Apo-Prazo Warnings





Full Prescribing Info
Prazosin may cause syncope with sudden loss of consciousness. In most cases this is believed to be due to an excessive postural hypotensive effect, although occa­sionally the syncopal episode has been associated with about of severe tachycardia with heart rates of 120 to 160 beats/minute. The incidence of syncopal episodes is approximately 0.8% when the gradual dose build-up is described under Dosage is followed. The incidence is higher if the initial dose exceeds 0.5 mg. Syncopal episodes have occurred within 30 to 90 minutes of the initial dose of the drug. They have also been reported in association with dosage increases or the introduction of prazosin into the regimen of a patient taking another antihypertensive agent or a diuretic. Physicians are therefore advised lo limit the initial dose of the drug to 0.5 mg b.i.d. or t.i.d., to subsequently increase the dosage slowly, and to introduce any additional antihypertensive drugs into the patient's regimen with caution.
Patients whose blood pressure is not adequately controlled by high doses of a beta-adrenergic blocking agent such as propranolol may develop acute hypotension when prazosin is added. To minimize the incidence of acute hypotension in such patients, the dose of beta-adrenergic blocking agent should be reduced before prazosin is administered. A low initial dose of prazosin is also strongly recommended (see Dosage & Administrtion).
If syncope occurs, the patient should be placed in the recumbent position and supportive measures instituted. This adverse effect is self-limiting and in most cases does not recur once a steady maintenance level is initiated. Patients should be cautioned to avoid situations where injury could result should syncope occur during prazosin therapy especially in the initial dose adjustment period.
Occupational Hazards: The patient should be cautioned about possible adverse effects often associated with lowering of blood pressure. Dizziness, lightheadedness or drowsiness may occur after the first dose of prazosin, or when rising from a lying or sitting position, standing for long periods of time, exercising, drinking alcohol, or if the weather is hot. The patient should be advised to avoid driving or performing hazardous tasks for the first 24 hours after taking prazosin or when the dose is increased, to stand up slowly and to use extra care during exercise, hot weather or if standing for long periods of time. While taking prazosin the patient should be careful in the amount of alcohol consumed.
Children: Prazosin is not recommended for the treatment of children under the age of 12 years since safe conditions for its use have not been established in this group.
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