ACTOS (pioglitazone)

ACTOS (pioglitazone)

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ACTOS (pioglitazone)

ACTOS tablets are a thiazolidinedione and an agonist for peroxisome proliferator-activated receptor (PPAR) gamma that contains an oral antidiabetic medication: pioglitazone.

Pioglitazone [(±)-5-[[4-[2-(5-ethyl-2-pyridinyl) ethoxy] phenyl] methyl]-2,4-] thiazolidinedione monohydrochloride contains one asymmetric carbon, and the compound is synthesized and used as the racemic mixture. The two enantiomers of pioglitazone interconvert in vivo. No differences were found in the pharmacologic activity between the two enantiomers.

Pioglitazone hydrochloride is an odorless white crystalline powder that has a molecular formula of C19H20N2O3S•HCl and a molecular weight of 392.90 daltons. It is soluble in N,Ndimethylformamide, slightly soluble in anhydrous ethanol, very slightly soluble in acetone and acetonitrile, practically insoluble in water, and insoluble in ether.

ACTOS is available as a tablet for oral administration containing 15 mg, 30 mg, or 45 mg of pioglitazone (as the base) formulated with the following excipients: lactose monohydrate NF, hydroxypropylcellulose NF, carboxymethylcellulose calcium NF, and magnesium stearate NF.

Indications and usage

ACTOS is a thiazolidinedione and an agonist for peroxisome proliferator-activated receptor (PPAR) gamma indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus in multiple clinical settings.

Important Limitations of Use:

  • Not for treatment of type 1 diabetes or diabetic ketoacidosis.

Mechanism of Action

ACTOS is a thiazolidinedione that depends on the presence of insulin for its mechanism of action. ACTOS decreases insulin resistance in the periphery and in the liver resulting in increased insulin-dependent glucose disposal and decreased hepatic glucose output. Pioglitazone is not an insulin secretagogue. Pioglitazone is an agonist for peroxisome proliferator-activated receptor-gamma (PPARγ). PPAR receptors are found in tissues important for insulin action such as adipose tissue, skeletal muscle, and liver. Activation of PPARγ nuclear receptors modulates the transcription of a number of insulin responsive genes involved in the control of glucose and lipid metabolism.

In animal models of diabetes, pioglitazone reduces the hyperglycemia, hyperinsulinemia, and hypertriglyceridemia characteristic of insulin-resistant states such as type 2 diabetes. The metabolic changes produced by pioglitazone result in increased responsiveness of insulindependent tissues and are observed in numerous animal models of insulin resistance.

Because pioglitazone enhances the effects of circulating insulin (by decreasing insulin resistance), it does not lower blood glucose in animal models that lack endogenous insulin.

Pharmacokinetics

Absorption: Following oral administration of pioglitazone, Tmax of pioglitazone was within two hours. Food delays the Tmax to three to four hours but does not alter the extent of absorption (AUC).

Distribution: The mean apparent volume of distribution (Vd/F) of pioglitazone following single-dose administration is 0.63 ± 0.41 (mean ± SD) L/kg of body weight. Pioglitazone is extensively protein bound (>99%) in human serum, principally to serum albumin. Pioglitazone also binds to other serum proteins, but with lower affinity. M-III and M-IV are also extensively bound (>98%) to serum albumin.

Metabolism: Pioglitazone is extensively metabolized by hydroxylation and oxidation; the metabolites also partly convert to glucuronide or sulfate conjugates. Metabolites M-III and M-IV are the major circulating active metabolites in humans.

In vitro data demonstrate that multiple CYP isoforms are involved in the metabolism of pioglitazone, which include CYP2C8 and, to a lesser degree, CYP3A4 with additional contributions from a variety of other isoforms including the mainly extrahepatic CYP1A1. In vivo study of pioglitazone in combination with gemfibrozil, a strong CYP2C8 inhibitor, showed that pioglitazone is a CYP2C8 substrate. Urinary 6ß-hydroxycortisol/cortisol ratios measured in patients treated with ACTOS showed that pioglitazone is not a strong CYP3A4 enzyme inducer.

Excretion and Elimination: Following oral administration, approximately 15% to 30% of the pioglitazone dose is recovered in the urine. Renal elimination of pioglitazone is negligible, and the drug is excreted primarily as metabolites and their conjugates. It is presumed that most of the oral dose is excreted into the bile either unchanged or as metabolites and eliminated in the feces.

The mean serum half-life (t1/2) of pioglitazone and its metabolites (M-III and M-IV) range from three to seven hours and 16 to 24 hours, respectively. Pioglitazone has an apparent clearance, CL/F, calculated to be five to seven L/hr.

