Antiprotozoal drugs are a class of medication used to treat infections caused by protozoa, which are single-cell organisms that belong to the type of parasites. Protozoal infections occur throughout the world and are a major cause of morbidity and mortality in some regions such as Africa and South-East Asia.

1. Memoona Arshad – Group 11
Antiprotozoal

2. Antiprotozoal
 Antiprotozoal agents is a class of pharmaceuticals used
in treatment of protozoan infection.
 Protozoans have little in common with each other(for
example, Entamoeba histolytica, a unikont eukaryotic
organism, is more closely related to Homo sapiens,
which belongs to the unikont phylogenetic group, than
it is to Naegleria fowleri, a bikont eukaryotic
organism) and so agents effective against
one pathogen may not be effective against another.
 They can be grouped by mechanism or by organism.

3. Introduction
 The use of antiprotozoal drugs in dogs and cats is frequently
extrapolated from their use in human patients or food animal species.
 Almost all antiprotozoal drugs are not specifically approved for
treatment of protozoal infections in dogs and cats.
 Some antibacterial and antifungal drugs also have antiprotozoal
activity.
 In vitro activity of antiprotozoal drugs, and monitoring of resistance, is
more difficult for antiprotozoal drugs because standardized
susceptibility testing is not routinely performed for these pathogens.
 In addition, many antiprotozoal drugs are designed to be active in the
lumen of the intestine for treatment of intestinal protozoal infections
and the concentration of active drug in the intestinal lumen after oral
administration is difficult to measure.
 Therefore, the concentration of drug to which these pathogens are
exposed is often not known.
 The activity and dosage regimens of antiprotozoal drugs are often based
on the results of clinical trials, rather than concentration-exposure
relationships between antiprotozoal drugs and the organism of interest.

4. Medical Uses
 Antiprotozoals are used to treat protozoal infections, which
include
 Amebiasis
 giardiasis
 Cryptosporidiosis
 Microsporidiosis
 Malaria
 Babesiosis
 Trypanosomiasis
 Chagas disease
 Leishmaniasis
 toxoplasmosis
 Currently, many of the treatments for these infections are
limited by their toxicity.

5. Metronidazole
 Metronidazole is usually given orally for
the treatment of vaginal infections caused
by Trichomonas vaginalis, and it is effective in treating
bacterial infections caused by anaerobes (organisms
that can survive without oxygen).
 It affects these organisms by causing nicks in, or
breakage of, strands of DNA or by preventing DNA
replication.
 Metronidazole is also the drug of choice in the
treatment of giardiasis, an infection of the intestine
caused by a flagellated amoeba.

6. Iodoquinol
 Iodoquinol inhibits several enzymes of protozoans. It
is given orally for treating asymptomatic amoebiasis
and is given either by itself or in combination with
metronidazole for intestinal and hepatic amoebiasis.

7. Pneumocystis
 Pneumocystis carinii causes pulmonary disease in
immunocompromised patients.
 These infections are treated with trimethoprim-
sulfamethoxazole, which inhibits folic acid synthesis
in protozoans.
 An alternative agent for treatment of these diseases
is pentamidine isethionate, which probably affects the
parasite by binding to DNA.

8. Trypanosomes
 Trypanosomes are flagellated protozoans that cause a
number of diseases.
 Trypanosoma cruzi, the causative agent of Chagas’ disease,
is treated with nifurtimox, a nitrofuran derivative.
 It is given orally and results in the production of activated
forms of oxygen, which are lethal to the parasite.
 Other forms of trypanosomiasis (African trypanosomiasis,
or sleeping sickness) are caused by T. brucei gambiense or
T. brucei rhodesiense.
 When these parasites invade the blood or lymph, the drug
of choice for either form is suramin, a nonmetallic dye that
affects glucose utilization and hence energy production.
Because suramin is not absorbed from the gastrointestinal
tract, it is given by intravenous injection.

9. Chloroquine
 Chloroquine phosphate, given orally, is a drug used for the
prevention and treatment of uncomplicated cases of malaria,
which is caused by species of Plasmodium.
 In regions where chloroquine-resistant P. falciparum is
encountered, mefloquine or doxycycline may be used for
prevention of the disease. Infection with chloroquine-resistant P.
falciparum may be treated with quinine sulfate, often in
combination with pyrimethamine and sulfadoxine, or
with artemisinin, in combination with agents such as mefloquine
or amodiaquine.
 A high level of quinine in the plasma frequently is associated
with cinchonism, a mild adverse reaction associated with such
symptoms as a ringing noise in the ears (tinnitus), headache,
nausea, abdominal pain, and visual
disturbance. Primaquine phosphate is given orally to prevent
malaria after a person has left an area where P. vivax and P.
ovale are endemic and to prevent relapses with the same
organisms.

10. Outdated terminology
 Once upon a time protists were considered protozoans,
but of late the categorization of unicellar organisms
has undergone rapid development, however in
literature, including scientific, there tends to persist the
usage of the term antiprotozoal when they really
mean anti-protist.
 Protists are a supercategory of eukaryota which
includes protozoa.

11. Mechanisms
 The mechanisms of antiprotozoal drugs differ
significantly drug to drug.
 For example, it appears that
 eflornithine,
 a drug used to treat trypanosomiasis,
 inhibits ornithine decarboxylase,
 while the aminoglycoside antibiotic/antiprotozoals
 used to treat leishmaniasis are thought to inhibit protein synthesis.

12. References
 Antiprotozoal drug | Britannica
 Antiprotozoal Drugs- Medicinal Chemistry-Pharmacy
(slideshare.net)
 Definition of Antiprotozoal (medicinenet.com)
 Antiprotozoal - Wikipedia

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