Defination– Anti malarial medications or simply anti malarials are a type of antiparasitic chemical agent, often naturally derived, that can be used to treat or to prevent malaria.
Cycle of malaria
ANTIMALARIAL DRUGS
- Chloroquine (CQ)
- Amodiaquine
- Piperaquine
- Mefloquine
- Quinine
- Quinidine
- Proguanil (Chloroguanide)
- Pyrimethamine
- Primaquine
- Tafenoquine
- Sulfadoxine
- Sulfamethopyrazine
- Tetracycline
- Doxycycline
- Clindamycin
OBJECTIVES AND USE OF ANTIMALARIAL DRUGS
(i) To prevent clinical attack of malaria _ prophylactic
(ii) To treat clinical attack of malaria _ clinical curative
(iii) To completely finished the parasite from the patient’s body radical curative
(iv) To cutdown human-to-mosquito transmitssion gametocidal
These objectives are achieved by attacking the parasite at its various stages of life cycle in the human host. As in;
- Anti malarial drugs that act on erythrocytic schizogony are called erythrocytic schizontocides.
- Those that act on preerythrocytic as well as exocrythrocytic in liver are called tissue schizontocides.
- which kill gametocytes in blood are called gametocides.
Proper therapy or diagnosis of malaria
- The pre-erythrocytic phase (in liver), which is the cause of malaria infection and clinical attacks is the target for this purpose
Primaquine a causal prophylactic for all species of malaria, it has toxic potential
Proguanil is causal prophylactic but has weak activity against liver stages hence not so used.
- The schizontocides which suppress the erythrocytic phase and thus attacks of malarial fever can be used as prophylactics. Though the exerythrocytic phase in case of vivax and other relapsing (worst) malaria continuous, clinical disease does not appear.
Chloroquine 300 mg or 5 mg per kg weekly.
Mefloquine 250 mg taken weekly till 4 weeks .
Proguanil 200 mg daily with chloroquine
Note– The faster acting drugs are preferred particularly in falciparum malaria where delay in treatment may result in death even if the parasites are cleared from blood by the drug.
CAUTION– An attack of falciparum malaria occuring during pregnancy is dangerous for both mother as well as the foetus. It must be treated promptly and aggressively.
Words by WHO- Intermittent preventive therapy (IPT) in the form of one dose pyrimethamine (75 mg) + sulfadoxine (1500 mg) each is 2nd and 3rd trimester, is recommended only in areas with high Pf endemicity (Pf >30%) for pregnant women,
3. Clinical cure– Drugs in this stage are used to terminate an episode of malarial fever. The available drugs are;
Proguanil, pyrimethamine sulfonamides, tetracycline and clindamycin etc.
- Radical cure– In case of vivax and ovale malaria, drugs which attack the exoerythrocytic stage given together with a clinical cure stage.
Primaquine 15 mg daily for 14 days.
- Eliminate the male and female gametes of Plasmodia formed in the patient’s blood called as Gametocidal action. It reduces the transmission in mosquito.
Primaquine is gametocidal to all species of Plasmodium
Artemisinin have weak lethal action on early-stage .
Gametes exposed to proguanil or pyrimethamine may fail to carry on the life cycle normally in the mosquito.
Note– A single 45 mg (0.75 mg kg) dose of primaquine is employed immediately after clinical cure of falciparum malaria to kill the gametes and cut down transmission to mosquito. This should be given even when an artemisinin is used for clinical cure because artemisinin do not kill all the gametes.
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