What Calistus said is one option-making a solid dispersion of the powder in an inert polymer like PEG or waxes / acrylic polymers. 

The other method is Microencapsulation of the water-sensitive powder by suitable methods  like solvent evaporation, Wurster process, Spray drying. Check out the suitable polymer and method to be used. 

Hi,

You can coat a solid dosage form but it may be difficult to coat a powder! and this would alter your salt's properties.To save time, simply protect your salt by replacing air it the flask by an inert gas such as nitrogen.

Best regards

you can mix it with a water insoluble polymer in the presence of surfactant.

I resolve similar problem by melting PEG 4000, disperse the water sensitive salt in it, allow to cool and solidify then granulate the mixture. Hope this will be of immense benefit to your situation.

Thank you all.

What Calistus said is one option-making a solid dispersion of the powder in an inert polymer like PEG or waxes / acrylic polymers. 

The other method is Microencapsulation of the water-sensitive powder by suitable methods  like solvent evaporation, Wurster process, Spray drying. Check out the suitable polymer and method to be used. 

Agree with Mala, you could use a Wurster/Spray coating process using a hydrophobic coating material in an organic solvent.  For this to work you would need your powder particle size to be probably 100micron and greater so that you don't lose the powder in the filter socks of the spray coater.  You also need a flammable rated coater and someone who knows how to operate it safely. What Calistus suggests may be more feasible in your average laboratory with equipment that is typically available.  Getting a good dispersion of the salt will be the main issue and again particle size and flowability of the powder will make a difference.

Thanks Colin. You have given details of what I had in mind. 

Thank you for your detailed suggestions. We considered spray drying salt with polymer. But, if we wanna use hydrophobic water resistant polymer, we need organic solvent. In that case, our Ionic salt doesn't get dissolved in Organic solvent. I am facing this particular issue.. 

Hello Kamal,

You need not dissolve the salt. The salt can be a dispersion in the hydrophobic polymer solution in the organic solvent. So the salt particles get coated with the hydrophobic polymer. 

If your drug is thermosensitive, you have the option of using spray congealing with waxy materials as coat.. 

Particle size of the drug particles needs to be controlled to prevent problems. 

Hope this addresses your problem.