What tools do I use to make a good suspension of the following formula? Salicylic acid 6g metronidazole 3g dexamethasone 0.03 g propylene glycol 30g aqua AD 300 ml

Since this preparation is for external use we avoid most mucous compounds. Carbomeer would be a good candidate as a viscosite booster but there is an incompatibility with salicylic acid. So I would use Bentonite or Aerosil. If you have the Galenic Formularium you can find some formulas of excipients based on these inorganic viscosifierende substances.