Pharmacotherapy of Malaria Subscribe
Date: 14. April 2018
The elucidation of Pharmacotherapy of Malaria is delivered in this Sqadia video. Malaria is a disease caused by protozoan of the genus Plasmodium in red blood cells, categorized by series of fever, sweating, and chills, which is transmitted by infected female anopheles mosquito to humans through bite. There are four types of Plasmodium species which infect humans that are P. Falciparum, P. Vivax, P. Ovale, and P. Malariae. Contaminated blood transfusion is one of the source for malaria transmission. Transportation of mosquitos from endemic areas also acquired few cases of malaria called Airport malaria. Incubation period ranges from 7 to 30 days. The Incubation periods of Plasmodium falciparum are mostly longer while that of plasmodium malariae are shorter.
Pathophysiology, Life Cycle and Risk Factors
In pathophysiology, there are two stages:
- Pre-erythrocytic stage
- Erythrocytic stage.
Hepatocytes are infected when sporozoites enter into the blood stream and move towards liver; this stage is called pre-erythrocytic stage of infection. The inactive intrahepatic sporozoites are called hypnozoites. Sporozoites are converted into merozoites inside the hepatocytes. When the merozoites are released from infected hepatocytes and start invading erythrocytes is called erythrocytic stage. Malarial parasites form new merozoites within the infected cells through a cycle called schizogony. Now these merozoites are released and re-infect other RBCs. One of the most common risk factor is to live or visit such place where malaria is common. Other risk factors include young children and infants, opening windows at night, little or no access to health care and poverty. In order to prevent malaria, you should know the ABCD of malaria that is Awareness, Bite prevention, Chemoprophylaxis, and Diagnosis.
Clinical Features and Complications
Malarial attack consists of prodrome and paroxysm. Prodrome includes rigors, fatigue, fever and headache. Paroxysm consist of rigors, sweating and high fever. Other initial symptoms include fever (nonspecific), orthostatic hypotension, vomiting, and electrolyte abnormalities. Cold Phase include cyanosis (cutis anserina and lips) and severe pallor. In Hot Phase, fever ranges between 40.5°C (104.9°F) and 41°C (105.8°F). Sweating Phase follow hot phase by 2–6 hours and is characterized by Hypoglycemia and Lactic acidosis. Cerebral Coma, Anemia, Pulmonary Edema, and Renal Failure are some of the complications associated with P. falciparum. Plasmodium vivax and P.ovale causes Splenic Rupture, Debilitating Fever and Anemia. The complications caused by P. malariae are Immune Complex and Glomerulonephritis.
Diagnosis and Classification of Anti-Malarial Drugs
Subjective Diagnosis is done by taking the history of patient’s fever pattern. This method is mostly used in areas not affording laboratory findings. Differential Diagnosis is used for differentiating the malarial coma or fever from non-malarial coma or fever. Tests that are regularly done in laboratory for diagnosis are Blood Test, Thin Film, Thick Film, and Serological Test. For carrying antigen test a Dipstick is use for investigating parasites in blood. Molecular Method is the most expensive and requiring highly sophisticated laboratory. This can be used for analyzing the resistant parasite presence. Anti-malarial drugs are classified on the basis of chemical structure and on the basis of action. 4-aminoquinolines, Diamino Pyrimidines, Biguanides, and Sulfones are some anti-malarial drugs based on chemical structure. Drugs based on action are Tissue Schizonticides, Blood Schizonticides or Suppressive Agents, and Gametocides.
Treatment of Malaria
For the Treatment of Uncomplicated Malaria, the drug of choice for susceptible parasites is chloroquine. P. vivax, P. ovale and P. malariae are almost always sensitive to this drug, the only exception being some strains of P. vivax from Oceania. Tinnitus and nausea are predictable side-effects of quinine, and do not require dose reduction unless severe. Severe malaria, or a parasite count above 1% in a non-immune patient, is a medical emergency. In this case Quinine should be given intravenously. In the First Trimester of pregnancy, Quinine plus clindamycin should be given for 7 days for the treatment of malaria. Artemisinin-based combination therapy known to be effective or artesunate plus clindamycin to be given for 7 days, or quinine plus clindamycin to be given for 7 days. Quinine is associated with an increased risk of hypo glycaemia in late pregnancy, and it should be used only if effective alternatives are not available. Clindamycin is also considered safe, but it must be given for seven days in combination with quinine. Primaquine and tetracycline’s should not be used in pregnancy.