Vildamet

Uses

This is used for an adjunct to diet and exercises to improve glycaemic control in patients with type 2 diabetes mellitus whose diabetes is not adequately controlled on Metformin Hydrochloride or Vildagliptin alone or who are already treated with the combination of Vildagliptin and Metformin Hydrochloride, as separate tablets.

Vildamet is also used to associated treatment for these conditions: Polycystic Ovaries Syndrome, Type 2 Diabetes Mellitus, Glycemic ControlType 2 Diabetes Mellitus

How Vildamet works

Metformin's mechanisms of action are unique from other classes of oral antihyperglycemic drugs. Metformin decreases blood glucose levels by decreasing hepatic glucose production (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 .

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) are incretin hormones that regulate blood glucose levels and maintain glucose homeostasis. It is estimated that the activity of GLP-1 and GIP contribute more than 70% to the insulin response to an oral glucose challenge. They stimulate insulin secretion in a glucose-dependent manner via G-protein-coupled GIP and GLP-1 receptor signalling. In addition to their effects on insulin secretion, GLP-1 is also involved in promoting islet neogenesis and differentiation, as well as attenuating pancreatic beta-cell apoptosis. Incretin hormones also exert extra-pancreatic effects, such as lipogenesis and myocardial function. In type II diabetes mellitus, GLP-1 secretion is impaired, and the insulinotropic effect of GIP is significantly diminished.

Vildagliptin exerts its blood glucose-lowering effects by selectively inhibiting dipeptidyl peptidase-4 (DPP-4), an enzyme that rapidly truncates and inactivates GLP-1 and GIP upon their release from the intestinal cells. DPP-4 cleaves oligopeptides after the second amino acid from the N-terminal end. Inhibition of DPP-4 substantially prolongs the half-life of GLP-1 and GIP, increasing the levels of active circulating incretin hormones. The duration of DPP-4 inhibition by vildagliptin is dose-dependent. Vildagliptin reduces fasting and prandial glucose and HbA1c. It enhances the glucose sensitivity of alpha- and beta-cells and augments glucose-dependent insulin secretion. Fasting and postprandial glucose levels are decreased, and postprandial lipid and lipoprotein metabolism are also improved.

Dosage

Vildamet dosage

Adults: Based on the patient's current dose of Metformin, Vildagliptin and Metformin may be initiated at either 50 mg/500 mg or 50 mg/850 mg twice daily, 1 tablet in the morning and the other in the evening. Patients receiving Vildagliptin and Metformin from separate tablets may be switched to Vildagliptin and Metformin containing the same doses of each component. Doses higher than 100 mg of vildagliptin are not recommended. There is no clinical experience of Vildagliptin and Metformin in triple combination with other antidiabetic agents. Taking Vildagliptin and Metformin with or just after food may reduce gastrointestinal symptoms associated with Metformin.

Side Effects

The majority of adverse reactions were mild and transient, not requiring treatment discontinuations. Lactic acidosis can occur due to Metformin. Rare cases of hepatic dysfunction. Some common side effects like tremor, headache, dizziness, nausea, hypoglycaemia, fatigue are seen. Clinical trials of up to and more than 2 years duration did not show any additional safety signals or unforeseen risks when use this combinatin.

Toxicity

Metformin (hydrochloride) toxicity data:

Oral LD50 (rat): 1 g/kg; Intraperitoneal LD50 (rat): 500 mg/kg; Subcutaneous LD50 (rat): 300 mg/kg; Oral LD50 (mouse): 1450 mg/kg; Intraperitoneal LD50 (mouse): 420 mg/kg; Subcutaneous LD50 (mouse): 225 mg/kg .

A note on lactic acidosis

Metformin decreases liver uptake of lactate, thereby increasing lactate blood levels which may increase the risk of lactic acidosis . There have been reported postmarketing cases of metformin-associated lactic acidosis, including some fatal cases. Such cases had a subtle onset and were accompanied by nonspecific symptoms including malaise, myalgias, abdominal pain, respiratory distress, or increased somnolence. In certain cases, hypotension and resistant bradyarrhythmias have occurred with severe lactic acidosis . Metformin-associated lactic acidosis was characterized by elevated blood lactate concentrations (>5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), as well as an increased lactate:pyruvate ratio; metformin plasma levels were generally >5 mcg/mL.

Risk factors for metformin-associated lactic acidosis include renal impairment, concomitant use of certain drugs (e.g. carbonic anhydrase inhibitors such as topiramate), age 65 years old or greater, having a radiological study with contrast, surgery and other procedures, hypoxic states (e.g., acute congestive heart failure), excessive alcohol intake, and hepatic impairment .

