Doxazosin 4mg Tablets
SUMMARY OF PRODUCT CHARACTERISTICS
1 NAME OF THE MEDICINAL PRODUCT
Doxazosin 4mg Tablets
2. QUALITATIVE AND QUANTITATIVE COMPOSITION
Each tablet contains Doxazosin Mesylate 4.85 mg equivalent to 4 mg doxazosin. Excipient with known effect: Contains 80 mg of Anhydrous Lactose P For the full list of excipients, see section 6.1
3 PHARMACEUTICAL FORM
Tablet
White, oblong, uncoated tablets debossed “D4” and score line on the same side.
The scoreline is not intended for breaking the tablet.
4 CLINICAL PARTICULARS
4.1 Therapeutic indications
Hypertension: Doxazosin is indicated for the treatment of hypertension and can be used as the sole agent to control blood pressure in the majority of patients. In patients inadequately controlled on single antihypertensive therapy, Doxazosin may be used in combination with a thiazide diuretic, beta-adrenoceptor blocking agent, calcium antagonist or an angiotensin-converting enzyme inhibitor.
Benign prostatic hyperplasia: Doxazosin is indicated for the treatment of urinary outflow obstruction and symptoms associated with benign prostatic hyperplasia (BPH). Doxazosin may be used in BPH patients who are either hypertensive or normotensive
4.2. Posology and method of administration
Posology
Hypertension: Doxazosin is used in a once daily regimen: the initial dose is 1mg to minimise the potential for postural hypotension and/or syncope (see section 4.4).
Dosage may then be increased after one or two weeks of therapy to 2mg and thereafter, if necessary to 4mg. The majority of patients who respond to Doxazosin will do so at a dose of 4mg or less. Dosage can be further increased if necessary to 8mg or the maximum recommended dose of 16mg.
Benign Prostatic Hyperplasia: The recommended initial dosage of Doxazosin is 1mg given once daily to minimise the potential for postural hypotension and/or syncope (see section 4.4). Depending on the individual patient's urodynamics and BPH symptomatology, dosage may then be increased to 2mg and thereafter to 4mg and up to the maximum recommended dose of 8mg. The recommended titration interval is 12 weeks. The usual recommended dose is 2-4mg daily.
Paediatric population: The safety and efficacy of Doxazosin mesilate in children and adolescents have not been established.
Elderly: Normal adult dosage.
Patients with renal impairment: Since there is no change in pharmacokinetics in patients with impaired renal function the usual adult dose of Doxazosin is recommended. Due to possible hypersensitivity in some of these patients, it may be necessary to take special care at the beginning of treatment. Doxazosin tablets are not dialysable due to the fact that it is highly protein-bound.
Patients with hepatic impairment: There are only limited data in patients with liver impairment and on the effect of drugs known to influence hepatic metabolism (e.g. cimetidine). As with any drug wholly metabolized by the liver, use of doxazosin in patients with altered liver function should be undertaken with caution (see section 4.4).
Method of administration
Doxazosin may be administered in the morning or the evening.
4.3 Contraindications
Doxazosin is contraindicated in
1 For the hypertension indication only for benign prostatic hyperplasia indication only
Doxazosin is contraindicated as monotherapy in patients with either overflow bladder or anuria with or without progressive renal insufficiency.
4.4 Special warnings and precautions for use
Postural Hypotension/Syncope:
Initiation of Therapy:
In relation with the alpha-blocking properties of doxazosin, patients may experience postural hypotension evidenced by dizziness
and weakness, or rarely loss of consciousness (syncope), particularly with the commencement of therapy (see section 4.2). Therefore, it is prudent medical practise to monitor blood pressure on initiation of therapy to minimise the potential for postural effects.
When instituting therapy with any effective alpha-blocker, the patient should be advised how to avoid symptoms resulting from postural hypotension and what measures to take should they develop .The patient should be cautioned to avoid situations where injury could result should dizziness or weakness occur during the initiation of doxazosin therapy.
