This topic is nicely covered in the leaflet edited by the BRITISH ASSOCIATION OF DERMATOLOGISTS (PATIENT INFORMATION LEAFLET JULY 2006) which I quote below. A copy of this leaflet can also be downloaded here.
What are the aims of this leaflet?
This leaflet has been written to help you understand more about mepacrine. It tells you what it is, how it works, how it is used to treat skin conditions, and where you can find out more about it.
What is mepacrine and how does it work?
Mepacrine was introduced as a treatment for malaria and for certain other tropical infections. It is one of several antimalarial drugs that have been found also to have anti-inflammatory properties, which can help some skin conditions.
Which skin conditions are treated with mepacrine?
Mepacrine is used particularly to treat discoid lupus erythematosus and for subacute cutaneous lupus erythematosus (see separate patient information leaflet on this website). Mepacrine has also been used in the treatment of erythema multiforme and sarcoidosis.
What dose of mepacrine should I take?
Your doctor will advise you about this. For skin conditions, the dose may be as small as 50mg (half a 100mg tablet) taken three times a week. A maximum dose would 100mg taken three times a day. A dose for children is 2 mg per kg body-weight given three times daily (to a maximum of 300 mg daily). It may take several weeks to reach its full effect.
What are the possible side effects of mepacrine?
Mepacrine is well tolerated at the low doses used in dermatology. Unlike some other antimalarials, it has negligible toxic effects on the eyes. However, it can have some undesirable side effects.
· Yellow discoloration of the skin and urine may occur during long-term treatment or with large doses. This is common but quite harmless, and should not be a cause for concern as it goes away when you stop the drug. Similarly, the palate, nails and eyes may be discoloured blue or black.
· Mepacrine can cause dizziness, particularly when you get up from sitting or lying down. Getting up slowly should help.
· Other possible side effects include: tummy upsets, headaches, feeling and being sick, skin rashes (including severe rashes), changes in mood or behaviour. Fits may occur with over-dosing. Liver inflammation and alterations in the blood count can occur but are rare.
Mepacrine should be used with caution in:
· patients with porphyria,
· elderly patients,
· the presence of liver disease.
· Mepacrine should be avoided by patients with psoriasis as it can make this eruption worse. It should also be avoided in myasthenia gravis and by patients with a history of the severe forms of mental illness called psychoses.
How will I be monitored for the side effects of mepacrine treatment?
Blood tests are usually performed about twice a year to check your blood count and how your liver is working.
Can I have vaccinations while I am on mepacrine?
Yes. This should not be a problem. If you are travelling to a place where malaria occurs, mepacrine will not provide adequate protection against it and you must see your General Practitioner about appropriate drugs.
Does mepacrine affect fertility or pregnancy?
There is no data on the use of this drug in pregnancy and breastfeeding. However it is recommended that you should avoid taking it if you are pregnant or planning a pregnancy, or if you are breast feeding.
May I drink alcohol while I am taking mepacrine?
Mepacrine has been reported to produce a mild flushing reaction when taken with alcohol. There may be symptoms such as a racing heartbeat, dizziness, headache, shortness of breath, and sickness.
Can I take other medicines at the same time as mepacrine?
Mepacrine is often used in conjunction with hydroxychloroquine for additional benefits. This is safe. However some drugs do interact with mepacrine. For example, mepacrine may increase the blood level of primaquine, resulting in a higher risk of toxicity, and it has been recommended that these two drugs should not be used together. Other drugs that can interact are ciclosporin, digoxin, amiodarone, anticonvulsants, penicillamine, cimetidine and antacids among others. Always inform your doctor and pharmacist if you are taking other medication.
It follows that you should always let any doctors who are treating you know that you are taking mepacrine.
Where can I find out more about mepacrine?
If you want to know more about mepacrine, or if you are worried about your treatment, you should speak to your doctor or pharmacist. This information sheet does not list all of the side effects of mepacrine. For fuller details, look at the drug information sheet which comes as an insert with your prescription for mepacrine.
