Terazosin Hydrochloride

×

Overview

What is Terazosin Hydrochloride?

Terazosin hydrochloride, an alpha-1-selective adrenoceptor blocking agent, is a quinazoline derivative represented by the following structural formula, molecular formula and chemical name:

Piperazine, 1-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-[(tetra-hydro-2-furanyl)carbonyl]-, monohydrochloride, anhydrous.

Terazosin hydrochloride is a white, crystalline substance, freely soluble in water and isotonic saline and has a molecular weight of 459.93. Each terazosin hydrochloride capsule, for oral administration, contains 1 mg, 2 mg, 5 mg or 10 mg of terazosin as terazosin hydrochloride anhydrous. Each capsule contains the following inactive ingredients: crospovidone, lactose (monohydrate), magnesium stearate and microcrystalline cellulose. The capsule shells and imprinting inks contain: D & C Yellow # 10 Aluminum Lake, FD & C Blue # 1 Aluminum Lake, FD & C Blue # 2 Aluminum Lake, FD & C Red # 40 Aluminum Lake, gelatine, pharmaceutical glaze, propylene glycol, silicon dioxide, sodium lauryl sulfate, synthetic black iron oxide, and titanium dioxide. The 5 mg also contains; D & C Red # 28.

What does Terazosin Hydrochloride look like?

What are the available doses of Terazosin Hydrochloride?

Sorry No records found.

What should I talk to my health care provider before I take Terazosin Hydrochloride?

Sorry No records found

How should I use Terazosin Hydrochloride?

Terazosin hydrochloride is indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH). There is a rapid response, with approximately 70% of patients experiencing an increase in urinary flow and improvement in symptoms of BPH when treated with terazosin hydrochloride. The long-term effects of terazosin hydrochloride on the incidence of surgery, acute urinary obstruction or other complications of BPH are yet to be determined.

Terazosin hydrochloride is also indicated for the treatment of hypertension. It can be used alone or in combination with other antihypertensive agents such as diuretics or beta-adrenergic blocking agents.

If terazosin hydrochloride administration is discontinued for several days, therapy should be reinstituted using the initial dosing regimen.

What interacts with Terazosin Hydrochloride?

Terazosin hydrochloride capsules are contraindicated in patients known to be hypersensitive to terazosin hydrochloride.

What are the warnings of Terazosin Hydrochloride?

Syncope and "First-Dose" Effect

Terazosin hydrochloride capsules, like other alpha-adrenergic blocking agents, can cause marked lowering of blood pressure, especially postural hypotension, and syncope in association with the first dose or first few days of therapy. A similar effect can be anticipated if therapy is interrupted for several days and then restarted. Syncope has also been reported with other alpha-adrenergic blocking agents in association with rapid dosage increases or the introduction of another antihypertensive drug. Syncope is believed to be due to an excessive postural hypotensive effect, although occasionally the syncopal episode has been preceded by a bout of severe supraventricular tachycardia with heart rates of 120 to 160 beats per minute. Additionally, the possibility of the contribution of hemodilution to the symptoms of postural hypotension should be considered.

To decrease the likelihood of syncope or excessive hypotension, treatment should always be initiated with a 1 mg dose of terazosin, given at bedtime. The 2 mg, 5 mg and 10 mg capsules are not indicated as initial therapy. Dosage should then be increased slowly, according to recommendations in the Dosage and Administration section and additional antihypertensive agents should be added with caution. The patient should be cautioned to avoid situations, such as driving or hazardous tasks, where injury could result should syncope occur during initiation of therapy.

In early investigational studies, where increasing single doses up to 7.5 mg were given at 3 day intervals, tolerance to the first dose phenomenon did not necessarily develop and the "first-dose" effect could be observed at all doses. Syncopal episodes occurred in 3 of the 14 subjects given terazosin at doses of 2.5 mg, 5 mg and 7.5 mg, which are higher than the recommended initial dose; in addition, severe orthostatic hypotension (blood pressure falling to 50/0 mmHg) was seen in two others and dizziness, tachycardia, and lightheadedness occurred in most subjects. These adverse effects all occurred within 90 minutes of dosing.

In three placebo-controlled BPH studies 1, 2, and 3 (see ), the incidence of postural hypotension in the terazosin treated patients was 5.1%, 5.2%, and 3.7% respectively.

In multiple dose clinical trials involving nearly 2,000 hypertensive patients treated with terazosin, syncope was reported in about 1% of patients. Syncope was not necessarily associated only with the first dose.

If syncope occurs, the patient should be placed in a recumbent position and treated supportively as necessary. There is evidence that the orthostatic effect of terazosin is greater, even in chronic use, shortly after dosing. The risk of the events is greatest during the initial seven days of treatment, but continues at all time intervals.

