Metazide

Uses

Glipizide and Metformin hydrochloride is used for an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.

Metazide is also used to associated treatment for these conditions: Type 2 Diabetes MellitusPolycystic Ovaries Syndrome, Type 2 Diabetes Mellitus, Glycemic Control

How Metazide works

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder with increasing prevalence worldwide. Characterized by higher-than-normal levels of blood glucose, T2DM is a complex disorder that arises from the interaction between genetic, environmental and behavioral risk factors. Insulin is a peptide hormone that plays a critical role in regulating blood glucose levels. In response to high blood glucose levels, insulin promotes the uptake of glucose into the liver, muscle cells, and fat cells for storage. Although there are multiple events occurring that lead to the pathophysiology of T2DM, the disorder mainly involves insulin insensitivity as a result of insulin resistance, declining insulin production, and eventual failure of beta cells of pancreatic islets that normally produce insulin. Early management with lifestyle intervention, such as controlled diet and exercise, is critical in reducing the risk of long-term secondary complications, such as cardiovascular mortality.

Glipizide, like other sulfonylurea drugs, is an insulin secretagogue, which works by stimulating the insulin release from the pancreatic beta cells thereby increasing the plasma concentrations of insulin. Thus, the main therapeutic action of the drug depends on the functional beta cells in the pancreatic islets. Sulfonylureas bind to the sulfonylurea receptor expressed on the pancreatic beta-cell plasma membrane, leading to the closure of the ATP-sensitive potassium channel and reduced potassium conductance. This results in depolarization of the pancreatic beta cell and opening of the voltage-sensitive calcium channels, promoting calcium ion influx. Increased intracellular concentrations of calcium ions in beta cells stimulates the secretion, or exocytosis, of insulin granules from the cells. Apart from this main mechanism of action, the blood-glucose-lowering effect of glipizide involves increased peripheral glucose utilization via stimulating hepatic gluconeogenesis and by increasing the number and sensitivity of insulin receptors.

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 .

Dosage

Metazide dosage

Initial therapy: For patients with type 2 diabetes whose hyperglycemia can not be satisfactorily managed with diet and exercise alone: the recommended starting dose of combination isGlipizide 2.5 mg + Metformin 250 mg once daily with meal. In clinical trials of this combination as initial therapy, there was no experience, with total daily doses greater than Glipizide 10 mg + Metformin 2000 mg per day.

Second line therapy: For patients not adequately controlled on either glipizide or metformin alone, the recommended starting dose of this combination isGlipizide 2.5 mg + Metformin 500 mg orGlipizide 5 mg + Metformin 500 mg twice daily with the morning and evening meals. The daily dose should be titrated in increments of not more thanGlipizide 5 mg + Metformin 500 mg up to the minimum effective dose to achieve adequate control of blood glucose or to a maximum dose ofGlipizide 20 mg + Metformin 2000 mg per day.

Side Effects

Glipizide: Gl upsets, diarrhoea, nausea; allergic skin reactions, leucopaenia, thrombocytopaenia, agranulocytosis, hyponatraemia; jaundice; haemolytic anaemia, pancytopaenia.

Metformin: Anorexia, nausea, vomiting, diarrhoea, wt loss, flatulence, occasional metallic taste; weakness; hypoglycaemia; rash, malabsorption of Vitamin

Potentially Fatal:

• Glipizide: Hypoglycaemia in presence of renal or hepatic damage and alcohol.
• Metformin: Lactic acidosis in presence of renal failure and alcoholism.

Toxicity

In rats, the oral LD₅₀ is reported to be greater than 4000 mg/kg and the intraperitoneal LD₅₀ is 1200 mg/kg. The lowest published toxic dose (TDLo) via oral route in child was 379 μg/kg.

Symptoms of overdose in sulfonylureas, including glipizide, may be related to severe hypoglycemia and may include coma, seizure, or other neurological impairment. These are symptoms of severe hypoglycemia and require immediate treatment with glucagon or intravenous glucose and close monitoring for a minimum of 24 to 48 hours since hypoglycemia may recur after apparent clinical recovery. Mild hypoglycemic symptoms without loss of consciousness or neurologic findings should be treated with oral glucose.

