Cardura (Doxazosin mesylate 4mg) Tablets

Cardura general information

What is Cardura used for?

High blood pressure can damage your artery walls and increase stress on your heart.  Lifestyle factors like obesity and smoking, and conditions like diabetes can also increase your risk of cardiovascular disease.  This includes heart attack, caused by blocked blood flow to the heart muscle and heart muscle cell damage, and stroke caused by a blocked blood vessel in the brain or a bleed into the brain, resulting in brain cell death if not treated quickly.  Cardura tablets 4mg are used to treat high blood pressure, to reduce the risk of heart attack and stroke.  They can be used alone or in combination with other antihypertensives (blood pressure lowering) drugs such as diuretics or beta-blockers.  Cardura tablets 4mg are also used to treat benign prostatic hyperplasia (BPH) in men with an enlarged prostate gland, to improve problems with restricted urinary flow, which is a symptom of BHP.

High blood pressure

Blood pressure is the force of your heart pumping blood around the body, combined with the resistance of the artery walls to the blood as it is forced into the circulation.  Two blood pressure measurements indicate whether your blood pressure is within the normal range.  Systolic pressure measures the force generated by the heart contracting with each heartbeat as it pumps blood out into the arteries.  Diastolic pressure is the resting phase between each heartbeat when the heart muscle relaxes and the heart fills with blood.  When your blood pressure is measured, it is expressed as systolic pressure (the highest measure) over diastolic pressure (the lowest measure). 

If the arteries become narrowed or constricted, this increases their resistance, and more force is needed to pump blood around the body.  The increased force causes hypertension, which is high blood pressure when your body is relaxed and at rest.  Essential hypertension is high blood pressure with usually no obvious and identifiable cause.  High blood pressure puts a strain on the heart by increasing its workload and its need for more oxygen.  The extra force of blood in the circulation can damage blood vessels, especially smaller blood vessels, such as those in the kidneys, which can lead to kidney damage.  There are usually no symptoms, so you will only know if you have high blood pressure by having a check. 

Benign prostatic hyperplasia (BPH)

As men age, problems with the passing urine is very common, particularly from the age of 50 onwards.  These are signs of a condition known as benign prostatic hyperplasia (BPH) or an enlarged prostate.  BPH is not cancer but may need medical attention to prevent it from getting worse. 

The prostate is a small walnut-sized gland that sits just below the bladder.  It surrounds the urethra, which is the tube that drains urine from the bladder.  An essential role of the prostate gland is producing a fluid that goes into semen to nourish sperm, which is forced into the urethra, mixing with other components of semen during ejaculation.  The prostate gland grows rapidly at puberty and then maintains its size.  At around the age of 40, the prostate begins to slowly grow again, increasing in size until eventually, most men will have an enlarged prostate.  As the prostate gland gets bigger, it squeezes the neck of the urethra, blocking urine flow from the bladder.  Overgrowth of prostate cells causes prostate enlargement, and increased muscle tone is caused by prostate gland muscle cells contracting more than usual.  Together, this constricts the urethra.  The glandular cells of the prostate also secrete a specific protein called prostate-specific antigen (PSA).  When the prostate gland is enlarged, blood levels of this protein increase, which is used in the diagnosis of BPH.

Symptoms of BPH include the need to pass urine more often and more urgently, including at night, difficulty starting to urinate, not being able to empty your bladder, loss of control so that urine continues to dribble.  As the condition worsens, irritation of the bladder can cause pain when you urinate.  The risk of bladder infection also increases if urine remains in the bladder.

How does Cardura work?

Cardura tablets 4mg contain doxazosin, an alpha-blocker (also known as alpha-adrenergic antagonist) that is used to treat high blood pressure and BPH.  

Smooth muscle tone (how much muscle cells contract) is controlled by the sympathetic nervous system (also known as the autonomic nervous system), which is the part of the nervous system that regulates our body’s unconscious actions, and supplies nerves to the internal organs.  Increased muscle tone is caused by the action of adrenaline, produced by specific nerve cells of the sympathetic nervous system, causing muscle cells to contract.  Adrenaline works by locking onto cell surface receptors called alpha-adrenergic receptors, many of which are found throughout the prostate and the neck of the bladder and increase in number as the prostate enlarges.  Adrenaline also causes blood vessels to contract, making them constricted and narrowed. 

Doxazosin in Cardura tablets 4mg works directly on the smooth muscle cells in blood vessel walls, in the prostate, and in the base of the bladder.  Doxazosin binds selectively to the alpha-adrenergic receptors, preventing adrenaline binding to its receptor, blocking its action, and allowing the smooth muscle cells to relax. 

Relaxation and widening of the arteries taking oxygenated blood to the rest of the body, decreases the resistance to blood flow in these peripheral arteries.  Reduced blood flow resistance directly affects blood pressure, allowing high blood pressure to return within normal levels. 

The action of Doxazosin in Cardura tablets 4mg relieves the pressure caused by the prostate on the bladder and widens the neck of the bladder, allowing urine to flow more freely.  This relieves urinary symptoms of an enlarged prostate, but it does not affect the prostate gland growth. 

What does Cardura contain?

Cardura tablets 4mg contain the active ingredient doxazosin, an alpha-blocker (also known as alpha-adrenergic antagonist) that is used to treat high blood pressure and BPH.  They also contain lactose, magnesium stearate, microcrystalline cellulose, sodium lauryl sulphate, sodium starch glycollate.

What are the side effects of Cardura?

Most medications have some side effects, but they are not experienced by everyone.  Some side effects are commonly experienced when taking Cardura tablets 4mg, but others are not so common, and you should discuss any problems or concerns with your primary care physician. 

Common side effects when taking Cardura include respiratory and urinary tract infection, asthenia (physical weakness), dizziness, postural hypotension (dizziness when standing up due to sudden drop in blood pressure), fatigue, headache, nasal congestion, nausea, peripheral oedema, somnolence, blurred vision, vertigo, palpitations, tachycardia (rapid heartbeat), itching, back pain.

When should Cardura not be used?

Have a talk with your primary healthcare physician before taking Cardura tablets 4mg so that you have a full understanding of what this medicine is for and how to use it.  There are some reasons for not taking a medication; these are called contraindications, and for Cardura you should consider the following before taking Cardura:

• Have you ever had an unusual reaction or an allergy when taking Cardura or any other quinazoline medication?
• Are you pregnant or breastfeeding?
• Do you have any problems with your liver?
• Do you have a heart condition or low blood pressure?
• Do you plan to have cataract eye surgery?

What medications interact with Cardura?

Some medicines interact with Cardura tablets 4mg and may affect the way it works, or are affected by Cardura or increase side effects; you should discuss possible interactions with your primary care physician.  These may include phosphodiesterase-5 (PDE-5) inhibitors like sildenafil for erectile dysfunction, ACE inhibitors and diuretics for hypertension.

If other medications may interact with Cardura, your doctor will discuss these with you. 

How should Cardura be taken and for how long?

You should take your Cardura tablets 4mg swallowed whole with a glass of water once daily with or without food.  Your dose may be increased gradually, depending on what you are being treated for and how well your respond.  Your doctor will probably advise you to take a lower dose at first and then increase your dose.  You should continue to take your Cardura tablets 4mg for as long as recommended by your doctor

Missed dose of Cardura

If you miss a dose of Cardura tablets 4mg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose.  Do not take a double dose.

How should Cardura be stored?

You should store your Cardura tablets 4mg below 25°C in a cool dry place.