C H A P T E R 1 2
Antiprotozoal agents
167
treatment of malaria caused by these resistant strains.
Box 12.3 lists the antibiotics used to treat malaria. See
Table 12.1 for usual indications. Mechanisms of action
are as follows:
• Hydroxychloroquine inhibits parasite reproduction,
and by blocking the synthesis of protein production,
it can cause the death of the
Plasmodium
. This
drug is used in combination therapy, usually with
primaquine, for greatest effectiveness.
• Mefloquine increases the acidity of plasmodial
food vacuoles, causing cell rupture and death. In
combination therapy, mefloquine is used in malarial
prevention, as well as treatment.
• Primaquine, another very old drug for treating malaria,
similar to quinine, disrupts the mitochondria of the
Plasmodium
. It also causes death of gametocytes and
exoerythrocytic (outside of the red blood cell) forms
and prevents other forms from reproducing.
Pharmacokinetics
Chloroquine is readily absorbed from the gastrointesti-
nal (GI) tract, with peak serum levels occurring in 1 to
6 hours. It is concentrated in the liver, spleen, kidney
and brain and is excreted very slowly in the urine, pri-
marily as an unchanged drug.
Hydroxychloroquine is readily absorbed from
the GI tract, with peak serum levels occurring in 1 to
6 hours. It is excreted slowly in the urine, primarily as
an unchanged drug.
Mefloquine is a mixture of molecules that are
absorbed, metabolised and excreted at different rates.
The terminal half-life is 13 to 24 days. Metabolism
TABLE 12.1
DRUGS IN FOCUS Antimalarials
Drug name
Dosage/route
Usual indications
artemether-lumefantrine
(Riamet)
Adults, adolescents and children over 35 kg or
12 years of age: six doses of four tablets over
60 hours
25 to <35 kg: 18 tablets over 60 hours
15 to <25 kg: 12 tablets over 60 hours
5 to <15 kg: 6 tablets over 60 hours
Treatment of acute, uncomplicated malaria
due to Plasmodium falciparum
doxycycline (Doryx,
Frakas)
Suppression:
Adult and paediatric (>8 years and 50 kg):
100 mg PO daily, beginning 2 days prior to
entering malaria area, continued throughout
stay in the area, then for 2 weeks after
leaving
Prevention of Plasmodium falciparum
malaria
Prevention of Plasmodium vivax malaria in
combination
hydroxychloroquine
(Plaquenil)
Suppression:
Adult: 310 mg PO every week, beginning
1–2 week before exposure and continuing for
4 weeks after leaving endemic area
Paediatric: 5 mg/kg/week, following adult
schedule
Acute attack:
Adult: 800 mg PO, followed by 400 mg PO in
6–8 hours on two consecutive days
Treatment of Plasmodium malaria in
combination with other drugs, particularly
primaquine
mefloquine (Lariam)
Treatment:
Adult: 1250 mg PO as a single dose
Prevention:
Adult: 250 mg PO once weekly, starting
1 week before travel and continuing for
4 weeks after leaving endemic area
Paediatric: 15–19 kg,1/4 tablet; 20–30 kg,
1/2 tablet; 31–45 kg, 3/4 tablet; >45 kg,
1 tablet; once a week, starting 1 week before
travel and continuing until 4 weeks after
leaving area
Prevention and treatment of Plasmodium
malaria in combination with other drugs
primaquine (Primacin)
Adult: 800 mg PO, followed by 400 mg PO in
6–8 hours on consecutive days.
Prevention of relapses of P. vivax and
P. malariae infections; radical cure of
P. vivax malaria
quinine (Quinbisul)
600 mg PO t.d.s. for 7–14 days
Treatment of malaria due to strains
of P. falciparum resistance to
4-amnoquinolones
