Antibiotics - Macrolides: Nursing pharmacology

Macrolides are a class of antibiotics used to treat a wide range of infections caused by gram-positive and gram-negative bacteria. These medications include erythromycin, azithromycin, and clarithromycin.

All can be administered orally to treat mild to moderate bacterial infections of the respiratory, gastrointestinal, and genitourinary tracts; erythromycin can also be given intravenously, and azithromycin has an ophthalmic formulation to treat bacterial conjunctivitis.

Now, once administered, macrolides target the bacterial 50S ribosomal subunit in order to inhibit protein synthesis. As a result, these medications have a bacteriostatic effect, meaning they stop bacterial growth.

They’re also considered broad spectrum antibiotics, as they’re active against most gram-positive bacteria and moderately active against some gram-negative bacteria.

Typically, macrolides are well tolerated, and rarely cause side effects. The most common ones can include headaches, a skin rash, and gastrointestinal disturbances like diarrhea, abdominal pain, nausea, and vomiting.

In addition, macrolides may disrupt the normal intestinal flora, which can allow certain bacteria like Clostridioides difficile to survive and overgrow within the gastrointestinal tract, rarely but potentially leading to Clostridioides difficile infection or CDI for short.

Some clients on macrolides may also develop vaginitis and candidiasis, and if they’re used for a prolonged time, they can also lead to ototoxicity and hearing loss.

Now, more serious side effects include a prolonged QT interval, ventricular arrhythmias like torsade de pointes, and hepatotoxicity, potentially leading to hepatitis.

They can also cause seizures, and rare but serious hypersensitivity reactions like angioedema, Stevens-Johnson syndrome, and toxic epidermal necrolysis.

Finally, regarding specific side effects, erythromycin can cause esophagitis, while azithromycin can rarely cause thrombocytopenia; while clarithromycin can cause abnormal taste and pancreatitis.

Now, macrolides are contraindicated in people with hepatic disease, and should be used with caution during pregnancy and breastfeeding, as well as in elderly clients, and in those with cardiovascular disease.

Regarding interactions, they shouldn’t be combined with medications that can prolong the QT interval, like quinidines or amiodarone; as well as with medications that inhibit CYP34A, as this can result in sudden cardiac death.

Finally, macrolides shouldn’t be used with ergot derivatives or statins, since it can affect their metabolism and increase their toxicity.

Okay, when caring for a client with nongonococcal urethritis who's been prescribed an oral macrolide like azithromycin, first perform a focused assessment, including vital signs, and noting symptoms of infection, such as dysuria, burning sensation, and type of urethral discharge.