Table 1.

Saturated Solubility of Monosodium Urate (MSU) in PBS in Vials After 24 Hours

Extra Component Added to Vials	Measured MSU Concentration (mg/mL)	Relative MSU Solubility	Temperature
Control (just PBS)	0.040	100%	25°C
GB no drug gel	0.049	123%	25°C
GB diclofenac gel 1%	0.049	123%	25°C
Sodium bicarbonate (pH 8.3)	0.026	66%	25°C
Sodium bicarbonate (re-adjusted to pH 7.4)	0.026	65%	25°C
Sodium carbonate (pH 11.3)	0.110	276%	25°C
Sodium carbonate (re-adjusted to pH 7.4)	0.033	83%	25°C
Control (just PBS)	0.074	100%	37°C
GB no drug gel	0.126	171%	37°C
GB diclofenac gel 1%	0.118	160%	37°C
Sodium bicarbonate (pH 8.3)	0.039	52%	37°C