can you find out the correct gap between the jaws?
Answer:
The gap depends on the volume of the gum and a bit apon the formulation itself. To find the correct setting is a trial and error issue. The in vitro dissolution profile should be related in some way to the in vivo profile. For instance; the final amount dissolved should be about the same level for in vitro as in vivo. A retarded in vivo profile should be reflected in a retarded in vitro profile etc. Normally Support Nets are used (see above). A too narrow gap will often be reflected in a destruction of the nets (see Picture 1). A too wide gap will result in poor mastication, a lost grip on the chewing gum and a resulting false slow release (see Picture 2).
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When the gap is correct, the chewing gum is masticated well and often may remains be left on the lower jaw after the dissolution test
(see Picture 3).
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Question:
When jaws are stuck or difficult to remove, any tricks or tools?
Answer:
Try to use a piece of dry paper tissue; it should normally be possible to remove them with finger force. Never use a metal tool directly on them, tools have to be carefully covered with some soft tape or cloth. A special tool is available.
Question:
Which importance does has the Warming up Period have?
Answer:
The chewing gum is harder att room temperature than at the temperature where dissolution is performed. With some formulations it is not even possible to masticate the gum with the Chewing Apparatus at room temperature since the gum is too hard. The dissolution testing should normally be performed at constant temperature close to 37 degrees Celsius. The Warming up Period is a waiting period for the chewing gum and the dissolution medium to stabilize and reach the constant temperature at which the dissolution testing will be performed. The gum, support nets, dissolution medium and the upper jaw are all temperated during this period. No dissolution from the contents in the gum base takes place before the mastication is started. Warming up takes place only once, before actual dissolution testing starts. A typical value is 5-10 min. If the gum is coated, the coating will normally be partly or totally disintegrated during the Warming up Period, leaving the gum with the active substances exposed before the mastication starts. If the coating contains active substance, some special measures can make it possible to chew a cold gum. Please consult i@fia.se.
Question:
How is sampling made?
Answer:
Manual sampling is made after lowering the lift. Before sampling the dissolution medium is stirred or samples are repeatedly withdrawn and put back to obtain a uniformly mixed liquid.
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Sampling is normally made with a pipette (volumes up to about 1 ml). The sampling volume may be compensated with fresh dissolution medium, but this is not necessary. Calculations to compensate for successively decreasing volume of dissolution medium may be made done with the same mathematical methods as for normal tablet dissolution. After sampling, nets and gum are put in the center of the lower jaw. No dissolution takes place when the gum is not masticated. The time that the sampling takes is of no importance to the dissolution test.
Automatic sampling is possible but we have yet little experience about it. A special cuvette with sampling tube is used and samples are withdrawn for instance with a peristaltic pump. Prior to sampling, the liquid must be mixed to obtain a homogeneous solution.
Question:
What about Service on Jaws; do we need it?
Answer:
Yes! The quality of the jaws depend from the character of the surfaces.
A whole lot of trials have been performed during the passed years (ie decades of years) in order to investigate different materials on the surfaces and patterns on the jaws (squares, waves, spirals etc). In short, the investigations shows that the original jaws with exactly this caracter of the blasted surface gives optimum performance concidering grip on the gum and resulting in low standard deviations on the dissolution results. A bit depending on the formulation, already after a few runs (5-10 runs) the standard deviations may increase. Some gums are more sensible to wearing of the surfaces than other. Since cleaning from gum remains, always have to be performed we have decided that jaws should only be used once before cleaning, reblasting and qualification. In this way the jaws are always put aside after a run and are replaced by fresh and qualified jaws before next run. The operator may leave the cleaning etc to other personell (ie normally the Supplier). The cleaning, blasting and qualification procedures are described in detail in the Manual. It is possible by the customer to perform the cleaning and blasting, but it must be made in a room separated from the analytical laboratory.
An Automatic Blaster Machine is also available since 2011.
