Chloroquine
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It kills trophozoites of E. histolytica and is highly concentrated in liver. Therefore, it is used in hepatic amoebiasis only. Because it is completely absorbed from the upper intestine and not so highly concentrated in the intestinal wall— it is neither effective in invasive dysentery nor in controlling the luminal cycle (cyst passers).
CHLOROQUINE
The pharmacology of chloroquine is described in Ch. No. 59. It
kills trophozoites of E. histolytica
and is highly concentrated in liver. Therefore, it is used in hepatic
amoebiasis only. Because it is completely absorbed from the upper intestine and
not so highly concentrated in the intestinal wall— it is neither effective in invasive
dysentery nor in controlling the luminal cycle (cyst passers).
Efficacy of
chloroquine in amoebic liver abscess approaches that of emetine, but duration
of treatment is longer and relapses are relatively more frequent. Amoebae do
not develop resistance to chloroquine.
Because of the
relative safety of chloroquine it may be given concurrently or immediately
after a course of metronidazole to ensure complete eradication of the trophozoites
in liver. A luminal amoebicide must always be given with or after chloroquine
to abolish the luminal cycle.
Dose for amoebic liver
abscess: 600 mg (base) for two days followed by 300 mg daily for 2–3 weeks. It
is now employed only when metronidazole is not effective or not tolerated.
