Peripheral vasodilators are medicines that are used to treat conditions that affect blood vessels in outer (peripheral) parts of the body such as the arms and legs. For example, they are used to treat peripheral arterial disease and Raynaud's phenomenon. They ease the symptoms of these conditions by dilating the blood vessels, preventing them from becoming narrower (constricting). These medicines are usually only prescribed after self-help measures have been tried and symptoms do not improve.
What are peripheral vasodilators?
Peripheral vasodilators are medicines that are used to treat conditions that affect blood vessels in outer (peripheral) parts of the body such as the arms and legs. For example:
Peripheral arterial disease (PAD), a narrowing of one or more of the larger blood vessels. It mainly affects arteries that take blood to your legs. Arteries to the arms are rarely affected. PAD is also sometimes called hardening of the arteries of the legs. Narrowing of the arteries is caused by atheroma. Atheroma is like fatty patches (plaques) that develop within the inside lining of arteries. A patch of atheroma starts as quite small, and causes no problems at first. Over the years, the patch can become thicker. (It is a bit like scale that forms on the inside of water pipes.) People with PAD develop pain in one or both calves when they walk or exercise, which is relieved when they rest for a few minutes. This is called intermittent claudication. The pain varies from person to person; some people may feel aching, cramping or tiredness in the legs. The symptoms are due to narrowing of one (or more) of the arteries in your leg.
Raynaud's phenomenon, often just called Raynaud's, a condition where the small blood vessels of the fingers become narrow (constrict), most commonly when they are in a cool environment. Sometimes blood vessels to other extremities such as the toes, ears and nose are affected. It is named after Dr Maurice Raynaud, the man who first described it in 1862.
Peripheral vasodilators are used in PAD to try to open up (dilate) the arteries; this helps to increase the distance you can walk before pain develops. In Raynaud's phenomenon they are used to dilate the small blood vessels and prevent them from constricting. This helps to maintain the blood supply to the fingers, etc. There are a number of peripheral vasodilators. They include, cilostazol, moxisylyte, naftidrofuryl, pentoxifylline and nifedipine. These medicines are available as tablets and capsules and come in various brand names.
Inositol nicotinate and pentoxifylline are not considered effective for PAD. Pentoxifylline and moxisylyte are not considered effective for Raynaud's phenomenon.
The rest of this leaflet discusses the use of peripheral vasodilators when they are used to treat intermittent claudication in people with PAD and Raynaud's phenomenon.
How do peripheral vasodilators work?
Peripheral vasodilators work in slightly different ways to one another.
- Cilostazol and inositol nicotinate work by widening the arteries that supply blood to the legs. Cilostazol also improves circulation by keeping platelets in the blood from sticking together and clotting.
- Naftidrofuryl works by widening blood vessels to improve the flow of blood to these areas and also by allowing your body to make better use of the oxygen in your blood.
- Nifedipine is a type of medicine called a calcium-channel blocker. It is sometimes used to treat high blood pressure but it is also a peripheral vasodilator. It works by widening the blood vessels and stopping them from going into a spasm or narrowing (constricting).
- Moxisylyte is a type of medicine called an alpha-blocker. It works by relaxing the blood vessels, which in turn maintains the supply of blood to the fingers, toes, ears or nose.
- Pentoxifylline works by decreasing the thickness of the blood. Blood is then able to flow more easily, especially in the small blood vessels of the hands and feet.
Which peripheral vasodilator is usually prescribed?
Peripheral arterial disease (PAD): national guidelines only recommend the use of naftidrofuryl for people with intermittent claudication caused by PAD. Other peripheral vasodilators are not normally prescribed because there is little evidence that any of the others work very well for this condition. However, cilostazol is licensed for the treatment of PAD in selected patients who do not respond to other treatments.
Raynaud's phenomenon: nifedipine is recommended to reduce the number and severity of 'vasospastic' attacks - when the blood vessels become narrower (constrict). Other peripheral vasodilators are not normally prescribed, as there is a lack of any studies to show that they work very well for Raynaud's phenomenon. Sometimes, if you cannot tolerate the side-effects of nifedipine, your doctor may consider prescribing a different calcium-channel blocker such as nicardipine, amlodipine or felodipine. These medicines are not licensed to treat Raynaud's disease. Rarely, naftidrofuryl or inositol nicotinate may also be prescribed by some doctors to treat Raynaud's phenomenon.
When are peripheral vasodilators usually prescribed?
If your have intermittent claudication, a vasodilator is usually only prescribed if self-help measures such as exercise have not improved your symptoms and you do not wish to be considered for surgery. However, they do not work in all cases. Therefore, there is no point in continuing with these medicines if you do not notice an improvement in symptoms within a few weeks. If your symptoms do not improve, your doctor will usually advise you to stop treatment. If symptoms improve, you can continue with treatment. Your doctor will usually review your treatment regularly to ensure that it is still being of benefit.
