SITAGIL M 50/500 ER

Indications

• Type 2 diabetes mellitus
• Gestational diabetes
• Management of pre-existing diabetes in pregnant women

Dosage

Children: For children aged 10 years and older, the usual starting dose is 500 mg taken with food, with gradual increases based on clinical response. Refer to the BNF for Children for specific dosing recommendations.

Adults: The initial dose is usually 500 mg to 1,000 mg taken orally with food, and the dosage may be gradually increased based on glycemic control and tolerance, with a maximum daily dose typically not exceeding 2,000 mg.

Mechanism of action

Metformin decreases hepatic glucose production and increases peripheral glucose utilization. It does not stimulate insulin release from the pancreas, making it antihyperglycemic rather than hypoglycemic. The drug also interacts with SIRT1, a protein involved in bile acid metabolism, contributing to its effects on glucose homeostasis.

Pharmacodynamics

Metformin improves glycemic control in patients with type 2 diabetes by reducing fasting and postprandial plasma glucose levels. It acts by decreasing intestinal absorption of glucose, increasing insulin sensitivity, and enhancing peripheral glucose uptake and utilization, without causing hypoglycemia.

Pharmacokinetics

Metformin is absorbed from the gastrointestinal tract and is excreted unchanged in the urine. It has a half-life of about 6 hours and does not undergo significant metabolism. The drug's pharmacokinetics can be affected by renal function, and caution is advised in patients with renal impairment.

Contra-indications

• Severe renal impairment (creatinine clearance less than 25 mL/minute)
• Acute or chronic metabolic acidosis, including diabetic ketoacidosis
• Hypersensitivity to metformin or any of its components

Adverse effects

• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Lactic acidosis (rare)
• Hepatic disorders (rare)
• Oedema (rare)
• Acute generalised exanthematous pustulosis (very rare)
• Thrombocytopenia (very rare)

Interactions

• Angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists may require monitoring and adjustments
• Antacids containing magnesium and aluminium salts may reduce the absorption of metformin
• Concomitant use with other antihyperglycemic agents requires careful monitoring for hypoglycemia

Precautions

• Caution in patients with hepatic impairment
• Monitor liver function regularly during treatment
• Patients should be advised to discontinue use in the event of significant illness, especially dehydration or infections

Pregnancy

Avoid use during pregnancy. Women planning to become pregnant should discontinue metformin and consult a healthcare provider for safer alternatives.

Breast-feeding

Avoid use during breastfeeding. Metformin is excreted in breast milk, and its effects on a nursing infant are unknown.

Storage

Store in a cool, dry place, below 25°C. Protect from light.

Formulations

• Metformin hydrochloride 500 mg tablets
• Metformin hydrochloride 850 mg tablets
• Metformin hydrochloride 1000 mg tablets

Indications

• Type 2 diabetes mellitus
• Polycystic ovary syndrome (PCOS)

Dosage

Children: The

Adults: The usual starting dose of metformin for adults is 500 mg taken orally twice a day or 850 mg once daily, with gradual increases based on tolerance and blood glucose levels. The maximum recommended daily dose is 2000-3000 mg, depending on the formulation used.

Mechanism of action

Metformin decreases blood glucose levels by decreasing hepatic glucose production (gluconeogenesis), decreasing intestinal absorption of glucose, and increasing insulin sensitivity, which enhances peripheral glucose uptake and utilization. It is known to inhibit mitochondrial complex I activity, leading to increased AMP:ATP ratios that activate AMP-activated protein kinase (AMPK), a key regulator of glucose metabolism. This activation results in reduced hepatic glucose output and improved cellular glucose uptake.

Pharmacodynamics

Metformin exerts its effects primarily by enhancing insulin sensitivity and reducing glucose production by the liver. Unlike sulfonylureas, which increase insulin secretion, metformin does not cause hyperinsulinemia. Its ability to lower fasting plasma glucose and glycosylated hemoglobin (HbA1c) levels makes it a cornerstone in the management of type 2 diabetes. Clinical studies have shown significant reductions in fasting plasma glucose and HbA1c levels in patients treated with metformin.