Dosage and administration

  • Initiate ACTOS at 15 mg or 30 mg once daily. Limit initial dose to 15 mg once daily in patients with NYHA Class I or II heart failure.
  • If there is inadequate glycemic control, the dose can be increased in 15 mg increments up to a maximum of 45 mg once daily.
  • Obtain liver tests before starting ACTOS. If abnormal, use caution when treating with ACTOS, investigate the probable cause, treat (if possible) and follow appropriately. Monitoring liver tests while on ACTOS is not recommended in patients without liver disease.
  • Concomitant Use with an Insulin Secretagogue or Insulin: If hypoglycemia occurs in a patient co-administered ACTOS and an insulin secretagogue (e.g., sulfonylurea), the dose of the insulin secretagogue should be reduced. If hypoglycemia occurs in a patient co-administered ACTOS and insulin, the dose of insulin should be decreased by 10% to 25%. Further adjustments to the insulin dose should be individualized based on glycemic response.
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  • Concomitant Use with Strong CYP2C8 Inhibitors: Coadministration of ACTOS and gemfibrozil, a strong CYP2C8 inhibitor, increases pioglitazone exposure approximately 3-fold. Therefore, the maximum recommended dose of ACTOS is 15 mg daily when used in combination with gemfibrozil or other strong CYP2C8 inhibitors

Contraindications

  • Initiation in patients with established New York Heart Association (NYHA) Class III or IV heart failure
  • Use in patients with known hypersensitivity to pioglitazone or any other component of ACTOS

Warnings and precautions

Congestive heart failure: Fluid retention may occur and can exacerbate or lead to congestive heart failure. Combination use with insulin and use in congestive heart failure NYHA Class I and II may increase risk. Monitor patients for signs and symptoms.

Hypoglycemia: When used with insulin or an insulin secretagogue, a lower dose of the insulin or insulin secretagogue may be needed to reduce the risk of hypoglycemia.

Hepatic effects: Postmarketing reports of hepatic failure, sometimes fatal. Causality cannot be excluded. If liver injury is detected, promptly interrupt ACTOS and assess patient for probable cause, then treat cause if possible, to resolution or stabilization. Do not restart ACTOS if liver injury is confirmed and no alternate etiology can be found.

Bladder cancer: May increase the risk of bladder cancer. Do not use in patients with active bladder cancer. Use caution when using in patients with a prior history of bladder cancer.

Edema: Dose-related edema may occur.

Fractures: Increased incidence in female patients. Apply current standards of care for assessing and maintaining bone health.

Macular edema: Postmarketing reports. Recommend regular eye exams in all patients with diabetes according to current standards of care with prompt evaluation for acute visual changes.

Macrovascular outcomes: There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with ACTOS.

Adverse effects

Most common adverse reactions (≥5%) are upper respiratory tract infection, headache, sinusitis, myalgia, and pharyngitis

Drug interactions

Strong CYP2C8 Inhibitors: An inhibitor of CYP2C8 (e.g., gemfibrozil) significantly increases the exposure (area under the serum concentration-time curve or AUC) and half-life (t½) of pioglitazone. Therefore, the maximum recommended dose of ACTOS is 15 mg daily if used in combination with gemfibrozil or other strong CYP2C8 inhibitors.

CYP2C8 Inducers: An inducer of CYP2C8 (e.g., rifampin) may significantly decrease the exposure (AUC) of pioglitazone. Therefore, if an inducer of CYP2C8 is started or stopped during treatment with ACTOS, changes in diabetes treatment may be needed based on clinical response without exceeding the maximum recommended daily dose of 45 mg for ACTOS.

Topiramate: A decrease in the exposure of pioglitazone and its active metabolites were noted with concomitant administration of pioglitazone and topiramate. The clinical relevance of this decrease is unknown; however, when ACTOS and topiramate are used concomitantly, monitor patients for adequate glycemic control.

Use in specific populations

Pregnancy: Limited data with ACTOS in pregnant women are not sufficient to determine a drug-associated risk for major birth defects or miscarriage. There are risks to the mother and fetus associated with poorly controlled diabetes in pregnancy.

Poorly controlled diabetes in pregnancy increases the maternal risk for diabetic ketoacidosis, pre-eclampsia, spontaneous abortions, preterm delivery, still birth and delivery complications. Poorly controlled diabetes increases the fetal risk for major birth defects, still birth, and macrosomia related morbidity.

Lactation: There is no information regarding the presence of pioglitazone in human milk, the effects on the breastfed infant, or the effects on milk production. Pioglitazone is present in rat milk; however due to species-specific differences in lactation physiology, animal data may not reliably predict drug levels in human milk. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for ACTOS and any potential adverse effects on the breastfed infant from ACTOS or from the underlying maternal condition.

Females and Males of Reproductive Potential: Discuss the potential for unintended pregnancy with premenopausal women as therapy with ACTOS, like other thiazolidinediones, may result in ovulation in some anovulatory women.

Pediatric Use: Safety and effectiveness of ACTOS in pediatric patients have not been established. ACTOS is not recommended for use in pediatric patients based on adverse effects observed in adults, including fluid retention and congestive heart failure, fractures, and urinary bladder tumors.

Overdosage

During controlled clinical trials, one case of overdose with ACTOS was reported. A male patient took 120 mg per day for four days, then 180 mg per day for seven days. The patient denied any clinical symptoms during this period.

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

Storage

Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature]. Keep container tightly closed, and protect from light, moisture and humidity.

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