Drug Description

Presentation

Indications

Adult Dosage

The tablets should be swallowed whole with a sufficient amount of liquid. The patient should not chew, divide or crush the tablet.

DoxaduraTM XL 4mg can be taken with or without food.

The maximum recommended dose is 8mg doxazosin once daily.

Essential hypertension:

Adults:

Most patients treated with DoxaduraTM XL 4mg once daily achieve control of blood pressure. It may take up to four weeks to reach optimal effect. If necessary, the dose can thereafter be increased to 8mg once daily depending on the clinical response.

DoxaduraTM XL 4mg can be used as monotherapy or in combination with another medicinal product e.g. a thiazide diuretic, a beta-adrenoceptor blocking agent, a calcium antagonist or an ACE-inhibitor if either of them alone does not provide sufficient effect.

Symptomatic treatment of Benign prostatic hyperplasia:

Adults:

Recommended dose is 4mg once daily. Depending on clinical response, the dosage may be increased to 8mg doxazosin once daily.

Doxazosin may be used in benign prostatic hyperplasia patients who are either hypertensive or normotensive, as the blood pressure reduction in normotensive patients is generally slight. Patients should be closely monitored in the initial phase of the treatment due to the risk of postural adverse events.

Elderly:

Same dosage recommendations as for adults.

Patients with renal impairment:

Since there is no change in pharmacokinetics in patients with impaired renal function and since there are no signs that doxazosin aggravates existing renal impairment, normal dose can generally be used in these patients.

Patients with hepatic impairment:

Doxazosin should be administered with caution in patients with signs of minor to moderate hepatic impairment. Since no clinical experience from patients with severe hepatic insufficiency exists, use in these patients is not recommended.

Paediatric patients:

There are not sufficient data to recommend the use in children and adolescents.

Contra Indications

- Hypersensitivity to the active substance, other quinazolines (e.g. prazosin, terazosin) or to any of the excipients.

- History of oesophageal or gastrointestinal obstruction or judged to be at increased risk for such obstruction.

- Benign prostatic hyperplasia and concomitant urinary outflow obstruction, chronic urinary tract infections or bladder stones

- Overflow bladder, anuria or progressive renal insufficiency

Special Precautions

Abnormally short transport time through the gastrointestinal tract could lead to incomplete absorption.

As for other antihypertensives, including alpha-blocking agents, the patient should be monitored on initiation of therapy to minimise the potential risk for postural effects.

Simultaneous administration of sildenafil or other PDE-5 inhibitors to patients taking alpha-blocker therapy 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 phosphodiesterase-5-inhibitors.

The 'Intraoperative Floppy Iris Syndorome' (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.

Patients with acute heart diseases:

As for other vasodilating antihypertensives, caution is recommended according to medical praxis, in patients with the following acute heart diseases:

- pulmonary oedema as a result of aortic or mitral stenosis

- heart failure at high output

- left or right sided heart failure as a result of pulmonary embolism, pericardial effusion, high output or low filling pressure

Patients with hepatic impairment:

Doxazosin, as other medicinal products metabolised by the liver, should be administered with caution in patients with signs of minor to moderate hepatic impairment. Since no clinical experience from patients with severe hepatic insufficiency exists, use in these patients is not recommended.

Use during lactation

Animal studies have shown that doxazosin accumulates in breast milk. The clinical safety during lactation has not been established, consequently use in nursing mothers is not recommended.

Interactions

Doxazosin potentiates the blood pressure lowering effect of other antihypertensives.

Non-steroidal antirheumatics or estrogens may reduce the antihypertensive effect of doxazosin.

Sympathomimetics may reduce the antihypertensive effect of doxazosin; doxazosin may reduce blood pressure and vascular reactions to dopamine, ephedrine, epinephrine, metaraminol, methoxamine and phenylephrine.

There are no studies available concerning interactions with agents influencing hepatic metabolism.

Doxazosin may influence the plasma renin activity and urinary excretion of vanillylmandelic acid. This should be considered when analysing laboratory data.

Simultaneous administration of sildenafil or other PDE-5 inhibitors to patients taking alpha-blocker therapy may lead to symptomatic hypotension in some patients. Therefore, sildenafil doses above 25 mg should not be taken within 4 hours of taking an alpha-blocker

Adverse Reactions

The following undesirable effects have been reported in controlled clinical trials with doxaszosin prolonged-release tablets.

The adverse reactions considered at least possibly related to treatment are listed below by body system organ class and absolute frequency. Frequencies are defined as very common (1/10); common (>1/100 to <1/10); uncommon (>1/1000 to <1/100); rare (>1/10 000 to <1/1000); very rare (<1/10 000).

Rare cases of syncope in association with orthostatic hypotension have been observed.

The following adverse events have been reported in clinical use of immediate release tablets of doxazosin:

Blood and lymphatic system disorders: Thrombocytopenia, leukopenia.

Metabolism and nutrition disorders : Gout.

Psychiatric disorders: Nervousness.

Nervous system disorders : Tremor.

Eye disorders : Blurred vision.

Ear and labyrinth disorders: Tinnitus, vertigo.

Cardiac disorderst: Arrhythmia, tachycardia, palpitations, angina pectoris, myocardial infarction.

Vascular disorders : Cerebrovascular accidents.

Respiratory, thoracic and mediastinal disorders : Dyspnoea, cough, bronchial spasms, epistaxis.

Gastrointestinal disorders: Anorexia, obstipation, increased appetite.

Hepatobiliary disorders : Icterus, increased liver transaminases.

Skin and subcutaneous tissue disorders: Rash, pruritus, purpura.

Musculoskeletal and connective tissue disorders: Myalgia, arthralgia, muscle cramps.

Renal and urinary disorders : Increased diuresis, haematuria, urinary incontinence.

Reproductive system and breast disorders: Priapism and impotence.

General disorders and administration site conditions : Chest pain, agitation, facial flushing.

Manufacturer

Drug Availability

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