Multivitamin and Multimineral tablet Granulation:-

1. Select excipients on the basis of compatibility study (eg. thiamine incompatible with lactose, millard reaction)

2. Granulate mineral by mineral granulation [Hot melt] method with castor oil and stearic acid (To avoid spots and decoration during stability)

3. Use non-alcoholic (IPA) wet granulation method for tabletting, to avoid hydrolysis and oxidation degradation

4. Add vitamin and mineral part in lubrication, to avoid degradation in drying stage

5. Due to low amount of vitamin and mineral in claim, Optimize mixing process to avoid uniformity issue

6. For DC method there are numbers of issue like, powder flow, compressibility and compactability, uniformity, seggregation to avoid these issue you can go with wet granulation method

7. Slugging and dry granulation is another process but there are possible seggregation issue

In addition to Deepak, I highly recommend you consider/follow these points:

1.-Run the preformulation studies and find out what excipients you will potentially employ in your formulation. Use FTIR or DSC to verify any incompatibility

2. Usually the vitamins A, B and K go in low quantity compared to the total weight of the tablet with an exception of vitamin B1 and E. There's in the market many co-processed of vitamin E with free flow. Depending on the quantity of vitamin E you could have sticking issues onto the punches during the compression process. Take note of this.

3. At least that the minerals represent more than 10-15 % of the tablet you should granulate them. ( Holt melt granulation won't really give you any advantage over wet/dry granulation since probably you won't run dissolution)

4.-Check out this stability data of vitamins from DSM

https://www.dsm.com/markets/anh/en_US/Compendium/vitamin_basics/vitamin_stability.html

5. I would try to design the formula and manufacturing process by direct compression as the first option. Employ ordered mixing and/or geometric dilution. Put the vitamins and minerals in this way in the final mixing stage previous to lubrication:

Diluent 2 fraction 1

Vitamins/Minerals premixing with diluent 1

Diluent 2 fraction 2

Note 1: if your vitamins/minerals are very cohesive employ aerosil/syloid to minimize the Van der Waals forces.

Note 2:There are many free flow excipients with high compaction properties, carry out a screening of the potential excipients to ensure you QA of the final tablet

6.- To avoid segregation try mixtures of some diluents with different distribution particle sizes. ex: Avicel 200: Avicel 102

Pls go through Textbook of Granulation Technology