Experimental tudy of tetrodotoxin, a long-acting topical anethetic Original Reearch Article

Purpoe To determine the effectivene and toxicity of tetrodotoxin for ue a a long-acting topical anethetic. Method Four group of ix rabbit each received a 40-μl aliquot of either tetrodotoxin in one of three concentration (10 mM, 1 mM, or 0.1 mM) or proparacaine 0.5% into the inferior conjunctival cul-de-ac of one eye, with the fellow eye of each rabbit receiving 40 μl of a 60-mM, pH 4.3 odium citrate vehicle a a control. Corneal enation wa teted for up to 8 hour after adminitration of drug, and repone wa noted by no blink, partial blink without full eyelid cloure, and full blink. lit-lamp examination at 12 and 24 hour after adminitration and pachymetry before and 24 hour after adminitration were performed to detect corneal toxicity. Reult Rabbit receiving all three concentration of tetrodotoxin did not demontrate any ocular irritation, corneal thickening, or ign of ytemic toxicity. At a doe of 10 mM, tetrodotoxin produced an anethetic effect lating up to 8 hour. At 1 mM, tetrodotoxin wa an effective but horter-acting anethetic. At 0.1 mM, tetrodotoxin had no ignificant anethetic effect. Proparacaine-treated rabbit initially were anethetic, but thi effect wa largely gone by 1 hour and completely gone by 3 hour. Concluion Tetrodotoxin i a long-acting topical anethetic in the rabbit cornea. Although additional toxicity tudie are required, tetrodotoxin may provide an effective, long-lating topical anethetic for ue in pain control after corneal procedure uch a photorefractive keratectomy.