Conmy Warnings

Syncope and "First dose" effect: Terazosin hydrochloride, like other alpha-adrenergic 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 the restarted. Syncope has also been reported with other alpha-adrenergic blocking agents in association with rapid dosage increases of 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 120-160 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 are not indicated as initial therapy. Dosage should then be increased slowly, according to recommendations in the DOSAGE & ADMINISTRATION and additional antihypertensive agents with caution. The patient should be cautioned to avoid situations, such driving or hazardous task, where injury could result, should syncope occur during initiation of therapy.
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.