Orally administered Hytrin is indicated in adults for the treatment of mild to moderate hypertension. It may be used in combination with thiazide diuretics and/or other antihypertensive drugs or as sole therapy where other agents are inappropriate or ineffective. The hypotensive effect is most pronounced on the diastolic pressure. Although the exact mechanism of the hypotensive action of terazosin is not established, the relaxation of peripheral blood vessels appears to be produced mainly by competitive antagonism of post-synaptic alpha-1-adrenoceptors. Hytrin usually produces an initial gradual decrease in blood pressure followed by a sustained antihypertensive action.

Orally administered Hytrin is also indicated in adults as a therapy for the symptomatic treatment of urinary obstruction caused by benign prostatic hyperplasia (BPH). Terazosin is a selective post synaptic alpha-1-adrenoceptor blocker. 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.

Posology

Hypertension.

Adults

Initial dose

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

Subsequent doses

The single daily dosage may be increased by approximately doubling the dosage at weekly intervals to achieve the desired blood pressure response.

The usual maintenance dose is 2mg to 10mg once daily. Doses over 20mg rarely improve efficacy and doses over 40mg have not been studied.

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

BPH

Adults

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

Initial dose

1mg 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 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.

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

Elderly

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

Renal impairment

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

Hepatic impairment

The terazosin dose should be titrated with particular caution in patients with impaired liver function since terazosin undergoes extensive hepatic metabolism and is mainly excreted by the biliary tract. As no clinical experience is available in patients with severe hepatic impairment, the use of terazosin is not recommended in these patients.

Paediatric population

Hytrin Tablets are not recommended for use in children. Safety and efficacy in children has not been established.

Method of administration

For oral use.

Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.

Known sensitivity to other alpha-adrenoceptor blockers.

Patients with a history of micturition syncope.

Terazosin hydrochloride, like other alpha-adrenoceptor blockers, 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-adrenoceptor blockers 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 a bout of severe supraventricular tachycardia with heart rates of 120 to 160 beats per minute.

In clinical trials, the incidence of postural hypotension was greater in BPH patients than in those with hypertension. In these cases, the incidence of postural hypotension 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.

Before treating the symptoms of benign prostatic hyperplasia (BPH) with alpha-blockers, other causes of impaired urinary flow or urinary symptoms should be excluded. Also where the diagnosis of BPH has been established, it should be confirmed that there is no concomitant obstruction of the upper urinary tract or any signs of infection before treating with terazosin. Patients with benign prostatic hyperplasia, who simultaneously suffer from congestion of the upper urinary tract, chronic urinary tract infection or bladder stones, should not be treated with terazosin.

Terazosin should not be given to patients with bladder overflow, anuria or advanced renal failure.

Due to the risk of an excessive decrease in blood pressure, caution is advised for the concomitant administration of terazosin and thiazides or other antihypertensive medications. If a thiazide diuretic or another antihypertensive medication is added during treatment with terazosin, the terazosin dose must be reduced or the drug discontinued. A new dose-titration is essential. When administering terazosin in addition to other antihypertensives, the dose of the other antihypertensives should be reduced before commencement of therapy and adjusted after discontinuation of terazosin.

Due to the vasodilatory effect of terazosin, it should be administered with caution if the following cardiac conditions are present:

• Pulmonary oedema due to aortic or mitral valve stenosis

• High output cardiac insufficiency

• Right-sided cardiac insufficiency due to pulmonary embolism or pericardial effusion

• Left-sided cardiac insufficiency with low filling pressure

In patients with severe coronary heart disease, a very rapid or excessive decrease in blood pressure can lead to an exacerbation of angina pectoris.

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.

Caution is also recommended, when terazosin is administered concomitantly with drugs, which may influence hepatic metabolism.

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-adrenoceptor blocker therapy before initiating use of phosphodiesterase-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-adrenoceptor blockers and the possibility of a class effect cannot be excluded. As IFIS may lead to increased procedural complications during cataract operation current or past use of alpha-adrenoceptor blockers should be made known to the ophthalmic surgeon in advance of surgery.

Hytrin 1mg Tablets contain lactose

Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this medicine.

In patients receiving terazosin 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.

Hypotensive effects is enhanced when Terazosin is taken along with adrenergic neurone blockers, alcohol, aldesleukin, alprostadil, anaesthetic (general), angiotensin – II receptor antagonists, antipsychotics, anxiolytics and hypnotics, baclofen, beta-blockers, calcium-channel blockers, clonidine, diazoxide, diuretics, hydralazine, levodopa, monoamine oxidase inhibitors (MAOIs), Methyldopa, Minoxidil, Moxisylyte, Moxonidine, nitrates, sodium nitroprusside, Tizanidine.

Hypotensive effects of terazosin are antagonised by the following: corticosteroids, non-steroidal anti-inflammatory drugs (NSAIDs) and oestrogens.

The hypotensive effect is enhanced when terazocin is given with Phosphodiesterase-5-inhibitors (e.g. avanafil, sildenafil, tadalafil, vardenafil) (see section 4.4). Avoid giving terazocin for 4 hours after Phosphodiesterase-5-inhibitor administration.

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

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

Pregnancy

Terazosin hydrochloride was not teratogenic in either rats or rabbits when administered at oral doses up to 1330 and 165 times, respectively, the maximum recommended human dose. Fetal resorptions occurred in rats dosed with 480mg/kg/day, approximately 1330 times the maximum recommended human dose. Increased fetal resorptions, decreased fetal weight and an increased number of supernumerary ribs were observed in offspring of rabbits dosed with 165 times the maximum recommended human dose. These findings (in both species) were most likely secondary to maternal toxicity. Although no teratogenic effects were seen in animal testing, the safety of Hytrin use during pregnancy or during lactation has not yet been established. Furthermore, data from animal studies show that terazosin may increase the duration of pregnancy or inhibit labour. Therefore, Hytrin should not be used in pregnancy unless the potential benefit outweighs the risk.

