Apraclonidine

Apraclonidine (INN), also known as Iopidine, is a sympathomimetic used in glaucoma therapy. It is an α₂-adrenergic agonist and a weak alpha-1 adrenergic receptor agonist.

Topical apraclonidine is administered at a concentration of 1% for the prevention and treatment of postsurgical intraocular pressure elevation and 0.5% for short-term adjunctive therapy in patients on maximally tolerated medical therapy who require additional redirection of intraocular pressure. One drop is usually added one hour prior to laser eye surgery and another drop is given after the procedure is complete.

Clinical uses

Apraclonidine is indicated for the short-term adjunctive treatment of patients on maximally tolerated medical therapy who require additional reduction. Patients on maximally tolerated medical therapy who are treated with apraclonidine to delay surgery should have frequent follow-up examinations and treatment should be discontinued if the intraocular pressure rises significantly.

Apraclonidine may be useful in the diagnosis of Horner's syndrome. In Horner's syndrome, the sympathetic innervation to the pupillary dilator muscle is lost. The affected pupil is thus miotic and the pupillary dilator responds to denervation by increasing alpha-1 receptors. Apraclonidine is useful in this case due to its weak alpha-1 adrenergic properties. When applied to the denervated (and thus hyper-sensitive) pupillary dilator muscle, a super-normal dilatory response is generated in which the pupil dilates to a degree greater than that which would be seen in a non-denervated muscle. This causes the reversal of anisocoria that is characteristic of Horner's.

Topical apraclonidine can also decrease IOP in glaucoma patients by increasing trabecular outflow, in a similar way to clonidine, but without the cardiovascular side effects.

External links

• Iopidine prescribing information (from the FDA website)
• Simple information on Apraclonidine

References

• Chen P, Chen J, Lu D, Chen Y, Hsiao C (2006). "Comparing efficacies of 0.5% apraclonidine with 4% cocaine in the diagnosis of horner syndrome in pediatric patients". J Ocul Pharmacol Ther 22 (3): 182â€"7. doi:10.1089/jop.2006.22.182. PMID 16808679. 
• Aslanides l, Tsiklis N, Ozkilic E, Coskunseven E, Pallikaris l, Jankov M (2006). "The effect of topical apraclonidine on subconjunctival hemorrhage and flap adherence in LASIK patients". J Refract Surg 22 (6): 585â€"8. PMID 16805122. 
• Koc F, Kansu T, Kavuncu S, Firat E (2006). "Topical apraclonidine testing discloses pupillary sympathetic denervation in diabetic patients". J Neuroophthalmol 26 (1): 25â€"9. doi:10.1097/01.wno.0000204648.79744.71. PMID 16518162. 
• Garibaldi D, Hindman H, Grant M, Iliff N, Merbs S (2006). "Effect of 0.5% apraclonidine on ptosis in Horner syndrome". Ophthal Plast Reconstr Surg 22 (1): 53â€"5. doi:10.1097/01.iop.0000196322.05586.6a. PMID 16418668. 
• Onal S, Gozum N, Gucukoglu A (2005). "Effect of apraclonidine versus dorzolamide on intraocular pressure after phacoemulsification". Ophthalmic Surg Lasers Imaging 36 (6): 457â€"62. PMID 16355950.