ANTIAMOEBIC DRUGS
PREPARED BY MR. ABHIJIT DAS
AMOEBIASIS
Amoebiasis
is a parasitic infection of the intestines caused by the amoeba Entamoeba histolytica.
The
symptoms of amoebiasis include loose stool, abdominal
cramping, stomach pain etc. However,
some people with amoebiasis won’t experience any symptom.
E.
histolytica is a protozoan than enters the
human body through water or food contaminated with
stool.
The
infection can also spread through the bloodstream to the liver.
PARASITE
A
parasite is any living thing that lives in or on another living organism (host)
for its life cycle.
Ex:
Fungi, Protozoa, Worms etc.
CLASSIFICATION
OF ANTIAMOEBIC DRUGS
1. TISSUE
AMOEBICIDES
a. FOR
BOTH INTESTINAL AND EXTRAINTESTINAL AMOEBIASIS:
NITROIMIDAZOLES: Metronidazole,
Tinidazole, Secnidazole, Ornidazole, satranidazole
ALKALOIDS: Emetine, Dehydroemetine
b. FOR
EXTRAINTESTINAL AMOEBIASIS: Chloroquine
2. LUMINAL
AMOEBICIDES
a. AMIDE:
Diloxanide furoate, Nitazoxanide
b. 8-HYDROXYQUINOLINES:
Quiniodochlor, Diiodohydroxyquin
c. ANTIBIOTICS:
Tetracyclines
METRONIDAZOLE
Metronidazole
is one of the popular drugs for protozoal infections (E. histolytica).
MECHANISM OF ACTION
Metronidazole
is selectively toxic to anaerobic microorganisms (E. histolytica is
an anaerobic microorganism). E. histolytica reduces
the nitro group of metronidazole by nitroreductase and convert it to a
cytotoxic derivative which binds to DNA and inhibits protein synthesis.
PHARMACOKINETICS
ABSORPTION:
Metronidazole is well absorbed from the small intestines.
DISTRIBUTION:
It is widely distributed in the body.
METABOLISM:
It is metabolized in the liver by oxidation and glucuronide conjugation.
EXCRETION:
Metronidazole is excreted in urine.
ADVERSE
EFFECTS
1. Anorexia
(fear of being overweight)
2. Metallic
taste
3. Abdominal
cramps
4. Dryness
of mouth
5. Rashes
6. Seizures
at high doses
THERAPEUTIC
USES
1. Metronidazole
is used to treat amoebiasis.
2. It
is used to treat giardiasis (an intestinal
infection caused by a giardia parasite).
3. It
is used to treat peptic ulcer.
4. It
is also used to treat trench mouth (a severe gum
infection).
5. It
is also used to treat anaerobic bacterial infections.