Tetracyclines and Chloramphenicol

Generic Name: Tetracycline

Brand Name

Oxytetracycline: Terramycin 250, 500 mg cap, 50 mg/ml in 10 vials inj; 3% skin ointment.

Tetracycline: Achromycin, Hostacycline, Restsclin 250, 500 mg cap; 3% skin ointment.

Doxycycline: Tetradox, Biodoxi, Doxt, Novadox 100 mg cap.

Mechanism of action

They inhibit protein synthesis by binding to 30S ribosome by interfering with attachment of aminoacyl-t-RNA to mRNA- ribosome complex.Thus preventing peptide bond formation.

Indication

• In the initial treatment of mixed infections.
• First choice of drugs in treatment of
  • Veneral diseases.
  • Atypical pneumonia.
  • Cholera.
  • Brucellosis.
  • Plague.
  • Borrelia recurrentis.
  • Rickettsial infections.
• Second choice of drugs in the treatment of:
  • Penicillin for tetanus, anthrax and listeria infections.
  • Ciprofloxacin for gonorrhoea.
  • Ceftriaxone for syphilis.
  • Azithromycin for chlamydial infections.
• It can also be used in
  • Urinary tract infection.
  • Community acquired pneumonia.
  • Prophylactic use in chronic lung disease.

Contraindication

• Tetracycline should not be used in pregnancy.
• Avoid in patients in diuretics.
• Cautiously used in renal and hepatic insufficiency.

Adverse effects

• Teeth and bones
  • Tetracycline has chelating property. They bind to calcium and get deposited in developing teeth and bone.
  • Given from mid-pregnancy to 5 months of intrauterine life the deciduous teeth are affected i.e. brown discolouration and ill formed teeth, more susceptible to caries.
  • Given from 3 months to 6 years it can affect the permanent teeth.
  • Tetracyline can cause temporary depression of the bone marrow.
• Phototoxicity
  A sun burn like or other severe skin reaction on exposed parts may be seen in few cases
• Liver damage
  Fatty infiltration of liver and jaundice can be seen occasionally.
• Kidney damage
  It is prominent in pre-existing kidney disease.
• Anti anabolic effect
  Tetracycline reduce protein synthesis and has an overall catabolic effect.

Generic name: Chloramphenicol

Mechanism of Action

They inhibit protein synthesis by binding to 30S ribosome by interfering with attachment of aminoacyl-t-RNA to mRNA- ribosome complex. Thus preventing peptide bond formation.

Indications

• Enteric fever.
• H.Influenza meningitis, Anaerobic infections.

Adverse Effects

• Bone Marrow Depression: This drug is the most common cause of aplastic anaemia, agranulocytosis, thrombocytopenia, pancytopenia.

Two forms of reaction are

Non-dose related Idiosyncratic type: It is a serious type of reaction seen rarely but is fatal. Aplastic anaemia is the common manifestation.

Dose and duration of therapy related Myelosupression: It is a direct toxic effect. This is often reversible with out long term effects.

• Hypersensitivity reaction: Rashes, fever, atrophic glossitis, angioedema are infrequent.
• Irritative effects: Nausea, vomiting, diarrhoea.
• Superinfections.
• Gray-Baby syndrome: It occurred when high doses (100mg/kg) were given prophylactically to neonates. The baby stopped feeding, vomited, became hypotonic and hypothermic, respiration became irregular; an ashen gray cyanosis developed.