Side Effects of Hytrin (terazosin)

Hytrin (terazosin) is an alpha 1 blocker used to treat the symptoms of urinary obstruction due to an enlarged prostate caused by benign prostatic hypertrophy (BPH). 

Hytrin also is used alone or in combination with other blood pressure medications to treat high blood pressure. Alpha 1 blockers relax the smooth muscles of the arteries, the prostate, and the bladder neck.

Common side effects of Hytrin include:

• dizziness,
• weakness,
• fatigue,
• headaches,
• swelling of the legs (edema),
• palpitations,
• nasal congestion,
• sleepiness,
• decreased sex drive,
• impotence, and
• blurred vision. 

By relaxing the smooth muscles and dilating the arteries, Hytrin can cause a marked lowering of blood pressure especially when the patient stands up (orthostatic or postural hypotension). Postural hypotension can cause dizziness and fainting upon standing. Postural hypotension and fainting usually are associated with the first dose or the first few days of treatment. 

Serious side effects of Hytrin include symptoms of obstruction to the flow of urine. Prostate cancer and prostatic hypertrophy can both cause these symptoms so patients being treated for prostate hypertrophy should be evaluated to exclude the presence of prostate cancer.

Drug interactions of Hytrin include PDE-5 inhibitors used primarily for erectile dysfunction, which add to the blood pressure-lowering effects. 

There are no adequate studies of Hytrin in pregnancy. It is not recommended during pregnancy unless the benefits justify the potential but unknown risks to the fetus. 

It is unknown if Hytrin is excreted in breast milk. Consult your doctor before breastfeeding.

Commonly reported side effects include:

• postural hypotension,
• dizziness,
• weakness,
• fatigue,
• headaches,
• swelling of the legs (edema),
• palpitations,
• nasal congestion,
• sleepiness,
• decreased libido,
• impotence, and
• blurred vision.

By relaxing the smooth muscles and dilating the arteries, terazosin can cause a marked lowering of the blood pressure especially when the patient stands up (orthostatic or postural hypotension). Postural hypotension can cause the patient to faint upon standing. Postural hypotension and fainting usually are associated with the first dose or the first few days of treatment. Hypotension and fainting also can occur when doses of medication are increased abruptly or another blood pressure medication is added. In order to decrease the likelihood of excessive hypotension and fainting, terazosin is initiated low doses.

Prostate cancer and prostatic hypertrophy both cause similar symptoms of obstruction to the flow of urine. Prostate cancer and prostatic hypertrophy can co-exist. Therefore, patients being treated for prostate hypertrophy should be evaluated to exclude the presence of prostate cancer.

Benign Prostatic Hyperplasia

The incidence of treatment-emergent adverse events has been ascertained from clinical trials conducted worldwide. All adverse events reported during these trials were recorded as adverse reactions. The incidence rates presented below are based on combined data from six placebo-controlled trials involving once-a-day administration of terazosin at doses ranging from 1 to 20 mg.

Table 1 summarizes those adverse events reported for patients in these trials when the incidence rate in the terazosin group was at least 1% and was greater than that for the placebo group, or where the reaction is of clinical interest. Asthenia, postural hypotension, dizziness, somnolence, nasal congestion/rhinitis, and impotence were the only events that were significantly (p = 0.05) more common in patients receiving terazosin than in patients receiving placebo.

The incidence of urinary tract infection was significantly lower in the patients receiving terazosin than in patients receiving placebo. An analysis of the incidence rate of hypotensive adverse events adjusted for the length of drug treatment has shown that the risk of the events is greatest during the initial seven days of treatment, but continues at all time intervals.

Table 1. Adverse Reactions During Placebo-controlled Trials Benign Prostatic Hyperplasia

Additional adverse events have been reported, but these are, in general, not distinguishable from symptoms that might have occurred in the absence of exposure to terazosin. The safety profile of patients treated in the long-term open-label study was similar to that observed in the controlled studies.

The adverse events were usually transient and mild or moderate in intensity, but sometimes were serious enough to interrupt treatment. In the placebo-controlled clinical trials, the rates of premature termination due to adverse events were not statistically different between the placebo and terazosin groups. The adverse events that were bothersome, as judged by their being reported as reasons for discontinuation of therapy by at least 0.5% of the terazosin group and being reported more often than in the placebo group, are shown in Table 2.

Table 2. Discontinuation During Placebo-controlled Trials Benign Prostatic Hyperplasia

Hypertension

The prevalence of adverse reactions has been ascertained from clinical trials conducted primarily in the United States. All adverse experiences (events) reported during these trials were recorded as adverse reactions. The prevalence rates presented below are based on combined data from fourteen placebo-controlled trials involving once-a-day administration of terazosin, as monotherapy or in combination with other antihypertensive agents, at doses ranging from 1 to 40 mg.

