Side Effects of Terazosin (Hytrin)
Terazosin commonly known as the brand Hytrin is a selective ╔æ1 adrenergic receptor antagonist. The drug is commonly used to treat the symptoms of benign prostatic hyperplasia (BPH) (overgrowth of the prostate that eventually blocks urine flow). It is sometimes used to control hypertension. Hytrin is also an ideal treatment for males with both an enlarged prostate and hypertension.
Mechanism of Action
Hytrin is selective for the ╔æ1 adrenoceptors found in the smooth muscle of the bladder. It is more selective to ╔æ1a receptors in the prostate than ╔æ1b receptors in blood vessels. Benign Prostatic Hyperplasia (BPH) often causes urinary retention. By inhibiting these receptors, the smooth muscle relaxes resulting in better urine flow and an improvement in the symptoms of BPH.
Common Side Effects
There a number of side effects associated with Hytrin. Common adverse effects that occur in more than 1% of patients include:
- Palpitations (rapid irregular heartbeats)
- Peripheral edema (accumulation of fluid causing swelling)
- Cold extremities (hands and feet)
- Chest pain
- Blurred vision
- Asthenia (lack of energy)
- Somnolence (sleepiness or drowsiness)
- Myalgia (pain in muscles)
- Nasal congestion
- Sinusitis (sinus infection)
- Dyspnea (cough)
- Abdominal pain
Rarer side effects of Hytrin that occur in less than 1% of patients are rash, anaphylaxis (life threatening allergic reaction), and syncope (fainting).
About Pharmacogenetic Testing
Polymorphisms in the genes that code for enzymes that metabolize Hytrin may increase the probability of developing side effects when taking the drug. Hytrin is metabolized by the cytochrome P450 superfamily of enzymes, namely isoenzyme CYP3A4. Polymorphisms in CYP3A4 have been associated with variable rates of metabolism of its substrates. This may increase or decrease probability of developing side effects.
Know Your Risk with the Rxight® Genetic Test
Some patients that take Hytrin develop no adverse effects while others may experience multiple. This inter patient variability may be due to differences in genetics between patients. Identifying these alleles can aid in clinical decision making when prescribing the drug. Clinicians may be able to alter the dose of the drug given a patient’s alleles. This may reduce the chances of developing adverse effects associated with the drug. MD Labs provides a genetic testing service, the Rxight® test, which sequences 18 genes (including CYP3A4) to establish how patients are likely to respond to hundreds of clinically relevant medications including Hytrin.
Contributors to this Article:
Michael Sapko, MD, PhD; and Deborah Kallick, PhD, Medicinal Chemistry
Read more about Rxight® Individualized Medicine