Ocular penetration of oral clarithromycin in humans

Clarithromycin has a wide spectrum of activity against many gram-positive a nd gram-negative organisms, intracellular pathogens, and opportunistic path ogens. To examine the penetration of clarithromycin in the ocular tissues, 21 patients who underwent elective cataract surgery (Group I) received a si ngle 500-mg dose of clarithromycin orally either 4, 8, 10, 12, or 22 hours before cataract surgery, and 21 patients who underwent elective retina/vitr eous surgery (Group II) received 500 mg every 12 hours orally for 3 days be fore the surgery with the last dose given either 3, 6, 8, 11, or 24 hours b efore the surgery. Serum from all patients was assayed for clarithromycin p rior to drug administration and at the time ocular specimen was taken. Aque ous, iris, and vitreous samples were also assayed for clarithromycin concen tration. The concentrations of clarithromycin in the aqueous fluid 4, 8, 10 , 12, and 22 hours after administration were: (mean +/- SD) 0.13+/-0.05, 0. 137+/-0.11, 0.074+/-0.03, 0.06+/-0.02, and 0.074+/-0.04 mu g/ml, respective ly. Concentration of clarithromycin in vitreous 3, 6, 8, 11, and 24 hours a fter administration were: (mean +/- SD) 0.11+/-0.02, 0.257+/-0.13, 0.27+/-0 .21, 0.307+/-0.26 and 0.108+/-0.07 mu g/ml, respectively. The mean concentr ation of clarithromycin in the iris was 6.2 mu g/g. In conclusion, this data suggest that clarithromycin widely penetrates and adequately concentrates in the aqueous humor, vitreous humor, and iris tiss ue after oral administration and therefore is effective in the management o f many infectious ocular conditions.