Chemotherapy | Sulfonamides | Antibiotics | Unit 2 Pharmacology 6th Semester

This is an extensive pharmacology lecture covering Unit 2 on chemotherapy, with the instructor explaining that the content overlaps significantly with medicinal chemistry but focuses more on ADME (absorption, distribution, metabolism, excretion) properties. The lecture begins by defining chemotherapy as chemical treatment derived from microorganisms, used not only for cancer but also for infectious diseases. The instructor covers sulfonamides in detail, explaining their para-aminobenzene structure and mechanism of inhibiting dihydropteroic synthase to prevent folic acid synthesis, thereby stopping bacterial DNA synthesis. Cotrimoxazole is discussed as a combination drug with dual action. The majority of the lecture focuses on antibiotics, starting with beta-lactam antibiotics and their mechanism of inhibiting bacterial cell wall synthesis by blocking penicillin-binding proteins. Detailed coverage is provided for penicillins and cephalosporins, including their classifications and pharmacological properties. Chloramphenicol is explained as the first synthetic antibiotic that inhibits protein synthesis by binding to the 50S ribosomal subunit. Macrolides are discussed with their large lactone ring structure and bacteriostatic action through protein synthesis inhibition. Quinolones and fluoroquinolones are covered for their DNA synthesis inhibition through topoisomerase enzyme blocking. Tetracyclines are explained as broad-spectrum antibiotics with a four-ring structure that inhibit protein synthesis by preventing tRNA attachment to ribosomes. Finally, aminoglycosides are discussed as bactericidal agents that cause protein misreading at the 30S ribosomal subunit, though their use is limited due to toxicity.