[Ocular pharmacokinetics of 0.5% pilocarpine with sodium hyaluronate in rabbits]

To compare the pharmacokinetics of 0.5% pilocarpine containing sodium hyaluronate with 1% generic pilocarpine solution.

One hundred albino rabbits were divided into 20 groups, each consisting of 5 animals. Ten groups received 0.5% pilocarpine containing sodium hyaluronate and 10 groups received 1% generic pilocarpine solution as control. The aqueous humor was withdrawn at 5, 10, 20, 30, 40, 60, 90, 120, 150, and 180 min after instillation. The drug was extracted from aqueous humor with dichloromethane and was detected by reversed phase high performance liquid chromatography (HPLC).

The average recovery rate of pilocarpine from aqueous humor was 98.2%. The minimum detectable concentration was 0.025 micro g/ml. The peak concentration and half-life of pilocarpine in aqueous humor were 4.46 micro g/ml at 10 min and 31.83 min, respectively, in the experimental group. Whereas, the peak concentration and half-life of pilocarpine in aqueous humor were 2.25 micro g/ml at 20 min and 22.98 min, respectively, in the control group. The peak concentration of pilocarpine in aqueous humor in the experimental group was 1.98 (P < 0.05) times higher than the control group. The area under curve of the drug concentration-time (AUC(0 - 180)) in the experimental group was 1.75 times higher than the control group.

Pilocarpine (0.5%) containing sodium hyaluronate significantly increased the peak concentration of pilocarpine, shortened the time of reaching peak concentration and prolonged the half-life in aqueous humor. These results indicate that 0.5% pilocarpine with sodium hyaluronate significantly increases ocular bioavailability of pilocarpine.