A Comprehensive Monograph on Pyrimethamine (DB00205)

Introduction and Drug Profile

Overview of Pyrimethamine: Class, Primary Use, and Clinical Significance

Pyrimethamine is a synthetic diaminopyrimidine derivative, pharmacologically classified as an antiprotozoal agent and a folic acid antagonist.[1] Its primary clinical application is in the treatment of toxoplasmosis, an infection caused by the protozoan parasite

Toxoplasma gondii. This therapeutic role is particularly critical in immunocompromised patient populations, such as individuals with Human Immunodeficiency Virus (HIV) and Acquired Immunodeficiency Syndrome (AIDS), where toxoplasmic encephalitis represents a life-threatening opportunistic infection.[4] Historically, pyrimethamine was a cornerstone in the global management of malaria, although its utility for this indication has been significantly curtailed by the widespread emergence of drug-resistant

Plasmodium strains.[6]

The enduring clinical importance of pyrimethamine is underscored by its inclusion on the World Health Organization's List of Essential Medicines, a designation reserved for medications considered most effective and safe to meet the most important needs in a health system.[9] Despite its long history of use and established efficacy, the drug has a dual identity in modern medicine. It is both a vital, often life-saving, therapeutic agent for a serious parasitic disease and, simultaneously, a prominent symbol of the complex and often contentious issues surrounding pharmaceutical pricing, access, and market ethics in the 21st century. This report provides a comprehensive monograph on pyrimethamine, detailing its chemical properties, pharmacology, clinical applications, safety profile, and the socio-economic context that has defined its recent history.

Chemical Identity and Physicochemical Properties