Enzyme inhibitors play a critical role in metabolic pathways by regulating the activity of enzymes. They can be classified into competitive and non-competitive inhibitors, and their primary function is to either reduce the activity or completely halt enzymatic reactions. This regulation is essential for maintaining homeostasis within a cell or organism, as it helps control the flow of metabolic processes, preventing excessive accumulation of substrates or end products. Additionally, enzyme inhibitors can serve as important therapeutic agents in medicine, targeting specific enzymes in diseases like cancer or microbial infections.