Chapter 31: Antimalarial, Anthelmintic & Peptide Drugs

The text details the parasite's life cycle, including the tissue and erythrocytic phases, and outlines three eradication strategies: prophylaxis, acute treatment, and relapse prevention. Key pharmaceutical agents such as chloroquine, mefloquine, primaquine, and quinine are examined regarding their mechanisms of action, which often involve inhibiting protein synthesis or heme polymerization within the parasite. Significant attention is placed on drug resistance and the severe adverse effects associated with these medications, such as retinal damage, ototoxicity involving cranial nerve VIII, and cardiovascular collapse. The chapter then transitions to helminthiasis, classifying parasitic worms into cestodes (tapeworms), trematodes (flukes), and nematodes (roundworms). Treatment protocols utilizing anthelmintics like ivermectin, praziquantel, and pyrantel are described, highlighting their ability to bind chloride ions or disrupt cellular uptake to paralyze and destroy the worms. Nursing considerations for helminth infections emphasize the critical role of hygiene, sanitation, and handwashing to prevent transmission and reinfection. The final section covers antimicrobial peptides, including polymyxins (colistimethate and polymyxin B) and bacitracin, which are reserved for treating severe gram-negative bacterial infections like Pseudomonas aeruginosa by disrupting cell membrane function. The chapter concludes with a detailed look at metronidazole, a nitroimidazole peptide effective against anaerobic bacteria and protozoa, and warns of serious toxicities associated with peptides, such as nephrotoxicity, neurotoxicity, and the disulfiram-type reaction that occurs when metronidazole is combined with alcohol.