Pharmacokinetics

Metformin is absorbed from the gastrointestinal tract, with peak plasma concentrations typically occurring 2-3 hours after ingestion. It has a bioavailability of approximately 50-60% when administered orally. The drug is primarily eliminated unchanged by the kidneys, and its clearance is proportional to renal function. The half-life of metformin is about 6.5 hours. Accumulation may occur in cases of renal impairment, necessitating caution in patients with reduced renal function.

Adverse effects

• Gastrointestinal disturbances (nausea, vomiting, diarrhea)
• Lactic acidosis
• Vitamin B12 deficiency

Interactions

• dolutegravir+metformin: Moderate (increases exposure)
• cimetidine+metformin: Moderate (increases exposure)
• risdiplam+metformin: Moderate (increases concentration)
• vandetanib+metformin: Moderate (increases exposure)
• bictegravir+metformin: Unknown (increases exposure)
• guanfacine+metformin: Unknown (increases concentration)
• mexiletine+metformin: Unknown (affects exposure)
• pitolisant+metformin: Unknown (increases exposure)
• ribociclib+metformin: Unknown (increases exposure)

Precautions

• Renal impairment
• Dehydration
• Excessive alcohol intake

Pregnancy

Metformin is classified as a Category B medication. It is often used during pregnancy for managing gestational diabetes but should be administered under medical supervision.

Breast-feeding

Metformin is excreted in breast milk, but is generally considered safe for use during breastfeeding. Consult with a healthcare provider for specific guidance.

Storage

Store in a cool, dry place, away from direct light. Keep out of reach of children.

Formulations

• Tablets
• Extended-release tablets
• Oral solution

Indications

• Type 2 diabetes mellitus as monotherapy (if metformin is inappropriate)
• Type 2 diabetes mellitus in combination with other antidiabetic drugs (including insulin) when metformin alone or in combination fails to achieve adequate glycemic control

Dosage

Adults: 100 mg once daily, or 50 mg twice daily when used in combination with a sulfonylurea or insulin. Dose adjustments may be required based on renal function.

Mechanism of action

Sitagliptin inhibits the enzyme dipeptidyl peptidase-4 (DPP-4), which is responsible for the degradation of incretin hormones. This inhibition results in prolonged active incretin levels, which enhances insulin secretion from pancreatic beta cells and decreases glucagon secretion from alpha cells in the pancreas, leading to lowered blood glucose levels.

Pharmacodynamics

Sitagliptin's pharmacodynamic effects include improved glycemic control, characterized by reduced fasting and postprandial blood glucose levels. The drug is effective in lowering HbA1c levels and is associated with a low risk of hypoglycemia. It has a beneficial effect on weight management, as it typically does not promote weight gain.

Pharmacokinetics

Sitagliptin is absorbed rapidly after oral administration, with peak plasma concentrations occurring within 1-4 hours. Its bioavailability is approximately 87%. The drug is predominantly eliminated via renal excretion, with about 80% of the dose excreted unchanged in the urine. The elimination half-life is approximately 12.4 hours. Renal impairment may necessitate dose adjustments, as clearance is significantly reduced in patients with decreased renal function.

Contra-indications

• History of pancreatitis
• Severe heart failure

Adverse effects

• Headache
• Constipation
• Dizziness
• Skin reactions
• Angioedema
• Back pain
• Cutaneous vasculitis
• Joint disorders
• Myalgia
• Acute pancreatitis
• Acute renal impairment
• Stevens-Johnson syndrome
• Vomiting

Interactions

• Concomitant use with sulfonylureas or insulin may require dose adjustments
• Moderate interaction with vemurafenib (increases exposure)

Precautions

• Monitor renal function before treatment and periodically thereafter
• Discontinue if symptoms of acute pancreatitis occur, such as persistent severe abdominal pain

Pregnancy

Avoid-toxicity observed in animal studies.

Breast-feeding

Avoid-present in milk in animal studies.

Storage

Store at room temperature, away from moisture and heat.

