ANTIMALARIALS - a patient's guide
Natalie Gauld - Pharmacy Educator

Use

Prevention of malaria when travelling to malarial areas.

Malaria is an infection by a parasite called Plasmodium that is passed by mosquitoes to humans. It is a problem in some countries including parts of Africa, Turkey, Central and South America, various Asian countries and other places. Malaria is unpleasant and can cause death. Over 2 million people per year die from malaria - these are mainly people living in the malarial area rather than travellers.

Medicines to prevent malaria should be taken by visitors to a malarial area. These medicines are also known as antimalarials or malarial prophylaxis. The medicines do not provide total protection and avoiding mosquito bites is still very important - for example by using insect repellents, using long sleeves, trousers rather than shorts, shoes and socks, and bed nets. It is also important that you follow the directions on the medicine exactly. Do not miss any doses, and remember to continue taking the tablets for the specified time once you return to a non-malarial area. Usually this is for at least four weeks after return, even if you feel well.

Even with taking the medicines correctly and avoiding mosquito bites there is still a small risk of becoming infected, even up to a year after leaving the malarial area. If you have any illness within a year of being in a malarial area see a doctor and mention that you have been in a malarial area.

The recommended medicine depends on the region you are visiting and your doctor should have up-to-date information on this. Sometimes a combination of different medicines may be needed to increase the effectiveness.

Anti-malarial medicines include:

Chloroquine (Nivaquine, Avloclor)
Proguanil or chloroguanide (Paludrine)
Mefloquine (Lariam)
Doxycycline (Doxy, Vibra-tabs, Doxine)
Pyrimethamine and dapsone (Maloprim)
Hydroxychloroquine (Plaquenil)
Quinine (Q 300, Quinoc)
Pyrimethamine and sulfadoxine (Fansidar)

Use in prevention of malaria:

Some of the above medicines are little used now, for example Maloprim is not available in some countries now.

Chloroquine does not work in some regions, but is still useful in others, and is taken once a week.

Doxycycline is taken every day and can increase sensitivity to the sun.

Mefloquine is used in areas with high risk of malaria and high resistance to chloroquine, and is taken once a week.

Proguanil is taken every day.

Quinine is used for treatment rather than prevention of malaria.

In most cases these medicines are taken one to two weeks before travel to the malarial area and continued while there and for four weeks after leaving the area.

It is very important not to miss doses or finish the course earlier than your doctor's recommendation - malaria is more likely in these cases.

While scientists are working on a malaria vaccine, this is not yet ready for humans.

Sometimes people do not want to take the antimalarials, or only take them for a short time because they are concerned about possible side effects. Talk this over with your doctor if you are concerned - avoiding malaria and risking occasional side effects is a better choice than risking malaria.

Standby treatment

If you are going to an isolated area where medical help will not be available, your doctor may give you an extra course to take in case you get the symptoms of malaria. This will be in addition to your prevention strategy. It is important to seek medical advice immediately if you may have malaria, even with this standby treatment.

Cautions

Chloroquine:
Do not use if hypersensitive to this or related medicines, or with certain eye problems (retinal or visual field changes).
Best avoided in pregnancy.
Take special care in patients with: epilepsy, liver or kidney problems, porphyria, psoriasis, severe stomach or intestinal problems, neurological (head) and blood problems, and in patients on anticoagulants (e.g. warfarin).
Eye examinations and blood counts are recommended if treatment is longer-term.

Mefloquine:
Do not use if hypersensitive to mefloquine or related medicines (e.g. quinine).
Do not use as preventative when there is a history of severe psychiatric illness or convulsions (e.g. epilepsy).
Take special care in patients with liver problems, pregnancy or breastfeeding.

Proguanil:
Take special care in patients with kidney problems.
The benefit in pregnancy outweighs the risk.

Side effects

Chloroquine:
Itching or redness of the skin, hair loss, pigmentation of nails, mucous membranes (e.g. inside mouth), and worsening of psoriasis.
Swelling of face (very uncommon).
Seizures, nerve inflammation, muscle and nerve problems, headaches, blurred vision and other eye problems (longer-term high dose treatment). Effects on the ear e.g. ringing in the ears.
Stomach upset.
Effects on the blood and heart are very rare.

Mefloquine:
Most common: nausea, vomiting, dizziness or vertigo, loss of balance, headache, sleepiness, insomnia (difficulty sleeping), abnormal dreams, diarrhoea and stomach pain.
Less common side effects include visual disturbances, tinnitus and balance problems, anxiety, restlessness, low mood, forgetfulness, confusion, hallucinations and psychotic or paranoid reactions. Heart beat may be faster or slower, erratic pulse. Itching, redness or rash of the skin, hair loss. Muscle weakness, cramps or pain. Tiredness, fever, chills, loss of appetite, low energy.
There has been media attention on the side effects of mefloquine - discuss this with your doctor if you are concerned.

Proguanil:
Most common: reduced appetite, nausea, vomiting, stomach pain, diarrhoea, mouth ulcers, sore mouth, headache.
Less common: vertigo, skin rash or itch, hair loss.
Rare: blood problems, allergy, convulsions, psychosis, hepatitis.
With any of the above medicines, do not drive or operate machinery if you experience dizziness, changes to eyesight, loss of balance or drowsiness.

There may be other side effects, so if you have any unexpected symptoms while taking this medicine, tell your doctor or pharmacist.

Interactions

Chloroquine
Ampicillin
Antacids
Chlorpromazine
Cholestyramine
Cimetidine
Cyclosporin
Diabetes tablets
Digoxin
Epilepsy medicines
Halofantrine
Mefloquine
Methotrexate
Penicillamine
Praziquantal

Theoretical: some medicines affecting the heart, tricyclic antidepressants and antipsychotics .

Mefloquine
Related medicines (e.g. quinine, chloroquine, quinidine)
Cimetidine
Epilepsy medicines
Halofantrine
Primaquine
Theoretical: some medicines affecting the heart, tricyclic antidepressants and antipsychotics
Do not start mefloquine until at least three days after the last dose of attenuated live bacteria (e.g. typhoid)
Proguanil
Possible: fluvoxamine
Magnesium trisilicate

There may be other interactions.

Patient information

Follow the instructions on the label of the medicine or as directed by your doctor.

Taking garlic, vitamin B1, use of ultrasonic buzzers or drinking alcohol do not prevent malaria.

Air-conditioned rooms or bed nets (impregnated with insect repellent) can reduce the incidence of malaria.

Spray your room for mosquitoes before bedtime.

Try to cover most of the body in clothing, including shoes and socks, in the evening.

Use insect repellents.

Breast-fed infants cannot rely on medicines being taken by the mother for protection, but need separate medicine.

In pregnancy it is better to avoid malarial areas if possible; if not possible antimalarial medicines are safer than getting malaria. You may need to take extra folic acid while taking antimalarials when pregnant.

Possible symptoms of malaria include fever (which may come and go), headache, vomiting, mild diarrhoea and cough. Serious complications can develop suddenly from an apparently mild illness. Seek medical treatment promptly if you have a fever or other symptoms.