What is the cause of the emulsion breaking in a preparation consisting of 800 mg metronidazole and 40 ml La Roche-Posay Hydranorme cream—a w/o emulsion containing aqua, squalane, paraffinum liquidum, cera alba, sorbitan oleate, stearic acid, glycerin, magnesium sulfate, dehydroacetic acid, phenoxyethanol, and parfum—given that the mixture initially appeared stable after processing with a three-roll mill but failed after the weekend?

How can Lipothene 133—a lipophilic, oleaginous vehicle described as a soft, unctuous, colorless, and oily-jelly-like substance with excellent lubricant and emollient properties—be prepared using a composition of 93.1% paraffin oil, 6% polyethylene, and 0.9% butylhydroxytoluene, and if an identical product is unavailable, can polyethylene glycol be used as a substitute, and if so, which type?

How can Tildiem 5% in a fatty ointment base be prepared up to 60g when the bulk product is unavailable, specifically regarding how to process the tablets, which base is best, and how this ointment works for hemorrhoids?

How can a stable, isotonic to slightly hypertonic ophthalmic solution be formulated for a variant of Bacicoline containing 100,000 IU polymyxin B, 50,000 IU bacitracine, 1 g hydrocortisone (or acetate), and 0.5% sodium borate buffer in 10 ml physiological water, considering that bacitracine is unstable in aqueous solutions, polymyxin B is incompatible with prednisolone sodium phosphate, and the preparation must maintain stability for one month at a specific pH without causing eye irritation?

What causes the precipitation (benzoic acid or promethazine) in a preparation containing 300 mg pholcodine, 300 mg promethazine, 600 mg ascorbic acid, 2 g sodium benzoate, 100 g codeine syrup, and tolu syrup up to 200 ml, and how can this precipitation be prevented?

How can "American" glycerin suppositories containing 80% glycerin, sodium stearate, and water be prepared when sodium stearate is unavailable, specifically regarding whether magnesium stearate can be easily converted into the sodium salt or if sodium stearate can be replaced by another soap in the formula?

Can paraformaldehyde powder be used instead of a formaldehyde solution for a preparation of 5% formaldehyde and talcum powder up to 100 grams, and if so, in what dosage?