Chapter 43: Antimalarial, Antiprotozoal, and Anthelmintic Drugs

falciparum, P. vivax, P. malariae, and P. ovale. The parasite undergoes complex life cycles involving exoerythrocytic and erythrocytic phases within the human host, producing characteristic fever cycles known as paroxysms accompanied by chills, sweating, headache, and arthralgias. Antimalarial agents such as chloroquine, hydroxychloroquine, quinine, mefloquine, primaquine, artesunate, and pyrimethamine work through distinct mechanisms including DNA and RNA polymerase inhibition, intracellular pH alterations, and protein synthesis disruption. Combination therapy is often employed to prevent resistance development. Significant adverse effects include gastrointestinal disturbances, visual disturbances, neuropsychiatric manifestations, hemolytic anemia in patients with glucose-6-phosphate dehydrogenase deficiency, and hepatotoxicity. The chapter then addresses other protozoal infections including amebiasis, giardiasis, toxoplasmosis, trichomoniasis, and pneumocystosis. Treatment agents including metronidazole, iodoquinol, paromomycin, atovaquone, and pentamidine act through mechanisms such as DNA synthesis interference and mitochondrial dysfunction. Metronidazole receives emphasis for its broad spectrum activity against bacteria, protozoa, and helminths, with the critical contraindication of alcohol co-administration due to disulfiram-like reactions. Protozoal infections pose particular risks for immunocompromised individuals, especially those with HIV and AIDS. The final section covers helminthic infections caused by nematodes, cestodes, and trematodes, treated with agents including albendazole, ivermectin, praziquantel, and pyrantel. These drugs paralyze parasites through microtubule disruption, neuromuscular junction inhibition, or calcium permeability alteration. Nursing responsibilities encompass infection history assessment, laboratory and hepatorenal function testing, complete blood count evaluation, and screening for contraindications including pregnancy, glucose-6-phosphate dehydrogenase deficiency, and psychiatric disorders. Patient education must address medication adherence, infection prevention strategies, specimen handling, sanitation practices, and monitoring for serious adverse effects including vision changes, peripheral neuropathy, and severe gastrointestinal reactions. Recognition of significant drug interactions, such as rifampin reducing antimalarial efficacy or cimetidine altering praziquantel metabolism, is essential for safe clinical practice.