RiteMED Terazosin Special Precautions

As with other alpha adrenoreceptor antagonists, terazosin is not recommended in patients with a history of micturition syncope.
Terazosin, in common with other alpha-adrenoreceptor antagonists, may cause syncope. Syncopal episodes have occurred within 30 to 90 minutes of the initial dose of the drug. Syncope has occasionally occurred in association with rapid dosage increases or the introduction of another antihypertensive agent.
In clinical studies in hypertension, the incidence of syncopal episodes was approximately one percent. In most cases, this was believed to be due to an excessive postural hypotensive effect although occasionally the syncopal episode has been preceded by a bout of tachycardia with heart rates of 120 to 160 beats per minute. If syncope occurs, the patient should be placed in a recumbent position and given supportive treatment as necessary.
Dizziness, light-headedness or fainting may occur when standing up quickly from a lying or sitting position. Patients should be advised of this possibility and instructed to lie down if these symptoms appear and then sit for a few minutes before standing to prevent re-occurrence.
These adverse effects are self-limiting and, in most cases, do not recur after the initial period of therapy or during subsequent titration.
First dose effect might occur after the first terazosin dose or during the initial period of treatment. This consists of marked reduction of blood pressure mainly as orthostatic hypotension (vertigo, unsteadiness, syncope). Volume depletion, restricted salt intake and advanced age (i.e. 65 years of age or over) increase the risk of postural hypotension. It should be borne in mind that this is also likely to happen when terazosin treatment is re-started after a few days break. In such cases, the 1 mg initial dose should be prescribed.
Concomitant use of phosphodiesterase-5-inhibitors (e.g. sildenafil, tadalafil, vardenafil) and terazosin may lead to symptomatic hypotension in some patients. In order to minimise the risk for developing postural hypotension, the patient should be stable on the alpha-blocker therapy before initiating use of phospodiesterase-5-inhibitors.
The "Intraoperative Floppy Iris Syndrome" (IFIS, a variant of small pupil syndrome) has been observed during cataract surgery in some patients on or previously treated with tamsulosin. Isolated reports have also been received with other alpha-1 blockers and the possibility of a class effect cannot be excluded. As IFIS may lead to increased procedural complications during the cataract operation, current or past use of alpha-1 blockers should be made known to the ophthalmic surgeon in advance of surgery.
Because of its vasodilator action, terazosin should be used with caution in patients with any of the following cardiac conditions: pulmonary oedema due to aortic or mitral stenosis; high-output cardiac insufficiency; right-ventricular heart failure caused by pulmonary embolism or pericardial effusion; left ventricular heart failure with low filling pressure.
Effects on ability to drive and use machines: Terazosin tablets have a major influence on the ability to drive and use machines.
Dizziness, light-headedness or drowsiness may occur with the initial dose or in association with missed doses and subsequent reinitiation of Terazosin therapy. Patients should be cautioned about these possible adverse effects and the circumstances in which they may occur and advised to avoid driving or hazardous tasks for approximately 12 hours after initial dose or when the dose is increased.