Priapism

Rarely, (probably less than once in every several thousand patients) terazosin and other α-antagonists have been associated with priapism (painful penile erection, sustained for hours and unrelieved by sexual intercourse or masturbation). Two or three dozen cases have been reported. Because this condition can lead to permanent impotence if not promptly treated, patients must be advised about the seriousness of the condition (see ).

What are the precautions of Terazosin Hydrochloride?

General

Prostatic Cancer

Carcinoma of the prostate and BPH cause many of the same symptoms. These two diseases frequently coexist. Therefore, patients thought to have BPH should be examined prior to starting terazosin hydrochloride therapy to rule out the presence of carcinoma of the prostate.

Intraoperative Floppy Iris Syndrome (IFIS)

Intraoperative Floppy Iris Syndrome (IFIS) has been observed during cataract surgery in some patients on/or previously treated with alpha-1 blockers. This variant of small pupil syndrome is characterized by the combination of a flaccid iris that billows in response to intraoperative irrigation currents, progressive intraoperative miosis despite preoperative dilation with standard mydriatic drugs, and potential prolapse of the iris toward the phacoemulsification incisions. The patient's ophthalmologist should be prepared for possible modifications to their surgical technique, such as the utilization of iris hooks, iris dilator rings, or viscoelastic substances. There does not appear to be a benefit of stopping alpha-1 blocker therapy prior to cataract surgery.

Orthostatic Hypotension

While syncope is the most severe orthostatic effect of terazosin (see ), other symptoms of lowered blood pressure, such as dizziness, lightheadedness and palpitations, were more common and occurred in some 28% of patients in clinical trials of hypertension. In BPH clinical trials, 21% of the patients experienced one or more of the following: dizziness, hypotension, postural hypotension, syncope, and vertigo. Patients with occupations in which such events represent potential problems should be treated with particular caution.

Information for Patients

(see )

Patients should be made aware of the possibility of syncopal and orthostatic symptoms, especially at the initiation of therapy, and to avoid driving or hazardous tasks for 12 hours after the first dose, after a dosage increase and after interruption of therapy when treatment is resumed. They should be cautioned to avoid situations where injury could result should syncope occur during initiation of terazosin therapy. They should also be advised of the need to sit or lie down when symptoms of lowered blood pressure occur, although these symptoms are not always orthostatic, and to be careful when rising from a sitting or lying position. If dizziness, lightheadedness, or palpitations are bothersome they should be reported to the physician, so that dose adjustment can be considered.

Patients should also be told that drowsiness or somnolence can occur with terazosin, requiring caution in people who must drive or operate heavy machinery.

Patients should be advised about the possibility of priapism as a result of treatment with terazosin and other similar medications. Patients should know that this reaction to terazosin is extremely rare, but that if it is not brought to immediate medical attention, it can lead to permanent erectile dysfunction (impotence).

Laboratory Tests

Small but statistically significant decreases in hematocrit, hemoglobin, white blood cells, total protein and albumin were observed in controlled clinical trials. These laboratory findings suggested the possibility of hemodilution. Treatment with terazosin for up to 24 months had no significant effect on prostate specific antigen (PSA) levels.

Drug Interactions

In controlled trials, terazosin has been added to diuretics, and several beta-adrenergic blockers; no unexpected interactions were observed. Terazosin has also been used in patients on a variety of concomitant therapies; while these were not formal interaction studies, no interactions were observed. Terazosin has 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 increased 11% after the first verapamil dose and after 3 weeks of verapamil treatment it increased by 24% with associated increases in C (25%) and C (32%) means. Terazosin mean T 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 (see ).

Carcinogenesis, Mutagenesis, Impairment of Fertility

Terazosin was devoid of mutagenic potential when evaluated and (the Ames test, cytogenetics, the dominant lethal test in mice, Chinese hamster chromosome aberration test and V79 forward mutation assay).

Terazosin, administered in the feed to rats at doses of 8, 40, and 250 mg/kg/day (70, 350, and 2100 mg/M/day), for two years, was associated with a statistically significant increase in benign adrenal medullary tumors of male rats exposed to the 250 mg/kg dose. This dose is 175 times the maximum recommended human dose of 20 mg (12 mg/M). Female rats were unaffected. Terazosin was not oncogenic in mice when administered in feed for 2 years at a maximum tolerated dose of 32 mg/kg/day (110 mg/M; 9 times the maximum recommended human dose). The absence of mutagenicity in a battery of tests, of tumorigenicity of any cell type in the mouse carcinogenicity assay, of increased total tumor incidence in either species, and of proliferative adrenal lesions in female rats, suggests a male rat species specific event. Numerous other diverse pharmaceutical and chemical compounds have also been associated with benign adrenal medullary tumors in male rats without supporting evidence for carcinogenicity in man.

