Overview

Mepacrine is a medicine that was first introduced in the 1930s as a treatment for malaria (a serious infection spread by mosquitoes). It is one of several malaria medicines that has also been found to reduce inflammation.

The medicine can help various conditions that cause skin inflammation, including systemic lupus erythematosus (SLE). This is a long-term condition that causes joint pain, skin rashes and tiredness.

Mepacrine is unlicensed (not officially approved) in the UK. This is because the number of patients taking mepacrine is small. It is not cost-effective for large pharmaceutical companies to make this medicine. Specialist pharmaceutical companies make mepacrine for the small numbers of patients who need it.

Although mepacrine is unlicensed, the lupus unit at Guy's Hospital has used it safely for many years.

Read more about taking an unlicensed medicine.

Conditions that can be treated with mepacrine

SLE causes inflammation in different parts of the body. Mepacrine cannot be used for all types of lupus. It is particularly useful to treat the types that cause skin inflammation, such as:

• Discoid lupus erythematosus, which causes a rash with inflammation and scarring. It is usually found on the face, ears and skin covering the head (scalp), and sometimes on other areas.
• Subacute cutaneous lupus erythematosus, which causes scaly patches on the skin. It is usually found on areas that are exposed to the sun, such as the neckline or the lower arms but not the face.

For more information about SLE, you can contact your consultant or specialist nurse and visit the Lupus UK website.

How to take the medicine

Your doctor explains how much medicine to take (the dose). The dose might be as small as 50mg (half a 100mg tablet) taken 3 times a week. The largest possible dose would be 100mg taken 3 times a day.

You might find that the tablets taste bitter. The medicine might take several weeks to reach its full effect. Although you might not notice any benefit immediately, it is important to keep taking your mepacrine.

If you forget to take the medicine

If you miss a single tablet of mepacrine, this is not likely to cause any harm. You simply need to take the next dose when you remember. There is no need to take double the amount of medicine because you missed the previous dose.

Side effects of mepacrine

Most people can take mepacrine without any serious problems because only small amounts are used to treat SLE.

As with all medicines, mepacrine can cause some possible side effects. These are different for each person.

• If you have long-term treatment with mepacrine or take large doses, it is possible for your skin or pee (urine) to turn yellow. This is common but harmless. It should not be a cause for concern because the yellow colour disappears when you stop taking the medicine.
• The roof of your mouth, nails and eyes may turn blue or black. This is also harmless and goes away when you stop taking the medicine.
• Mepacrine can cause dizziness, particularly when you get up from sitting or lying down. Getting up slowly should help.

Other possible side effects include:

• an upset tummy
• headaches
• feeling and being sick (nausea and vomiting)
• skin rashes (including severe rashes)
• changes in mood or behaviour
• seizures or fits (when the body jerks and shakes uncontrollably) if you take too much medicine

Rare side effects include:

• inflammation of the liver
• changes in the types and numbers of cells in your blood (blood count)

Monitoring you for side effects

You may have blood tests about 2 times a year to check your blood count and how your liver is working. However, there is no need for frequent blood tests because mepacrine does not weaken the immune system.

Your lupus team in hospital usually take your blood tests, but sometimes we might ask your GP to do them.

Some patients take mepacrine with another malaria medicine called hydroxychloroquine. If you take hydroxychloroquine, you will need an eye check every year. This is not necessary if you only take mepacrine because it does not affect your eyesight.

Vaccinations while taking mepacrine

If you have vaccinations while taking mepacrine, this should not cause any problems. 

Fertility and pregnancy

There is no evidence about how mepacrine affects people who are pregnant or breastfeeding. It is recommended that you avoid taking the medicine if you are:

• pregnant
• planning to get pregnant
• breastfeeding

If you think you are pregnant or are planning a pregnancy, please speak to your doctor.

Alcohol

We recommend that you do not drink alcohol when taking mepacrine. The medicine can make your skin become slightly red and hot (flushed) if you take it with alcohol. The redness may be harder to notice on brown and black skin. You may also have other symptoms, such as:

• a racing heartbeat
• dizziness
• a headache
• shortness of breath
• sickness

Taking other medicines with mepacrine

Mepacrine is often used together with hydroxychloroquine (another malaria medicine used to treat lupus) for extra benefits. This is safe.

Some medicines do not mix with mepacrine. For example, mepacrine may increase the level of primaquine (a malaria medicine) in your blood. There is then a higher risk of poisoning. It has been recommended that these 2 medicines should not be used together. 

It is important to tell your doctor and pharmacist if you take any other medicines.

Repeat prescriptions

Mepacrine is only prescribed in hospitals. Your lupus team can prescribe more supplies of the medicine, which you can collect from the hospital pharmacy.

Treatment for malaria

Although mepacrine was once used to treat malaria, it is now thought that the medicine does not give enough protection against the infection.

If you plan to travel to a country where there is a risk of getting malaria, you need to speak with your GP. They can give you suitable treatment to prevent malaria.

Useful information

Lupus UK is a national registered charity supporting people with systemic lupus and discoid lupus.