Antimalaria

The Life Cycle of the Malaria Parasite

• Malaria is caused by various species of plasmodia, which are carried by the female anopheles mosquito
• Sporozoites (the asexual form of the parasite) are introduced into the host by bite of the insect, and these develop in the liver into three stages:
o Pre-erythrocytic stage: Schizonts which liberate merozoites
o Erythrocytic cycle: Merozoites infect red blood cells, forming motile trophozoites,
which after development release another batch of erythrocyte-infecting merozoites, causing fever
o Exo-erythrocytic stage: Dormant hypnozoites may liberate merozoites later
• The main malarial parasites causing tertian (every third day) malaria are:
o P. vivax, which causes benign tertian malaria
o P. falciparum, which causes malignant tertian malaria. Unlike P. vivax, this
plasmodium has no exo-erythrocytic stage
• Some merozoites develop into gametocytes, the sexual forms of the parasite.
• When the gametocytes are ingested by the mosquito, these give rise to further stages of the parasite's life cycle within the insect.

Classification of Anti-Malarial Drugs according to the Malarial Activity
Drugs Used in the Treatment of Malaria, Sites of Action
• Drugs used to treat the acute attack of malaria act on the parasites in the blood (blood schizonticides).
• They can cure infections with parasites (e.g. Plasmodium falciparum) that have no exo-erythrocytic stage.
• Drugs used for chemoprophylaxis (causal prophylactics) act on merozoites emerging from liver cells.
• Drugs used for radical cure are active against parasites in the liver.
• Drugs that act on gametocytes prevent transmission by the mosquito.

Treat Uncomplicated Malaria
The first line drug for treatment of a patient with uncomplicated malaria is Artemether –Lumefantrine (ALU)

The first dose should be given at any time, but preferably in the morning so as enhance compliance and timing of the second dose.
• The second dose should be strictly given after 8 hours.
• Subsequent doses should be given twice daily in the second and third day of treatment ideally starting 12 hours after the second dose.
• For convenience and to make ALu administration simple, it is suggested to administer 3rd,4th, 5th and 6th ALu doses in the morning and evening of the second and third day of treatment.

Management of Severe Malaria
• Provision of appropriate treatment with intravenous Quinine
• Hypoglyceamia remains a major problem in the management of severe malaria especially in young children and pregnant women

Administration of Intravenous Quinine
• Quinine dihydrochloride 10mg salt/kg body weight.
• Diluted in 5-10ml/kg body weight of 5% dextrose or dextrose – saline.
• Infused over 4 hours and repeated every 8 hours.
• The total volume given will depend on the patients overall fluid balance.
• The drop rate calculated as follows:
• Drop rate per minute = amount of fluid to be infused (in ml) x 20 ( drop factor)
Time period to be (in minutes)
• Infusion should be discontinued as soon as the patient is able to take oral medications.
• Oral quinine maintenance dose should be the same for the remaining days to complete seven days treatment.
• Oral Quinine maintenance dose should be 7mg/kg body weight in patients with impaired renal function.
• Patient should be properly instructed to complete the seven-day treatment.
• Alternatively, a full course of ALu may be administered to complete the treatment once the need to go to oral medication has been sought.
• Where facilities for intravenous administration of Quinine are not available
o Injectable quinine should be given by the intramuscular route of 10mg/kg body
weight in dilution of quater strength of water for injection every 8 hours until the
patient is able to take oral medication.

o Once oral medication can be tolerated, Quinine tablets should be continued to
complete a 7 day course or a full course of ALu may be administered to complete
treatment (except in pregnant women in first trimester and children below 5kg body weight).
• Dilutions of quinine for intramuscular use
o Quinine dihydrochloride injection supplied as ampoules (300mg/ml) for intramuscular use
o Dose of 10mg of salt /kg body weight
o Dilution: Diluted four fold in water for injection or normal saline 1:4 to a
concentration of 60mg/ml.
This dilution will minimize the risk of sterile abscess formation.

o Preferable the dose should be calculated for each single patient according to body weight
o The calculated dose should be divided into two halves and then administered by deep intra-muscular injection preferably in different sites.

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Welfare Jambo