This chapter provides guidelines for the friability determination of compressed,uncoated tablets.The test procedure presented in this chapter is generally applicable to most compressed tablets.Measurement of tablet friability supplements other physical strength measurements,such as tablet crushing strength.

Use a drum,*with an internal diameter between 283and 291mm and a depth between 36and 40mm,of transparent synthetic polymer with polished internal surfaces,and not subject to static build-up (see figure for a typical apparatus).One side of the drum is removable.The tablets are tumbled at each turn of the drum by a curved projection with an inside radius between 75.5and 85.5mm that extends from the middle of the drum to the outer wall.The drum is attached to the horizontal axis of a device that rotates at 25±1rpm.Thus,at each turn the tablets roll or slide and fall onto the drum wall or onto each other.

Tablet Friability Apparatus

For tablets with a unit mass equal to or less than 650mg,take a sample of whole tablets corresponding to 6.5g.For tablets with a unit mass of more than 650mg,take a sample of 10whole tablets.The tablets should be carefully dedusted prior to testing.Accurately weigh the tablet sample,and place the tablets in the drum.Rotate the drum 100times,and remove the tablets.Remove any loose dust from the tablets as before,and accurately weigh.

Generally,the test is run once.If obviously cracked,cleaved,or broken tablets are present in the tablet sample after tumbling,the sample fails the test.If the results are doubtful or if the weight loss is greater than the targeted value,the test should be repeated twice and the mean of the three tests determined.Amaximum weight loss of not more than 1%of the weight of the tablets being tested is considered acceptable for most products.In the case of new formulations,an initial weight loss of 0.8%would be permitted until sufficient packaging data are obtained to extend the limit to a targeted value of 1%.

If tablet size or shape causes irregular tumbling,adjust the drum base so that the base forms an angle of about 10with the bench top and the tablets no longer bind together when lying next to each other,which prevents them from falling freely.

Effervescent tablets and chewable tablets may have different specifications as far as friability is concerned,and these tablets normally require special packaging.In the case of hygroscopic tablets,a humidity-controlled environment (relative humidity less than 40%)is required for testing.

Adrum with dual scooping supports for the running of two samples at one time is also available.