The effect of terazosin on fertility was assessed in a standard fertility/reproductive performance study in which male and female rats were administered oral doses of 8, 30 and 120 mg/kg/day. Four of 20 male rats given 30 mg/kg (240 mg/M; 20 times the maximum recommended human dose) and five of 19 male rats given 120 mg/kg (960 mg/M; 80 times the maximum recommended human dose) failed to sire a litter. Testicular weights and morphology were unaffected by treatment. Vaginal smears at 30 and 120 mg/kg/day, however, appeared to contain less sperm than smears from control matings and good correlation was reported between sperm count and subsequent pregnancy.

Oral administration of terazosin for one or two years elicited a statistically significant increase in the incidence of testicular atrophy in rats exposed to 40 and 250 mg/kg/day (29 and 175 times the maximum recommended human dose), but not in rats exposed to 8 mg/kg/day (> 6 times the maximum recommended human dose). Testicular atrophy was also observed in dogs dosed with 300 mg/kg/day (> 500 times the maximum recommended human dose) for three months but not after one year when dosed with 20 mg/kg/day (38 times the maximum recommended human dose). This lesion has also been seen with prazosin, another selective alpha-1 blocking agent.

Pregnancy

Teratogenic Effects

Pregnancy Category C

Terazosin was not teratogenic in either rats or rabbits when administered at oral doses up to 280 and 60 times, respectively, the maximum recommended human dose. Fetal resorptions occurred in rats dosed with 480 mg/kg/day, approximately 280 times the maximum recommended human dose. Increased fetal resorptions, decreased fetal weight and an increased number of supernumerary ribs were observed in offspring of rabbits dosed with 60 times the maximum recommended human dose. These findings (in both species) were most likely secondary to maternal toxicity. There are no adequate and well controlled studies in pregnant women and the safety of terazosin in pregnancy has not been established. Terazosin hydrochloride is not recommended during pregnancy unless the potential benefit justifies the potential risk to the mother and fetus.

Nonteratogenic Effects

In a peri- and post-natal development study in rats, significantly more pups died in the group dosed with 120 mg/kg/day (> 75 times the maximum recommended human dose) than in the control group during the 3 week postpartum period.

Nursing Mothers

It is not known whether terazosin is excreted in breast milk. Because many drugs are excreted in breast milk, caution should be exercised when terazosin is administered to a nursing woman.

Pediatric Use

Safety and effectiveness in pediatric patients have not been determined.

What are the side effects of Terazosin Hydrochloride?

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 mg 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 (see ) 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.

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 1 ADVERSE REACTIONS DURING PLACEBO-CONTROLLED TRIALS**
Body System	Terazosin (N=636)	Placebo (N=360)
Asthenia	7.4%	3.3%
Flu Syndrome	2.4%	1.7%
Headache	4.9%	5.8%
Hypotension	0.6%	0.6%
Palpitations	0.9%	1.1%
Postural Hypotension	3.9%	0.8%
Syncope	0.6%	0.0%
Nausea	1.7%	1.1%
Peripheral Edema	0.9%	0.3%
Weight Gain	0.5%	0.0%
Dizziness	9.1%	4.2%
Somnolence	3.6%	1.9%
Vertigo	1.4%	0.3%
Dyspnea	1.7%	0.8%
Nasal Congestion/Rhinitis	1.9%	0.0%
Blurred Vision/Amblyopia	1.3%	0.6%
Impotence	1.6%	0.6%
Urinary Tract Infection	1.3%	3.9%
Body System	Terazosin (N=636)	Placebo (N=360)
Fever	0.5%	0.0%
Headache	1.1%	0.8%
Postural Hypotension	0.5%	0.0%
Syncope	0.5%	0.0%
Nausea	0.5%	0.3%
Dizziness	2.0%	1.1%
Vertigo	0.5%	0.0%
Dyspnea	0.5%	0.3%
Blurred Vision/Amblyopia	0.6%	0.0%
Urinary Tract Infection	0.5%	0.3%

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 mg 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.

