SGLT2 inhibitor: Difference between revisions

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{{Short description|Class of medication}}

'''SGLT2 inhibitors,''' also called '''gliflozins''' or '''flozins''', are a class of medications that inhibit [[sodium-glucose transport proteins]] in the [[nephron]] (the functional units of the [[kidney]]), unlike [[SLC5A1|SGLT1 inhibitor]]s that perform a similar function in the [[intestinal mucosa]]. The foremost metabolic effect of this is to inhibit [[renal glucose reabsorption|reabsorption of glucose in the kidney]] and therefore lower [[blood sugar]]. They act by inhibiting [[sodium-glucose transport protein 2]] (SGLT2). SGLT2 inhibitors are used in the treatment of [[type 2 diabetes]]. Apart from blood sugar control, gliflozins have been shown to provide significant cardiovascular benefit in people with [[type 2 diabetes]]. {{As of|2014}}, several medications of this class had been approved or were under development. In studies on [[canagliflozin]], a member of this class, the medication was found to enhance blood sugar control as well as reduce [[body weight]] and systolic and diastolic [[blood pressure]].

The 2022 [[American Diabetes Association|ADA]] standards of medical care in diabetes include SGLT2 inhibitors as a first line [[pharmacological therapy]] for type 2 diabetes (usually together with metformin), specifically in patients with [[chronic kidney disease]], [[cardiovascular disease]] or [[heart failure]].

A [[systematic review]] and [[network meta-analysis]] comparing SGLT-2 inhibitors, [[Glucagon-like peptide-1 receptor agonist|GLP-1 agonists]], and [[DPP-4 inhibitors]] demonstrated that use of SGLT2 inhibitors was associated with a 20% reduction in death compared with placebo or no treatment. Another systematic review discussed the mechanisms by which SGLT-2 inhibitors improve cardio-renal function in patients with type 2 diabetes, emphasizing the impacts in improving neural tone.

A meta-analysis including 13 cardiovascular outcome trials found that SGLT-2 inhibitors reduce the risk for three-point [[Major adverse cardiovascular events|MACE]], especially in subjects with an [[estimated glomerular filtration rate]] (eGFR) below 60 ml/min, whereas [[Glucagon-like peptide-1 receptor agonist|GLP-1 receptor agonists]] were more beneficial in persons with higher eGFR. Likewise, the risk reduction due to SGLT-2 inhibitors was larger in populations with a higher proportion of [[albuminuria]], but this relationship was not observed for GLP-1 receptor agonists. This suggests a differential use of the two substance classes in patients with preserved and reduced renal function or with and without [[diabetic nephropathy]], respectively.

Two reviews have concluded that SGLT2 inhibitors benefit patients with atherosclerotic [[major adverse cardiovascular events]] (MACE). One of those studies defined MACE as the composite of [[myocardial infarction]], [[stroke]], or cardiovascular death.

Genital infections seem to be the most common [[adverse effect]] of gliflozins. In [[clinical trial]]s [[mycosis|fungal infections]], [[urinary tract infection]]s and [[osmotic diuresis]] were higher in patients treated with gliflozins.

In May 2015, the [[FDA]] issued a warning that gliflozins can increase risk of [[diabetic ketoacidosis]] (DKA, a serious condition in which the body produces high levels of blood acids called ketones). By reducing glucose blood circulation, gliflozins cause less stimulation of endogenous [[insulin]] secretion or lower dose of exogenous insulin that results in diabetic ketoacidosis. They can specifically cause ''euglycemic'' DKA (euDKA, DKA where the blood sugar is not elevated) because of the renal tubular absorption of ketone bodies. A particularly high risk period for ketoacidosis is the perioperative period. SGLT2 inhibitors may need to be discontinued before surgery, and only recommended when someone is not unwell, is adequately hydrated and able to consume a regular diet. Symptoms of ketoacidosis include nausea, vomiting, abdominal pain, tiredness, and trouble breathing. To lessen the risk of developing ketoacidosis after surgery, the FDA has approved changes to the prescribing information for SGLT2 inhibitor diabetes medicines to recommend they be stopped temporarily before scheduled surgery. [[Canagliflozin]], [[dapagliflozin]], and [[empagliflozin]] should each be stopped at least three days before, and ertugliflozin should be stopped at least four days before scheduled surgery.

