Antibiotics Review _ __________________________________________________________________________
THE MACROLIDES
Agent
Adult Dosing Range
Pediatric Dosing Range
Route
Common Side Effects
Comments
Azithromycin
PO: 250–600 mg/ day, or 1–2 g/day IV: 250–500 mg/ day 250–500 mg every 12 hrs, or 1 g/day extended-release formulation for 7 to 14 days Base: 250–500 mg PO every 6 to 12 hrs Max: 4 g/day Ethylsuccinate: 400–800 mg PO every 6 to 12 hrs Max: 4 g/day Lactobionate: 15–20 mg/kg/day IV in 4 divided doses, or 0.5–1 g IV every 6 hrs, or continuous infusion over 24 hrs (Max: 4 g/day)
PO: 5–12 mg/kg/day Max: 500 mg/day Otitis media: 30 mg/ kg as single dose (not to exceed 1,500 mg) >6 mos of age: 7.5 mg/kg every 12 hrs
PO, IV, ophthal- mic drops
GI upset
One dose of 1 g given PO can be used for non- GC urethritis/cervicitis. Interaction with pimozide/ cyclosporine. Inhibits liver CYP 450 enzyme 3A4, resulting in multiple significant drug interactions. Special dosing combined with omeprazole and amoxicillin or lansoprazole and amoxicillin is one regimen used for H. pylori treatment. Inhibits liver CYP 450 enzymes 3A4 and 1A2, resulting in multiple significant drug interactions.
Clarithromycin
PO GI upset, metallic taste
Erythromycin
Base: 30–50 mg/ kg/day PO in 2 to 4 divided doses Max: 2 g/day
PO, IV, ophthal- mic solution, topical ointment, gel, or pad
GI intolerance (common), phlebitis at IV infusion site
Ethylsuccinate: 30–50 mg/kg/day PO in 2 to 4 divided doses Max: 4 g/day Stearate: 30–50 mg/ kg/day PO in 2 to 4
divided doses Max: 2 g/day
Lactobionate: 15–50 mg/kg/day IV in 4
divided doses Max: 4 g/day
Fidaxomicin
PO Nausea,
Used for treatment of diarrhea due to C. difficile
200 mg twice daily for 10 days
Not studied in pediatric patients
abdominal pain
Prescribing information is given for comparison purposes only. The higher dosage ranges reflect dosages for more severe infections. Please consult the manufacturer’s package insert for the antibiotic for complete prescribing information, maximum dosages, and indications. Non-GC = nongonococcal infection. Source: [6; 16] Table 5
DRUG INTERACTIONS Drug interactions are extensive. Erythromycin and clarithromy- cin are inhibitors and substrate for the 3A isoform subfamily of the cytochrome P450 enzyme system (CYP3A4). If they are given with a drug that is primarily metabolized by CYP3A, the drug serum levels may be increased and/or prolonged [6]. Erythromycin is contraindicated with concurrent use of cis- apride, pimozide, dihydroergotamine, ergotamine, lovastatin, simvastatin, astemizole, or terfenadine. Clarithromycin is contraindicated with concurrent use of cisapride, pimozide, ergot alkaloids (e.g., ergotamine), or lomitapide [6]. Serum lev- els of theophylline, cyclosporine, ergotamine, carbamazepine,
benzodiazepines, warfarin, amiodarone, and tacrolimus may also be affected by concurrent administration with erythromy- cin and clarithromycin. Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors levels may also be elevated, with increased risk for rhabdomyolysis [6; 106]. Azithromycin is not likely to interact with drugs metabolized by CYP3A4. However, azithromycin interacts with pimozide, potentially resulting in QT interval prolongation and arrhyth- mia [107]. Co-administration with pimozide is therefore contraindicated. Levels of cyclosporine could potentially be increased and therefore should be monitored closely [6; 108].
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