A note on renal function

In patients with decreased renal function, the plasma and blood half-life of metformin is prolonged and the renal clearance is decreased .

Metformin should be avoided in those with severely compromised renal function (creatinine clearance < 30 ml/min), acute/decompensated heart failure, severe liver disease and for 48 hours after the use of iodinated contrast dyes due to the risk of lactic acidosis . Lower doses should be used in the elderly and those with decreased renal function. Metformin decreases fasting plasma glucose, postprandial blood glucose and glycosolated hemoglobin (HbA1c) levels, which are reflective of the last 8-10 weeks of glucose control. Metformin may also have a positive effect on lipid levels.

A note on hypoglycemia

When used alone, metformin does not cause hypoglycemia, however, it may potentiate the hypoglycemic effects of sulfonylureas and insulin when they are used together .

Use in pregnancy

Available data from post-marketing studies have not indicated a clear association of metformin with major birth defects, miscarriage, or adverse maternal or fetal outcomes when metformin was ingested during pregnancy. Despite this, the abovementioned studies cannot definitively establish the absence of any metformin-associated risk due to methodological limitations, including small sample size and inconsistent study groups .

Use in nursing

A limited number of published studies indicate that metformin is present in human milk. There is insufficient information to confirm the effects of metformin on the nursing infant and no available data on the effects of metformin on the production of milk. The developmental and health benefits of breastfeeding should be considered as well as the mother’s clinical need for metformin and any possible adverse effects on the nursing child .

The oral Lowest published toxic dose (TDLO) is 0.3 mg/kg in rats and 1 mg/kg in mice.

There is limited information regarding overdose with vildagliptin. In one study, patients experienced muscle pain, mild and transient paresthesia, fever, edema, and a transient increase in lipase levels at a dose of 400 mg. At 600 mg, one subject experienced edema of the feet and hands and increases in creatine phosphokinase (CPK), aspartate aminotransferase (AST), C-reactive protein (CRP) and myoglobin levels. Supportive management is recommended in case of an overdose. There is no known antidote, and vildagliptin and its major metabolite cannot be removed via hemodialysis.

Precaution

Lactic acidosis can occur due to Metformin accumulation. If metabolic acidosis is suspected, treatment should be discontinued and the patient should be hospitalized immediately. Serum creatinine should be monitored at least once a year in patients with normal renal function and 2–4 times a year in patients with serum creatinine levels at the upper limit of normal and in elderly patients. Special caution should be exercised in elderly patients where renal function may become impaired (e.g. when initiating antihypertensives, diuretics or NSAIDs). It is recommended that Liver Function Tests (LFTs) are monitored prior to initiation of this drug, at three-monthly intervals in the first year and periodically thereafter. If transaminase levels are increased, patients should be monitored with a second liver function evaluation to confirm the finding and be followed thereafter with frequent liver function tests until the abnormality return to normal. If AST or ALT persist at 3 x ULN, Vildagliptin & Metformin tablets should be stopped Patients who develop jaundice or other signs of liver dysfunction. Following withdrawal of treatment with Vildagliptin & Metformin and LFT normalization, treatment with Vildagliptin & Metformin should not be reinitiated. Vildagliptin & Metformin tablets should be discontinued 48 hours before elective surgery with general anaesthesia and should not usually be resumed earlier than 48 hours afterwards.

Interaction

In pharmacokinetic studies, no interactions were seen with pioglitazone, metformin, glibenclamide, digoxin, warfarin, amlodipine, ramipril, valsartan or simvastatin. As with other oral antidiabetic medicinal products the glucose-lowering effect of Vildagliptin may be reduced by certain active substances, including thiazides, corticosteroids, thyroid products and sympathomimetics. Close monitoring of glycemic control is required, when cationic drugs are co-administered. Glucocorticoids, beta 2 agonists, diuretics and ACE inhibitors may alter blood glucose. The patient should be informed and more frequent blood glucose monitoring performed, especially at the beginning of treatment. If necessary, the dosage of Vildagliptin & Metformin tablets may need to be adjusted during concomitant therapy and on its discontinuation.

Volume of Distribution

The apparent volume of distribution (V/F) of metformin after one oral dose of metformin 850 mg averaged at 654 ± 358 L .

The mean volume of distribution of vildagliptin at steady-state after intravenous administration is 71 L, suggesting extravascular distribution.

Elimination Route

Regular tablet absorption

The absolute bioavailability of a metformin 500 mg tablet administered in the fasting state is about 50%-60%. Single-dose clinical studies using oral doses of metformin 500 to 1500 mg and 850 to 2550 mg show that there is a lack of dose proportionality with an increase in metformin dose, attributed to decreased absorption rather than changes in elimination .

