Gliclazide is used for control of hyperglycemia in gliclazide-responsive diabetes mellitus of stable, mild, non-ketosis prone, type 2 diabetes. It is used when diabetes cannot be controlled by proper dietary management and exercise or when insulin therapy is not appropriate.
National Kidney Foundation (2012 Update) claims that Gliclazide does not require dosage uptitration even in end stage kidney disease.
Hypoglycemia - while it was shown to have the same efficacy as glimepiride, one of the newer sulfonylureas, the European GUIDE study has shown that it has approximately 50% less hypoglycaemic confirmed episodes in comparison with glimepiride.
Gliclazide overdose may cause severe hypoglycemia, requiring urgent administration of glucose by IV and monitoring.
Mechanism of action
Gliclazide selectively binds to sulfonylurea receptors (SUR-1) on the surface of the pancreatic beta-cells. It was shown to provide cardiovascular protection as it does not bind to sulfonylurea receptors (SUR-2A) in the heart. This binding effectively closes these K+ ion channels. This decreases the efflux of potassium from the cell which leads to the depolarization of the cell. This causes voltage dependent Ca2+ ion channels to open increasing the Ca2+ influx. The calcium can then bind to and activate calmodulin which in turn leads to exocytosis of insulin vesicles leading to insulin release. The mouse model of MODY diabetes suggested that the reduced gliclazide clearance stands behind their therapeutic success in human MODY patients, but Urbanova et al. found that human MODY patients respond differently and that there was no consistent decrease in gliclazide clearance in randomly selected HNF1A-MODY and HNF4A-MODY patients.
Its classification has been ambiguous, as literature uses it as both a first-generation and second-generation sulfonylurea.
According to the Biopharmaceutical Classification System (BCS), gliclazide falls under the BCS Class II drug, which is poorly soluble and highly permeable.
Gliclazide undergoes extensive metabolism to several inactive metabolites in human beings, mainly methylhydroxygliclazide and carboxygliclazide. CYP2C9 is involved in the formation of hydroxygliclazide in human liver microsomes and in a panel of recombinant human P450s in vitro. But the pharmacokinetics of gliclazide MR are affected mainly by CYP2C19 genetic polymorphism instead of CYP2C9 genetic polymorphism.
^Schernthaner, G.; Grimaldi, A.; Di Mario, U.; Drzewoski, J.; Kempler, P.; Kvapil, M.; Novials, A.; Rottiers, R.; et al. (2004). "GUIDE study: Double-blind comparison of once-daily gliclazide MR and glimepiride in type 2 diabetic patients". European Journal of Clinical Investigation. 34 (8): 535–42. doi:10.1111/j.1365-2362.2004.01381.x. PMID15305887.
^Park, J; Kim, KA; Park, PW; Park, CW; Shin, JG (2003). "Effect of rifampin on the pharmacokinetics and pharmacodynamics of gliclazide". Clinical Pharmacology & Therapeutics. 74 (4): 334–40. doi:10.1016/S0009-9236(03)00221-2. PMID14534520.
^Lawrence, C. L.; Proks, P.; Rodrigo, G. C.; Jones, P.; Hayabuchi, Y.; Standen, N. B.; Ashcroft, F. M. (2001). "Gliclazide produces high-affinity block of KATP channels in mouse isolated pancreatic beta cells but not rat heart or arterial smooth muscle cells". Diabetologia. 44 (8): 1019–25. doi:10.1007/s001250100595. PMID11484080.
^Urbanova, J.; et al. (2015). "Half-Life of Sulfonylureas in HNF1A and HNF4A Human MODY Patients is not Prolonged as Suggested by the Mouse Hnf1a-/- Model". Current Pharmaceutical Design. 21: 5736–5748. doi:10.2174/1381612821666151008124036.
^Ballagi-Pordány, György; Köszeghy, Anna; Koltai, Mária-Zsófia; Aranyi, Zoltán; Pogátsa, Gábor (1990). "Divergent cardiac effects of the first and second generation hypoglycemic sulfonylurea compounds". Diabetes Research and Clinical Practice. 8 (2): 109–14. doi:10.1016/0168-8227(90)90020-T. PMID2106423.
^Shimoyama, Tatsuhiro; Yamaguchi, Shinya; Takahashi, Kazuto; Katsuta, Hidenori; Ito, Eisuke; Seki, Hiroyuki; Ushikawa, Kenji; Katahira, Hiroshi; et al. (2006). "Gliclazide protects 3T3L1 adipocytes against insulin resistance induced by hydrogen peroxide with restoration of GLUT4 translocation". Metabolism. 55 (6): 722–30. doi:10.1016/j.metabol.2006.01.019. PMID16713429.