Naphazoline hydrochloride and naphazoline nitrate are white or almost white crystalline powders soluble 1 in 6 and 1 in 36 water, respectively. These are potent sympathomimetic vasoconstrictors with a direct alpha-adrenergic receptor stimulatory action, and may be used as topical decongestants in 0.05% or 0.1% eyedrops. Frequent application of these solutions will produce a reactive hyperaemia. Instillation should not be repeated in less than 4-6 hours to avoid this rebound congestion.
Naphazoline eyedrops cause slight mydriasis and are contra-indicated in patients with actual or suspected closed-angle glaucoma.
Although not administered systemically, topical application of naphazoline has resulted in systemic absorption, and it is readily absorbed from the gastro-intestinal tract (Martindale, 1977).