At usual clinical doses and dosing schedules of metformin, steady-state plasma concentrations of metformin are achieved within 24-48 hours and are normally measured at Label.

Extended-release tablet absorption

After a single oral dose of metformin extended-release, Cmax is reached with a median value of 7 hours and a range of between 4 and 8 hours. Peak plasma levels are measured to be about 20% lower compared to the same dose of regular metformin, however, the extent of absorption of both forms (as measured by area under the curve - AUC), are similar .

Effect of food

Food reduces the absorption of metformin, as demonstrated by about a 40% lower mean peak plasma concentration (Cmax), a 25% lower area under the plasma concentration versus time curve (AUC), and a 35-minute increase in time to peak plasma concentration (Tmax) after ingestion of an 850 mg tablet of metformin taken with food, compared to the same dose administered during fasting .

Though the extent of metformin absorption (measured by the area under the curve - AUC) from the metformin extended-release tablet is increased by about 50% when given with food, no effect of food on Cmax and Tmax of metformin is observed. High and low-fat meals exert similar effects on the pharmacokinetics of extended-release metformin .

In a fasting state, vildagliptin is rapidly absorbed following oral administration. Peak plasma concentrations are observed at 1.7 hours following administration. Plasma concentrations of vildagliptin increase in an approximately dose-proportional manner.

Food delays T_max to 2.5 hours and decreases C_max by 19%, but has no effects on the overall exposure to the drug (AUC). Absolute bioavailability of vildagliptin is 85%.

Half Life

Approximately 6.2 hours in the plasma and in the blood, the elimination half-life is approximately 17.6 hours, suggesting that the erythrocyte mass may be a compartment of distribution .

The mean elimination half-life following intravenous administration is approximately two hours. The elimination half-life after oral administration is approximately three hours.

Clearance

Renal clearance is about 3.5 times greater than creatinine clearance, which indicates that tubular secretion is the major route of metformin elimination. Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the first 24 hours .

After intravenous administration to healthy subjects, the total plasma and renal clearance of vildagliptin were 41 and 13 L/h, respectively.

Elimination Route

This drug is substantially excreted by the kidney .

Renal clearance of metformin is about 3.5 times higher than creatinine clearance, which shows that renal tubular secretion is the major route of metformin elimination. After oral administration, about 90% of absorbed metformin is eliminated by the kidneys within the first 24 hours post-ingestion .

Vildagliptin is eliminated via metabolism. Following oral administration, approximately 85% of the radiolabelled vildagliptin dose was excreted in urine and about 15% of the dose was recovered in feces. Of the recovered dose in urine, about 23% accounted for the unchanged parent compound.

Pregnancy & Breastfeeding use

PREGNANCY: There are no adequate data on the use of Vildagliptin & Metformin in pregnant women; hence the potential risk for human is unknown.

NURSING MOTHERS: It is not known whether Vildagliptin is excreted in human milk. Due to lack of human data, Vildagliptin & Metformin should not be used during lactation.

Contraindication

Vildagliptin & Metformin is contraindicated in patients with:

• Hypersensitivity to the active substance or to any of the excipients
• Patients with Renal Impairment: Creatinine clearance
• Patients with acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma.
• Diabetic ketoacidosis should be treated with insulin
• Patients with type 1 diabetes

Special Warning

PEDIATRIC USE: Combination of Vildagliptin & Metformin is not recommended in patients 18 years of age.

GERIATRIC USE: Their renal function monitored regularly. Combination of Vildagliptin & Metformin has not been studied in patients >75 years. Therefore, the use of Combination of Vildagliptin & Metformin is not recommended in thispopulation.

Patients with renal impairment: This combination should not be used in patients with renal failure or renal dysfunction, e.g. serum creatinine levels > 1.5 mg/dL (>135 micro mol/L) in males and > 1.4 mg/dL (>110 micro mol/L) in females.

Patients with hepatic impairment: This combination is not recommended in patients with hepatic impairment including patients with a pre-treatment ALT or AST >3 X the upper limit of normal.

Acute Overdose

Hypoglycemia has not been seen with metformin doses up to 85g, although lactic acidosis has occurred in such circumstances. High overdose or concomitant risks of metformin may lead to lactic acidosis. Lactic acidosis is a medical emergency and must be treated in hospital. The most effective method to remove lactate and metformin is hemodialysis.

Storage Condition

Keep out of the reach of children. Do not store above 25°C. Keep in the original package in a cool & dry place in order to protect from light and moisture.

Store in a cool and dry place. Protect from light and moisture. Keep out of the reach of the children.

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