In September 2015, the FDA issued a warning related to canagliflozin (Invokana) and canagliflozin/metformin (Invokamet) due to decreased bone mineral density and therefore increased risk of bone fractures. Using gliflozins in combination therapy with metformin can lower the risk of [[hypoglycemia]] compared to other type 2 diabetes treatments such as sulfonylureas and insulin.

Increased risk of lower [[limb amputation]] is associated with canagliflozin but further data is needed to confirm this risk associated with different gliflozins. A [[European Medicines Agency]] review concluded that there is a potential increased risk of lower limb amputation (mostly affecting the toes) in people taking canagliflozin, dapagliflozin and empagliflozin.

In August 2018, the FDA issued a warning of an increased risk of [[Fournier gangrene]] in patients using SGLT2 inhibitors. The absolute risk is considered very low.

In the [[FDA Adverse Event Reporting System]] an increase was reported in events of [[acute kidney injury]] associated with SGLT2 inhibitors, though data from clinical trials actually showed a reduction in such events with SGLT-2 treatment.

Interactions are important for SGLT2 inhibitors because most people with type 2 diabetes are taking many other medications. Gliflozins appear to increase the diuretic effect of [[thiazides]], [[loop diuretics]] and related [[diuretics]] and may increase the risk of [[dehydration]] and [[hypotension]]. It is important to adjust the dose of antidiabetics if the treatment is combination therapy to avoid hypoglycemia. For example, interactions with sulfonylureas have led to severe hypoglycemia presumably due to [[cytochrome P450]].

These are the known members of the gliflozin class:

* [[Bexagliflozin]] was approved in the United States under the brand name Brenzavvy in January 2023.

*[[Enavogliflozin]]

Sodium Glucose cotransporters (SGLTs) are proteins that occur primarily in the kidneys and play an important role in maintaining glucose balance in the blood. SGLT1 and SGLT2 are the two most known SGLTs of this family. SGLT2 is the major transport protein and promotes [[reabsorption]] from the [[glomerular filtration]] glucose back into circulation and is responsible for approximately 90% of the kidney's glucose reabsorption. SGLT2 is mainly expressed in the kidneys on the [[epithelial cells]] lining the first segment of the proximal convoluted tubule. By inhibiting SGLT2, gliflozins prevent the kidneys' reuptake of glucose from the glomerular filtrate and subsequently lower the glucose level in the blood and promote the excretion of glucose in the urine ([[glucosuria]]).

[[File:Mechanism of action .png|thumb|center|upright=3.0|Reabsorption of glucose in the nephron]]

The mechanism of action on a cellular level is not well understood. Work is underway to define this mechanism as a prodiuretic with great promise. However, it has been shown that binding of different sugars to the glucose site affects the orientation of the [[aglycone]] in the access vestibule. So when the aglycone binds it affects the entire inhibitor. Together these mechanisms lead to a synergistic interaction. Therefore, variations in the structure of both the sugar and the aglycone are crucial for the pharmacophore of SGLT inhibitors.

Dapagliflozin is an example of an SGLT-2 inhibitor, it is a competitive, highly selective inhibitor of SGLT. It acts via selective and potent inhibition of SGLT-2, and its activity is based on each patient's underlying [[glycemic control|blood sugar control]] and [[kidney function]]. The results are decreased kidney reabsorption of glucose, glucosuria effect increases with higher level of glucose in the blood circulation. Therefore, dapagliflozin reduces the blood glucose concentration with a mechanism that is independent of insulin secretion and sensitivity, unlike many other [[antidiabetic drugs|antidiabetic medications]]. Functional pancreatic [[Beta cell|β-cell]]s are not necessary for the activity of the medication so it is convenient for patients with diminished β-cell function.

