Classifications: macrolide antibiotic;
Therapeutic: antibiotic

Prototype: Erythromycin
Pregnancy Category: C


250 mg enteric tablets


Dirithromycin is an analog of erythromycin. It binds reversibly to the 50-S ribosomal subunit of the bacteria, thus inhibiting RNA-dependent protein synthesis in bacterial cells. It has no apparent effect on the cytochrome P-450 hepatic enzyme system as erythromycin does.

Therapeutic Effect

It is more active against gram-positive organisms than gram-negative organisms.


Acute bacterial exacerbations of chronic bronchitis, community-acquired pneumonia, pharyngitis/tonsillitis, uncomplicated skin/skin structure infections due to susceptible bacteria.


Known hypersensitivity to dirithromycin, erythromycin, or any other macrolide antibiotic; known or suspected bacteremias; viral infections; pregnancy (category C).

Cautious Use

Severe hepatic impairment, GI disease; lactation. Safety and effectiveness in children <12 y are not established.

Route & Dosage

Bacterial Infections
Adult/Child: PO 500 mg once/d


  • Give with food or within 1 h of eating.
  • Do not cut, crush, or chew tablets.
  • Store at 15°–30° C (59°–86° F).

Adverse Effects (≥1%)

CNS: Headache, dizziness, asthenia. CV: Chest pain. GI: Abdominal pain, nausea, diarrhea, vomiting, dyspepsia, flatulence; elevated liver function tests (ALT, AST, GGT). Skin: Rash, urticaria. Respiratory: Dyspnea, asthma-like symptoms, rhinitis, pharyngitis, increased coughing.


Drug: May increase theophylline levels.


Absorption: Readily absorbed from GI tract; 60–90% hydrolyzed to active metabolite, erythromycylamine, within 35 min. Peak: 1.5 h. Distribution: High tissue concentrations of active metabolite; slowly released back into the circulation. Metabolism: Rapidly converted to active metabolite, erythromycylamine, in absorption and distribution phases. Elimination: 81–97% in bile and feces. Half-Life: 20–50 h.

Nursing Implications

Assessment & Drug Effects

  • Take history of previous hypersensitivity to other macrolides (e.g., erythromycin) prior to initiation of therapy.
  • Withhold drug and notify physician if signs and symptoms of hypersensitivity occur (see Appendix F).
  • Monitor liver and renal function in patients with mild liver or renal impairment.
  • Monitor for S&S of superinfection (see Appendix F).
  • Monitor theophylline levels if given concurrently with dirithromycin.
  • Note: Dirithromycin may increase the blood level of theophylline, necessitating theophylline dosage adjustment.

Patient & Family Education

  • Take tablets whole and within 1 h of meals.
  • Monitor for and report S&S of superinfection or pseudomembranous enterocolitis (see Appendix F).
  • Report any worsening of signs and symptoms of infection.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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