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A detailed description on tetracycline from book Katzung 11th edition, for medical & dental students

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  1. 1. TETRACYCLINESByDr.Riffat FarooquiAssistant Professor
  2. 2. Bacterial Protein SynthesisInhibitors• Tetracyclines• Macrolides• Clindamycin• Chloramphenicol• Streptogramins
  3. 3. TetracyclinesInhibit bacterial protein synthesis by binding toand interfering with ribosomes1) Short-acting (6-8 hours)Chlortetracycline, Tetracycline, Oxytetracycline2) Intermediate-acting (12 hours)Demeclocycline and Methacycline3) Long-acting (16-18 hours)Doxycycline and Minocycline
  4. 4. Antimicrobial Activity• Broad-Spectrum Bacteriostatic Antibiotics• Active against many gram-positive and gram-negativebacteria, includingAnaerobesRickettsiaeChlamydiaeMycoplasmasProtozoa, e.g. amebas
  5. 5. Pharmacodynamics(MOA)The Tetracyclines bind to the 30S subunit and prevent bindingof the incoming charged tRNA unit (Inhibit step 1 in bacterialprotein synthesis).Tetracyclines enter microorganismsSusceptible cells concentrate the drug intracellularlyTetracyclines bind to 30S subunit of the bacterial ribosomeBlocking the binding of tRNA to the acceptor site on the mRNA-ribosome complexThis prevents addition of amino acids to the growing peptide
  6. 6. RESISTANCEThree mechanism of resistance totetracycline analogs(1) Impaired influx or increased efflux byan active transport protein pump(2) Ribosome protection due toproduction of proteins that interferewith tetracycline binding to theribosome(3) Enzymatic inactivation
  7. 7. • Tet (AE) efflux pump-expressing gram-negative speciesResistant toOlder TetracyclinesDoxycyclineMinocycline.Susceptible toTigecycline• Tet (K) efflux pump of staphylococciResistance toTetracyclinesSusceptible toDoxycycline,Minocycline,Tigecycline• Tet (M) ribosomal protection protein expressed by gram-positivesResistance toTetracyclines,Doxycycline,Minocycline,Susceptible toTigecycline,
  8. 8. PHARMACOKINETICSAbsorption• 60-70% tetracycline, oxytetracycline,demeclocycline, and methacycline• 95-100% doxycycline and minocycline• Tigecycline is poorly absorbed orally and must beadministered intravenously.Absorption occurs in upper small intestine and isimpaired by• Food (except doxycycline and minocycline)• Divalent cations (Ca2+, Mg2+, Fe2+) or Al3+• Dairy products• Antacids
  9. 9. PHARMACOKINETICS• 40-80% bound by serum proteins• Distributed widely to tissues and body fluidsexcept for CSF(10-25%)• Tetracyclines cross the placenta to reach the fetusand are also excreted in milk Chelation withcalcium, damage growing bones and teeth• 10 – 50 % excreted into the urine10 - 40 % excreted in feces• Doxycycline and Tigecycline eliminated bynonrenal mechanisms do not accumulate inrenal insufficiency
  10. 10. DRUG INTERACTION• Antacid Impaired absorption• Carbamazepine• Phenytoin• Barbiturates• Chronic alcohol ingestion• Diuretics Nitrogen retentionDecreases thehalf-life ofDoxycycline
  11. 11. INDICATIONS ( Clinical uses)Tetracycline• Drug of choice in infection withMycoplasma pneumoniaeChlamydiaeRickettsiaeSome spirochetes• Used in PEPTIC ULCER caused by H.pylori• Vibrio infections( Cholera)• Chlamydial infections, including sexually transmitteddiseases• In combination with an aminoglycoside, indicated forplague, tularemia, and brucellosis
  12. 12. • Treatment of acne• Exacerbations of bronchitis• Community-acquired pneumonia• Lyme disease• Relapsing fever• Leptospirosis• Nontuberculous mycobacterial infections (e.g.,Mycobacterium marinum)Minocycline Meningococcal carrier stateDemeclocycline Inhibits the action of ADH Soused in inappropriate secretion of ADH
  13. 13. Tigecycline• Tetracycline-resistant strains are susceptible to Tigecycline.• Methicillin& Vancomycin-resistant Staphylococci• Penicillin-susceptible and – resistant streptococci• Vancomycin-resistant enterococci• Gram-positive rods• Enterobacteriaceae• Multidrug-resistant strains of Acinetobacter sp• Gram-positive and gram-negative anaerobes• Rickettsiae, chlamydia, and legionella• Rapidly growing mycobacteria• Proteus and P aeruginosa, are intrinsically resistant.
  14. 14. ADVERSE EFFECTS1) GASTROINTESTINAL ADVERSE EFFECTS• Nausea, vomiting, anorexia and diarrhea• Anal Pruritus• Vaginal or oral candidiasis• Enterocolitis2) BONY STRUCTURES AND TEETHWhen a tetracycline is given during pregnancyDeposited in the fetal Teeth& BonesFluorescence, Discoloration, and Enamel Dysplasia;Bone deformity or Growth inhibition
  15. 15. 3) LIVER TOXICITY• Impair hepatic function• Hepatic necrosis (4 g)4) KIDNEY TOXICITYAdministration of outdated tetracyclineDamage to renal proximal tubuleRenal tubular acidosis(Fanconi-like syndrom)
  16. 16. 5) LOCAL TISSUE TOXICITYI/V injection Venous ThrombosisI/M injection Painful local irritation6) PHOTOSENSITIZATIONDemeclocycline Sensitivity to sunlight or ultraviolet light7) VESTIBULAR REACTIONSDizzinessVertigoNauseaVomiting