Formulations

• Tablets: 50 mg, 100 mg

Mechanism of action

Metformin is widely used to treat hyperglycemia. However, metformin treatment may induce intrahepatic cholestasis and liver injury in a few patients with type II diabetes through an unknown mechanism. Here we show that metformin decreases SIRT1 protein levels in primary hepatocytes and liver. Both metformin-treated wild-type C57 mice and hepatic SIRT1-mutant mice had increased hepatic and serum bile acid levels. However, metformin failed to change systemic bile acid levels in hepatic SIRT1-mutant mice. Molecular mechanism study indicates that SIRT1 directly interacts with and deacetylates Foxa2 to inhibit its transcriptional activity on expression of genes involved in bile acids synthesis and transport. Hepatic SIRT1 mutation elevates Foxa2 acetylation levels, which promotes Foxa2 binding to and activating genes involved in bile acids metabolism, impairing hepatic and systemic bile acid homeostasis. Our data clearly suggest that hepatic SIRT1 mediates metformin effects on systemic bile acid metabolism and modulation of SIRT1 activity in liver may be an attractive approach for treatment of bile acid-related diseases such as cholestasis. Metformin is antihyperglycemic, not hypoglycemic. It does not cause insulin release from the pancreas and does not cause hypoglycemia, even in large doses. Metformin has no significant effects on the secretion of glucagon, cortisol, growth hormone or somatostatin. Metformin reduces glucose levels primarily by decreasing hepatic glucose production and by increasing insulin action in muscle and fat. ... May decrease plasma glucose by reducing the absorption of glucose from the intestine. /Salt not specified/ Metformin potentiates the effect of insulin by mechanisms not fully understood. Metformin does not stimulate pancreatic beta cells to increase secretion of insulin; insulin secretion must be present for metformin to work properly. It is postulated that metformin decreases hepatic glucose production and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. /Salt not specified/ People with Type 2 diabetes mellitus (T2DM) have reduced bone mineral density and an increased risk of fractures due to altered mesenchymal stem cell (MSC) differentiation in the bone marrow. This leads to a shift in the balance of differentiation away from bone formation (osteogenesis) in favour of fat cell development (adipogenesis). The commonly used anti-diabetic drug, metformin, activates the osteogenic transcription factor Runt-related transcription factor 2 (Runx2), which may suppress adipogenesis, leading to improved bone health. Here we investigate the involvement of the metabolic enzyme, AMP-activated protein kinase (AMPK), in these protective actions of metformin. The anti-adipogenic actions of metformin were observed in multipotent C3H10T1/2 MSCs, in which metformin exerted reciprocal control over the activities of Runx2 and the adipogenic transcription factor, PPARgamma, leading to suppression of adipogenesis. These effects appeared to be independent of AMPK activation but rather through the suppression of the mTOR/p70S6K signalling pathway. Basal AMPK and mTOR/p70S6K activity did appear to be required for adipogenesis, as demonstrated by the use of the AMPK inhibitor, compound C. This observation was further supported by using AMPK knockout mouse embryo fibroblasts (MEFs) where adipogenesis, as assessed by reduced lipid accumulation and expression of the adipogeneic transcription factor, C/EBPbeta, was found to display an absolute requirement for AMPK. Further activation of AMPK in wild type MEFS, with either metformin or the AMPK-specific activator, A769662, was also associated with suppression of adipogenesis. It appears, therefore, that basal AMPK activity is required for adipogenesis and that metformin can inhibit adipogenesis through AMPK-dependent or -independent mechanisms, depending on the cellular context.

