Carteolol HCl

Beta-adrenergic antagonist are an important class of drugs for the treatment of various heart diseases, such as high blood pressure, insufficiency of blood flow to the heart muscle, irregular heart beat, thickened heart muscle, and decreased ability of the heart to empty or fill normally. β-Blockers can also be used to treat migraine headache and increased eye pressure (glaucoma). Carteolol is a nonselective beta-adrenoceptor antagonist.

In vitro: Previous findings demonstrate that carteolol, unlike xamoterol, is a nonconventional partial agonist, which causes agonistic effects via interaction with the low-affinity propranolol-resistant site of β1-adrenoceptors and antagonistic actions by the high-affinity site of the same receptors [1].

In vivo: Both 8-OH carteolol and carteolol suppressed the water-load induced intraocular pressure (IOP) rise in rabbits. 8-OH carteolol was more effective in suppressing water-load induced IOP rise in rabbits compared with carteolol on equimolar basis. Both 8-OH carteololand carteolol caused a significant decrease in IOP in monkeys. 8-OH carteolol was estimated to be more potent than carteolol in lowering IOP on equimolar basis in monkeys [2].

Clinical trial: The new alginate formulation of long-acting carteolol 1% given once daily is as effective as standard 1% carteolol given twice daily, with no meaningful differences regarding safety. The new alginate formulation of long-acting 1% carteolol given once a day is effective and well tolerated by glaucoma patients requiring chronic treatment [3].

Reference:
[1] Maura Floreani, Guglielmina Froldi, Luigi Quintieri, Katia Varani, Pier Andrea Borea, Maria Teresa Dorigo and Paola Dorigo.  In Vitro Evidence That Carteolol Is a Nonconventional Partial Agonist of Guinea Pig Cardiac β1-Adrenoceptors: A Comparison with Xamoterol. JPET 315:1386–1395, 2005
[2] Sugiyama K, Enya T, Kitazawa Y.  Ocular hypotensive effect of 8-hydroxycarteolol, a metabolite of carteolol. Int Ophthalmol. 1989 Jan;13(1-2):85-9.
[3] Trinquand C, Romanet JP, Nordmann JP, Allaire C; Groupe d'étude.  Efficacy and safety of long-acting carteolol 1% once daily. A double-masked, randomized study. J Fr Ophtalmol. 2003 Feb;26(2):131-6.


A comparison of the opacifying effects of carteolol.HCl and 8-hydroxycarteolol.HCl in the isolated porcine cornea.[Pubmed:2340982]

Fundam Appl Toxicol. 1990 Apr;14(3):554-9.

Using an in vitro method the authors have investigated whether 8-hydroxycarteolol.HCl(8-OH carteolol) and 8-OH carteolol with benzalkonium chloride affected intact isolated porcine corneas to the same or to a different degree as carteolol.HCl (carteolol) or carteolol with benzalkonium chloride. These ophthalmically used drugs were applied as solutions of varying concentrations to the epithelial surface only, to the endothelial surface only, or to both surfaces of porcine corneas. The resultant opacities were determined using an opacitometer. In general, 8-OH carteolol and 8-OH carteolol with benzalkonium chloride caused less opacity to develop than carteolol and carteolol with benzalkonium chloride. This suggests that 8-OH carteolol may be a safer drug than carteolol for ophthalmic use. It is very interesting to note that compounds with two nitrogens, e.g., 8-OH carteolol, caused greater opacity in the intact cornea when applied to the endothelial surface than when applied to both the epithelial and endothelial surfaces; however, compounds with none or one nitrogen caused greater opacity in the intact cornea when applied to both surfaces than when applied to the endothelial surface.