[[Sodium]] and glucose are co-transported by the SGLT-2 protein into the tubular epithelial cells across the brush-border membrane of the [[proximal convoluted tubule]]. This happens because of the sodium gradient between the tubule and the cell and therefore provides a secondary active transport of glucose. Glucose is later reabsorbed by passive transfer of [[endothelial cells]] into the interstitial glucose transporter protein.

{| class="wikitable"

|+ TABLE 1: Where are SGLTs expressed?

Ratios of activity between SGLT1 and SGLT2 may be helpful in defining expression.

The [[elimination half-life]], [[bioavailability]], [[protein binding]], the blood concentration [[Cmax (pharmacology)|Cmax]] at time tmax, and other [[pharmacokinetic]] parameters of various medications of this class are present in table 2. These medications are excreted in the urine as inactive metabolites.

{| class="wikitable"

|+ TABLE 2: PHARMACOKINETIC PARAMETERS OF VARIOUS SGLT-2 INHIBITORS

|-

| [[Tofogliflozin]] (10 mg) || 97.50% || 83% || 0.75 || 6.8 || 489 ng/mL || 2900 fold

|}

*'''''C_max:''''' Maximum serum concentration that drug achieves in body after the drug has been administered

*'''''t_max:''''' Time to achieve maximum plasma concentration

*'''''t_1/2:''''' [[Biological half-life]]

In studies that were made on healthy people and people with type 2 diabetes, who were given dapagliflozin in either single ascending dose (SAD) or multiple ascending dose (MAD) showed results that confirmed a [[pharmacokinetic profile]] of the medication. With dose-dependent concentrations the half-life is about 12–13 hours, Tmax 1–2 hours and it is protein-bound, so the medication has a rapid absorption and minimal [[renal excretion|excretion by the kidney]].

Dapagliflozin disposition is not evidently affected by BMI or [[body weight]], therefore the pharmacokinetic findings are expected to be applicable to patients with a higher [[Body mass index|BMI]]. Dapagliflozin resulted in [[dose-dependent]] increases excretions in urinary glucose, up to 47g/d following single-dose administration, which can be expected from its [[mechanism of action]], dapagliflozin.

Some studies found that dapagliflozin is associated with a decrease in body weight which is statistically superior compared to placebo or other active comparators. It is primarily associated with caloric rather than fluid loss.

In contrast with other [[Hyperglycemia|anti-hyperglycemic]] [[diabetes medication]]s, SGLT2 inhibitors enhance, rather than suppress, [[gluconeogenesis]] and [[ketogenesis]]. Because SGLT2 inhibitors activate [[sirtuin 1]] (and thus [[PPARGC1A|PGC-1α]] and [[FGF21]]), they are more [[Cardioprotection|cardioprotective]] than the other medications used to treat [[diabetes]].

The [[structure-activity relationship]] (SAR) of gliflozins is not fully understood.

The most common gliflozins are dapagliflozin, empagliflozin and canagliflozin. The differences in the structures is relatively small. The general structure includes a glucose sugar with an [[aromatic]] group in the β-position at the [[anomeric]] carbon. In addition to the glucose sugar moiety and the β-isomeric aryl substituent the aryl group is composed of a [[diphenylmethane|diarylmethylene]] structure.

The synthesis of Gliflozins involves three general steps. The first one is the construction of the aryl substituent, the next one is the introduction of the aryl moiety onto the sugar or glucosylation of the aryl substituent and the last one the deprotection and modification of the arylated anomeric center of the sugar.

