To determine, in vitro, the solubility in silicone oil (SO) of triamcinolone acetonide, dexamethasone, and some nonsteroideal antiinflammatory drugs including phenylbutazone and nabumetone.
Antiinflammatory drugs were initially dissolved in organic solvents (chloroform or diethyl ether). The solubilized drugs were then added to 1,000 centipoise purified SO to yield final concentrations that were therapeutically relevant. The degree of solubilization was judged by the transparency of the final mixture. The kinetics of phenylbutazone diffusion from SO into water were measured for 30 days by derivative spectrophotometry.
Most of the tested drugs, including triamcinolone acetonide, were not soluble in SO. Only phenylbutazone and nabumetone, each at 80 μg/mL, were soluble in SO. The release of phenylbutazone from SO into water over a 30 day period followed zero order kinetics during the first 15 days.
Triamcinolone acetonide and most other antiinflammatory drugs tested are not soluble in SO. This fact must be taken into consideration when using these drugs in combination with SO.