Use in patients with Acute Cardiac Conditions:
As with any other vasodilatory antihypertensive agent it is prudent medical practise to advise caution when administering doxazosin to patients with the following acute cardiac conditions:
-pulmonary oedema due to aortic or mitral stenosis - high output cardiac failure
-right-sided heart failure due to pulmonary embolism or pericardial effusion -left ventricular heart failure with low filling pressure
Use in Hepatically Impaired Patients:
As with any drug wholly metabolised by the liver, doxazosin should be administered with particular caution to patients with evidence of impaired hepatic function (see section 4.2). Since there is no clinical experience in patients with severe hepatic impairment use in these patients is not recommended.
Use with PDE-5 inhibitors:
Concominant use of phosphodiesterase-5-inhibitors (e.g.sildenafil, tadalafil, vardenafil) and doxazosin should be done with caution as both drugs have vasodilating effects and may lead to symptomatic hypotension in some patients. In order to minimise the risk for developing postural hypotension the patient should be hemodynamically stable on the alpha-blocker therapy before initiating use of phosphodiesterase-5-inhibitors. Furthermore, it is recommended to initiate phosphodiesterase-5-inhibitor treatment with the lowest possible dose and to respect a 6-hour time interval from intake of doxazosin.
Use in patients undergoing cataract surgery:
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.
Priapism
Prolonged erections and priapism have been reported with alpha-1 blockers including doxazosin in post marketing experience. If priapism is not treated immediately, it could result in penile tissue damage and permanent loss of potency, therefore the patient should seek immediate medical assistance.
Important information regarding the ingredients of this medicine
Doxazosin Tablets contain lactose. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.
4.5 Interaction with other medicinal products and other forms of interaction
Phosphodiesterase-5-inhibitors (e.g. sildenafil, tadalafil. vardenafil)
Concominant use of phosphodiesterase-5-inhibitors and doxazosin may lead to symptomatic hypotension in some patients (see section 4.4).
Doxazosin is highly bound to plasma proteins (98%). In vitro data in human plasma indicates that doxazosin has no effect on protein binding of the drugs tested (digoxin, phenytoin, warfarin or indomethacin).
Conventional doxazosin has been administered without any adverse drug interaction in clinical experience with thiazide diuretics, furosemide, beta-blockers, non-steroidal antiinflammatory drugs, antibiotics, oral hypoglycaemic drugs, uricosuric agents, and anticoagulants. However, data from formal drug/drug interaction studies are not present.
Doxazosin potentiates the blood pressure lowering activity of other alpha-blockers and other antihypertensives.
In an open-label, randomised, placebo-controlled trial in 22 healthy male volunteers, the administration of a single 1mg dose of doxazosin on day 1 of a four-day regimen of oral cimetidine (400mg twice daily) resulted in a 10% increase in mean AUC of doxazosin, and no statistically significant changes in mean Cmax and mean half-life of doxazosin. The 10% increase in the mean AUC for doxazosin with cimetidine is within intersubject variation (27%) of the mean AUC for doxazosin with placebo.
4.6 Fertility, pregnancy and lactation
For the hypertension indication:
Pregnancy:
As there are no adequate and well controlled studies in pregnant women, the safety of doxazosin during pregnancy has not been established. Accordingly, during pregnancy, doxazosin should be used only if the potential benefit outweighs the risk. Although no teratogenic effects were seen in animal testing, reduced foetal survival was observed in animals at high doses (see section 5.3). These doses were approximately 300 times the maximum recommended human dose.
Lactation:
Doxazosin is contraindicated during lactation as animal studies have shown that doxazosin accumulates in milk of lactating rats and there is no information about the excretion of the drug into the milk of lactating women. The clinical safety of Doxazosin during lactation has not been established, consequently Doxazosin is contra-indicated in nursing mothers
Alternatively, mothers should stop breast-feeding when treatment with doxazosin is necessary (Please see section 5.3: Preclinical Safety Data).
For the benign prostatic hyperplasia indication:
This section is not applicable.
4.7 Effects on ability to drive and use machines
The ability to drive or use machinery may be impaired, especially when initiating therapy.
