Which filler is suitable for processing nitrofurantoin macrocrystals into capsules, given that the use of lactose, even at 80 mesh, results in rapid segregation during filling, and considering the requirement for a more crystalline filler that also has a registration number for use in preparations?

How can a stable solution be prepared with 5 g NaHCO3, 5 g borax, 10 g glycerin, 2 g lidocaine HCl, 3 g peppermint spirit, and aqua conservans up to 100 ml, to prevent the formation of a gel-like top layer and very fine crystals?

What is the cause of discoloration and crystallization after one day in a solution containing 2% resorcinol, 4% erythromycin, 50% isopropyl alcohol, and water up to 100 mL?

What is the best preservative to use for a 10 ml eye drop solution containing 25 mg sodium bicarbonate, 25 mg sodium borate (borax), and 63 mg sodium chloride, is benzalkonium chloride suitable, and what is the purpose of sodium bicarbonate in eye drops?

How can 1% salicylic acid be solubilized in an external use emulsion containing 200 g miglyol, 50 g comperlan KD, 50 g eumulgin B1 (Eumulgine 05), and 50 ml cetiol, with paraffin oil added up to 500 ml, considering that adding cetomacrogol 1000 results in a solid form after cooling while levigating with cetiol leads to crystallization?

How can the incompatibility between trometamol and acids be resolved when preparing a flufenamic acid 3% gel using the TMF carbomer gel formulation?

What are the stability problems of a solution containing 3 grams of Phenobarbital sodium and purified water up to 300 cc?