Aminosalicylates

What are aminosalicylates?

Aminosalicylates are a class (group) of drugs that can help to control the symptoms of some inflammatory bowel (gut) diseases. They include: balsalazide, mesalazine, olsalazine and sulfasalazine, and come in various different brand names. They also come in a variety of different forms: tablets or liquid to be taken by mouth, liquid or foam enemas, or suppositories to be inserted into the rectum (back passage).

What conditions are they used to treat?

• To help keep people with ulcerative colitis in remission. That is, to keep symptoms away and prevent flare ups.
• To treat flare ups of ulcerative colitis and Crohn’s disease.

There is also some evidence that if you have ulcerative colitis then taking an aminosalicylate long term can significantly reduce your risk of developing bowel cancer. Aminosalicylates are also used to treat some forms of arthritis.

How do aminosalicylates work?

The precise way these drugs work is not fully understood. It is thought they work on the cells lining the gut to change the way the cells release certain chemicals including cytokines. These chemicals can contribute to making the gut inflamed, and may be a factor in causing the symptoms of inflammatory bowel diseases.

Are there different types of aminosalicylates?

All of the aminosalicylate drugs contain the active component called 5-aminosalicylic acid (5-ASA). However:

• Mesalazine comes in three different brand names: Salofalk®, Asacol® and Pentasa®. The way the manufacturers make each of these is a little different. Salofalk® and Asacol® have a resin coating which 'dissolves' to release the active ingredient (5-aminosalicylic acid) at a certain pH (acidity) within the gut. Each Pentasa® tablet is made up of tiny granules and the active ingredient is gradually released over the length of the gut.
• Dipentum® and Colazide® have a special chemical 'bond' in the formulation which bonds the active ingredient. The bond is broken to release the active ingredient by the natural bacteria that live in the colon (large bowel).
• Sulfasalazine has an additional molecule attached called sulfapyridine. Some people may not be able to take drugs with sulfapyridine included – see below for details.

The above minor differences in each of the drugs make up may be important because inflammatory bowel conditions can affect different parts of the gut. To effectively treat your symptoms your doctor may prescribe a particular forms of medication. For example:

• If your condition affects the rectum only, you may be prescribed an aminosalicylate suppository or enema.
• If your gut is affected higher up, you may be prescribed an aminosalicylate tablet.
  • Dipentum® and Colazide® target the colon (large intestines).
  • Salofalk® and Asacol® work a little higher in the gut in the ileum (the last part of the small intestine).
  • Pentasa® is designed to work along the entire length of the gut.

Which is the best one?

In general, medical studies show that aminosalicylates are probably equally effective. However, the evidence also suggests that sulfasalazine may cause more side effects than the other types of aminosalicylates. Also, the one chosen may depend on the site and extent of your disease in the gut.

Can I buy aminosalicylates or are they just on prescription?

These drugs are prescription only and are usually prescribed by a specialist doctor.

How do I take aminosalicylates?

These drugs come in a variety of forms as mentioned above. Your doctor will advise you how to take your medication including how often. Read the leaflet that comes with your particular brand for detailed information.

You will usually need special monitoring for the first three months of your treatment, with checks every three months after that. This involves a blood test before you start taking the medication to see how well your liver and kidneys are functioning. Your liver function will then be checked every three months while you are taking the drugs.

You may also be encouraged to keep a record of the frequency of your bowel movements to check how well the medication is working.

How quickly do aminosalicylates work?

Aminosalicylates may work quickly - within a week or so - to deal with symptoms that are severe and come on suddenly. In other cases they may be used continually to help to keep symptoms away and prevent flare-ups.

How long is treatment needed?

This can vary depending on the reason for treating you. In some people these drugs are used to treat flare-ups. In others they may be used on a long-term basis to keep symptoms away. Your doctor can advise you on this.

Who cannot take aminosalicylates?

Aminosalicylates may not be suitable for people with certain liver or kidney problems or for pregnant or breastfeeding women. People with a known drug reaction to salicylates, such as aspirin, should not take these drugs. You should also inform your doctor if you have a sensitivity to sulphonamide, a chemical used in some diuretics and anti-inflammatory drugs.

A full list of people who should not take aminosalicylates is included with the information leaflet that comes in the drug packet. If you are prescribed aminosalicylates, read this to be sure you are safe to take it.

What about side-effects?

The most common side-effects when taking aminosalicylates are: diarrhoea, headache, nausea (feeling sick) and rash. These are generally not serious. Most people who take aminosalicylates do not have any serious side-effects.

Note: A rare but serious side-effect is an effect on the blood-making cells which can greatly reduce the number of blood cells in your body, including the cells that fight off infection and those that help to stop bleeding. Therefore, if you develop a sore throat, mouth ulcers, unexplained bruising or bleeding, rash, fever or any other signs of infection then you must stop the drug and report this to your doctor immediately. (As noted above, a mild rash is a common side-effect. The rash associated with this rare but serious affect on blood-making cells is different. Therefore, when taking these drugs always report a rash to a doctor who can then decide if it is a common and minor problem or the more serious rash.)

There are other rare side-effects. For example, rarely, some people taking aminosalicylates may experience a hypersensitivity reaction. This may make you feel itchy, become more sensitive to sunlight or cause skin peeling. Sulfasalazine can cause a reduced sperm count in some men.

For a full list of all the side-effects and possible interactions associated with your drug consult the leaflet that comes with your medication.

Other considerations

Sulfasalazine may change the colour of your urine and tears making these fluids slightly orange. This can stain soft contact lenses in some people.