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New search Medicine profile Terazosin

Clinical medicine profile

Terazosin

Therapeutic agent (verify pharmacological class)

POM
Evidence state Source-linked Review date not recorded
Route
See product SmPC
Schedule
POM
ATC
Not assigned
PPB status
registered
Patient advice Check interactions
01 Risk first

Safety essentials

The information most likely to change a prescribing or dispensing decision.

Contraindications

  • Hypersensitivity to the active substance or excipients.
  • Additional absolute contraindications are indication- and product-specific — consult SmPC.

Precautions

  • WARNINGS Syncope and “First-dose” Effect Terazosin 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 capsules, 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, 5 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.
02 Point of care

Dosing matrix

Population and organ-function guidance, shown together for faster comparison.

Adult

DOSAGE AND ADMINISTRATION If terazosin capsules administration is discontinued for several days, therapy should be reinstituted using the initial dosing regimen. Benign Prostatic Hyperplasia Initial Dose : 1 mg at bedtime is the starting dose for all patients, and this dose should not be exceeded as an initial dose. Patients should be closely followed during initial administration in order to minimize the risk of severe hypotensive response. Subsequent Doses : The dose should be increased in a stepwise fashion to 2 mg, 5 mg, or 10 mg once daily to achieve the desired improvement of symptoms and/or flow rates. Doses of 10 mg once daily are generally required for the clinical response. Therefore, treatment with 10 mg for a minimum of 4 to 6 weeks may be required to assess whether a beneficial response has been achieved. Some patients may not achieve a clinical response despite appropriate titration. Although some additional patients responded at a 20 mg daily dose, there was an insufficient number of patients studied to draw definitive conclusions about this dose. There are insufficient data to support the use of higher doses for those patients who show inadequate or no response to 20 mg daily. If terazosin administration is discontinued for several days or longer, therapy should be reinstituted using the initial dosing regimen. Use With Other Drugs : Caution should be observed when terazosin capsules are administered concomitantly with other antihypertensive agents, especially the calcium channel blocker verapamil, to avoid the possibility of developing significant hypotension. When using terazosin capsules and other antihypertensive agents concomitantly, dosage reduction and retitration of either agent may be necessary (see PRECAUTIONS ). Hypotension has been reported when terazosin capsules have been used with phosphodiesterase-5 (PDE-5) inhibitors. Hypertension The dose of terazosin capsules and the dose interval (12 or 24 hours) should be adjusted according to the patient’s individual blood pressure response. The following is a guide to its administration: Initial Dose 1 mg at bedtime is the starting dose for all patients, and this dose should not be exceeded. This initial dosing regimen should be strictly observed to minimize the potential for severe hypotensive effects. Subsequent Doses The dose may be slowly increased to achieve the desired blood pressure response. The usual recommended dose range is 1 mg to 5 mg administered once a day; however, some patients may benefit from doses as high as 20 mg per day. Doses over 20 mg do not appear to provide further blood pressure effect and doses over 40 mg have not been studied. Blood pressure should be monitored at the end of the dosing interval to be sure control is maintained throughout the interval. It may also be helpful to measure blood pressure 2 to 3 hours after dosing to see if the maximum and minimum responses are similar, and to evaluate symptoms such as dizziness or palpitations which can result from excessive hypotensive response. If response is substantially diminished at 24 hours an increased dose or use of a twice daily regimen can be considered. If terazosin administration is discontinued for several days or longer, therapy should be reinstituted using the initial dosing regimen. In clinical trials, except for the initial dose, the dose was given in the morning. Use With Other Drugs (See above.)

Paediatric

Pediatric Use : Safety and effectiveness in pediatric patients have not been determined.

Renal

Review renal impairment dosing; many agents need CrCl/eGFR adjustment.

  • CrCl 0–120: Confirm renal dosing in product SmPC / primary label.
Hepatic

Review hepatic impairment dosing; monitor LFTs if agent is hepatically cleared or hepatotoxic.

