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1、MethodEnsure that the reference volume and the calibration volume have been determined for the gas pycnometer by an appropri-ate calibration procedure. The test gas is helium, unless another gas is specified in the individual monograph. The temperatureof the gas pycnometer should be between 15 and 3
2、0 and should not vary by more than 2 during the course of the meas-urement. Load the test cell with the substance under examination that has been prepared according to the individual mono-graph. Where 699D is indicated, dry the substance under examination as directed for Loss on drying in the monogr
3、aph unlessother drying conditions are specified in the monograph Density of solids test. Where 699U is indicated, the substance underexamination is used without drying. Use a quantity of powder recommended in the operating manual for the pycnometer.Seal the test cell in the pycnometer, and purge the
4、 pycnometer system with the test gas according to the procedure given inthe manufacturers operating instructions. If the sample must be degassed under vacuum, follow the recommendations in theindividual monographs and the instructions in the operating manual for the pycnometer.The measurement sequen
5、ce above describes the procedure for the gas pycnometer shown in Figure 1. If the pycnometerdiffers in operation or in construction from the one shown in Figure 1, follow the operating procedure given in the manual forthe pycnometer.Repeat the measurement sequence for the same powder sample until co
6、nsecutive measurements of the sample volume, Vs,agree to within 0.2%. Unload the test cell and measure the final powder weight, w. Calculate the pycnometric density, r, ofthe sample according to Equation 2.701 DISINTEGRATIONThis general chapter is harmonized with the corresponding texts of the Europ
7、ean Pharmacopoeia and/or the Japanese Phar-macopoeia. The texts of these pharmacopeias are therefore interchangeable, and the methods of the European Pharmacopoeiaand/or the Japanese Pharmacopoeia may be used for demonstration of compliance instead of the present general chapter.These pharmacopeias
8、have undertaken not to make any unilateral change to this harmonized chapter.Portions of the present general chapter text that are national USP text, and therefore not part of the harmonized text, aremarked with symbols () to specify this fact.This test is provided to determine whether tablets or ca
9、psules disintegrate within the prescribed time when placed in a liquidmedium at the experimental conditions presented below. Compliance with the limits on Disintegration stated in the individualmonographs is required except where the label states that the tablets or capsules are intended for use as
10、troches, or are to bechewed, or are designed as extended-release dosage forms or delayed-release dosage forms. Determine the type of units un-der test from the labeling and from observation, and apply the appropriate procedure to 6 or more dosage units.For the purposes of this test, disintegration d
11、oes not imply complete solution of the unit or even of its active constituent.Complete disintegration is defined as that state in which any residue of the unit, except fragments of insoluble coating or cap-sule shell, remaining on the screen of the test apparatus or adhering to the lower surface of
12、the disk, if used, is a soft masshaving no palpably firm core.APPARATUSThe apparatus consists of a basket-rack assembly, a 1000-mL, low-form beaker, 138 to 160 mm in height and having aninside diameter of 97 to 115 mm for the immersion fluid, a thermostatic arrangement for heating the fluid between
13、35 and39, and a device for raising and lowering the basket in the immersion fluid at a constant frequency rate between 29 and 32cycles per minute through a distance of not less than 53 mm and not more than 57 mm. The volume of the fluid in the vesselis such that at the highest point of the upward st
14、roke the wire mesh remains at least 15 mm below the surface of the fluid anddescends to not less than 25 mm from the bottom of the vessel on the downward stroke. At no time should the top of thebasket-rack assembly become submerged. The time required for the upward stroke is equal to the time requir
15、ed for the down-ward stroke, and the change in stroke direction is a smooth transition, rather than an abrupt reversal of motion. The basket-rack assembly moves vertically along its axis. There is no appreciable horizontal motion or movement of the axis from the ver-tical.Basket-Rack AssemblyThe bas
16、ket-rack assembly consists of six open-ended transparent tubes, each 77.5 2.5 mm longand having an inside diameter of 20.7 to 23 mm and a wall 1.0 to 2.8 mm thick; the tubes are held in a vertical position bytwo plates, each 88 to 92 mm in diameter and 5 to 8.5 mm in thickness, with six holes, each 22 to 26 mm in diameter, equi-distant from the center of the plate and equally spaced from one another. Attached to the under surface of the lower plate is awoven stainless steel wi