Breast-feeding

It is not known whether terazosin hydrochloride is excreted in breast milk. Because many drugs are excreted in breast milk, caution should be exercised when terazosin hydrochloride is administered to a nursing woman.

Fertility

No data available on human fertility. Animal studies show reduced fertility (see 5.3 Preclinical).

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 Hytrin 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.

Hytrin in common with other alpha-adrenoceptor blockers 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 trials 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 supportive treatment applied 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 their recurrence.

These adverse effects are self-limiting and in most cases do not recur after the initial period of therapy or during subsequent re-titration.

Adverse drug effects reported with terazosin from multiple sources including clinical trials and spontaneous reports:

Reporting of suspected adverse reactions

Reporting of suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme, website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

Symptoms

Acute hypotension

Management

Cardiovascular support is of first importance. Restoration of blood pressure and normalisation of heart rate may be accomplished by keeping the patient in a supine position. If this measure is inadequate, shock should first be treated with volume expanders and if necessary, vasopressors could then be used. Renal function should be monitored and general supportive measures applied as required. Dialysis may not be of benefit since laboratory data indicate that terazosin is highly protein bound.

Pharmacotherapeutic group: alpha-adrenoreceptor antagonists, ATC Code: G04CA03

Mechanism of action and Pharmacodynamic effects

Hypertension

Although the exact mechanism of the hypotensive action is not established, the relaxation of peripheral blood vessels appears to be produced mainly by competitive antagonism of post-synaptic alpha-adrenoceptors. Hytrin usually produces an initial gradual decrease in blood pressure followed by a sustained antihypertensive action.

Clinical experience indicates that a 2-5% decrease in total cholesterol plasma concentration and a 3-7% decrease in the combined LDL_C + VLDL_C fraction plasma concentration from pretreatment values are associated with the administration of therapeutic doses of terazosin.

In clinical trials, plasma concentrates of total cholesterol and combined low density and very low density lipoproteins were found to be slightly reduced following Hytrin administration. Additionally, the increase in total cholesterol seen with other hypertensive agents did not occur when these were used in combination with Hytrin.

Benign Prostatic Hyperplasia

Studies suggest that alpha-1-adrenoreceptor antagonism is useful in improving the urodynamics in patients with chronic bladder obstruction such as in benign prostatic hyperplasia (BPH).

The symptoms of BPH are caused mainly by the presence of an enlarged prostate and by the increased smooth muscle tone of the bladder outlet and prostate, which is regulated by alpha-1 -adrenergic receptors.

Clinical efficacy and safety

In in-vitro experiments, terazosin has been shown to antagonise phenylephrine-induced contractions of human pro static tissue. In clinical trials terazosin has been shown to improve the urodynamics and symptomatology in patients with BPH.

Absorption

Terazosin is well absorbed (80-100%). Terazosin has a minimal “ first pass” effect and almost the complete dose of terazosin is systematically available. The plasma concentration of the parent drug is a maximum about 1 hour post administration and declines with a half-life of approximately 12 hours. Food has little or no effect on bioavailability.

Distribution

Approximately 90-94% of terazosin is bound to plasma proteins. Protein binding is independent of total active substance concentrations.

Biotransformation

Main metabolites of terazosin are caused by demethylation and conjugation.

Elimination

Approximately 10% and 20% of orally administered terazosin is excreted as unchanged active substance in urine and in faeces, respectively. Approximately 40% of the administered dose is eliminated in the urine and 60% in the faeces.

Linearity / non-linearity of pharmacokinetics

After oral dosing of terazosin AUC and C_max increase in proportion with dose over the recommended dose range (2-10 mg).

Preclinical data reveal no special hazards for humans based on conventional studies of safety pharmacology.

No evidence of a genotoxic effect of terazosin has been reported from in vitro and in vivo investigations of the mutagenic potential of the substance.

Decreased fertility and testicular atrophy were seen in rats at repeated administration of doses ≥ 20-30 times higher than the maximum recommended human dose. Foetal resorptions, decreased foetal weights, increased number of supernumerary ribs and decreased post-natal survival were noted in reproductive toxicity studies in rats and rabbits at maternally toxic doses (60-280 times the maximum recommended human dose).

In male rats, terazosin induced benign adrenal medullary tumours at the highest administered dose corresponding to 175 times the maximum human dose.

Carcinogenicity: In male rats, terazosin induced benign adrenal medullary tumours at the highest administered dose corresponding to 175 times the maximum human dose. No such occurrences were seen in female rats or in a similar study in mice. The relevance of these findings with respect to the clinical use of the drug in man is unknown.

Lactose

Maize starch

Pregelatinised starch

Purified talc

Magnesium stearate

Purified water

Not applicable.

36 months.

Do not store above 25° C

Tablets in a blister original pack.

Starter Pack for Hypertension:

Tablets in a blister original pack. The 1mg tablets form part of a starter pack of 28 tablets which also contains 21 x 2mg tablets. Blisters are packaged in a carton with a package insert.

Starter pack for BPH:

Tablets in a blister pack. The starter pack consists of 7 x 1mg, 14 x 2mg and 7 x 5mg tablets. The blisters, of PVC/PVdC, are heat sealed with 20 micron hard tempered aluminium foil and packaged in a carton with a pack insert.

No special requirements.

Any unused medicinal product or waste material should be disposed of in accordance with local requirements.