FACTORS INFLUENCING THE SELECTION OF ANTIMALARIAL DRUGS PATIENT FACTORS Specialised advice is required for
specific individuals as discussed below. In Table 3 is a summary of factors influencing the choice of drugs for these persons. Infants and young children Infants and young children (specially
those under the age of 5 years) are particularly at risk of severe malaria disease since malaria can develop and progress very rapidly. They should preferably not be taken into
malaria risk areas. If this is unavoidable, every precaution should be taken to prevent mosquito bites.
* Chloroquine and proguanil are the drugs of choice for prophylaxis in young children and infants.
* Mefloquine is contraindicated in children weighing less than 15 kg. * Doxycycline is contraindicated in children under 8 years.
Breast-feeding infants Although chloroquine is secreted into the breast milk, the levels are not high enough to provide adequate protection for the infant. The dose in
breast fed infants should be adjusted as follows:
- Fully breast fed infants (four or more feeds per day): half the recommended paediatric dose of chloroquine. - Partially breast fed infants (less than
four feeds per day plus supplementary diet): the full recommended paediatric dose of chloroquine.
There is currently no information available to suggest that the dose of proguanil should be adjusted in breast feeding infants. NB: Overdoses of
chloroquine can be very toxic to children and all antimalarial drugs should be stored out of the reach of children in childproof containers (especially since these drugs are often
taken on holiday and packed in accessible suitcases). Pregnancy and lactation In pregnancy, malaria poses a particular risk to the health of both the mother and foetus, increasing the risk of
maternal death, neonatal death, miscarriage and stillbirth. Pregnant women should be advised to avoid malaria areas. If this is not possible, special precautions should be taken to
avoid being bitten by mosquitoes and the appropriate antimalarial drugs should be taken.
* Chloroquine and proguanil are the drugs of choice during pregnancy and lactation. A folic acid supplement of 5 mg/day should be taken together with these drugs.
* There is currently insufficient evidence regarding the safety of mefloquine in pregnancy and it is best to avoid taking it if possible. If unavoidable,
mefloquine should only be taken during the second and third trimester.1 Women who are of child bearing potential should avoid becoming pregnant during and for 3 months
after using mefloquine. Mefloquine is contraindicated while a mother is breast feeding. * Doxycycline should be avoided during pregnancy and the lactation period.
Porphyria
* The safety of chloroquine in porphyria is the subject of much controversy. Although rare, chloroquine may
exacerbate porphyria. * Proguanil is the only drug that can be used with confidence.
* There is insufficient information on the use of mefloquine to establish its safety in porphyria. * Doxycycline should be avoided.
* Pyrimethamine in combination with dapsone (Maloprim ®) should also not be used.
Epilepsy
Malarial chemoprophylaxis may interact with anti epileptic medicines and may also affect the stability of the patients epileptic condition.
* Although chloroquine is generally not recommended for epileptics, it can be used in certain cases where the patient's condition is stable and he/she will be at
high risk of contracting malaria. In these instances, prophylaxis should be initiated earlier than normal to assess the risk of adverse reactions.
* Proguanil is safe to use. * Mefloquine should be avoided. * Although doxycycline does not affect epilepsy (and may be recommended as short term
prophylaxis for epileptics), it may interact with some anti-convulsants such as carbamazepine (e.g.Tegretol®), resulting in the doxycycline serum levels being reduced and its
therapeutic efficacy compromised. The degree to which doxycycline levels are affected is not clearly understood but chronic carbamazepine therapy may reduce the half life of
doxycycline by 50% in some cases. This could result in malaria prophylaxis failure.
Chronic illnesses Individuals with chronic illnesses must discuss malaria prophylaxis with their medical practitioners (see Table 3 for more
details). Liver disease may result in normal doses of anti-malarial drugs becoming toxic. The extent of this depends on the degree of liver damage. Persons with cardiac conditions and
on medication can only take certain drugs (See details under "Comments on drugs used in chemoprophylaxis"). Persons taking medication should discuss possible
interactions with their doctor or pharmacist. Individuals with impaired immune mechanisms, e.g. by splenectomy or steroid usage are at risk of developing severe infections and should
ensure that adequate prophylactic measures are taken.Sensitivity to sulpha drugs Persons sensitive to sulpha drugs should not take
sulfadoxine-pyrimethamine (Fansidar®) or pyrimethamine-dapsone (Maloprim®).
Exposure to sunlight Persons who will be exposed to sunlight for extended periods of time should be aware
that doxycycline (as with tetracyclines in general) can cause skin photosensitivity and measures such as the use of sun screens should be considered. The guidelines are endorsed by the Medical Association of South Africa. |
