摘要：

The potential of liposomes as an ophthalmic drug delivery system was investigated by comparing disposition and pupillary dilatory effect of atropine base and atropine sulphate in solution and various liposomal forms when topically instilled to the rabbit eye. Atropine base entrapped in multilamellar lipid vesicles (MLVs) with positive surface charge displayed the most prolonged effect lasting up to 12 h. MLVs with neutral and negative charges maintained the effect for 9 h while atropine in solution form was effective for only 7 h. Preparations containing atropine sulphate displayed a similar pattern although were shorter-acting than corresponding base products. All preparations whether salt or base, were equally effective in producing maximal response. In vivo drug disposition studies indicated the liposomal form produced significantly higher drug levels in the anterior tissues of the eye up to 8 h after instillation. Increased ocular bioavailability of atropine to these tissues was attributed to enhancement of pulse entry with little evidence of sustained drug release. It could be concluded that liposome encapsulation extended the duration of action and favourably altered disposition of atropine when topically instilled to the rabbit eye.

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