Title: Apraclonidine
CAS Registry Number: 66711-21-5
CAS Name: 2,6-Dichloro-N1-(4,5-dihydro-1H-imidazol-2-yl)-1,4-benzenediamine
Additional Names: 2,6-dichloro-N¢-2-imidazolidinylidene-1,4-benzenediamine; 2-[(4-amino-2,6-dichlorophenyl)imino]imidazolidine; p-aminoclonidine; aplonidine
Manufacturers' Codes: NC-14
Molecular Formula: C9H10Cl2N4
Molecular Weight: 245.11
Percent Composition: C 44.10%, H 4.11%, Cl 28.93%, N 22.86%
Literature References: a2-Adrenergic agonist; structural analog of clonidine, q.v. Synthesis: B. Rouot, G. LeClerc, Bull. Soc. Chim. Fr. Pt. 2, 520 (1979). Prepn (not claimed) and use in treatment of intraocular pressure: B. M. York, Jr., US 4517199 (1985 to Alcon). Pharmacology: B. Rouot et al., C.R. Seances Acad. Sci. Ser. D 286, 909 (1978). Receptor binding studies: D. C. U'Prichard, Prog. Clin. Biol. Res. 71, 53 (1981). D. C. Stump, D. E. MacFarlane, J. Lab. Clin. Med. 102, 779 (1983). Clinical pharmacology: D. A. Abrams et al., Arch. Ophthalmol. 105, 1205 (1987). Clinical evaluation in treatment of intraocular pressure: A. L. Robin et al., ibid. 1208; as additive to maximally tolerated medical therapy in glaucoma: A. L. Robin et al., Am. J. Ophthalmol. 120, 423 (1995).
Properties: Solid, mp >230°.
Melting point: mp >230°
Derivative Type: Hydrochloride
CAS Registry Number: 73218-79-8
Manufacturers' Codes: ALO-2145
Trademarks: Iopidine (Alcon)
Molecular Formula: C9H10Cl2N4.HCl
Molecular Weight: 281.57
Percent Composition: C 38.39%, H 3.94%, Cl 37.77%, N 19.90%
Derivative Type: Dihydrochloride
CAS Registry Number: 73217-88-6
Molecular Formula: C9H10Cl2N4.2HCl
Molecular Weight: 318.03
Percent Composition: C 33.99%, H 3.80%, Cl 44.59%, N 17.62%
Properties: uv max (ethanol): 254, 304 nm (e 1800, 2500).
Absorption maximum: uv max (ethanol): 254, 304 nm (e 1800, 2500)
Therap-Cat: Treatment of post-surgical elevated intraocular pressure.
Keywords: a-Adrenergic Agonist; Antiglaucoma.
Apramycin Aprepitant Aprindine Aprinocarsen Aprobarbital

Systematic (IUPAC) name
2,6-dichloro-N- (4,5-dihydro-1H-imidazol-2-yl) benzene-1,4-diamine
Clinical data
Trade names Iopidine
AHFS/Drugs.com monograph
MedlinePlus a608005
Legal status Rx only
Routes Ophthalmic solution
Pharmacokinetic data
Protein binding 98.7%
Half-life 8 hours
CAS number 66711-21-5 YesY
ATC code S01EA03
PubChem CID 2216
DrugBank DB00964
ChemSpider 2130 YesY
KEGG D07461 YesY
Chemical data
Formula C9H10Cl2N4 
Mol. mass 245.108 g/mol
 YesY (what is this?)  (verify)

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.