Side Effects of Torsemide (Demadex)
Torsemide, commonly known under the brand Demadex, is a loop diuretic. The drug is normally used to treat edema (swelling) associated with congestive heart failure. Demadex can also be used to treat hypertension in some patients in low to moderate doses.
Mechanism of Action
Torsemide exhibits its clinical effects in the same way as all loop diuretics. Diuretics are a class of drugs that increases diuresis (passing urine). Loop diuretics work by inhibiting the Na+/Cl-/2Cl- co transporter, reducing osmolarity (the measure of solute concentration) in the thick ascending portion of the loop of Henle. This results in less water being lost by osmosis and increased diuresis. Lower volumes of fluid works to reduce edema and hypertension.
Common Side Effects
Studies show 4% of patients discontinue Demadex treatment due to adverse effects. The FDA reports that the most common side effects of these occur in more than 1% of patients:
- Asthenia (lack of energy)
- Hypovolemia (plasma of the blood is too low)
- Dyspepsia (indigestion)
- Excessive thirst
- Excessive urination
- Syncope (fainting)
About Pharmacogenetic Testing
Demadex is primarily metabolized by the cytochrome P450 superfamily of enzymes. It is primarily metabolized by CYP2C9. Polymorphisms in CYP2C9 have been shown to significantly alter the biotransformation of the drug and may affect the probability of developing adverse effects when taking Demadex. Identifying these polymorphisms can therefore be crucial to clinical decision-making. Pharmacogenetics is how the drug interacts with a patient’s specific genetic profile, which is responsible for a significant portion of this variability. Polymorphisms in the genes that encode enzymes and receptors have been shown to cause inter patient variability in the therapeutic and adverse effects of a drug (The Pharmacogenomics Journal “Genetic Variation at the CYP2C9 Locus and Its Association with Torsemide Biotransformation” September 2006).
Understand Your Risk for Side Effects with the Rxight® Genetic Test
Most patients do not experience side effects when taking Demadex, although a small portion may suffer significant side effects that in rare cases cause discontinuation of the medication or death. A number of reasons have been suggested to explain this inter patient variability. With the Rxight® test, a physician may alter drug concentration, or not prescribe the drug at all, given an individual’s known polymorphisms. MD Labs provides this genetic testing service, which sequences 18 genes (including cytochrome P450 genes such as CYP2C9) to establish how an individual is likely to respond to hundreds of clinically relevant medications including Demadex.
Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry
Read more about Rxight® Genetic Testing Labs