Anti-Parasite Drugs

Anti-malarial drugs

These drugs target various stages of the malaria parasite life cycle.

Chloroquine

This drug raises the pH of parasitic vacuoles inhibiting haem-polymerase.

This stops the parasite feeding in RBCs, stopping the life cycle.

It is used for malaria prophylaxis and acute attacks.

Resistance to chloroquine is emerging in many species of P. falciparum. In these cases, mefloquine is used to treat chloroquine-resistance strains.

Side effects

Headache

Contraindicated in epilepsy

Unfortunately, resistance to chloroquine is emerging in many species of P. Falciparum.

Mefloquine

This acts similarly to chloroquine and is used for prophylaxis and treatment of chloroquine-resistance strains

Side effects

Dizziness

Psychiatric signs (suicidal thoughts)

It is contraindicated in epilepsy

 

Artemisinins – Dihydroartemisin, artensuante

These are semi-synthetic drugs which are used in combination therapy to treat P. falciparum.

– These drugs are converted to dihydroartemisinin, which leads to the generation of free radicals to kill the parasite.

Side effects

GI upset

Dizziness

Quinine

This interferes with the erythrocytic stage of the parasite by inhibiting its ability to metabolise haemoglobin.

It used in the management of P. falciparum when artemisinins are not available.

Side effects

Produces curare-like effects on skeletal muscle, tinnitus and visual disturbances

Blackwater fever, a haemolytic crisis that occasionally complicates malaria infection.

  • Large numbers of red blood cells undergo haemolysis releasing haemoglobin into the bloodstream
  • This can cause an AKI.

Proguanil

This is a prodrug whose active metabolite inhibits dihydrofolate reductase to stop parasite DNA synthesis.

It is commonly used in combination with chloroquine or atovaquone (electron transport chain inhibitor).

Fansidar

This is Pyrimethamine (inhibits dihydrofolate reductase) and Sulfadoxine (inhibits dihydropteroate synthase)

It acts to prevent folic acid synthesis in order prevent DNA synthesis

Side effects

Megaloblastic anaemia

Folate deficiency

Drugs against other parasites

 

Mebendazole

This drug is used to treat many parasitic worm infections including threadworms, hookworms and giardia.

It inhibits the synthesis of microtubules which stops the uptake of glucose and nutrients, killing the helminth.

Side effects

GI upset

Hepatotoxicity

Praziquantel

This drug is used to treat schistosomiasis, potentially by increasing cell permeability to Ca2+ ions, leading to parasite paralysis (exact mechanism of action unknown).

Side effects

GI upset

CNS disturbance (dizziness, headache)

Ivermectin

This is a drug which is used against parasites like head lice and scabies. It opens Cl- channels, causing cell hyperpolarisation and death.

Side effects

CNS depression

Ataxia

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