If you have Raynaud's phenomenon, nifedipine is usually only prescribed after self-help measures (such as keeping the whole body warm, including the hands and feet, and stopping smoking) have been tried and your symptoms have not improved. Usually a short course of nifedipine is prescribed to begin with. This is in order to see if nifedipine will work for you.
How should I take peripheral vasodilators?
How you take nifedipine will depend upon the pattern of your symptoms and how well your symptoms improve with treatment. Some people take nifedipine regularly, each day, to prevent symptoms. Some people take nifedipine just during the winter, or just during cold weather spells. Most people start off with a low dose. If necessary, the dose may be increased. Nifedipine is available as a short-acting preparation and this is usually taken up to three times a day. It is also available as a long-acting preparation which is taken once a day.
All the other vasodilators are taken every day. Depending on the medicine that has been prescribed, this can vary between 2-4 times each day. For example, cilostazol is usually taken twice a day and moxisylyte four times a day.
What are the possible side-effects?
Most people who take peripheral vasodilators have no side-effects, or only minor ones. It is not possible in this leaflet to list all the possible side-effects for these medicines. However, see below for a list of the most common side-effects. For more detailed information, see the leaflet that comes with the medicine packet.
Nifedipine - because nifedipine relaxes and widens arteries, some people develop flushing and headache. These tend to ease over a few days if you continue to take the tablets. Mild ankle swelling is also quite a common side-effect, as is constipation. You can often deal with constipation by increasing the amount of fibre that you eat and increasing the amount of water and other fluids that you drink. Less common side-effects include:
- Feeling sick (nausea).
- The sensation of having a 'thumping heart' (palpitations).
Serious side-effects are rare.
Naftidrofuryl - the most commonly reported side-effects are feeling sick, skin rash, stomach pains and runny stools (diarrhoea). On rare occasions, some people taking naftidrofuryl have developed a liver disorder. If you notice any yellowing of your skin or the whites of your eyes, speak with your doctor straightaway.
Cilostazol - the most common side-effects include headache and diarrhoea. Less common side-effects include dizziness, weakness, feeling or being sick, indigestion, tummy (abdominal) pain, fast heartbeat, chest pain, runny nose, bruising, swollen ankles or feet, skin rash and itching.
Inositol nicotinate - side-effects are thought to be uncommon but may include flushing, dizziness, headache, feeling sick, being sick (vomiting), fainting and a rash.
Moxisylyte - the most common side-effects include mild nausea, diarrhoea, dizziness with a spinning sensation (vertigo), headache, facial flushing and a rash. On rare occasions, some people taking moxisylyte have developed a liver disorder. If you notice any yellowing of your skin or the whites of your eyes, speak with your doctor straightaway.
Pentoxifylline - the most common side-effects include nausea, vomiting, and dizziness which may occur. Uncommonly, some people experience a fast or irregular heartbeat.
If you are taking nifedipine, do not drink grapefruit juice. This can interact with the medicine and alter its effect.
Can I buy peripheral vasodilators?
No - you cannot buy oral peripheral vasodilators; you need a prescription to obtain these medicines.
Who cannot take peripheral vasodilators?
Most people are able to take a peripheral vasodilator; however, in some cases these medicines are best avoided.
Nifedipine - should not be given to people who:
- Have severe damage to the heart muscle (cardiogenic shock).
- Have a valve in the heart that does not open fully (advanced aortic stenosis).
- Are within one month of having had a heart attack.
- Have acute attacks of angina.
Naftidrofuryl - should not be given to people with a history of kidney stones.
Cilostazol - should not be given to people with:
- Severe kidney or liver problems.
- Heart failure.
- Heart rhythm problems.
- Uncontrolled high blood pressure.
- A stomach ulcer.
- A history of having had surgery in the previous three months.
- A history of having had a stroke in the previous six months.
Inositol nicotinate - should not be given to people who have had a recent heart attack (myocardial infarction) or stroke.
Moxisylyte - is safe to use in most people.
Pentoxifylline - should not be given to people who have had:
- A stroke.
- Extensive back of the eye (retinal) bleeding.
- A heart attack.
- Heart rhythm problems.
For more detailed information, see the leaflet that comes with the medicine packet.
How to use the Yellow Card Scheme
If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at the following web address: www.mhra.gov.uk/yellowcard.
The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:
- The side-effect.
- The name of the medicine which you think caused it.
- The person who had the side-effect.
- Your contact details as the reporter of the side-effect.
It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.
Further help & information
Dr Laurence Knott
Dr Hannah Gronow