Products
Available dosage forms include tablets, powders and granules for the preparation of oral suspensions, injectables, and topical medications. Erythromycin was the first active ingredient from this group to be discovered in the 1950s.
Structure and properties
Erythromycin is a natural substance produced by the bacterium (formerly: ). Other agents such as clarithromycin are derived from it and have improved pharmacokinetic and pharmacodynamic properties. The name macrolides refers to the large central heterocyclic macrolactone ring with 14, 15, or 16 atoms. Cyclic esters are referred to as lactones. Aminosugars or other side chains are attached to this ring.
Effects
Macrolides (ATC J01FA) have bacteriostatic to bactericidal properties. The effects are based on inhibition of bacterial protein synthesis by binding to the 50S subunit of ribosomes. They prevent the newly formed polypeptide from exiting through a pathway called (NPET). Recent studies show that protein synthesis does not completely stop because not all proteins are affected (Vázquez-Laslop, Mankin, 2018).
Indications
For the treatment of bacterial infectious diseases with susceptible pathogens.
Dosage
According to the prescribing information. As with other antibiotics, attention must be paid to the time of administration. Some drugs must be administered fasting. A probiotic may be recommended for prevention and treatment of gastrointestinal disorders.
Active Ingredients
Macrolide antibiotics approved in many countries:
- Azithromycin (Zithromax, generics).
- Clarithromycin (Klacid, generic).
- Erythromycin (e.g., Erythrocin, Erythrocin ES)
No longer commercially available as a human drug in many countries:
- Roxithromycin (Rulid, out of commerce).
- Spiramycin (Rovamycine, out of commerce).
- There are other active ingredients that are not approved in many countries.
Veterinary drugs:
- Tylosin
Contraindications
Contraindications include (selection):
- Hypersensitivity
- Drugs that prolong the QT interval
- Combination with critical CYP450 substrates.
- Hypokalemia
For complete precautions, see the drug label.
Interactions
Macrolides usually have a high potential for drug-drug interactions because they inhibit CYP450 isozymes and P-glycoprotein. This is not true for azithromycin.
Adverse effects
The most common possible adverse effects include:
- Digestive symptoms such as changes in taste, loss of appetite, nausea, vomiting, diarrhea, abdominal pain, and constipation.
- Central disorders such as insomnia, headache and drowsiness.
- Skin rash, itching, hives.
Macrolides may prolong the QT interval and cause cardiac arrhythmias.
