Side Effects of Doxazosin (Cardura)
Doxazosin, available under the brand Cardura and Doxadura, is an alpha 1 adrenoceptor blocker and inhibits other molecules such as noradrenaline from binding to the receptor. This results in smooth muscle relaxation and can help in a number of conditions such as high blood pressure and urinary retention secondary to benign prostatic hyperplasia (enlarged prostate gland) associated with urinary retention. Varying rates of metabolism of doxazosin could be linked to the probability of developing side effects when taking Cardura. As such, pharmacogenetics (i.e. the genetic sequencing of patients to identify how they metabolize the drug) is a new and important tool for reducing the probability of developing side effects.
Common Side Effects
As a smooth muscle relaxant, Cardura, is associated with a number of side effects. However, the drug is usually well tolerated and only associated with mild side effects.
The FDA outlines the common side effects of Cardura, which are present in more than 1% of patients:
- Dizziness (occurs in more than 3% of patients)
- Syncope (fainting)
- Peripheral edema (swelling of the ankles and feet)
- Palpitations (extra heart beats)
- Chest pain
- Tachycardia (increased heart rate)
- Paresthesia (loss of sensation)
- Dizziness (happens in up to 17% of patients)
- Somnolence (sleepiness)
- Dyspnea (cough)
- Diarrhea (occurs in over 1% of patients)
About Pharmacogenetic Testing
Cardura is metabolized by the cytochrome P450 superfamily of hepatic enzymes. Studies suggest that the drug is primarily broken down by isoform CYP3A4. The recent advance of pharmacogenetics has shown that polymorphisms in CYP genes, amongst others, can cause individual variation in the response to medications. Polymorphisms in CYP3A4 for instance can result in poor or ultra-rapid metabolism of a variety of drugs. This may increase the probability of suffering adverse effects to drugs. Understanding which polymorphisms an individual holds can reduce the risk of suffering from side effects as dosage of the drug can be adjusted.
Understand Your Genetic Risk with the Rxight® Genetic Test
Rxight® pharmacogenetics testing identifies common polymorphisms on a number of genes. These genes include many of the cytochrome P450 family, including CYP3A4, and as such we can identify how a patient is likely to respond to more than 200 clinically relevant medications (including Cardura).
Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry
Read more about Rxight® DNA Testing for Medications