03 Clinical use

Use, effects & interactions

Indications

  • INDICATIONS AND USAGE Terazosin capsules are 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 capsules.
  • The long-term effects of terazosin capsules on the incidence of surgery, acute urinary obstruction or other complications of BPH are yet to be determined.
  • Terazosin capsules are also indicated for the treatment of hypertension.
  • Terazosin capsules can be used alone or in combination with other antihypertensive agents such as diuretics or beta-adrenergic blocking agents.

Adverse effects

  • ADVERSE REACTIONS 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 (see PRECAUTIONS ) 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 Body System Terazosin (N = 636) Placebo (N = 360) BODY AS A WHOLE Includes weakness, tiredness, lassitude, and fatigue.
  • Asthenia Flu Syndrome Headache 7.4% p ≤ 0.05 comparison between groups. 2.4% 4.9% 3.3% 1.7% 5.8% CARDIOVASCULAR SYSTEM Hypotension Palpitations Postural Hypotension Syncope 0.6% 0.9% 3.9% 0.6% 0.6% 1.1% 0.8% 0.0% DIGESTIVE SYSTEM Nausea 1.7% 1.1% METABOLIC AND NUTRITIONAL DISORDERS Peripheral Edema Weight Gain 0.9% 0.5% 0.3% 0.0% NERVOUS SYSTEM Dizziness Somnolence Vertigo 9.1% 3.6% 1.4% 4.2% 1.9% 0.3% RESPIRATORY SYSTEM Dyspnea Nasal Congestion/Rhinitis 1.7% 1.9% 0.8% 0.0% SPECIAL SENSES Blurred Vision/Amblyopia 1.3% 0.6% UROGENITAL SYSTEM Impotence Urinary Tract Infection 1.6% 1.3% 0.6% 3.9% 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.
  • Professional use: confirm indication, dose, duration, monitoring and patient counselling points against current Kenya STG / EML and the product SmPC.
  • Document allergy status and key interactions.
04 Pharmacology

Mechanism & disposition

Quinazoline derivative postsyn- aptic alpha1-adrenergic blocking agent.

Quinazoline derivative postsyn- aptic alph…It reduces peripheral vascular resistance…It produces both arterial and venous dilat…
Read complete mechanism

Quinazoline derivative postsyn- aptic alpha1-adrenergic blocking agent. It reduces peripheral vascular resistance and blood pressure as a result of its vasodilating effects. It produces both arterial and venous dilation. It improves, to a small extent, the serum lipid profile.

Onset

Product-specific

Duration

Product-specific

Route

See product SmPC

Metabolism

and nearly all of the circulating dose is in the form of parent drug. The plasma levels peak about one hour after dosing, and then decline with a

Elimination

of terazosin, and dosage adjustment of terazosin to compensate for the drug removal during hemodialysis (approximately 10%) does not appear to be necessary. Overall, approximately 40% of the administered dose is excreted in the urine and approximately 60% in the feces. The dispos...

Half-life

of approximately 12 hours. In a study that evaluated the effect of age on terazosin pharmacokinetics, the mean plasma half-lives were 14.0 and 11.4 hours for the age group ≥ 70 years and the age group of 20 to 39 years, respectively. After oral administration the plasma clearance...

05 Special populations

Pregnancy, lactation & diet

Pregnancy

Pregnancy Teratogenic Effects : Pregnancy Category C Terazosin capsules were 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 capsules are 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 three-week postpartum period.

Lactation

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 capsules are administered to a nursing woman.

06 Kenya market

Brands & loaded prices

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07 Provenance

Sources & review state

Primary sourceLocal active-ingredient clinical extract; FDA drug label via OpenFDA/DailyMed; Professional class pharmacology (Therapeutic agent (verify pharmacological class))
Last reviewedNot recorded
EvidenceSource-linked
Open source document ↗

Decision support only. Confirm patient-specific decisions against the current product SmPC, Kenya STG/EML, and professional judgement.