[[Phlorizin]] was the first type of gliflozin and it was non-selective against SGLT2/SGLT1. It is a natural O-aryl glycoside composed of a d-glucose and an aromatic ketone. However Phlorizin is very unstable, it is rapidly degraded by glucosidases in the small intestines, so it can not be used as an oral administration medication to treat diabetes. Structural modifications have been made to overcome this instability problem. The most efficient way was to conjugate aryl moiety with glucose moiety since C-glucosides are more stable in the small intestines than O-glucoside derivatives (C-C bond instead of C-O-C bond).

[[File:Phlorhizin.svg|thumb|Phlorizin]]

In the sugar analogues of dapagliflozin, the β-C series are more active than α-C series so it is critical that the β-configuration is at C-1 for the inhibitory activity. Both dapagliflozin and empagliflozin contain a [[chlorine]] (Cl) atom in their chemical structure. Cl is a [[halogen]] and it has a high [[electronegativity]]. This electronegativity withdraws electrons off the bonds and therefore it reduces the metabolism. The Cl atom also reduces the IC50 value of the medication so the medication has better activity. The carbon-fluorine bond (C-F) has also has a very low [[electron density]].

[[File:Dapagliflozin structure.svg|thumb|Dapagliflozin]]

[[File:Empagliflozin.svg|thumb|Empagliflozin]]

For example, in the chemical structure of canagliflozin a fluorine atom is connected to an aromatic ring then the compound is more stable and the metabolism of the compound is reduced.

Empagliflozin contains a tetrahydrofuran ring but not canagliflozin nor dapagliflozin.

[[File:Canagliflozin.svg|thumb|Canagliflozin]]

In the development of gliflozins the distal ring contains a thiophene ring instead of an aromatic ring. However the final chemical structures of the marketing gliflozins does not contain this thiophene ring.

{{Main|Discovery and development of gliflozins}}

SGLT2 inhibitors increase circulating [[ketone]] body concentrations. The [[Cardioprotection|cardioprotective]] effects of SGLT2 inhibitors have been attributed to the elevated ketone levels.

Gliflozins have been posited to exhibit protective effects on the heart, liver, kidneys, anti‐hyperlipidemic, anti‐[[Atherosclerosis|atherosclerotic]], anti‐[[obesity]], anti‐[[Neoplasm|neoplastic effects]] in ''in vitro'', pre‐clinical, and clinical studies. Pleiotropic effects of this class have been attributed to a variety of its pharmacodynamic actions such as natriuresis, hemoconcentration, deactivation of renin-angiotensin-aldosterone system, ketone body formation, alterations in energy [[homeostasis]], [[glycosuria]], [[lipolysis]], [[Anti-inflammatory|anti‐inflammatory]], and [[Antioxidant|antioxidative]] actions.

SGLT2 inhibitors have shown beneficial effects on liver function in clinical trials on individuals with [[NAFLD]] and type 2 diabetes, and also on those without type 2 diabetes.

* {{cite web | title=FDA revises label of diabetes drug canagliflozin | website=U.S. Food and Drug Administration | date=15 January 2016 | url=https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-fda-revises-label-diabetes-drug-canagliflozin-invokana-invokamet }}

* {{cite web | title=FDA Drug Safety Communication: FDA confirms increased risk of leg and foot amputations with the diabetes medicine canagliflozin (Invokana, Invokamet, Invokamet XR) | website=U.S. Food and Drug Administration | date=18 May 2016 | url=https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-fda-confirms-increased-risk-leg-and-foot-amputations-diabetes-medicine }}

* {{cite web | title=Warning: infection of genital area with SGLT2 inhibitors for diabetes | website=U.S. Food and Drug Administration | date=7 September 2018 | url=https://www.fda.gov/drugs/drug-safety-and-availability/fda-warns-about-rare-occurrences-serious-infection-genital-area-sglt2-inhibitors-diabetes }}

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{{二次利用|date=15 January 2024}}

[[Category:SGLT2 inhibitors| ]]

[[Category:Anti-diabetic drugs]]