Piperaquine is a bisquinoline antimalarial drug that was first synthesized in the 1960s and used extensively in China and Indochina as prophylaxis and treatment during the next 20 years. Usage declined in the 1980s as piperaquine-resistant strains of P. falciparum arose and artemisinin-based antimalarials became available. However, during the next decade, piperaquine was rediscovered by Chinese scientists as one of a number of compounds suitable for combination with an artemisinin derivative. The rationale for such artemisinin combination therapies (ACTs) was to provide an inexpensive, short-course treatment regimen with a high cure rate and good tolerability that would reduce transmission and protect against the development of parasite resistance. Piperaquine is characterized by slow absorption and a long biological half-life, making it a good partner drug with artemisinin derivatives which are fast acting but have a short biological half-life.

Clefamide is an aromatic ether and antiprotozoal agent that was used to treat and chemoprophylaxis of amoebiasis in the 1960s

Tilbroquinol is a 8-hydroxyquinoline compound exerting antiprotozoal actions. The mechanism of action for 8-hydroxyquinolines remains unknown, although it has been proposed that these compounds chelate metals necessary for multiple enzymatic catalysis reactions, including DNA synthesis. Tilbroquinol in combination with tiliquinol (INTETRIX capsules) is indicated for the treatment of intestinal amebiasis. Some countries (France, Saudi Arabia) have withdrawn from the market products containing tilbroquinol because of the hepatoxicity.

Copper oleate is a pesticide and insecticide compound. Its use was calcelled by EPA in 1991.

Artemotil (also known as beta-arteether) is an antimalarial artemisinin derivative, approved for the treatment of severe cases of P. falciparum malaria. The mixture of artemotil and alpha-arteether is used in patients with cerebral malaria. Most of the artemisinin compounds including artemotil are metabolized into dihydroartemisinin, which is responsible for antimalarial activity. These compounds contain stable endoperoxide bridge. The antimalarial activity of the drug thus is dependent on the cleavage of the endoperoxide by intraparasitic heme. The cleaved endoperoxide ultimately becomes a carbon centered free radical, which then functions as an alkylating agent, reacting with both heme and parasitic proteins (but not DNA). In P. falciparum, one of the principal alkylation target is the translationally controlled tumor protein (DHA-TCTP) homolog. Some intraparasitic TCTP is situated in the membrane surrounding the heme-rich food vacuole, where heme could catalyse the formation of drug-protein (DHA-TCTP) adduct and inhibit the parasite's growth.

Oxantel is a narrow-spectrum anthelmintic effective against whipworms in dogs and cats. It is ineffective against other roundworms, flukes, tapeworms or external parasites. Oxantel acts on the nervous system of the worms as inhibitors of acetylcholinesterase. Oxantel, a cholinergic anthelmintic and fumarate reductase inhibitor, significantly inhibited biofilm formation by P. gingivalis and disrupted established biofilms at concentrations below its MIC against planktonic cells. Oxantel was more effective against P. gingivalis in biofilm than metronidazole, a commonly used antibiotic for periodontitis. When oxantel was administrated to human beings for the treatment of trichuriasis, no drug reaction or side effects were reported, and the results of hematologic, biochemical and urinary examinations didn’t reveal any significant drug-related changes.

Dimethyl phthalate, an organic compound, is used as repellents. This compound is a pollutant that is very harmful to organisms due to its mutagenicity, teratogenicity and carcinogenicity. It was discovered, that dimethyl phthalate could alter the biological function of the one of the most important bacteria in the environment, P. fluorescens.

Ornidazole is nitroimidazole derivative. It is an antiprotozoal drug that has proven to be effective against Trichomonas vaginalis, Entoamoeba histolytica, Giardia lamblia and Helicobacter pylori. The reduction of the nitro group and the generation of short-lived reactive intermediates are the basis of its parasiticidal activity. Ornidazole is a DNA-tropic drug with selective activity against microorganisms with enzyme systems capable of reducing the nitrogroup and catalyze the interaction between ferrodoxin proteins and nitrocompounds. After the drug penetrates the microbial cell, the mechanism of its action is based reducing the nitrogroup under the influence of the microorganism’s nitroreductases and the activity of the reduced nitroimidazole. The reduction products create compounds with DNA causing it to degrade, and disrupt the DNA replication and transcription processes. Furthermore, the drug’s metabolism products have cytotoxic properties and disrupt cellular respiration processes. It is indicated for the treatment of anaerobic systemic infections caused by ornidazole-sensitive microflora, prevention of infections caused by anaerobic bacteria, during operative treatment (especially middle and straight intestine surgeries), gynecological surgeries, severe intestinal ameobiasis, all extra-intestinal ameobiasis forms, giardiasis. Ornidazole was shown to be effective for the prevention of recurrence of Crohn's disease after ileocolonic resection.

Tenonitrozole is an antiprotozoal given in the treatment of trichomoniasis. It is given orally in a dose of 250 mg twice daily with meals, for 4 days.

Cycloguanil is a dihydrofolate reductase inhibitor and is a metabolite of the antimalarial drug proguanil. The parent drug proguanil was suggested to contribute to the antimalarial activity as well, but the mechanism of action is unknown. Proguanil is a prodrug that is metabolized to its main active metabolite, cycloguanil, mostly via CYP2C19. There is significant variation in proguanil pharmacokinetics.12 CYP2C19 is the predominant enzyme catalyzing the bioactivation of proguanil to cycloguanil. Cycloguanil is one of the few antimalarial drugs that act on both the erythrocytic and on the pre-erythrocytic (hepatic) forms of the malaria parasites. Although cycloguanil is not currently in general use as an antimalarial, the continuing development of resistance to current antimalarial drugs has led to renewed interest in studying the use of cycloguanil in combination with other drugs.