Category: 10. Chemotherapeutic Agents

Members: Streptomycin, neomycin, kanamycin, amikacin, gentamicin, netilmicin. Pharmacokinetics: Aminoglycosides are absorbed very poorly from the intact gastrointestinal tract. After intramuscular injection, aminoglycosides are well absorbed. They are highly polar compounds that do not enter cells readily. The kidney clears aminoglycosides, and excretion is directly proportionate to creatinine clearance. Adverse effects: Aminoglycosides damage the VIII nerve…

Clindamycin is active against streptococci, staphylococci, bacteroides species and other anaerobes, both grampositive and gram-negative. It resembles erythromycin in activity and mechanisms of resistance. Clindamycin is well absorbed orally and about 90% protein-bound. Excretion is mainly via the liver, bile, and urine. It penetrates well into most tissues. Clinical uses: Clindamycin is used for the…

The spectrum of activity and clinical uses of azithromycin is identical to those of clarithromycin.It is rapidly absorbed and well tolerated orally. Azithromycin does not inactivate cytochrome P450 enzymes like erythromycin.

Clarithromycin is derived from erythromycin. It is better absorbed compared with erythromycin. Clarithromycin and erythromycin are virtually identical with respect to antibacterial activity except that clarithromycin has high activity against H. influenzae, M. leprae and T. gondii. Clarithromycin penetrates most tissues, with concentrations equal to or exceeding serum concentrations. It is metabolized in the liver.…

Erythromycin is poorly soluble in water but dissolves readily in organic solvents. They Erythromycins are usually dispensed as various esters and salts. Antimicrobial Activity: Erythromycin is effective against gram-positive organisms, especially pneumococci, streptococci, staphylococci, and corynebacteria. Mycoplasma, Legionella, Chlamydia trachomatis, Helicobacter, Listeria, Mycobacterium kansasii, and Mycobacterium scrofulaceum are also susceptible. Gram-negative organisms such as Neisseria…

The tetracyclines are a large group of drugs with a common basic structure and activity. Tetracyclines are classified as short acting (chlortetracycline, tetracycline, oxytetracycline), intermediate acting (demeclocycline and methacycline), or long-acting (doxycycline and minocycline) based on serum half-lives. Antimicrobial activity: Tetracyclines are broad-spectrum antibiotics. They are active against for many gram-positive and gram-negative bacteria, including…

Gastrointestinal disturbances: Adults occasionally develop nausea, vomiting, and diarrhea. Oral or vaginal candidiasis may occur as a result of alteration of normal microbial flora. Bone marrow disturbances: Chloramphenicol commonly causes a dose-related reversible suppression of red cell production at dosages exceeding 50 mg/kg/d after 1-2 weeks. Aplastic anemia is a rare consequence of chloramphenicol administration…

Chloramphenicol is a bacteriostatic broad-spectrum antibiotic that is active against both aerobic and anaerobic gram-positive and gram-negative organisms. It is active also against rickettsiae. Haemophilus influenzae, N. meningitidis, and some strains of Bacteroides are highly susceptible, and for them chloramphenicol may be bactericidal. Clinically significant resistance emerges and may be due to production of chloramphenicol…

Chloramphenicol blocks proper binding of 50S site which, stops protein synthesis. It does inhibit mitochondrial ribosomal protein synthesis because these ribosomes are 70S, the same as those in bacteria. It does not bind to the 80S mammalian ribosomes. This may be responsible for the dose related anemia caused by chloramphenicol. Macrolides, clindamycin, prevent transfer of…

Bacteria have two ribosomal subunits; 30S and 50S. The 30S subunit binds mRNA in initiation and holds growing peptide chain. The 50S subunit accepts / translocates charged tRNAs. Protien synthesis inhibitors are divided into two groups: bacteriostatic and bactericidal. Chloramphenicol, macrolides, clindamycin (Lincosamides), and tetracyclines are bacteriostatic whereas aminoglycosides are bactericidal.