An Evaluation of the Effectiveness of Intramuscular Atropine or Homatropine Eyedrops in Preventing the Effects of Physostigmine Eyedrops on Human Vision

Abstract

SUMMARYAn intramuscular injection of 2 mg atropine sulphate was given at either 8 or 120 min prior to instillation of 0-25 % physostigmine sulphate eyedrops. In this way, the maximum accommodative change and the concomitant reduction in contrast sensitivity caused by physostigmine coincided with, respectively, the peak plasma atropine concentration or the fully developed mydriasis and reduction of near-point accommodation caused by atropine. Atropine at both times did not affect the miosis, the reduction in near-point, the increase in accommodation or the reduction in contrast sensitivity caused by physostigmine. Contrast sensitivity to a phasereversed grating pattern was actually diminished by atropine, though this was not statistically significant. By contrast, 2 % homatropine hydrobromide eyedrops did effectively anatagonize physostigmine's actions. This indicates that the rate of delivery of atropine from the intramuscular injection was insufficient to compete against the ocular effects of physostigmine.

Synergism Between Anticholinergic and Oxime Treatments Against Sarin-Induced Ocular Insult in Rats

“…Following the sarin terrorist attack experience in Japan, it has been reported that systemic atropine treatment showed no benefit in counteracting the sarin-induced miosis (Ohbu et al, 1997;Yanagisawa et al, 2006). This lack of effect of im atropine treatment on pupil diameter following ChE inhibition was also shown in clinical trials where volunteers were topically exposed to physostigmine and treated with im 2 mg atropine (Kay and Morrison, 1988). In an unexposed group, 1 mg of im administered atropine showed a weak pupil widening of only 20% (Mirakhur and Dundee, 1980).…”

“…In casualties with additional symptoms such as lacrimation, increased salivation, rhinorrhea, tightness in the chest, sweating, nausea, vomiting, and abdominal cramps (considered mild casualties), systemic treatment of atropine and oximes intramuscular (im) should be used with the addition of topical treatment if ocular symptoms are present (Holstege et al, 1997;Sidell, 1997;Weissman and Raveh, 2011). Although im atropine treatment showed no beneficial role in ameliorating ocular symptoms in humans, (Grob and Harvey, 1958;Kay and Morrison, 1988;Ohbu et al, 1997;Yanagisawa et al, 2006) unless given at very high doses (Cannard, 2006;Nozaki and Aikawa, 1995a), the use of 2-PAM or HI-6 im treatment alone or 2-PAM with atropine has been shown to widen pupils in rabbits following VX (O-ethyl-S-[2 (diisopropylamino)ethyl] methylphosphonothioate) or after sarin exposure (Macic et al, 1990;Vijayaraghavan et al, 2007) and reactivate inhibited ChE (Lund-Karlsen et al, 1976). In 2 cases of sarinexposed individuals, a combined im treatment of 2-PAM and atropine presented a pupil widening benefit compared with others, who received atropine alone (Nozaki et al, 1995b;Ohbu et al, 1997).…”

Η επίδραση της ενστάλαξης οφθαλμικών σταγόνων στην ευαισθησία στις αντιθέσεις φωτεινότητας (contrast sensitivity)

“…Ζ έλεζε δελ απέηξεςε ηελ παξνδηθή κείσζε ηεο ΔΑΦ απφ ηε θπζνζηηγκίλε. Αληίζεηα, νη νθζαικηθέο ζηαγφλεο νκναηξνπίλεο πδξνβξσκηθήο 2% αληαγσλίζηεθαλ απνηειεζκαηηθά ηελ επίδξαζε ηεο θπζνζηηγκίλεο 165. Ο Zulauf ην 1990 κειέηεζε ηε βξαρππξφζεζκε (2 ψξεο) επίδξαζε ηεο ελζηάιαμεο ησλ νθζαικηθψλ θνιιπξίσλ πηλδνιφιεο 1% θαη ηηκνιφιεο 0,5% ζηελ ΔΑΦ θπζηνινγηθψλ αηφκσλ.…”