Dirithromycin

Pronunciation: die-RITH-row-MY-sin
Class: Macrolide

Trade Names:
Dynabac
- Tablets, enteric coated 250 mg

Pharmacology

Interferes with microbial protein synthesis.

Pharmacokinetics

Absorption

Rapidly absorbed and converted by nonenzymatic hydrolysis to erythromycylamine (active). For erythromycylamine, the C _max is approximately 0.3 to 0.4 mcg/mL. T _max approximately 3.9 to 4.1 h. AUC approximately 0.9 to 1.8 mcg•h/mL.

Distribution

For erythromycylamine, the protein binding is 15% to 30% and the Vd is 800 L.

Elimination

81% to 97% excreted in the feces and approximately 2% eliminated through the kidneys. For erythromycylamine, the plasma t _½ is approximately 8 h, the terminal t _½ is approximately 44 h, and the Cl is approximately 23 L/h.

Special Populations

C _max and AUC are increased. No dosage adjustment necessary.

In those with mild hepatic impairment, the C _max , AUC, and Vd are increased. No dosage adjustment necessary.

C _max and AUC increase with age. No dosage adjustment necessary.

Indications and Usage

Treatment of acute bacterial infection of chronic bronchitis, secondary bacterial infection of acute bronchitis, community-acquired pneumonia, pharyngitis/tonsillitis, and uncomplicated skin and skin structure infections caused by susceptible organisms.

Contraindications

Hypersensitivity to erythromycin or any macrolide antibiotic.

Dosage and Administration

PO 500 mg once daily for 7 to 14 days.

Storage/Stability

Store at room temperature.

Drug Interactions

Since cardiotoxicity and death have occurred with other macrolide antibiotics, monitor patient during concurrent use; however, available clinical data indicate that there is no interaction.

Slight decrease in theophylline serum concentrations may occur.

Laboratory Test Interactions

None well documented.

Adverse Reactions

CNS

Headache; dizziness; vertigo; insomnia.

Dermatologic

Rash; pruritus; urticaria.

GI

Abdominal pain; nausea; diarrhea; vomiting; dyspepsia; flatulence.

Hematologic

Increased platelet count; eosinophilia; increased segmented neutrophils.

Metabolic

Decreased bicarbonate.

Respiratory

Increased cough; shortness of breath.

Miscellaneous

Increased serum potassium; pain; weakness; increased CPK.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy in children younger than 12 yr of age not established.

Superinfection

Prolonged use of antibiotics may result in bacterial or fungal overgrowth of nonsusceptible microorganisms.

Pseudomembranous colitis

Consider possibility in patients who develop diarrhea.

Overdosage

Symptoms

Nausea, vomiting, epigastric distress, diarrhea.

Patient Information

• Instruct patient to take medication with food or within 1 h after meals.
• Instruct patient to notify healthcare provider if rash develops or difficulty breathing occurs.
• Stress to patient that entire course of therapy must be completed, and not to stop taking medication when feeling better.
• Warn patient that if infection does not seem to improve after 5 days, to notify healthcare provider.
• Instruct patient to drink 2 to 3 liters of fluid per day while taking oral antibiotics.

Copyright © 2009 Wolters Kluwer Health.