Antibacterial Drugs - Inhibitors of Protein Synthesis Flashcards
Tetracyclines - Drugs
Tetracycline
Doxycycline
Minocycline
Tetracyclines - MOA
Bacteriostatic
Bind to 30S subunit (binding is reversible)
Tetracyclines - Kinetics
GIT absorption = variable Excreted via bile (in faeces) Absorption decreased by: 1. Calcium 2. Magnesium 3. Iron preparations (forms chelates)
Tetracyclines - Spectrum
Broad spectrum Acne vulgaris Chronic bronchitis Chlamydia Cholera Rickettsia (NB: strepto and staphlococci, pseudomonas and proteus are resistant)
Tetracyclines - Adverse Effects
GIT disturbances (flatulence, cramping) Disruption of normal gut flora (candida) Pseudomembranous colitis Photosensitivity ↓ efficacy of COCP Binds to calcium in bones and teeth - orange tooth syndrome & retarding Overgrowth of C.albicans (thrush)
Tetracyclines - C/I
Children under 8 Pregnancy Lactation Hepatic impairment Porphyria
Tetracyclines - D/I
↓ Levels of doxycycline
↑ Intercranial pressure (vit a and retinoids)
COCP
Tetracyclines - Administration
Oral
Parenteral
Aminoglycosides - Drugs
Gentamycin
Streptomycin
Neomycin
Amikacin
Aminoglycosides - MOA
Bactericidal
Bind to 30S subunit
Interfere with ribosomal subunit
Post-antibiotic effect
Aminoglycosides - Kinetics
Half life: 2-3 hours
Weak penetration to CSF
70-90% excreted in urine
Prolonged post-antibiotic effect
Aminoglycosides - Spectrum
Aerobic gram-negative bacilli. Gram-positive aerobes. Drug of choice for P.Aeruginosa Mycobacterial infxns Vibrio cholerae Yersinia pestis
Aminoglycosides - Adverse Effects
V. Narrow therapeutic index
Ototoxic
Nephrotoxic
Neuromuscular paralysis (decreases Ach)
Aminoglycosides - C/I
Elderly Renal Insufficiency Neonates Pregnancy Myasthenia gravis
Aminoglycosides - D/I
Penicillins (Coadministration of aminoglycosides with penicillin result in inactivation of the aminoglycoside)
Heparin (Heparin will also decrease the measured aminoglycoside blood levels.)
General anaesthetics
Oto/nephrotoxic agents (vancomycin/amphotericin)
Aminoglycosides - Administration
Oral (poor)
Intramuscular (good absorption)
Macrolides - Drugs
Erythromycin
Clarithromycin
Azithromycin
Macrolides - MOA
Bacteriostatic (Inhibits bacterial RNA-dependent protein synthesis)
Bind to the 50S subunit of the 70S ribosome
which causes dissociation of t-RNA
Erythromycin - Spectrum
RTIs caused by strepto/pneumococci Mycoplasma Chlamydia Legionella Mycobacterium avium-intracellulare
Macrolides - Kinetics
Food alters absorption
Accumulates in macrophages
Macrolides - Adverse Effects
Epigastric distress
Cholestatic jaundice
Ototoxicity
Macrolides - C/I
Hepatic dysfunction (inhibits CYT P450)
Macrolides - Administration
Oral
Parenteral
Chloramphenicol - MOA
Bactericidal
Binds 50s ribosomal subunit
Inhibits peptidyl transferase
