Terazosin
{{DrugProjectFormSinglePage |authorTag=João André Alves Silva, M.D. [1] |genericName=Terazosin |aOrAn=a |drugClass=alpha-adrenergic blocker |indication=symptomatic benign prostatic hyperplasia (BPH) and hypertension |adverseReactions=orthostatic hypotension, palpitations, peripheral edema, nausea, asthenia, dizziness headache, somnolence and nasal congestion |blackBoxWarningTitle=Warning Title |blackBoxWarningBody=Condition Name: (Content) |fdaLIADAdult======Condition 1=====
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|contraindications=* Terazosin capsules are contraindicated in patients known to be hypersensitive to terazosin hydrochloride. |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. These adverse effects all occurred within 90 minutes of dosing. In three placebo-controlled BPH studies 1, 2, and 3, 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 2000 hypertensive patients treated with terazosin capsules, 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, terazosin and other α1-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.
- Since this condition can lead to permanent impotence if not promptly treated, patients must be advised about the seriousness of the condition.
|clinicalTrials======Benign Prostatic Hyperplasia=====
- The incidence of treatment-emergent adverse events has been ascertained 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.
- 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.
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Hypertension
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|postmarketing=* 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 also 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.
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(Description) |useInPregnancyFDA=(Description) |useInPregnancyAUS=(Description) |useInLaborDelivery=(Description) |useInNursing=(Description) |useInPed=(Description) |useInGeri=(Description) |useInGender=(Description) |useInRace=(Description) |useInRenalImpair=(Description) |useInHepaticImpair=(Description) |useInReproPotential=(Description) |useInImmunocomp=(Description) |othersTitle=Others |useInOthers=(Description) |administration=(Oral/Intravenous/etc) |monitoring======Condition 1=====
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(Description regarding monitoring, from Warnings section) |IVCompat====Solution===
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|overdose====Acute Overdose===
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(Description) |drugBox=
Terazosin
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(Description) |howSupplied=(Description) |fdaPatientInfo=(Patient Counseling Information) |alcohol=Alcohol-Terazosin interaction has not been established. Talk to your doctor about the effects of taking alcohol with this medication. |brandNames=* Hytrin |lookAlike=* (Paired Confused Name 1a) — (Paired Confused Name 1b)
- (Paired Confused Name 2a) — (Paired Confused Name 2b)
- (Paired Confused Name 3a) — (Paired Confused Name 3b)
|nlmPatientInfo=(Link to patient information page) |drugShortage=Drug Shortage }}