Anti ameobic drugs

1. AMEBIASIS
 Amebiasis (also called amebic dysentry) is an
infection of intestinal tract caused by Entamoeba
histolytica. The disease can be acute or chronic, with
the patients showing varying degrees of illness, from
no symptoms to mild diarrhea to fulminating
dysentery (Dysentery in which the symptoms are
intensely acute, leading to prostration, collapse, and often
death).

2.  The diagnosis is established by isolating E. histolytica from
fresh feces.
 Therapy is aimed not only at the acutely ill patients but also at those
who are asymptomatic carriers, because dormant E. histolytica may
cause future infections in the carrier and be a potential source of
infections for others.
 Protozoal infections are common among the people in underdeveloped
topical and subtropical countries, where sanitary conditions, hygienic
practices and control of vectors of transmission are inadequate

3.  Entamoeba histolytica exists in two forms:
1. Cysts form (That can survive out side the
body).
2. Trophozoites form (That are labile and don’t persist
outside the body).

4. Life cycle
 Life cycle consists of following steps:
1 Ingestion of cysts
Cysts are ingested through feces, contaminated food or
water.
2. Formation of trophozoites
Cysts are passed into the lumen of intestine, where the
trophozoites are liberated.
3. Penetration and multiplication of trophozoites
Trophozoites are penetrated in intestinal wall and multiply within
colon wall. They either invade and ulcerate the mucosa of
large intestine or simply feed on intestinal bacteria

5. 4. Systemic invasion
 Large numbers of trophozoites within the colon wall
can also lead to systemic invasion and caused liver
abscess.
5. Cysts discarded
The trophozoites within the intestine are slowly
carried toward the rectum, where they return to
cyst form and are excreted in feces.

7. Tissue Amoebiasis
 Both intestinal & extra intestinal
 Nitroimidazoles – Metronidazole , Tinidazole
 Secnidazole , Ornidazole
 Alkaloids - Emetine , Hydroemetine
 * Extra intestinal amoebiasis only - Chloroquine
Luminalamoebiasis
 Amide –Diloxanide furoate
 8-Hydroxy quinolones –Quinidochlor
 Antibiotics – Tetracycline, Paromomycin

15. Disulfiram like -effect
When metronidazole is given with alcohol abdominal
distress, nausea, vomiting, flushing, or headache,
tachycardia, hyperventilation
alcohol aldehyde
dehydrogenase dehydrogenase
Ethanol Acetaldehyde Acetate
Metronidazole inhibitsthis
enzyme inhibits

18.  Tinidazole is a
synthetic antiprotozoal and antibacterial agent.
It is 1-[2-(ethylsulfonyl)ethyl]-2-methyl- 5-
nitroimidazole, a second-generation 2-methyl-5-
nitroimidazole, which has the following chemical
structure:

19. Tinidazole is indicated for the treatment of intestinal amebiasis and
amebic liver abscess caused by Entamoeba histolytica in both adults
and pediatric patients older than three years of age. It is not
indicated in the treatment of asymptomatic cyst passage

20. Ornidazole
 A nitro imidazole derivative, Antiprotozoal
antibiotic,Antimicrobial.
Mechanism of Action of Ornidazole
 Ornidazole is a nitro imidazole which has broad spectrum cidal
activity against Protozoa and some anaerobic bacteria.
 Its selective toxicity to anaerobic microbes involves
1. Drug enters the cell by diffusion,
2. Nitro group of drug is reduced by redox proteins present only in
anaerobic organisms to reactive nitro radical which excerts
cytotoxic action by damaging DNA and other critical
biomolecules.
3. DNA helix destabilization &strand breakage has been observed.

22.  Pharmacokinets of Ornidazole
 Absorption: Well absorbed orally,
 Distribution: Widely distributed,
Metabolism: Metabolized in liver by conjugation,
Excretion: Excreted in urine and small portion is
excreted in bile
Onset of Action for OrnidazoleWithin 2 h
 Duration of Action for Ornidazole14hours
 Half Life of Ornidazole 12 to 14 hours

23. ADRS
 1.Abdominal pain
2.Vertigo
3.Nausea
4.Vomiting
5.Fatigue
6.Dry mouth
7.Headache
8.Rash
9.Urticaria
10.Abdominal distress
11.Dizziness
12.Vertigo

24. Contra-indications of Ornidazole
 1.Hypersensitivity to the drug or other imidazoles
Special Precautions while taking Ornidazole
1.Vertigo
2.Mental confusion
3.Ataxia

25. Typical Dosage
uses
 OrnidazoleAmoebiasis:
Adults: 1gm daily in 2 divided doses for 7
to 10 days
Children: 10 to 25mg/kg once daily for
3days
Amoebic dysentery:
Adults: 1.5gm once daily for 3 days
Children: 40mg/kg once daily for 3 days
Trichomoniasis
Adults: 1.5gm single daily dose or 0.5gm
12hourly for 5 days,
Male partner should be concurrently
treated.
Children: 25mg/kg as a single dose
Giardiasis:
Adults: 1 to 1.5gm once daily for 2days
Children: 40mg/kg for 2days
Bacterial vaginosis: 1.5gm once or 500mg
once daily for 5 to7 days
 Ornidazole1.Amoebiasis
2.Giardiasis
3.Trichomonas vaginitis
4.Anaerobic bacterial
infections
5.Bacterial vaginosis

32.  Emetine is a drug used as both an anti-protozoal and
to induce vomiting. It is produced from the ipecac
root. It takes its name from its emetic properties.

34.  Have erratic oral absorption.Given preferably
subcutaneously but could be given by IM, NEVER
I.V.Has long plasma half life about 5 days.Metabolized
& excreted slowly via kidney so they have a cumulative
effect.Should not be used for more than 10 days
(usually 3-5 days).

35.  Clinical Uses
 Amoebic liver abscess.
 Intestinal wall infections
 Severe forms of amebiasis acute amoebic dysentery
dehydroemetine is preferable due to less toxicity (3-5
days).

36. Adverse Effects
 GIT: nausea, vomiting, diarrhea.
 Serious toxicities: cardiotoxicityHypotension, cardiac
arrhythmias, heart failure
 Caution: the drug should not be used in patients with
cardiac or renal disease, in young children,or in
pregnancy.