Potential role of Rho-associated protein kinase inhibitors for glaucoma treatment.

Rho kinase inhibitors are widely considered as a new treatment for glaucoma. Rho kinase inhibition has been shown in vitro and in vivo to lower intraocular pressure. Furthermore in the first clinical reports involving healthy human subjects, the results were quite promising. The potential of this new class of medicines is enormous in a field where there were not many developments lately. The inhibition of Rho kinase lowers the intraocular pressure by increasing the outflow through the trabecular meshwork. Increased blood flow to the optic nerve and a possible delay of optic nerve cell death has also been reported. As a consequence, the exploration of pharmacological inhibitors of Rho kinase signaling is actively being pursued by a number of pharmaceutical companies such as Senju Pharmaceuticals, Novartis, Kowa, Santen, Aerie, Inspire and others. In this article, we review the latest patents in this field, with their corresponding literature, regarding Rho kinase inhibitors for the treatment of intraocular pressure and summarize the many roles of Rho kinase signaling in the eye.

Effects of diadenosine tetraphosphate on FGF9-induced chloride flux changes in achondroplastic chondrocytes.

Achondroplasia, the most common type of dwarfism, is characterized by a mutation in the fibroblast growth factor receptor 3 (FGFR3). Achondroplasia is an orphan pathology with no pharmacological treatment so far. However, the possibility of using the dinucleotide diadenosine tetraphosphate (Ap(4)A) with therapeutic purposes in achondroplasia has been previously suggested. The pathogenesis involves the constitutive activation of FGFR3, resulting in altered biochemical and physiological processes in chondrocytes. Some of these altered processes can be influenced by changes in cell volume and ionic currents. In this study, the action of mutant FGFR3 on chondrocyte size and chloride flux in achondroplastic chondrocytes was investigated as well as the effect of the Ap(4)A on these processes triggered by mutant FGFR3. Stimulation with the fibroblast growth factor 9 (FGF9), the preferred ligand for FGFR3, induced an enlarged achondroplastic chondrocyte size and an increase in the intracellular chloride concentration, suggesting the blockade of chloride efflux. Treatment with the Ap(4)A reversed the morphological changes triggered by FGF9 and restored the chloride efflux. These data provide further evidence for the therapeutic potential of this dinucleotide in achondroplasia treatment.

Design of novel melatonin analogs for the reduction of intraocular pressure in normotensive rabbits.

Melatonin, the MT(2) melatonin receptor agonist IIK7 [N-butanoyl-2-(2-methoxy-6H-isoindolo[2,1-a]indol-11-yl)ethanamine], and the putative MT(3) melatonin receptor agonist 5-MCA-NAT [5-methoxycarbonylamino-N-acetyltryptamine] have previously been shown to reduce intraocular pressure (IOP) in ocular normotensive rabbits. To gain a better understanding of the structure-activity relationship of compounds that activate MT(2) and MT(3) receptors mediating reductions in IOP, novel melatonin analogs with rationally varied substitutions were synthesized and tested for their effects on IOP in ocular normotensive rabbits (n = 160). All synthesized melatonin analogs reduced IOP. The best-effect lowering IOP was obtained with the analogs INS48848 [methyl-1-methylene-2,3,4,9-tetrahydro-1H-carbazol-6-ylcarbamate], INS48862 [methyl-2-bromo-3-(2-ethanamidoethyl)-1H-indol-5-ylcarbamate], and INS48852 [(E)-N-(2-(5-methoxy-1H-indol-3-yl)ethyl)-3-phenylprop-2-enamide]. These compounds produced dose-dependent decreases in IOP that were maximal at 0.1 mM (total dose of 0.259 µg for INS48848, 0.354 µg for INS48862, and 0.320 µg for INS48852) and 1 mM (total dose of 2.59 µg for INS48848, 3.54 µg for INS48862, and 3.20 µg for INS48852), with maximal reductions of 36.0 ± 4.0, 24.0 ± 1.5, and 30.0 ± 1.5% for INS48848, INS48862, and INS48852, respectively. Studies using melatonin receptor antagonists (luzindole, prazosin, and DH97 [N-pentanoyl-2-benzyltryptamine]) indicated that INS48862 and INS48852 activate preferentially a MT(2) melatonin receptor and suggest that INS48848 may act mainly via a MT(3) receptor. The most effective compounds were also well tolerated in a battery of standard ocular surface irritation studies. The implication of these findings to the design of novel drugs to treat ocular hypertension is discussed.