Drug Guide
Dirithromycin
Classification
Therapeutic: Antibiotic, Macrolide
Pharmacological: Macrolide antibiotic
FDA Approved Indications
- Respiratory tract infections caused by susceptible bacteria, including bronchitis, pharyngitis, tonsillitis, and sinusitis.
- Skin and skin structure infections.
Mechanism of Action
Dirithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, thereby preventing peptide bond formation and inhibiting bacterial growth.
Dosage and Administration
Adult: 500 mg orally once daily for 5 to 7 days.
Pediatric: Dosage based on weight and severity of infection; consult specific pediatric dosing guidelines.
Geriatric: Adjust dosage if renal or hepatic impairment is present; otherwise, no special modification.
Renal Impairment: Use with caution; adjust dose as needed.
Hepatic Impairment: Use with caution; hepatic function should be monitored.
Pharmacokinetics
Absorption: Well absorbed orally, with peak plasma concentrations occurring approximately 2-4 hours post-dose.
Distribution: Extensive distribution into tissues and body fluids.
Metabolism: Metabolized hepatically; primarily via demethylation.
Excretion: Excreted mainly in bile and feces; minor renal excretion.
Half Life: Approximately 2-3 days, allowing once-daily dosing.
Contraindications
- Known hypersensitivity to dirithromycin or other macrolides.
- Concurrent use with lovastatin or simvastatin due to risk of severe adverse reactions.
Precautions
- Use with caution in patients with hepatic impairment, proarrhythmic conditions, or cardiac conduction abnormalities.
- Monitor QT interval in susceptible patients.
Adverse Reactions - Common
- Nausea (Common)
- Diarrhea (Common)
- Abdominal pain (Uncommon)
Adverse Reactions - Serious
- QT prolongation and arrhythmias such as torsades de pointes (Rare)
- Hepatotoxicity (Rare)
- Clostridioides difficile-associated diarrhea (Rare)
Drug-Drug Interactions
- Cisapride, pimozide, quinidine, and other drugs known to prolong QT interval.
- Hepatotoxic drugs.
- Warfarin and other anticoagulants.
Drug-Food Interactions
- None significant
Drug-Herb Interactions
- None well-documented
Nursing Implications
Assessment: Monitor for signs of hypersensitivity, gastrointestinal disturbances, and cardiac arrhythmias.
Diagnoses:
- Risk for electrolyte imbalance related to diarrhea.
- Risk for cardiac arrhythmias related to QT prolongation.
Implementation: Administer orally with or without food. Monitor ECG in at-risk patients. Educate patient about potential side effects.
Evaluation: Assess for resolution of infection, monitor for adverse effects, and evaluate QT interval if indicated.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report any abnormal heart rhythms, severe diarrhea, or allergic reactions.
- Avoid concurrent use of drugs that prolong QT interval.
Special Considerations
Black Box Warnings:
- Potential for QT prolongation and arrhythmias.
Genetic Factors: QT prolongation risk may be increased in certain genetic predispositions.
Lab Test Interference: None significant.
Overdose Management
Signs/Symptoms: Nausea, vomiting, diarrhea, reversible hearing loss, and cardiac arrhythmias.
Treatment: Supportive care; activated charcoal may be used if ingestion is recent. Cardiac monitoring and management of arrhythmias as needed.
Storage and Handling
Storage: Store at room temperature, 20-25°C (68-77°F). Keep container tightly closed.
Stability: Stable under recommended storage conditions for the duration of the shelf life.