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 .

Precaution

Hypoglycaemia, stress, elderly. Thyroid impairment, monitor blood-glucose cone and renal function regularly.

Interaction

Glipizide: Decreased effect with beta-blockers, cholestyramine, hydantoins, thiazide diuretics and urinary alkalinizers.

Metformin: Additive effect with sulphonylureas. Antagonistic effects with diuretics, corticosteroids, phenothiazines, thyroid products, oestrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, Ca channel blockers and isoniazid.

Lactic acidosis with alcohol and potentiation of hypoglycaemic effect. Cimetidine and furosemide may increase plasma-metformin levels. Drugs eliminated via renal tubular secretion may increase metformin levels.

Potentially Fatal: Glipizide: Increased glipizide levels and effects with fluconazole, gemfibrozil, ketoconazole, NSAIDs, pioglitazone and sulfonamides. Increased hypoglycaemic effects with H2 antagonists, anticoagulants, androgens, cimetidine, salicylates, tricyclic antidepressants, probenecid, MAOIs, methyldopa, digitalis glycosides and urinary acidifiers.

Volume of Distribution

The mean volume of distribution was approximately 10 L following administration of single intravenous doses in patients with type 2 diabetes mellitus. In mice and rat studies, the presence of the drug and its metabolites was none to minimal in the fetus of pregnant female animals. Other sulfonylurea drugs were shown to cross the placenta and enter breast milk thus the potential risk of glipizide in fetus or infants cannot be excluded.

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

Elimination Route

Gastrointestinal absorption of glipizide is uniform, rapid, and essentially complete. The absolute bioavailability of glipizide in patients with type 2 diabetes receiving a single oral dose was 100%. The maximum plasma concentrations are expected to be reached within 6 to 12 hours following initial dosing. The steady-state plasma concentrations of glipizide from extended-release oral formulations are maintained over the 24-hour dosing interval. In healthy volunteers, the absorption of glipizide was delayed by the presence of food but the total absorption was unaffected.

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 .

Half Life

The mean terminal elimination half-life of glipizide ranged from 2 to 5 hours after single or multiple doses in patients with type 2 diabetes mellitus.

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 .

Clearance

The mean total body clearance of glipizide was approximately 3 L/hr following administration of single intravenous doses in patients with type 2 diabetes mellitus.

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 .

Elimination Route

Glipizide is mainly eliminated by hepatic biotransformation, where less than 10% of the initial dose of the drug can be detected in the urine and feces as unchanged glipizide. About 80% of the metabolites of glipizide is excreted in the urine while 10% is excreted in the feces.

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 .

Pregnancy & Breastfeeding use

Pregnancy Category C. Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks

Lactation: Enters breast milk; not recommended

Contraindication

Hypersensitivity. Type 2 diabetes mellitus; ketoacidosis; severe renal or hepatic insufficiency, diabetic coma, cardiac failure, recent Ml, CHF. IDDM; severe infection; acute or chronic metabolic acidosis with or without coma; stress, trauma; severe impairment of thyroid function; dehydration, acute or chronic alcoholism. Pregnancy, lactation.

Special Warning

Pediatric Use: Safety and effectiveness in children have not been established.

Geriatric Use: There were no overall differences in effectiveness or safety between younger and older patients.

Renal Impairment: Severe: Contraindicated.

Hepatic Impairment: Severe: Contraindicated.

Renal Impairment: Metformin is contraindicated in patients with an eGFR < 30 mL/minute/1.73 m2 . Starting metformin in patients with an eGFR between 30-45 mL/minute/1.73 m2 is not recommended. In patients taking metformin whose eGFR later falls below 45 mL/minute/1.73 m2 , assess the benefits and risks of continuing treatment. Discontinue metformin if the patient’s eGFR later falls below 30 mL/minute/1.73 m2 .

Acute Overdose

There is no well-documented experience with Glipizide tablets overdosage in humans.

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

The tablets should be protected from moisture and humidity and stored at room temperature (below 30&deg; C).

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.

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