Friday, September 22, 2023

Macrolides : Introduction, Side-effects, Dosage and More

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Quick Information

  1. Introduction
  2. Uses
  3. Mechanism of action
  4. Side effects
  5. Dosage
  6. Using During Breastfeeding and Pregnancy
  7. Contraindications to Macrolides


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Macrolides belong to a group of natural products, which consists of a large macrocyclic lactone ring to which one or more deoxy sugars, normally desosamine and cladinose are attached.  It also belongs to the polyketide that is a group of natural products. Some macrolides have an antifungal and antibiotic activity that are used as pharmaceutical drugs.

Macrolides are bacteriostatic and they suppress or block inhibit bacterial growth rather than killing bacteria completely. These medicines are relatively poorly absorbed orally, and Fidaxomicin is minimally absorbed.


Macrolides are a group of antibiotics, which includes roxithromycin, clarithromycin, erythromycin, and azithromycin. These medicines are useful to treat skin, sexually transmitted, respiratory, tissue, and atypical mycobacterial infections. They share a similar spectrum of antimicrobial activity with benzylpenicillin that makes them beneficial options for people with a history of penicillin allergy. It interferes with a bacterial protein that depends on concentration and bacterial species are either bacteriostatic (prevent the growth of bacteria), or bactericidal (kill bacteria).

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This group of antibiotics have immunomodulatory and anti-inflammatory effects that may be helpful in some situations. They are also effective against gram-positive and gram-negative bacteria. Macrolides are also active against Chlamydia trachomatis, Treponema pallidum, Mycoplasma, and many more. There are several infections in which macrolides would be considered for second-line treatment. Macrolides quickly produce a reaction that causes fatal digestive disturbance and can be used in horses less than one-year-old. But it should care for your horses that do not come into contact with the macrolide treatment.

Mechanism of action

The mechanism of action of macrolides prevents the growth of bacterial protein biosynthesis. It also prevents peptidyltransferase and bacterial ribosomal translation. There is another potential mechanism is premature dissociation of the peptidyl-tRNA from the ribosome. Macrolides are focused within leukocytes and transported into the site of infection.

Side effects

There are some of the side-effects of macrolides are given below –

  • QT-interval prolongation by erythromycin
  • Gastrointestinal (GI) disturbances
  • Inhibition to lead several drug interactions
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Generally, Erythromycin causes dose-related disturbances such as abdominal cramps, nausea, vomiting, and diarrhea. To lower the effect of side effects, you should take this medicine with food. Erythromycin can also cause dose-related tinnitus such as reversible hearing loss and dizziness. Cholestatic jaundice also occurs most commonly due to erythromycin. After 10 days of use of this medicine, it may cause jaundice mainly in adults.

Erythromycin causes QT-interval predisposes and prolongation to ventricular tachyarrhythmia especially in women who are suffering from QT electrolyte abnormalities.


There is no dosage adjustment is need for renal insufficiency with azithromycin. Erythromycin interacts with several medicines as they inhibit hepatic metabolism through the cytochrome system. Azithromycin is the minimum possible to interact with other medicines. Interaction with other medicines may occur when clarithromycin or erythromycin is taken are given below –

  • Simvastatin and lovastatin: Rhabdomyolysis
  • Theophylline: vomiting, seizures, and nausea
  • Triazolam and Midazolam: Somnolence

Using During Breastfeeding and Pregnancy

As per animal reproduction studies with azithromycin or erythromycin, these medicines have not shown any risk to the fetus during pregnancy. According to other studies, the risk was not observed in pregnant ladies after using this drug. It is important to note that erythromycin is safer than azithromycin due to clinical use has been much more extensive. According to animal reproduction studies with clarithromycin, this medicine is not used in those women who are pregnant except if there is no alternative therapy.

As per studies, Erythromycin is compatible with those women who breastfeed their babies. But there is no information on harmful in other medicines for breastfeeding women.

Contraindications to Macrolides

Macrolides are contraindicated in those people who are suffering from any allergic problems. Macrolides are associated with cisapride, pimozide, and astemizole is contraindicated because if erythromycin or clarithromycin is taken with these medicines then it may cause fatal cardiac arrhythmias. The effects of these medicines are most probably because inhibition of metabolism of these medicines by using clarithromycin or erythromycin.


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