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Side Effects of



Thiazolidinediones (TZDs) are a class of oral hypoglycemic medications used in patients with diabetes mellitus (type II diabetes). The drugs of this class on the market are Avandia and Actos. The main effect is an increase in storage of fatty acids in adipocytes (fat cells), thereby decreasing the amount of fatty acids present in circulation. As a result, cells rely more on carbohydrates for energy, such as glucose. TZDs also reduce triglycerides and increase the high-density lipoprotein cholesterol (HDL) as well as increase the low-density lipoprotein cholesterol (LDL).

Serious Side Effects of TZDs

Serious side effects can occur during the course of TZD treatment. The FDA recommends two to three months of checking liver enzymes. (JAMA “Liver enzyme monitoring in patients treated with troglitazone” (Aug 2001). France and Germany suspended the use of Actos after it was shown that some patients developed bladder cancer.
(American Health and Drug Benefits “Diabetes Medications and Cancer Risk: Review of the Literature,” Jul 2012). Additionally, heart failure can result from excess fluid build up in the body. (Pharmacogenomics “Pharmacogenomics and pharmacogenetics of thiazolidinediones: role in diabetes and cardiovascular risk factors,” Oct 2015).

Common Side Effects

The main side effect of thiazolidinediones is water retention, possibly leading to edema (excess fluid in the tissues). Weight gain and macular edema can also occur. Additionally, TZDs may cause hypoglycemia when used with additional antidiabetic drugs and may decrease hematocrit and hemoglobin levels. (Pharmacogenomics “Pharmacogenomics and pharmacogenetics of thiazolidinediones: role in diabetes and cardiovascular risk factors,” Oct 2015).

Understand Your Risks with the Rxight® Genetic Test

You can identify your genetic potential for side effects of not only thiazolidinedione drugs but many other drugs on the market with the Rxight® genetic test from MD Labs. This state-of-the-art platform is grounded in the analysis of your ability to metabolize over 200 drugs and over-the-counter medications across dozens of clinically significant medication classes through a process called “single nucleotide polymorphism (SNP) genotyping.” The ability to metabolize drugs depends on your genetic makeup, specifically the genes that are responsible for encoding the enzymes that process medications. Your prescribers may use the results of this test to more safely prescribe any number of drugs on the market. This test heralds the use of precision medicine in your individual care. One simple cheek swab can give you and your physician a great deal of information about your ability to process drugs so that the safest and most effective dose be used, preferably before treatment begins.

How Does Pharmacogenetic Testing Work?

Pharmacogenetics is an important emerging field of medicine that arose from the sequencing of the human genome. Specifically, PGx testing reveals if an individual’s drug metabolism genes may have variations that encode for less or more efficient enzymatic activity – determining a patient’s potential for developing adverse reactions or, conversely, not responding to a medication. In this way, pharmacogenetic testing obviates the need to go through the traditional trial-and-error approach – a process that can take months or even years – putting the patient at risk for serious side effects. Instead, pharmacological treatment can be tailored the individual patient’s unique genetic makeup, and optimal dosing determined – preferably before medication treatment begins. It thus provides an invaluable “pharmacogenetic blueprint” for life to help guide future pharmacological treatment and achieve maximum therapeutic benefit.

Contributors to this Article:
Michael Sapko, MD, PhD; Deborah Kallick, PhD, Medicinal Chemistry

TZDs Tested Include:

Read more about Rxight® Genetic Testing for Diabetes Medications