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薬理と治療
Abstract
Objectives Gellan gum is a thickening agent and is used for pharmaceutical formulations including eyedrops. To investigate whether gellan gum improves the availability of eyedrops, we conducted the ocular retention tests using albino rabbits on formulations containing gellan gum or hypromellose(HPMC)/alginate, and compared the remaining amounts of active ingredients after antimicrobial eyedrops instillation. Methods Fluorescein sodium solutions containing gellan gum or HPMC/alginate were instilled in the conjunctiva of albino rabbits. The luminescence of fluid was observed under cobalt blue light, and measured the retention time when no luminescence was detected on the tear meniscus. For the availability tests, sulphamethoxazole(SMX)formulation containing gellan gum and commercial formulation containing HPMC/alginate was instilled, and highperformance liquid chromatography(HPLC)determined the amounts of the active ingredients in tear fluids collected at 15, 30 and 60 minutes after instillation. Results Gellan gum improved fluid retention in a concentration-dependent manner, with significant increase at 0.4%(P<0.05). The retention times of formulations containing gellan gum or HPMC/alginate were significantly longer than control(0.9% saline). The HPLC analysis showed SMX instilled with gellan gum remained on the ocular surface until 60 min after instillation at more than MIC. In HPMC/alginate formulation, the active ingredients remained until 15 min but not at 60 min after instillation. The gellan gum formulation retained significantly higher amount of SMX than HPMC/alginate formulation at 60 min(P<0.05). Conclusions Gellan gum prolonged the eyedrops retention, and its antimicrobial formulation showed its availability as long as 60 min with biologically active concentration in the eye.
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