Thiazolidinedione

Aka: Thiazolidinedione, Glitazone, Rosiglitazone, Avandia, Pioglitazone, Actos, Troglitazone, Rezulin

1. Indications
   1. Oral Hypoglycemic for Type II Diabetes Mellitus
      1. Second line agent
      2. Add to other Oral Hypoglycemic agents
   2. Diabetes with coronary Vasospastic Angina pectoris
      1. Murakami (1999) Am J Cardiol 84:92-4
   3. Insulin Resistance Syndromes (experimental)
      1. Polycystic Ovary Syndrome
   4. Psoriasis (experimental)
      1. Thiazolidinediones activate PPARs
         1. Peroxisome proliferator-activated receptors (PPARs)
      2. PPARs have antiinflammatory activity in Psoriasis
         1. Ellis (2000) Arch Dermatol 136(5):609-16
2. Contraindications
   1. Liver disease (ALT > 2.5x upper limit of normal)
   2. CHF NYA Class III or Class IV Heart Failure
3. Precautions
   1. CHF exacerbation risk (and contraindicated for NYHA Class III or IV) for ALL Glitazones (FDA Black Box warning)
4. Mechanism
   1. Thiazolidinedione derivative
   2. Primary mechanism: Increases peripheral tissue Insulin sensitivity
   3. Secondary mechanism: Decreases hepatic Glucose production
   4. Acts at liver, skeletal muscle and fat cells
   5. Activates peroxisome proliferator activated receptors
      1. Receptors known as PPARS
      2. Reduces Insulin Resistance
      3. May independently reduce cardiovascular risk
      4. Increases Glucose uptake
      5. Decreases hepatic Glucose output
   6. Shifts fat deposition from visceral to subcutaneous
   7. Decreases free Fatty Acid levels
5. Adverse Effects
   1. Hepatotoxicity and Liver Failure
      1. Associated with Troglitazone use
      2. Troglitazone removed from U.S. market in March 2000
      3. Rosiglitazone and Pioglitazone may also cause
      4. Follow Liver Function Tests closely
         1. Especially follow in first year
      5. References
         1. May (2002) Ann Intern Med 136:449-52
   2. Fluid retention
      1. Congestive Heart Failure risk (see below)
      2. Peripheral edema (in 3-5% of patients)
      3. Moderate weight gain (1-3 kg)
      4. Mild Anemia
   3. Variable lipid effects
      1. Pioglitazone (Actos)
         1. Lowers Triglycerides by 9-12%
         2. Raises HDL Cholesterol by 12-19%
      2. Rosiglitazone (Avandia):
         1. RAISES Triglycerides by 15%
         2. Raises HDL Cholesterol by 8-19%
         3. Raises LDL Cholesterol
      3. References
         1. (2005) Prescriber's Letter 12(8):43
   4. Risks of adverse effects compounded with Insulin
      1. Weight gain (3-4 kg)
      2. Edema (8-10% of cases)
      3. Congestive Heart Failure
         1. Observe patients with CHF risk closely
      4. Hypoglycemia risk
   5. Decrease Bone Density (Osteoporosis risk)
      1. Class effect
      2. Odds Ratio approaches 2.5 for Glitazone use >8 months
      3. (2008) Arch Intern Med 168:820-5
   6. Cardiovascular risk
      1. Rosiglitazone (Avandia) appears to increase CAD risk
         1. No longer recommended as a first-line agent
      2. Pioglitazone (Actos) may slightly decrease CAD risk
         1. Atherosclerosis may be slowed by Actos
         2. Nissen (2008) JAMA 299(13):1561-73
6. Preparations: Pioglitazone
   1. Preferred of the Glitazones due to vascular disease risk increase with Rosiglitazone
   2. Protocol
      1. Discontinue if no improvement in 8-12 weeks
   3. Dosing
      1. Initial: 15 to 30 mg orally daily
      2. Maximum: 45 mg per day
7. Preparations: Rosiglitazone (use only with caution)
   1. Precautions
      1. Limited use now due to increased cardiovascular risk
      2. FDA has restricted further Rosiglitazone use to those with refractory Type II Diabetes on other agents
   2. Conversion to Pioglitazone
      1. Rosiglitazone 2 mg is equivalent to Pioglitazone 15 mg
      2. Rosiglitazone 4 mg is equivalent to Pioglitazone 30 mg
      3. Rosiglitazone 8 mg is equivalent to Pioglitazone 45 mg
   3. Rosiglitazone (Avandia)
      1. Initial: 4 mg PO qd (or 2 mg PO bid)
      2. Maximum: 8 mg per day (4 mg if on Insulin)
8. Pharmacokinetics
   1. Hepatic metabolism by Cytochrome P450: CYP2C8
9. Monitoring
   1. Liver Function Tests
      1. Initial: Baseline and in 6-12 weeks
      2. Later: Every 6 months
   2. Do not start medication if LFTs > 2.5x normal
   3. Stop medication if LFTs >3x normal
   4. Follow weight for weight gain (esp. if CHF risk)
10. Efficacy
    1. Add to Metformin, Sulfonylurea - delays Insulin need
    2. References
       1. Aljabri (2004) Am J Med 116:230-5
       2. Dailey (2004) Am J Med 116:223-9
11. Cost
    1. Expensive! (Up to $175 to $192 per month)
12. References
    1. (1999) Med Lett Drugs Ther 41(1059):71-3
    2. Krische (2000) West J Med 173:54-7
    3. Schwartz (1998) N Engl J Med 338:861-6
    4. Saltiel (1996) Diabetes 45:1661-9