4.8 Undesirable effects
Hypertension: In clinical trials involving patients with hypertension, the most common reactions associated with Doxazosin therapy were of a postural type (rarely associated with fainting) or non-specific.
Benign prostatic hyperplasia: Experience in controlled clinical trials in BPH indicates a similar adverse event profile to that seen in hypertension.
The following undesirable effects have been observed and reported during treatment with Doxazosin with the following frequencies: Very common > 1/10, Common > 1/100 and < 1/10, Uncommon > 1/1,000 and < 1/100, Rare > 1/10,000 and < 1/1,000, Very rare < 1/10,000, not known (cannot be estimated from the available data).
|
MedDRA System Organ Class |
Frequency |
Undesirable Effects |
|
Infections and infestations |
Common |
Respiratory tract infection, urinary tract infection |
|
Blood and lymphatic system disorders |
Very Rare |
Leukopenia, thrombocytopenia |
|
Immune System Disorders |
Uncommon |
Allergic drug reaction |
|
Metabolism and Nutrition Disorders |
Uncommon |
Gout, increased appetite, anorexia |
|
Psychiatric Disorders |
Uncommon |
Agitation, depression, anxiety, insomnia, nervousness |
|
Nervous System Disorders |
Common |
Dizziness, headache, somnolence |
|
Uncommon |
Cerebrovascular accident, hypoesthesia,syncope,tre mor | |
|
Very Rare |
Dizziness postural, paraesthesia | |
|
Eye Disorders |
Very Rare |
Blurred vision |
|
Unknown |
Introperative floppy iris syndrome (see Section 4.4) | |
|
Ear and Labyrinth |
Common |
Vertigo |
|
Disorders | ||
|
Uncommon |
Tinnitus | |
|
Cardiac Disorders |
Common |
Palpitation, tachycardia |
|
Uncommon |
Angina pectoris, myocardial infarction | |
|
Very rare |
Bradycardia, cardiac arrhythmias | |
|
Vascular Disorders |
Common |
Hypotension, postural hypotension |
|
Very Rare |
Hot flushes | |
|
Respiratory, Thoracic and Mediastinal Disorders |
Common |
Bronchitis, cough, dyspnea, rhinitis |
|
Uncommon |
Epistaxis | |
|
Very Rare |
Bronchspasm | |
|
Gastrointestinal Disorders |
Common |
Abdominal pain, dyspepsia,dry mouth, nausea |
|
Uncommon |
Constipation, flatulence, vomiting, gastroenteritis, , diarrhoea | |
|
Hepatobiliary Disorders |
Uncommon |
Abnormal liver function tests |
|
Very Rare |
Cholestasis, hepatitis, jaundice | |
|
Skin and Subcutaneous Tissue Disorders |
Common |
Pruritis |
|
Uncommon |
Skin rash | |
|
Very rare |
Urticaria, alopecia, purpura | |
|
Musculoskeletal and Connective Tissue Disorders |
Common |
Back pain, myalgia |
|
Uncommon |
Arthralgia, | |
|
Rare |
Muscle cramps, muscle weakness | |
|
Renal and Urinary Disorders |
Common |
Cystitis, urinary incontinence |
|
Uncommon |
Dysuria, micturition frequency, hematuria, | |
|
Rare |
Polyuria | |
|
Very Rare |
Increased diuresis, |
|
micturition disorder, nocturia | ||
|
Reproductive System and Breast Disorders |
Uncommon |
Impotence |
|
Very Rare |
Gynecomastia, priapism | |
|
Unknown |
Retrograde ejaculation | |
|
General Disorders and Adminostration Site Conditions |
Common |
Asthenia, chest pain, influenza-like symptoms, peripheral oedema, |
|
Uncommon |
Pain, facial oedema | |
|
Very Rare |
Fatigue, malaise | |
|
Investigations |
Uncommon |
Weight increase |
Reporting of Suspected Adverse Reactions
Reporting 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 at: www.mhra.gov.uk/yellowcard.
