Telithromycin is a ketolide, a novel form of macrolide antibiotic that is recommended for treatment of community-acquired pneumonia. Telithromycin was approved for use in the United States in 2004 and subsequently linked to several cases of severe drug-induced liver injury.

Telithromycin, a semi-synthetic erythromycin derivative, belongs to a new chemical class of antibiotics called ketolides. It is used to treat community-acquired pneumonia of mild to moderate severity. Ketolides have been recently added to the macrolide-lincosamide-streptogramin class of antibiotics. Similar to the macrolide antibiotics, telithromycin prevents bacterial growth by interfering with bacterial protein synthesis. Telithromycin binds to the 50S subunit of the 70S bacterial ribosome and blocks further peptide elongation. Binding occurs simultaneously at to two domains of 23S RNA of the 50S ribosomal subunit, domain II and V, where older macrolides bind only to one.

Mechanism of Action of Telithromycin

Telithromycin acts by binding to domains II and V of 23S rRNA of the 50S ribosomal subunit. By binding at domain II, telithromycin retains activity against gram-positive cocci (e.g. Streptococcus pneumoniae) in the presence of resistance mediated by methylases (erm genes) that alter the binding site at domain V. Telithromycin may also inhibit the assembly of nascent ribosomal units. Compared to erythromycin A, telithromycin binds to the 23S rRNA with 10 times greater affinity in erythromycin-susceptible organisms and 25 times greater affinity in macrolide-resistant strains. This increased binding affinity may be conferred by the C11-12 carbamate side chain of telithromycin. The side chain appears to maintain binding at domain II in the presence of resistance mediated by alterations in domain V.

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Or

Telithromycin may be bacteriostatic or bactericidal in action. Like conventional macrolides, telithromycin inhibits protein synthesis in susceptible organisms by binding to the 50S ribosomal subunit. Telithromycin binds to domains II and V of the 23S rRNA of the 50S subunit and has a higher affinity for these ribosomal targets than conventional macrolides, apparently because of additional interactions and increased binding at domain II. This allows telithromycin to retain activity against some gram-positive cocci (e.g., some strains of S. pneumoniae) that have methylase-mediated resistance (erm genes) that alter the domain V binding site. In addition to inhibiting protein synthesis, telithromycin may inhibit assembly of nascent ribosomal units.

Indications of Telithromycin

Therapeutic Indications

  • When prescribing, consideration should be given to official guidance on the appropriate use of antibacterial agents and the local prevalence of resistance. It is indicated for the treatment of the following infections
  • Community-acquired pneumonia, mild or moderate.
  • When treating infections caused by known or suspected beta-lactam and/or macrolide-resistant strains (according to the history of patients or national and/or regional resistance data) covered by the antibacterial spectrum of telithromycin
  • Acute exacerbation of chronic bronchitis,
  • Acute sinusitis
  • Tonsillitis/pharyngitis caused by Streptococcus pyogenes, as an alternative when beta-lactam antibiotics are not appropriate in countries/regions with a significant prevalence of macrolide-resistant.
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Contra-Indications of Telithromycin

  • Clostridium difficile infection
  • low amount of magnesium in the blood
  • low amount of potassium in the blood
  • Myasthenia Gravis
  • Very Rapid Heartbeat – Torsades de Pointes
  • prolonged QT interval on EKG
  • Abnormal EKG with QT changes from Birth
  • Hepatitis caused by Drugs
  • Liver Problems
  • Diarrhea

Dosages of Telithromycin

Strengths: 300 mg; 400 mg

Pneumonia

  • 800 mg orally once a day for 7 to 10 days

Side Effects of Telithromycin

The most common

 Common

Rare

Drug Interactions of Telithromycin

Telithromycin may interact with the following drugs, supplements & may change the efficacy of drugs

Pregnancy & Lactation of telithromycin

Pregnancy Category C

Pregnancy

There are no adequate and well-controlled studies in pregnant women. Telithromycin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

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Telithromycin was not teratogenic in the rat or rabbit. Reproduction studies have been performed in rats and rabbits, with effect on pre-post natal development studied in the rat. At doses of 150 and 20 mg/kg/day in rats and rabbits respectively (approximately 2 and 0.5 times the recommended clinical dose), no evidence of fetal terata was found.

Lactation

Tell your doctor if you are breast feeding or plan to breastfeed. It is not known if telithromycin passes into your breast milk. Talk to your doctor about the best way to feed your baby if you take telithromycin.

References

 

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