Friability of Uncoated Tablets

This test is applicable to compressed tablets and is intended to determine the physical strength of tablets.

Apparatus

It consists of a drum of transparent synthetic polymer with polished internal surfaces and subject to minimum static build-up. It has a diameter of 283-291 mm and a depth of 36-40 mm (fig.); one side of the drum is removable. A curved projection with an inner radius of 75.5 mm to 85.5 mm and extending from the middle of the drum to the outer wall enables the tumbling of the tablets at each turn of the drum.

The outer diameter of the central ring is 24.5 mm to 25.5 mm. The drum is attached to the horizontal axis of a device that rotates at 25 ± 1 rpm. It should be ensured that with every turn of the drum the tablets roll or slide and fall onto the drum wall or onto each other.

Method

For tablets with an average weight of 0.65 g or less take a sample of whole tablets corresponding to about 6.5 g and for tablets with an average weight of more than 0.65 g take a sample of 10 whole tablets.

Dedust the tablets carefully and weigh accurately the required number of tablets. Place the tablets in the drum and rotate it 100 times. Remove the tablets, remove any loose dust from them and weigh them accurately. The test is run only once unless the results are difficult to interpret or if the weight loss is greater than the targeted value, in which case, the test is repeated twice and the mean of the three tests is determined.

Related: Calibration of Friability Test Apparatus

A maximum loss of weight (from a single test or from the mean of the three tests) not greater than 1.0 percent is acceptable for most tablets.

If obviously cracked, chipped or broken tablets are present in the sample after tumbling, the sample fails the test. If the size or shape of the tablet causes irregular tumbling, adjust the drum base so that it forms an angle of about 10° with the horizontal and the tablets do not bind together when lying next to each other, which prevents them from falling freely.

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