Mechanism of action

Metformin's mechanisms of action are unique from other classes of oral antihyperglycemic drugs. Metformin decreases blood glucose levels by decreasing hepatic glucose production (also called gluconeogenesis), decreasing the intestinal absorption of glucose, and increasing insulin sensitivity by increasing peripheral glucose uptake and utilization. It is well established that metformin inhibits mitochondrial complex I activity, and it has since been generally postulated that its potent antidiabetic effects occur through this mechanism. The above processes lead to a decrease in blood glucose, managing type II diabetes and exerting positive effects on glycemic control. After ingestion, the organic cation transporter-1 (OCT1) is responsible for the uptake of metformin into hepatocytes (liver cells). As this drug is positively charged, it accumulates in cells and in the mitochondria because of the membrane potentials across the plasma membrane as well as the mitochondrial inner membrane. Metformin inhibits mitochondrial complex I, preventing the production of mitochondrial ATP leading to increased cytoplasmic ADP:ATP and AMP:ATP ratios. These changes activate AMP-activated protein kinase (AMPK), an enzyme that plays an important role in the regulation of glucose metabolism. Aside from this mechanism, AMPK can be activated by a lysosomal mechanism involving other activators. Following this process, increases in AMP:ATP ratio also inhibit _fructose-1,6-bisphosphatase_ enzyme, resulting in the inhibition of gluconeogenesis, while also inhibiting _adenylate cyclase_ and decreasing the production of cyclic adenosine monophosphate (cAMP), a derivative of ATP used for cell signaling. Activated AMPK phosphorylates two isoforms of acetyl-CoA carboxylase enzyme, thereby inhibiting fat synthesis and leading to fat oxidation, reducing hepatic lipid stores and increasing liver sensitivity to insulin. In the intestines, metformin increases anaerobic glucose metabolism in enterocytes (intestinal cells), leading to reduced net glucose uptake and increased delivery of lactate to the liver. Recent studies have also implicated the gut as a primary site of action of metformin and suggest that the liver may not be as important for metformin action in patients with type 2 diabetes. Some of the ways metformin may play a role on the intestines is by promoting the metabolism of glucose by increasing glucagon-like peptide I (GLP-1) as well as increasing gut utilization of glucose. In addition to the above pathway, the mechanism of action of metformin may be explained by other ways, and its exact mechanism of action has been under extensive study in recent years. Metformin is widely used to treat hyperglycemia. However, metformin treatment may induce intrahepatic cholestasis and liver injury in a few patients with type II diabetes through an unknown mechanism. Here we show that metformin decreases SIRT1 protein levels in primary hepatocytes and liver. Both metformin-treated wild-type C57 mice and hepatic SIRT1-mutant mice had increased hepatic and serum bile acid levels. However, metformin failed to change systemic bile acid levels in hepatic SIRT1-mutant mice. Molecular mechanism study indicates that SIRT1 directly interacts with and deacetylates Foxa2 to inhibit its transcriptional activity on expression of genes involved in bile acids synthesis and transport. Hepatic SIRT1 mutation elevates Foxa2 acetylation levels, which promotes Foxa2 binding to and activating genes involved in bile acids metabolism, impairing hepatic and systemic bile acid homeostasis. Our data clearly suggest that hepatic SIRT1 mediates metformin effects on systemic bile acid metabolism and modulation of SIRT1 activity in liver may be an attractive approach for treatment of bile acid-related diseases such as cholestasis. Metformin is antihyperglycemic, not hypoglycemic. It does not cause insulin release from the pancreas and does not cause hypoglycemia, even in large doses. Me

Pharmacodynamics

**General effects** Insulin is an important hormone that regulates blood glucose levels. Type II diabetes is characterized by a decrease in sensitivity to insulin, resulting in elevations in blood glucose when the pancreas can no longer compensate. In patients diagnosed with type 2 diabetes, insulin is unable to exert adequate effects on tissues and cells (i.e. insulin resistance) and insulin deficiency may also be present. Metformin reduces hepatic production of glucose, decreases the intestinal absorption of glucose, and enhances insulin sensitivity by increasing both peripheral glucose uptake and utilization. In contrast with drugs of the sulfonylurea class, which lead to hyperinsulinemia, the secretion of insulin is unchanged with metformin use. **Effect on fasting plasma glucose (FPG) and Glycosylated hemoglobin (HbA1c)** HbA1c is an important periodic measure of glycemic control used to monitor diabetic patients. Fasting plasma glucose is also a useful and important measure of glycemic control. In a 29-week clinical trial of subjects diagnosed with type II diabetes, metformin decreased the fasting plasma glucose levels by an average of 59 mg/dL from baseline, compared to an average increase of 6.3 mg/dL from baseline in subjects taking a placebo. Glycosylated hemoglobin (HbA1c) was decreased by about 1.4% in subjects receiving metformin, and increased by 0.4% in subjects receiving placebo only.

