What is the shelf life of a nasal solution composed of 100 mg neomycin sulfate, 0.9 g NaCl, 0.2 g propylene glycol, 0.2 g glycerin, and purified water up to 100 ml when prepared without a preservative, and is it recommended to add a preservative such as benzalkonium chloride given that these solutions are typically for short-term use?

Which of the three types of colloidal SiO2 found on the list of recognized raw materials—Silica colloidalis anhydrica, Silica colloidalis hydrica, or Silica hydrophobica colloidalis anhydrica—can be used as an excipient in the preparation of capsules with dry extracts to absorb moisture, and can precipitated hydrated silica (heavy), also found on the Acapharma website, be used as well?

How can erythromycin be added to Locoid Crelo considering that erythromycin is stable at pH 8 while Locoid Crelo has an acidic character due to citric acid, and would Betnelan lotion be a suitable alternative given it also has an acidic character due to phosphoric acid?

How can a loco Terra-Cortril suspension for use as nose drops, containing 123 mg oxytetracycline HCl, 340 mg hydrocortisone acetate, 228,000 IU polymyxin B sulfate, 2.5 g vaseline, and liquid paraffin up to 20 ml, be prepared to achieve better viscosity and stability, given that dissolving 3% zinc stearate in liquid paraffin at 110°C and adding heated vaseline resulted in a product too liquid for a tube, and is it acceptable to dispense this in a dropper bottle?

What causes and can mitigate the formation of precipitation in a 20% borax solution used for bladder irrigation, given that it occurs when packaged in a plastic bottle, is delayed when using a glass bottle, and is not improved by the addition of bicarbonate?

What are the recommended alternatives for Carbomer 940 and Carbomer 974P in an aphthous ulcer pasta, given that both are unavailable, and is there a specific reason why Carbomer 980 should not be used for oral applications?

Why does Unguentum emulsificans cum aquosum (30 g emulsifying ointment and 70 g water) remain very liquid even after being reheated and cooled three times, why does the ointment turn pink upon the addition of salicylic acid, and how can these issues be resolved?