Category: 10. Chemotherapeutic Agents

Antimirobials such as polymyxins acting on gram negative bacteria and affects the functional integrity of the cytoplasmic membrane, macromolecules and ions escape from the cell and cell damage and death occurs. The two most well known agents are poymyxin B and colistin. Polymyxins are effective against Gram-negative bacteria, particularly pseudomonas species. The major adverse effects…

Cycloserine inhibits many gram-positive and gram-negative organisms, but it is used almost exclusively to treat tuberculosis caused by strains of M tuberculosis resistant to first-line agents. It is widely distributed in tissues. Most of the drug is excreted in active form into the urine. Cycloserine causes serious dose-related central nervous system toxicity with headaches, tremors,…

Bacitracin is active against gram-positive microorganisms. It inhibits cell wall formation. It is markedly nephrotoxic if administered systemically, thus limited to topical use. Bacitracin is poorly absorbed.

Vancomycin is active only against gram-positive bacteria, particularly staphylococci. It inhibits cell wall synthesis. Vancomycin is poorly absorbed from the intestinal tract and is administered orally only for the treatment of antibiotic-associated enterocolitis caused by Clostridium difficile. Parenteral doses must be administered intravenously. The drug is widely distributed in the body. Ninety percent of the…

Cephalosporins can be classified into four generations depending mainly on the spectrum of antimicrobial activity. First-generation compounds have better activity against gram-positive organisms and the later compounds exhibit improved activity against gram-negative aerobic organisms. First-generation cephalosporins Members: Cefadroxil, cefazolin, cephalexin, and cephalothin. These drugs are very active against gram-positive cocci (pneumococci, streptococci, and staphylococci). Escherichia…

Cell wall synthesis inhibitors Members the group: Beta-lactam antibiotics, vancomycin, bacitracine, and cycloserine Beta-lactam antibiotics: Penicillins, cephalosporins, carbapenems, and monobactams are members of the family. All members of the family have a beta-lactam ring and a carboxyl group resulting in similarities in the pharmacokinetics and mechanism of action of the group members. They are water-soluble,…

Mechanisms of antimicrobial drug action: Inhibition of cell wall synthesis Cell membrane function inhibitors Inhibition of protein synthesis Inhibition of nucleic acid synthesis Antimetabolites Mechanisms of resistance to antibiotics Production of enzymes that inactivate the drug (eg. b -lactamase, which inactivates beta lactam antibiotics; acetyl transferases, which inactivate chloramphenicol; kinases and other enzymes, which inactivate…

Chemotherapy: is the use of chemical agents (either synthetic or natural) to destroy infective agents (microorganisms’ i.e bacteria, fungus and viruses, protozoa, and helminthes) and to inhibit the growth of malignant or cancerous cells. Chemotherapeutic agents: are chemical which are intended to be toxic for parasitic cell but non toxic to the host, such selective…