Macrolide antibiotics are antibiotics that are bacteriostatic and have a macrolide. They inhibit the protein biosynthesis of bacteria. The first and best known macrolide antibiotic is erythromycin. Macrolide antibiotics are often used in children.
What are macrolide antibiotics?
Macrolide antibiotics (abbreviated as macrolides) are antibiotics with bacteriostatic activity. They represent a separate “classification” within the various antibiotics. The common abbreviation macrolides is, in a narrow sense, the name for a ring-shaped molecule found in all macrolide antibiotics, the macrolide. Macrolide antibiotics have a favorable spectrum of action with few side effects and are therefore also well suited for use in children. However, resistance to macrolide antibiotics is increasing. Many bacteria are already resistant to macrolide antibiotics, which is due to the fact that modification of ribosomal enzymes is sufficient for the acquisition of resistance. The acquisition of resistance is therefore relatively simple. Furthermore, there is a so-called cross-resistance between the different macrolide antibiotics. This means that once a bacterium is resistant to one macrolide antibiotic, it is resistant to all macrolide antibiotics. The “prototype” macrolide antibiotic is erythromycin, which is derived from a type of fungus. In addition, the antibiotics josamycin and spiramycin, which are also derived from fungal species, exist. In an effort to improve the spectrum of activity and pharmacokinetic properties, the semisynthetic derivatives roxithromycin, azithromycin, and clarithromycin have been developed.
Pharmacologic Action
Macrolide antibiotics have bacteriostatic activity. They inhibit the protein biosynthesis of bacteria. They do this by attaching to the 50S subunit of ribosomes. In doing so, they block the enzyme translocase, which leads to the prevention of further migration and growth of the polypeptide chain. This results in the bacteriostatic effect of the macrolide antibiotics. They are thus effective primarily against metabolically active bacteria. The macrolide antibiotics are generally lipophilic and therefore distribute well in the tissue after absorption in the gastrointestinal tract. Excretion is predominantly billiary (via bile). Macrolides are broken down in the liver. They are metabolized by the CYP3A4 enzyme system during biotransformation. Interference may therefore occur in the degradation of drugs taken or applied at the same time. The degradation of one of the drugs is thereby delayed.
Medical application and use
Macrolide antibiotics are effective against Gram-positive cocci and rods and against Gram-negative cocci. Furthermore, they are effective against Legionella pneumophila, Bordetella pertussis, mycoplasma, spirochetes, chlamydia, and Haemophilus influenzae. The indications can be derived from the spectrum of activity of the macrolide antibiotics. However, it should be noted that the semisynthetic macrolide antibiotics roxithromycin, clarithromycin, and azithromycin have a broader spectrum of activity against Gram-negative bacteria than erythromycin, josamycin, and spiramycin. Systemically, erythromycin is indicated for bronchitis, pneumonia, pertussis (whooping cough), otitis media (middle ear infection), sinusitis (sinusitis), acne vulgaris, conjunctivitis (conjunctivitis) due to chlamydia, diphtheria, and urethritis due to Chlamydia trachomatis or Ureaplasma urealyticum. As an alternative to penicillins, e.g., in cases of penicillin allergy, erythromycin is also used in the treatment of pharyngitis (pharyngitis), tonsillitis (tonsillitis), scarlet fever, erysipelas (erysipelas), and syphilis. Azithromycin, a semisynthetic derivative of the macrolide antibiotic group, can be used for upper respiratory tract infections, including sinusitis, pharyngitis, and tonsillitis. Lower respiratory tract infections, including bronchitis and pneumonia, acute otitis media, skin and soft tissue infections, and uncomplicated genital infections caused by Chlamydia trachomatis or Neisseria gonorrhoeae (non-multidrug-resistant strains) can also be treated with azithromycin. Thus, a slightly expanded spectrum of activity of azithromycin compared with erythromycin can be seen. Furthermore, azithromycin has a significantly longer half-life.For this reason, it can be used as a “three-day antibiotic”: Only three tablets are administered, each 24 hours apart, but the effect lasts 10 days due to the long half-life.
Risks and side effects
The potential side effects of macrolide antibiotics are harmless. For this reason and because of their broad spectrum of activity, macrolide antibiotics are often used in children. The most common side effects include gastrointestinal tract discomfort, e.g., diarrhea, nausea, and vomiting. Furthermore, hypersensitivity reactions are possible in cases of existing hypersensitivity (allergy) to macrolide antibiotics. Rare side effects also include liver damage. However, it should be noted that the individual antibiotics from the group of macrolides can also have side effects that go beyond this. These can be found in the package insert and are available from doctors and pharmacists. Furthermore, interactions (interactions) with other drugs are possible. There are also contraindications. However, these cannot be listed generally for the group of macrolide antibiotics, as they are different for each antibiotic of the macrolide antibiotics. All of these antibiotics have in common that they must not be used in case of hypersensitivity to a macrolide antibiotic.
