Xmet P

Uses

Pioglitazone & Metformin combination is used for an adjunct to diet and exercise to improve glycemic control in patients with type 2 diabetes who are already treated with a combination of Pioglitazone and Metformin or whose diabetes is not adequately controlled with Metformin alone or for those patients who have initially responded to Pioglitazone and require additional glycemic control.

Xmet P is also used to associated treatment for these conditions: Polycystic Ovaries Syndrome, Type 2 Diabetes Mellitus, Glycemic ControlDiabetes, Diabetic Neuropathies, Type 2 Diabetes Mellitus

How Xmet P 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 .

Pioglitazone is a selective agonist at peroxisome proliferator-activated receptor-gamma (PPARγ) in target tissues for insulin action such as adipose tissue, skeletal muscle, and liver. Activation of PPARγ increases the transcription of insulin-responsive genes involved in the control of glucose and lipid production, transport, and utilization. Through this mechanism, pioglitazone both enhances tissue sensitivity to insulin and reduces the hepatic production of glucose (i.e. gluconeogenesis) - insulin resistance associated with type 2 diabetes mellitus is therefore improved without an increase in insulin secretion by pancreatic beta cells.

Dosage

Xmet P dosage

General: The use of antihyperglycemic therapy in the management of type 2 diabetes should be individualized on the basis of effectiveness and tolerability while not exceeding the maximum recommended daily dose of Pioglitazone 45 mg and Metformin 2550 mg.

Dosage Recommendations: Selecting the starting dose of Pioglitazone & Metformin should be based on the patient's current regimen of Pioglitazone and/or Metformin. Pioglitazone & Metformin should be given in divided daily doses with meals to reduce the gastrointestinal side effects associated with Metformin.

Starting dose for patients inadequately controlled on Metformin monotherapy Based on the usual starting dose of Pioglitazone (15-30 mg daily), Pioglitazone & Metformin may be initiated at either the 15 mg/500 mg or 15 mg/850 mg tablet strength once or twice daily, and gradually titrated after assessing adequacy of therapeutic response. Starting dose for patients who initially responded to Pioglitazone monotherapy and require additional glycemic control

Based on the usual starting doses of Metformin (500 mg twice daily or 850 mg daily), Pioglitazone & Metformin may be initiated at either the 15 mg/500 mg twice daily or 15 mg/850 mg tablet strength once daily, and gradually titrated after assessing adequacy of therapeutic response.

Starting dose for patients switching from combination therapy of Pioglitazone plus Metformin as separate tablets Pioglitazone & Metformin may be initiated with either the 15 mg/500 mg or 15 mg/850 mg tablet strengths based on the dose of Pioglitazone and Metformin already being taken.

Maximum Recommended Dose: Pioglitazone & Metformin tablets are available as a 15 mg Pioglitazone plus 500 mg Metformin or a 15 mg Pioglitazone plus 850 mg Metformin formulation for oral administration. The maximum recommended dose for Pioglitazone is 45 mg daily. The maximum recommended daily dose for Metformin is 2550 mg in adults. Special Patient Populations: The initial and maintenance dosing of combination of Pioglitazone and Metformin should be conservative in patients with advanced age, due to the potential for decreased renal function in this population. Generally, elderly, debilitated, and malnourished patients should not be titrated to the maximum dose of combination of Pioglitazone and Metformin. Monitoring of renal function is necessary to aid in prevention of Metformin associated lactic acidosis, particularly in the elderly. Therapy with combination of Pioglitazone and Metformin should not be initiated if the patient exhibits clinical evidence of active liver disease or increased serumtransaminase levels (ALT greater than 2.5 times the upper limit of normal) at start of therapy. Liver enzyme monitoring is recommended in all patients prior to initiation of therapy with combination of Pioglitazone and Metformin and periodically thereafter

Side Effects

Generally this combined preparation is well tolerated. However, the most common side effects are upper respiratory tract infection, diarrhea, peripheral edema and headache, respectively. These are mild in severity.

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 TDLo observed in mice is 24 mg/kg for 4 days and for rats is 3 mg/kg for 6 days.

One instance of overdose was reported during clinical trials with pioglitazone in which a patient took an oral dose of 120mg daily for four days, followed by 180mg daily for seven days - this patient did not report any adverse clinical symptoms during this time. In the event of overdosage, employ symptomatic and supportive measures according to the patient's clinical status.

Precaution

Pioglitazone exerts its antihyperglycemic effect only in the presence of insulin. Therefore, Pioglitazone should not be used in patients with type 1 diabetes or for the treatment of diabetic ketoacidosis. Pioglitazone should be used with caution in combination especially with insulin, hepatic insufficiency and heart diseases.

Metformin is known to be substantially excreted by the kidney and the risk of Metformin accumulation and lactic acidosis increases with the degree of impairment of renal function. Thus patients with serum creatinine levels above the upper limit of normal for their age should not receive this combination.

Interaction

May impair vit B12 absorption. Increased plasma levels with strong CYP2C8 inhibitors (e.g. gemfibrozil). Decreased plasma levels with CYP2C8 inducers (e.g. rifampicin). Reduced metabolism with cationic drugs eliminated by renal tubular secretion.

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 average apparent volume of distribution of pioglitazone is 0.63 ± 0.41 L/kg.

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 .

Following oral administration of pioglitazone, peak serum concentrations are observed within 2 hours (T_max) - food slightly delays the time to peak serum concentration, increasing T_max to approximately 3-4 hours, but does not alter the extent of absorption. Steady-state concentrations of both parent drug and its primary active metabolites are achieved after 7 days of once-daily administration of pioglitazone. C_max and AUC increase proportionately to administered doses.

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 serum half-life of pioglitazone and its metabolites (M-III and M-IV) range from 3-7 hours and 16-24 hours, respectively.

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 .

The apparent clearance of orally administered pioglitazone is 5-7 L/h.

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 .

Approximately 15-30% of orally administered pioglitazone is recovered in the urine. The bulk of its elimination, then, is presumed to be through the excretion of unchanged drug in the bile or as metabolites in the feces.

Pregnancy & Breastfeeding use

Pregnancy: There are no adequate and well-controlled studies in pregnant women with this combination or its individual components. So, it should only be used if the potential benefit justifies the potential risk to the fetus.

Nursing mother: It is not known whether Pioglitazone and/or Metformin are secreted in human milk. Because many drugs are excreted in human milk, this combination should not be administered to a breastfeeding woman.

Contraindication

Contraindicated in patients with:

• Renal disease or renal dysfunction (e.g. as suggested by serum creatinine levels >1.5 mg/dl in male, >1.4 mg/dl in females or abnormal creatinine clearance), which may also result from conditions such as cardiovascular collapse (shock), acute myocardial infarction and septicemia.
• Known hypersensitivity to Pioglitazone, Metformin or any other component of this combination.
• Acute or chronic metabolic acidosis including diabetic ketoacidosis with or without coma.

Special Warning

The initial and maintenance dose of Pioglitazone & Metformin should be carefully selected in patients with advanced age due to the potential for decreased renal function in these populations. Monitoring of renal function is necessary to aid in prevention of Metformin associated lactic acidosis, particularly in the elderly. Pioglitazone & Metformin should not be initiated if the patients exhibit clinical evidence of active liver disease. Liver enzyme monitoring is recommended in all patients prior to initiation of therapy with combination of Pioglitazone and Metformin and periodically thereafter.

Acute Overdose

In the event of Overdosage, appropriate supportive treatment should be initiated according to patient's clinical signs and symptoms.

Storage Condition

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

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