Mechanism of action

Inhibition of DPP-4 by sitagliptin slows DPP-4 mediated inactivation of incretins like GLP-1 and GIP. Incretins are released throughout the day and upregulated in response to meals as part of glucose homeostasis. Reduced inhibition of incretins increase insulin synthesis and decrease glucagon release in a manner dependant on glucose concentrations. These effects lead to an overall increase in blood glucose control which is demonstrated by reduced glycosylated hemoglobin (HbA1c). Januvia is a member of a class of oral anti-hyperglycemic agents called dipeptidyl peptidase 4 (DPP-4) inhibitors. The improvement in glycemic control observed with this medicinal product may be mediated by enhancing the levels of active incretin hormones. Incretin hormones, including glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are released by the intestine throughout the day, and levels are increased in response to a meal. The incretins are part of an endogenous system involved in the physiologic regulation of glucose homeostasis. When blood glucose concentrations are normal or elevated, GLP-1 and GIP increase insulin synthesis and release from pancreatic beta cells by intracellular signaling pathways involving cyclic AMP. Treatment with GLP-1 or with DPP-4 inhibitors in animal models of type 2 diabetes has been demonstrated to improve beta cell responsiveness to glucose and stimulate insulin biosynthesis and release. With higher insulin levels, tissue glucose uptake is enhanced. In addition, GLP-1 lowers glucagon secretion from pancreatic alpha cells. Decreased glucagon concentrations, along with higher insulin levels, lead to reduced hepatic glucose production, resulting in a decrease in blood glucose levels. The effects of GLP-1 and GIP are glucose-dependent such that when blood glucose concentrations are low, stimulation of insulin release and suppression of glucagon secretion by GLP-1 are not observed. For both GLP-1 and GIP, stimulation of insulin release is enhanced as glucose rises above normal concentrations. Further, GLP-1 does not impair the normal glucagon response to hypoglycemia. The activity of GLP-1 and GIP is limited by the DPP-4 enzyme, which rapidly hydrolyzes the incretin hormones to produce inactive products. Sitagliptin prevents the hydrolysis of incretin hormones by DPP-4, thereby increasing plasma concentrations of the active forms of GLP-1 and GIP. By enhancing active incretin levels, sitagliptin increases insulin release and decreases glucagon levels in a glucose-dependent manner. In patients with type 2 diabetes with hyperglycemia, these changes in insulin and glucagon levels lead to lower hemoglobin A1c (HbA1c) and lower fasting and postprandial glucose concentrations. The glucose-dependent mechanism of sitagliptin is distinct from the mechanism of sulfonylureas, which increase insulin secretion even when glucose levels are low and can lead to hypoglycemia in patients with type 2 diabetes and in normal subjects. Sitagliptin is a potent and highly selective inhibitor of the enzyme DPP-4 and does not inhibit the closely-related enzymes DPP-8 or DPP-9 at therapeutic concentrations. Sitagliptin is a DPP-4 inhibitor, which is believed to exert its actions in patients with type 2 diabetes by slowing the inactivation of incretin hormones. Concentrations of the active intact hormones are increased by Januvia, thereby increasing and prolonging the action of these hormones. Incretin hormones, including glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are released by the intestine throughout the day, and levels are increased in response to a meal. These hormones are rapidly inactivated by the enzyme, DPP-4. The incretins are part of an endogenous system involved in the physiologic regulation of glucose homeostasis. When blood glucose concentrations are normal or elevated, GLP-1 and GIP increase insulin synthesis and release from pancreatic beta cells by

Pharmacodynamics

Sitagliptin inhibits DPP-4 which leads to increased levels of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide(GIP), decreased levels of glucagon, and a stronger insulin response to glucose.