A Novel Selective Soluble Guanylate Cyclase Activator, MGV354, Lowers Intraocular Pressure in Preclinical Models, Following Topical Ocular Dosing.

Purpose: The nitric oxide/soluble guanylate cyclase/protein kinase G (NO/sGC/PKG) is known to be involved in the regulation of intraocular pressure (IOP) and may be dysregulated in glaucoma. The purpose is to demonstrate that the sGC activator MGV354 lowers IOP in a monkey model of glaucoma and could be considered as a possible new clinical drug candidate. Methods: Changes to cGMP were assessed in primary human trabecular meshwork (hNTM) cells and binding studies were conducted using human sGC full-length protein. Ocular safety tolerability, exposure, and efficacy studies were conducted in rabbit and monkey models following topical ocular dosing of MGV354. Results: sGC was highly expressed in the human and cynomolgus monkey outflow pathways. MGV354 had a 7-fold greater Bmax to oxidized sGC compared to that of reduced sGC and generated an 8- to 10-fold greater cGMP compared to that of a reduced condition in hTM cells. A single topical ocular dose with MGV354 caused a significant dose-dependent reduction of 20% to 40% (versus vehicle), lasting up to 6 hours in pigmented rabbits and 24 hours postdose in a cynomolgus monkey model of glaucoma. The MGV354-induced IOP lowering was sustained up to 7 days following once-daily dosing in a monkey model of glaucoma and was greater in magnitude compared to Travatan (travoprost)-induced IOP reduction. Mild to moderate ocular hyperemia was the main adverse effect noted. Conclusions: MGV354 represents a novel class of sGC activators that can lower IOP in preclinical models of glaucoma. The potential for sGC activators to be used as effective IOP-lowering drugs in glaucoma patients could be further determined in clinical studies.

Does Profile of Hemoglobin Eß-thalassemia Patients Change After Splenectomy? Experience of a Tertiary Thalassemia Care Centre in Eastern India.

Hemoglobin Eß-thalassemia is by far the commonest form of thalassemia intermedia. Its phenotype ranges from mild anemia to severe transfusion-dependency necessitating splenectomy in many patients. The present study aimed to systematically analyze both clinical as well as laboratory parameters in profile of Eß-thalassemia patients after splenectomy in terms of transfusion requirement, infections and other complications. Retrospective study conducted over a period of 3 years included 72 cases of splenectomized Eß-thalassaemia patients, considering decrease in transfusion requirements, new complications, antibiotic, anti-malarial prophylaxis and iron chelation therapy. Out of 1380 registered Eß-thalassemia patients, 618 (44.78 %) were regularly transfused and 72(5.22 %) underwent splenectomy. Mean age of diagnosis was 10.3 years. Nineteen patients (26.4 %) underwent splenectomy between 5 and 10 years, 38 cases (52.7 %) between 10 and 20 years. The leading cause (51.39 %) for splenectomy was mechanical discomfort. Mean steady state hemoglobin raised from pre-splenectomy level of 5.43-6.8 gm/dl after splenectomy. Mean transfusion requirement reduced from 18.1 to 7.8 units/year. Mean serum ferritin level increased from 907.58 to 1,091.6 ng/ml. Post-splenectomy; 21 (29.17 %) patients developed facial deformities, 17 (23.6 %) delayed pubertal growth, 11 (15.28 %) venous thromboembolism, five (6.94 %) pulmonary hypertension and four (5.5 %) had extramedullary hematopoiesis. Five (6.96 %) patients had documented bacterial infections and two (2.78 %) suffered from malaria. Forty eight patients (66.67 %) started with iron chelation therapy; but majority (52.7 %) stopped. Major advantage of splenectomy is reduced transfusion requirement, though it cannot prevent skeletal abnormalities and delayed pubertal growth. In resource constraint countries like India, routine anti-malarial and antibacterial prophylaxis is not desirable; iron chelation therapy should be encouraged and ensured.