Class broad spectrum antibiotics
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This document discusses tetracycline antibiotics. It notes that tetracyclines reversibly bind to the 30S ribosome and inhibit aminoacyl-tRNA binding. They are broad spectrum antibiotics active against most bacteria except Proteus and Pseudomonas. Resistance can develop through decreased cell permeability, increased drug efflux, ribosomal protection, or enzymatic inactivation. Common tetracyclines include doxycycline, minocycline and tetracycline itself. Adverse effects include gastrointestinal issues, renal impairment, hepatotoxicity and tooth discoloration in children. Drug interactions and contraindications are also discussed.
Class broad spectrum antibiotics
- 1. Dr. RAGHU PRASADA M S MBBS,MD ASSISTANT PROFESSOR DEPT. OF PHARMACOLOGY SSIMS & RC.
- 2. The tetracyclines reversibly bind to the 30S ribosome and inhibit binding of aminoacyl-t-RNA to the acceptor site on the 70S ribosome. G+ve -active transport G-ve-porin channels
- 3. Shorter acting: TETRACYCLINE CHLORTETRACYCLINE OXYTETRACYCLINE Intermediate acting: DEMECLOCYCLINE METHACYCLINE Long acting: DOXYCYCLINE MINOCYCLINE
- 4. Spectrum of activity - Broad spectrum; Useful against intracellular bacteria They are broad spectrum antibiotics, active against most bacteria except Proteus or Pseudomonas.
- 5. Decreased cell permeability of the drug Increased drug efflux from bacterial cell by an energy dependent process Ribosomal protection Enzymatic inactivation of the drug
- 6. Tetracycline, oxytetracycline have short half-lives. Doxycycline has a longer half-life and can be given once per day. They bind avidly to heavy metal ions and so absorption is greatly reduced if taken with food, milk, antacids or iron tablets. They should be taken at least half an hour before food. Tetracyclines concentrate in bones and teeth.
- 7. Distribution: wide Concentrated in liver, spleen and bone & teeth – minocycline in fats Good CSF penetration Excretion: Primarily in urine (dose adjustment in renal failure) Doxycycline is exception (bile)
- 8. Longer t1/2, biliary excreation Demeclocycline-inhibits ADH Minocycline- 100mg BD for meningococcal carriers Swimming pool granuloma, Chronic facial dermatosis ADR- vestibular toxicity, skin pigmentation
- 9. 1. Rocky mountain spotted fever 2. Relapsing fever 3. Psittacosis 4. Pasteurella abscess 5. Plague 6. Pneumonia (mycoplasma) 7. Peptic ulcer 8. Acne 9. Amoebiasis 10. Brucellosis 11. Borrelia burgdorferi (Lymes disease) 12. Granuloma inguinale 13. Tularensis 14. Typhus fever 15. Malaria
- 10. Gastrointestinal upsets Superinfection- Destruction of normal intestinal flora resulting in increased secondary infections; Discolouration and deformity in growing teeth and bones (contraindicated in pregnancy and in children < 12 years) Renal impairment (should be also avoided in renal disease) Hepatotoxicity Pulmonary eosinophillic syndrome Pseudo tumor cerebri
- 11. fancony like syndrome – outdated tetracycline (epitetracycline, anhydrotetracycline and anhydroepitetracycline) – glycosuria, proteinuria and aminoacidria etc. 1. Phototoxicity: Sunburn like - Skin rashes, mainly after topical application 1. Erythema, brown black discolouration of nails and loosening etc. 2. Teeth and Bones: Brown discolouration - Calcium tetracycline chelate (orthophosphate) 3. Antianabolic effect: reduction in Protein synthesis 4. Diabetes Insipidus: antagonizes ADH and urine conc. property 5. Vestibular toxicity: Minocycline (ataxia, vertigo, nystagmus)
- 12. Al, Ca, Zn, Mg and iron preparations decrease tetracycline absorption by chelation. Barbiturates, phenytoin, and carbamazapine Inhibit vitamin K producing intestinal flora Contraindications Renal impairment Hepatic insufficiency Pregnancy
- 13. Tigecycline It is a minocycline analogue It binds to 30s ribosomal subunits Spectrum –MRSA, VRE, MDR-strepto.pneummoniae Gram neg cocci-N.gonorrhoea Clostridium, bacteroides 100 mg loading dose, 50mg 12th hourly Eliminated through bile
- 14. From streptomyces venezuelae Antimicrobial spectrum- salmonella typhi Haemophilus influenzae,Nisseria meningitidis Streptococcus pneumoniae,Bacteroides fragilis
- 15. These antimicrobials bind to the 50S ribosome and inhibit peptidyl transferase activity. This inhibits bacterial protein synthesis by binding to 50s ribosome and hinder access to amino acyl t-rna site. prevents formation of peptide bond.
- 16. -Chloramphenicol palmitate used for oral suspension Orally/IV Glucuronide conjugation and excreated through urine T1/2 -3-5hrs It is well absorbed and widely distributed , including to the CNS. It is metabolized by glucoronidation in the liver. Although an effective broad-spectrum antibiotics, its uses are limited by its serious toxicity.
- 17. The major indication is to treat bacterial meningitis caused by Haemophilus influenzae, or to Neisseria menigitidis or if organism is unknown.It is also specially used for Rickettsia (typhus). It was used for typhoid fever Dose -50-75mg/kg/day Pelvic and brain abscess Conjunctivitis and external ear infections
- 18. Idiosyncratic apastic anaemia : A rare irreversible anemia, probably immunological in origin but often fatal, Reversible bone marrow depression caused by its effect on protein synthesis in humans Gray baby syndrome-abdominal distension, progressive cyanosis, hypothermia, vomiting Super infection
- 19. PCT- increases bioavailability Potent enzyme inhibitor- inhibits metabolism of morphine, clhorpropamide, warfarin THANK YOU