Hello sir, wet granulation is a preferred method for low dose drugs as it fixes the drug in the granule, however where content uniformity is concerned, the size of the drug is very relevant in assuring content uniformity.Pls find the references

A chart helps you to determine the size that will help you pass the content uniformity.

Particle Size Limits to Meet USP Content Uniformity Criteria for Tablets and Capsules, BR Rohrs,

GE Amidon, RH Meury, PJ Secreast, HM King and CJ Skoug, J. Pharm. Sci., (2006), 95 (5), 1049 -

1059

Hello sir, yes wet granulation is the best method for potent drugs because, as you said ensure homogenous distribution of drug.

But if the drug is soluble in the granulating solvent, the drug will migrate with granulating solvents to be concentrated at the periphery of granules. Particle size reduction can lead to high concentrated and low concentrated granules that may be the possible cause of content uniformity problem after that if they will be subjected to further processes like mixing.

ya its true but what you say of the drug like Vitamin D?

Hello, yes vitamin D3 is a known problem of content uniformity test particularly stability issues.

Adsorption of Vitamin D3 on Aerosil (colloidal silicon dioxide), that has the higher surface area, may be able to ensure homogenous distribution of Vitamin D3. Also, colloidal silicon dioxide is claimed to have antinucleant effect against crystalization of amorphous form of drug like solid dispersions. This claim may stabilize vitamin D3 formulation.

The low bulk density of colloidal silicon dioxide indicates the large volume of it that leads to very higher susceptibility for good results with direct compression techniques when mixed with other excipients. Further processing of vitamin D3 and colloidal silicon dioxide by wet granulation technique may cause decrease the hardness values of tablets during storage. This can be attributed to some mild surfactant properties of Aerosil 200, besides its hygroscopicity, that can cause emulsification. So, some grades of aerosil 200 was developed to overcome this hygroscopic nature.

So, adsorption and direct compression may give better results of content uniformity and stability.

Hello,

cocentrate on particle size for proper distribution of API

Evaluate the effect of excipients/grades, API particle size, mixing times, binder amounts and different feeders for compression, and you will find the cause.