Enzymes as Drug Targets

Introduction

• Drug-target classes — receptors ~47%, enzymes ~30%, ion channels ~15%, transporters ~5%, others ~3%; enzymes are the second-largest class.
• Why enzymes — (i) selective, often rate-limiting roles in essential biochemical pathways; (ii) molecular logic of catalysis and allosteric regulation amenable to rational pharmacological manipulation.
• Therapeutic breadth — lisinopril, atorvastatin, metformin, ibuprofen, aspirin, warfarin, allopurinol, finasteride, apixaban, sitagliptin, omeprazole — every major therapeutic area uses enzyme-targeting drugs.
• Microbial extension — Ehrlich's selective-toxicity principle drives antibacterial, antifungal, antiviral chemotherapy; selectivity rests on target absence, pathway absence, or differential affinity between pathogen and host enzymes.