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: chest pain, facial edema, fever, abdominal pain, neck pain, shoulder pain; arrhythmia, vasodilation; constipation, diarrhea, dry mouth, dyspepsia, flatulence, vomiting; gout; arthralgia, arthritis, joint disorder, myalgia; anxiety, insomnia; bronchitis, cold symptoms, epistaxis, flu symptoms, increased cough, pharyngitis, rhinitis; pruritus, rash, sweating; abnormal vision, conjunctivitis, tinnitus; 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 3 ADVERSE REACTIONS DURING PLACEBO-CONTROLLED TRIALS**
Body System	Terazosin (N=859)	Placebo (N=506)
Asthenia	11.3%	4.3%
Back Pain	2.4%	1.2%
Headache	16.2%	15.8%
Palpitations	4.3%	1.2%
Postural Hypotension	1.3%	0.4%
Tachycardia	1.9%	1.2%
Nausea	4.4%	1.4%
Edema	0.9%	0.6%
Peripheral Edema	5.5%	2.4%
Weight Gain	0.5%	0.2%
Pain-Extremities	3.5%	3.0%
Depression	0.3%	0.2%
Dizziness	19.3%	7.5%
Libido Decreased	0.6%	0.2%
Nervousness	2.3%	1.8%
Paresthesia	2.9%	1.4%
Somnolence	5.4%	2.6%
Dyspnea	3.1%	2.4%
Nasal Congestion	5.9%	3.4%
Sinusitis	2.6%	1.4%
Blurred Vision	1.6%	0.0%
Impotence	1.2%	1.4%
Body System	Terazosin (N=859)	Placebo (N=506)
Asthenia	1.6%	0.0%
Headache	1.3%	1.0%
Palpitations	1.4%	0.2%
Postural Hypotension	0.5%	0.0%
Syncope	0.5%	0.2%
Tachycardia	0.6%	0.0%
Nausea	0.8%	0.0%
Peripheral Edema	0.6%	0.0%
Dizziness	3.1%	0.4%
Paresthesia	0.8%	0.2%
Somnolence	0.6%	0.2%
Dyspnea	0.9%	0.6%
Nasal Congestion	0.6%	0.0%
Blurred Vision	0.6%	0.0%

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 (see ).

What should I look out for while using Terazosin Hydrochloride?

Terazosin hydrochloride capsules are contraindicated in patients known to be hypersensitive to terazosin hydrochloride.

What might happen if I take too much Terazosin Hydrochloride?

Should overdosage of terazosin hydrochloride lead to hypotension, support of the cardiovascular system is of first importance. Restoration of blood pressure and normalization of heart rate may be accomplished by keeping the patient in the supine position. If this measure is inadequate, shock should first be treated with volume expanders. If necessary, vasopressors should then be used and renal function should be monitored and supported as needed. Laboratory data indicate that terazosin is 90 to 94% protein bound; therefore, dialysis may not be of benefit.

How should I store and handle Terazosin Hydrochloride?

Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F).Terazosin Hydrochloride Capsules, 1 mg, 2 mg, 5 mg and 10 mg contain 1 mg, 2 mg, 5 mg or 10 mg of terazosin as terazosin hydrochloride anhydrous, respectively.They are supplied by as follows:Terazosin Hydrochloride Capsules, 1 mg, 2 mg, 5 mg and 10 mg contain 1 mg, 2 mg, 5 mg or 10 mg of terazosin as terazosin hydrochloride anhydrous, respectively.They are supplied by as follows:

×

Clinical Information

Chemical Structure

No Image found

Clinical Pharmacology

Non-Clinical Toxicology

Terazosin hydrochloride capsules are contraindicated in patients known to be hypersensitive to terazosin hydrochloride.

In controlled trials, terazosin has been added to diuretics, and several beta-adrenergic blockers; no unexpected interactions were observed. Terazosin has also been used in patients on a variety of concomitant therapies; while these were not formal interaction studies, no interactions were observed. Terazosin has 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).

×

Reference

This information is obtained from the National Institute of Health's Standard Packaging Label drug database.
"https://dailymed.nlm.nih.gov/dailymed/"

While we update our database periodically, we cannot guarantee it is always updated to the latest version.

×

Review

×

Professional

Clonazepam Description Each single-scored tablet, for oral administration, contains 0.5 mg, 1 mg, or 2 mg Clonazepam, USP, a benzodiazepine. Each tablet also contains corn starch, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and povidone. Clonazepam tablets USP 0.5 mg contain Yellow D&C No. 10 Aluminum Lake. Clonazepam tablets USP 1 mg contain Yellow D&C No. 10 Aluminum Lake, as well as FD&C Blue No. 1 Aluminum Lake. Chemically, Clonazepam, USP is 5-(o-chlorophenyl)-1,3-dihydro-7-nitro-2H-1,4-benzodiazepin-2-one. It is a light yellow crystalline powder. It has the following structural formula: C15H10ClN3O3 M.W. 315.72

×

Tips

×

Interactions

A total of 440 drugs (1549 brand and generic names) are known to interact with Imbruvica (ibrutinib). 228 major drug interactions (854 brand and generic names) 210 moderate drug interactions (691 brand and generic names) 2 minor drug interactions (4 brand and generic names) Show all medications in the database that may interact with Imbruvica (ibrutinib).

Disclaimer: