(Mode of Action of Drugs)

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Chapter

1.4

Chapter

9.8 Antimalarial Agents

Human malaria is caused by four species
of Plasmodium namely Plasmodium
falciparum, P. vivax, P. malariae and P. ovale.
P. vivax is mainly responsible for most of
the infections (70%) which results in
benign tertian malaria. In P. falciparum
and P. vivax infections, the patient has fever
with rigors every third day and termed as
tertian. The other two, P. ovale and P.
malariae are mild in nature in which fever
develops every fourth day and termed as
benign quartan. Symptoms and
complications in P. falciparum malaria are
more severe than P. vivax malaria.

The antimalarial drugs can be classified
as in table 9.8.1.

4-AMINOQUINOLINE DERIVATIVES

CHLOROQUINE

Chloroquine is a 4-aminoquinoline
antimalarial agent used for the suppression
and clinical cure of malaria. It is an
excellent erythrocytic schizontocide. It
does not prevent relapse in P. vivax and P.
ovale malaria. It has no effect on pre and
exoerythrocytic phase of the parasite. It also

has antiinflammatory and local irritant

properties.

It probably influences haemoglobin

degradation by parasitic lysosomes by

raising intravesicular pH in malarial

parasite cells. It also interferes with

synthesis of nucleoproteins by the parasite.

It is well absorbed (about 90%) from

gastrointestinal tract. After IM injection

absorption is rapid. Elimination is very slow

and it may persist in tissue for months or

years after discontinuation of therapy

Adverse reactions include nausea,

vomiting, epigastric distress, headache,

anorexia, difficulty in accommodation and

chronic therapy may cause loss of vision

due to retinal damage. On prolonged use

it may also cause skin rash, photoallergy,

myopathy, loss of hearing, greying of hair

and mental disturbances.

Parenteral administration may cause

hypotension, arrhythmia and CNS toxicity.

Therapeutic Uses

It is a drug of choice for clinical cure

and suppressive prophylaxis of acute ma-

laria but not for the resistant cases of P.

falciparum. It can be safely used in preg-

Antimalarial Agents