Friability
Friability
Test Apparatus & Method
A standard friability drum has an inside diameter of 287 mm and a depth of 38 mm. Each drum is fitted with a curved baffle which subjects tablets to a drop of 156 mm during rotation.
The sample (normally 10 tablets) to be tested is first weighed and then placed into the drum. The drum is then rotated 100 times at a speed of 25 rpm. Any loose dust from the sample is removed and the sample re-weighed. Friability of a sample is defined in terms of percentage (%) weight loss (loss in weight expressed as a % of the original sample weight). A maximum weight loss of no more than 1% is considered acceptable for most tablets. Attrition caused by tablets rubbing together can also be measured using this method with a special abrasion drum.
For coated tablets, granules and spheroids, friability cannot be
determined using a conventional friability tester, as the dosage form is too hard for meaningful weight loss measurements. Alternative equipment that oscillates the sample at high frequencies is available for this purpose (see Ph. Eur. 2.9.41). The abrasive forces generated by the horizontal shaking movement of the oscillating arm of this equipment allows users to easily optimise test conditions for each type of formulation with simple-to-use programmable controls.
A
C
ø 10.0 ± 0.1 mm
156.0 ± 2.0 mm
ø 287.0 ± 4.0 mm
(int)
B
80.5 ± 5.0 mm (inside radius)
ø 25.0 ± 0.5 mm
ø 302.5 ± 4.0 mm
38.0 ± 2.0 mm
A
B
C
Friability drum
Fraibility drum (drop height)
Friability drum (side view)
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