| Objective: To study the pharmacokinetics of avastin in aqueous humor and vitreous after interanterior chamber injection of avastin 1.25mg (0.05ml) in rabbit eyes in order to provide evidence for the clinical application of this drug.Methods: Fifty rabbits/one hundred eyes were assigned randomly to three groups (A, B, C). Group A, Avastin (1.25mg /0.05ml) were injected into the anterior chamber of left eyes of rabbits, and equal amount (0.05ml) of balanced salt solution were injected into the anterior chamber of right eyes; Group B, Avastin (1.25mg /0.05ml) were injected into the anterior chamber of left eyes, and no drug were injected into the anterior chamber of right eyes; Group C, 0.05ml of balanced salt solution were injected into the anterior chamber of left eyes, and no drug were injected into the anterior chamber of right eyes. The both eyes of experimental animals were enucleated at the 1 st,4 st,7 st,14 st,30 st day after anterior chamber injection, and then the aqueous humor and vitreous of both eyes of all experimental animals were collected . The concentration of avastin in aqueous humor and vitreous were measured by enzyme linked immunosorbent assay (ELISA). The parameters of pharmacokinetics of avastin both in aqueous humor and vitreous were calculated through 3p97 software .The concentration of avastin in aqueous humor and vitreous were analyzed by t-test.Results:Pharmacokinetic parameters: Group A and B, after interanterior chamber injection of avastin 1.25mg (0.05ml) of left eyes,the avastin concentration in aqueous humor of left eyes reached a peak at the 1st day, the avastin concentration were (18.247±0.06)μg/ml and (19.248±0.12)μg/ml, respectively. The aqueous humor half-life of the left eyes were about 4.55 days and 4.79 days, respectively. Group A, the avastin concentration in aqueous humor of right eyes reached a peak concentration of (10.241±0.23)μg/ml 7 days after drug administration. At the 30st day, the avastin concentration in aqueous humor of left and right eyes were (3.953±0.16)μg/ml and (2.852±0.25)μg/ml, respectively. Group A and B, the avastin concentration in vitreous of left eyes reached a peak at the 4st day, the avastin concentration were (17.847±0.26)μg/ml and (18.275±0.30)μg/ml, respectively. The vitreous half-life of the left eyes were about 5.12 days and 5.69 days, respectively. Group A, the avastin concentration in vitreous of right eyes were from (1.104±0.10)μg/ml at the 1st day to (3.214±0.16)μg/ml at the 30st day, which reached a peak concentration of (6.25±0.21)μg/ml 4 days after drug administration. The avastin con- centration showed parallel changes in aqueous humor and vitreous between group A and B.The comparison results of the avastin concentration in aqueous humor and vitreous at different times after interanterior chamber injection of avastin:The left eyes of rabbits, avastin concentration in aqueous humor were higher than the avastin concentration in vitreous at the 1st day, the avastin concentration in aqueous humor were lower than the avastin concentration in vitreous at the 4st,7st,14st,30st day. There were statistical significant of the comparison results of the avastin concentration in aqueous humor and vitreous(P < 0.01). The right eyes of rabbits,the avastin concentration in aqueous humor were higher than the avastin concentration in vitreous at the 1st,4st day,the avastin concentration in aqueous humor were lower than the avastin concentration in vitreous at the 7st,14st,30st day. Except the 14st,30st day, about the other times, there were statistical significant of the comparison results of the avastin con- centration in aqueous humor and vitreous (P < 0.01).The comparison results of the avastin concentration in aqueous humor and vitreous between group A and B: The avastin concentration in aqueous humor of left eyes,vitreous of left eyes,aqueous humor of right eyes and vitreous of right eyes were almost the same. No significant difference of the avastin concentration in aqueous humor and vitreous of the left eyes and right eyes between group A and group B (P>0.05).Conclusions: Avastin concentration are detected in both eyes of rabbits after interanterior chamber injection of avastin 1.25mg (0.05ml) in left eyes of rabbits. The aqueous humor half-life are about 4.55-4.79 days in the injected eyes. Avastin concentration in aqueous humor of the injected eyes reach a peak at the 1st day after drug administion. Avastin concentration in aqueous humor of the uninjected eyes reach a peak at the 7st day after drug administion. The vitreous half-life are about 5.12-5.69 days in the injected eyes. Avastin concentration in vitreous of the injected eyes reach a peak at the 4st day after drug administion. Avastin concentration in aqueous humor are higher at the beginning. However avastin concentration in vitreous gradually exceed the avastin concentration in aqueous humor from lower to higher.
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