Table 3 summarizes those adverse experiences reported for patients in these trials where the prevalence rate in the terazosin group was at least 5%, where the prevalence rate for the terazosin group was at least 2% and was greater than the prevalence rate for the placebo group, or where the reaction is of particular interest.

Asthenia, blurred vision, dizziness, nasal congestion, nausea, peripheral edema, palpitations and somnolence were the only symptoms that were significantly (p < 0.05) more common in patients receiving terazosin than in patients receiving placebo. Similar adverse reaction rates were observed in placebo-controlled monotherapy trials.

Table 3. Adverse Reactions During Placebo-controlled Trials Hypertension

Additional adverse reactions have been reported, but these are, in general, not distinguishable from symptoms that might have occurred in the absence of exposure to terazosin. The following additional adverse reactions were reported by at least 1% of 1987 patients who received terazosin in controlled or open, short- or long-term clinical trials or have been reported during marketing experience:

Body as a Whole

chest pain, facial edema, fever, abdominal pain, neck pain, shoulder pain

Cardiovascular System

arrhythmia, vasodilation

Digestive System

constipation, diarrhea, dry mouth, dyspepsia, flatulence, vomiting

Metabolic/Nutritional Disorders

gout

Musculoskeletal System

arthralgia, arthritis, joint disorder, myalgia

Nervous System

anxiety, insomnia

Respiratory System

bronchitis, cold symptoms, epistaxis, flu symptoms, increased cough, pharyngitis, rhinitis

Skin and Appendages

pruritus, rash, sweating

Special Senses

abnormal vision, conjunctivitis, tinnitus

Urogenital System

urinary frequency, urinary incontinence primarily reported in postmenopausal women, urinary tract infection.

The adverse reactions were usually mild or moderate in intensity but sometimes were serious enough to interrupt treatment. The adverse reactions that were most bothersome, as judged by their being reported as reasons for discontinuation of therapy by at least 0.5% of the terazosin group and being reported more often than in the placebo group, are shown in Table 4.

Table 4. Discontinuations During Placebo-controlled Trials Hypertension

Post-marketing Experience

Post-marketing experience indicates that in rare instances patients may develop allergic reactions, including anaphylaxis, following administration of terazosin hydrochloride. There have been reports of priapism and thrombocytopenia during post-marketing surveillance. Atrial fibrillation has been reported.

During cataract surgery, a variant of small pupil syndrome known as Intraoperative Floppy Iris Syndrome (IFIS) has been reported in association with alpha-1 blocker therapy.

Concomitant administration of Hytrin (terazosin hcl) with a phosphodiesterase-5 (PDE-5) inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension.

In controlled trials, Hytrin (terazosin hcl) tablets have been added to diuretics, and several beta-adrenergic blockers; no unexpected interactions were observed. Hytrin (terazosin hcl) tablets have also been used in patients on a variety of concomitant therapies; while these were not formal interaction studies, no interactions were observed. Hytrin (terazosin hcl) tablets have been used concomitantly in at least 50 patients on the following drugs or drug classes:

• 1) analgesic/anti-inflammatory (e.g., acetaminophen, aspirin, codeine, ibuprofen, indomethacin);
• 2) antibiotics (e.g., erythromycin, trimethoprim and sulfamethoxazole);
• 3) anticholinergic/sympathomimetics (e.g., phenylephrine hydrochloride, phenylpropanolamine hydrochloride, pseudoephedrine hydrochloride);
• 4) antigout (e.g., allopurinol);
• 5) antihistamines (e.g., chlorpheniramine);
• 6) cardiovascular agents (e.g., atenolol, hydrochlorothiazide, methyclothiazide, propranolol);
• 7) corticosteroids;
• 8) gastrointestinal agents (e.g., antacids);
• 9) hypoglycemics;
• 10) sedatives and tranquilizers (e.g., diazepam).

Use with Other Drugs

In a study (n=24) where terazosin and verapamil were administered concomitantly, terazosin's mean AUC_0-24 increased 11% after the first verapamil dose and after 3 weeks of verapamil treatment it increased by 24% with associated increases in Cmax (25%) and Cmin (32%) means. Terazosin mean Tmax decreased from 1.3 hours to 0.8 hours after 3 weeks of verapamil treatment. Statistically significant differences were not found in the verapamil level with and without terazosin.

In a study (n=6) where terazosin and captopril were administered concomitantly, plasma disposition of captopril was not influenced by concomitant administration of terazosin and terazosin maximum plasma concentrations increased linearly with dose at steady-state after administration of terazosin plus captopril.