Selective a1 -blockers (alpha- blockers / alpha-adrenoceptor blocking drugs).

Terazosin

1 mg white, 2 mg yellow, 5 mg brown, 10 mg blue tablets marked with logo and triangular symbols.

Tablets, terazosin (as hydrochloride) 1mg , 2mg , 5mg , 10mg .

Orally administered Hytrin BPH is indicated as a therapy for the symptomatic treatment of urinary obstruction caused by benign prostatic hyperplasia (BPH). Terazosin is a selective post synaptic alpha-1-adrenoreceptor antagonist. Antagonism of alpha-1-receptors on prostatic and urethral smooth muscle has been shown to improve urinary tract flow and relieve the urinary obstruction caused by BPH.

Adults Only:

The dose of terazosin should be adjusted according to the patient's response. The following is a guide to administration:

Initial dose

1 mg before bedtime is the starting dose for all patients and should not be exceeded. Strict compliance with this recommendation should be observed to minimise acute first-dose hypotensive episodes.

Subsequent dose

The dose may be increased by approximately doubling at weekly or bi-weekly intervals to achieve the desired reduction in symptoms. The maintenance dose is usually 5 to 10mg once daily. Improvements in symptoms have been detected as early as two weeks after starting treatment with terazosin.

At present there are insufficient data to suggest additional symptomatic relief with doses above 10mg once daily.

Treatment should be initiated using the Hytrin BPH Starter Pack and response to treatment reviewed at four weeks. Transient side effects may occur at each titration step. If any side effects persist, consideration should be given to reducing the dose.

Use in renal insufficiency

Pharmacokinetic studies indicate that patients with impaired renal function need no alteration in the recommended dosages.

Use in Children

Use in children for BPH is not applicable.

Use in the Elderly

Pharmacokinetic studies in the elderly indicate that no alteration in dosage recommendation is required.

Postural Hypotension

Postural hypotension has been reported to occur in patients receiving terazosin for the symptomatic treatment of urinary obstruction caused by BPH. In these cases, the incidence of postural hypotensive events was greater in patients aged 65 years and over (5.6%) than those aged less than 65 years (2.6%)

Not recommended.  Known sensitivity to alpha- adrenoceptor antagonists (alpha- blockers).

Terazosin is contraindicated in patients known to be hypersensitive to alpha-adrenoreceptor antagonists.

As with other alpha adrenoreceptor antagonists, terazosin is not recommended in patients with a history of micturition syncope.

In clinical trials, the incidence of postural hypotension was greater in patients who received terazosin for BPH than in patients who received terazosin for hypertension. In this indication the incidence of postural hypotensive events was greater in patients aged 65 years and over (5.6%) than those aged less than 65 years (2.6%).

If administration is discontinued for more than several days, therapy should be re-instituted using the initial dosing regimen.

There have been reports of hypotension following the use of a phosphodiesterase-5 (PDE-5) inhibitor and terazosin. Concomitant treatment with tadalafil is not recommended and caution is advised when sildenafil or vardenafil is administered with terazosin.

In patients receiving terazosin for BPH, plus ACE inhibitors or diuretics, the proportion reporting dizziness or related side effects was greater than in the total population of terazosin treated patients from clinical trials.

Caution should be observed when terazosin is administered with other antihypertensive agents, to avoid the possibility of significant hypotension. When adding terazosin to a diuretic or other antihypertensive agent, dosage reduction and retitration may be necessary.

Terazosin has been given without interaction with analgesics/anti-inflammatories, cardiac glycosides, hypoglycaemics, antiarrhythmics, anxiolytics/sedatives, antibacterials, hormones/steroids and drugs used for gout.

Hypotension has been reported when terazosin has been used with phosphodiesterase-5 (PDE-5) inhibitors. Concomitant treatment with terazosin and sildenafil or vardenafil should only be initiated if the patient is stabilised on terazosin. In addition, vardenafil should not be administered within 6 hours of terazosin, and sildenafil should not be initiated within 4 hours of terazosin therapy.

Hytrin, 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.

Adverse events reported with terazosin

The most common events were asthenia, palpitations, nausea, peripheral oedema, dizziness, somnolence, nasal congestion/rhinitis and blurred vision/amblyopia.

In addition, the following have been reported: back pain; headache; tachycardia; postural hypotension; syncope; oedema; weight gain; pain in extremities; decreased libido; depression; nervousness; paraesthesia; vertigo; dyspnoea; sinusitis and impotence.

Additional adverse reactions reported in clinical trials or reported during marketing experience but not clearly associated with the use of terazosin include the following: chest pain; facial oedema; fever; abdominal pain; neck pain; shoulder pain; vasodilation; arrhythmia; constipation; diarrhoea; dry mouth; dyspepsia; flatulence; vomiting; gout; arthralgia; arthritis; joint disorders; myalgia; anxiety; insomnia; bronchitis; epistaxis; flu symptoms; pharyngitis; rhinitis; cold symptoms; pruritis; rash; increased cough; sweating; abnormal vision; conjunctivitis; tinnitus; urinary frequency; urinary tract infection and urinary incontinence primarily reported in post-menopausal women.

At least two cases of severe anaphylactoid reactions have been reported with the administration of terazosin.

Post marketing experience: Thrombocytopenia and priapism have been reported. Atrial fibrillation has been reported: however, a cause and effect relationship has not been established.

Laboratory tests: Small but statistically significant decreases in haematocrit, haemoglobin, white blood cells, total protein and albumin were observed in controlled clinical trials. These laboratory findings suggest the possibility of haemodilution. Treatment with terazosin for up to 24 months had no significant effect on prostate specific antigen (PSA) levels.

Amdipharm

(POM)

31 August 2010