4.9 Overdose
Should overdosage lead to hypotension, the patient should be immediately placed in a supine, head down position. Other supportive measures may be appropriate in individual cases. Since Doxazosin is highly protein bound, dialysis is not indicated.
If this measure is inadequate, shock should first be treated with volume expanders. If necessary, vasopressor should then be used. Renal function should be monitored and supported as needed.
5 PHARMACOLOGICAL PROPERTIES
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Alpha-adrenoceptor antagonists ATC code: C02CA04
Doxazosin is a potent and selective post-junctional alpha-1-adrenoceptor antagonist. This action results in a decrease in systemic blood pressure. Doxazosin is appropriate for oral administration in a once daily regimen in patients with essential hypertension.
Doxazosin has been shown to be free of adverse metabolic effects and is suitable for use in patients with coexistent diabetes mellitus, gout and insulin resistance.
Doxazosin is suitable for use in patients with co-existent asthma, left ventricular hypertrophy and in elderly patients. Treatment with Doxazosin has been shown to result in regression of left ventricular hypertrophy, inhibition of platelet aggregation and enhanced activity of tissue plasminogen activator. Additionally, Doxazosin improves insulin sensitivity in patients with impairment.
Doxazosin, in addition to its antihypertensive effect, has in long term studies produced a modest reduction in plasma total cholesterol, LDL-cholesterol and triglyceride concentrations and therefore may be of particular benefit to hypertensive patients with concomitant hyperlipidaemia.
Administration of Doxazosin to patients with symptomatic BPH results in a significant improvement in urodynamics and symptoms. The effect in BPH is thought to result from selective blockade of the alpha-adrenoceptors located in the muscular stroma and capsule of the prostate, and in the bladder neck.
5.2 Pharmacokinetic properties
Absorption: Following oral administration in humans (young male adults or the elderly of either sex), doxazosin is well absorbed and approximately two thirds of the dose is bioavailable.
Biotransformation/Elimination: Approximately 98% of doxazosin is protein-bound in plasma.
Doxazosin is extensively metabolised in man and in the animal species tested, with the faeces being the predominant route of excretion. The mean plasma elimination half-life is 22 hours thus making the drug suitable for once daily administration.
After oral administration of Doxazosin the plasma concentrations of the metabolites are low. The most active (6' hydroxy) metabolite is present in man at one fortieth of the plasma concentration of the parent compound, which suggests that the antihypertensive activity is in the main due to doxazosin.
There are only limited data in patients with liver impairment and on the effects of drugs known to influence hepatic metabolism (e.g. cimetidine). In a clinical study in 12 subjects with moderate hepatic impairment, single dose administration of doxazosin resulted in an increase in AUC of 43% and a decrease in apparent oral clearance of 40%. As with any drug wholly metabolised by the liver, Doxazosin should be administered with caution to patients with impaired liver function (see section 4.4).
5.3 Preclinical safety data
Preclinical data reveal no special hazard for humans based on conventional animal studies in safety pharmacology, repeated dose toxicity, genotoxicity and carcinogenicity. For further information see section 4.6.
6 PHARMACEUTICAL PARTICULARS
6.1 List of excipients
Anhydrous lactose Magnesium stearate Microcrystalline cellulose Sodium lauryl sulfate Sodium starch glycollate Colloidal anhydrous silica
6.2 Incompatibilities Not applicable
6.3 Shelf life 3 years
6.4 Special precautions for storage Do not store above 30°C
6.5 Nature and contents of container
PVC/PVdC - Aluminium blisters in pack sizes of 28 tablets
6.6 Special precautions for disposal
No special requirements
7 MARKETING AUTHORISATION HOLDER
BRISTOL LABORATORIES LIMITED
UNIT 3, CANALSIDE NORTHBRIDGE ROAD BERKHAMSTED HERTS HP4 1EG
UNITED KINGDOM
8 MARKETING AUTHORISATION NUMBER(S)
PL 17907/0257
9 DATE OF FIRST AUTHORISATION/RENEWAL OF THE AUTHORISATION
30/03/2009
10 DATE OF REVISION OF THE TEXT
21/10/2016