Measuring and testing – Testing of material
Reexamination Certificate
2000-05-11
2001-10-30
Raevis, Robert (Department: 2856)
Measuring and testing
Testing of material
Reexamination Certificate
active
06308584
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a process for introducing a particulate material, for example pellets, granules or powder into a liquid.
In the development and in particular in the routine quality control of solid drug forms, the determination of the active substance dissolution rate in the dissolution process of a drug is of great importance. For this reason, the national pharmacopeias and the European Pharmacopoeia contain exact specifications regarding the instrument parameters of the tester as well as regarding the test procedure. Of primary importance in this regard is the United States Pharmacopeia (USP). Every dissolution tester must comply with the USP specifications. Regular inspections by the health authorities, such as, for example, the Food and Drug Administration (FDA) of the USA, stringently check for compliance with the specifications.
According to the USP specifications, the determination of the active substance dissolution is performed simultaneously with six test specimens, which are introduced in each case into a test vessel containing simulated gastric or intestinal fluid. The dissolution process takes place, for example, at 37 degrees Celsius, the dissolution medium being stirred by means of a standardized stirrer at a specified speed. In many cases, these tests are carried out with tablets or capsules.
SUMMARY OF THE INVENTION
A problem is encountered when carrying out such a test with the use of, for example, medicaments which are administered as fine particulate material, for example in the form of pellets, in capsules. Pellets are approximately spherical particles which typically have a diameter of 0.4 to 1.2 mm. Owing to their size and their composition, they tend to be readily electrostatically chargeable. If the pellets must be introduced automatically, for example through a metal tube, into the liquid, they therefore tend to adhere to the tube wall. Moreover, owing to the service tension of the liquid, they tend to remain on its surface and not to become immersed in the liquid. An important problem is also the wettability of the pellets, powder or granules. However, the wettability of the material to be tested is an important precondition for the reproducible test. For these reasons, in dissolution tests to date, pellets have frequently been weighed on a spoon and stirred into the liquid with said spoon manually, whereupon the spoon has to be cleaned again. The process is of course therefore considerably timeconsuming and expensive.
It is therefore the object of the present invention to provide a process which permits the manual, semiautomatic or automatic introduction of fine particulate material, for example of pellets, of granules or of powder, into a liquid, so that the dosage can be checked with sufficient accuracy, the total intended amount can be introduced as far as possible simultaneously, at a defined time, into the liquid and at the same time good distribution and hence as good wetting of the material as possible in the liquid are ensured.
This object is achieved by a process for introducing a particulate material into a liquid, wherein the material is introduced into a cartridge having a sleeve, an axis and a base arranged in the interior of the sleeve and displaceable along the axis away from a stop, and wherein the cartridge, in a position in which its axis is approximately perpendicular and the base, as a result of its weight, rests against the stop, is allowed to fall into the liquid, so that the base is displaced by the liquid upward away from the stop and at least the major part of the material is ejected from the cartridge.
The present invention also relates to a cartridge for carrying out the process, wherein the cartridge has a sleeve with an axis and a stop and a base arranged displaceably in the sleeve and resting against the stop as a result of its own weight in one position of the cartridge.
The invention furthermore relates to a device for carrying out the abovementioned process, which comprises at least one cartridge of the type defined above and at least one guide tube with a perpendicular axis and a lower open end for guiding a cartridge falling into a container coordinated with a guide tube and containing liquid.
The process according to the invention, the cartridge according to the invention and the device according to the invention have different advantages compared with the prior art. Thus, the invention has the advantage that exactly a specified amount of particulate material can be easily introduced into the liquid, even in the case of a small particle size, without particles remaining adhering to any part of the device outside the liquid or remaining on the surface of the liquid. The process according to the invention, the cartridge and the device are therefore particularly suitable for use in an automatic or semiautomatic solubility test, for example in quality controls. Process, cartridge and device are also especially suitable for introducing particulate materials comprising very small particles into a liquid, i.e. materials comprising particles having a particle size of usually not more than 1.2 mm and generally at least 0.4 mm or comprising even smaller particles.
Raevis Robert
Sidley Austin Brown & Wood LLP
Sotax AG
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