Hytrin Special Precautions

Syncope and "First-dose" Effect: Terazosin hydrochloride, 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 doses of therapy. A similar effect can be anticipated if therapy is interrupted for more than a few doses and then re-started. 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 about of severe supraventricular tachycardia with heart rates of 120 to 160 beats per minute.
To decrease the likelihood of syncope or excessive hypotension, treatment should always be initiated with a 1 mg dose of terazosin hydrochloride, given at bedtime. The 2 mg, and 5 mg tablets are not indicated as initial therapy. Dosage should then be increased slowly, according to recommendations in the Dosage & Administration and additional antihypertensive agents should be added with caution. The patient should be cautioned to avoid situations where injury could result should syncope occur during initiation of therapy.
In multiple dose clinical trials involving nearly 2000 hypertensive patients, syncope was reported in about 1% of patients, in no case severe or prolonged, and was not necessarily associated with early doses. In clinical studies involving treatment of approximately 1200 patients with BPH, the incidence of syncope was 0.7%.
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 hydrochloride is greater, even in chronic use, shortly after dosing.
Patients with a history of micturition syncope should not receive an alpha-blocker.
General: Orthostatic Hypotension: While syncope is the most severe orthostatic effect of terazosin hydrochloride (see Precautions), other symptoms of lowered blood pressure, such as dizziness, lightheadedness, and palpitations, are more common. Patients with occupations in which such events represent potential problems should be treated with particular caution.
Information for Patients: 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 hydrochloride 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 drowsiness or somnolence can occur with terazosin hydrochloride, requiring caution in people who must drive or operate heavy machinery.
PDE-5 Inhibitors: Hypotension has been reported when terazosin has been used with phosphodiesterase-5 (PDE-5) inhibitors (see Interactions).
Cataract Surgery: 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.
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 hydrochloride for up to 24 months had no significant effect on prostate specific antigen (PSA) levels.
Effects on Ability to Drive and Use Machines: Syncopal and orthostatic symptoms are possible, especially at the initiation of therapy, and driving or hazardous tasks should be avoided for 12 hours after the first dose, after a dosage increase, and after interruption of therapy when treatment is resumed. Drowsiness or somnolence can also occur with terazosin hydrochloride, requiring caution in people who must drive or operate heavy machinery.
Use in Children: Safety and effectiveness in children have not been determined.