Macrolide antibiotics include- Azithromycibn. clarithromycin, dirithromycin, erythromycin and troleandomycin

Interacting drugs- summary 

Dirithromycin +

  Antihistamines non sedating- Terfenadine                                                                                 an interaction does not appear to occur. Monitor levels during concurrent use

Theophylline -                                                                                                                  monitor theophylline plasma levels with dosage adjustments as appropiate, 

+ Dirithromycin-                                                                                                             Antacids-                                                                                                                         when given immediately, the absorption of dirithromycin is slightly enhanced

H2 antagonists-                                                                                                                when given immediately after H2 antagonists, dirithromycin absorption is slightly enhanced 

  Drug/food interaction- Dirithromycin should be administered with food or within an hour of having eaten

Susceptible infections

Macrolide antibiotics include- Azithromycibn. clarithromycin, dirithromycin, erythromycin and troleandomycin

Abdominal pain, headache, nausea, diarrhea, platelet count increased, vomiting, dyspepsia, potassium increased, Dizzines/vertigo, pain(non- specific) asthenia,

GI disorder, increased cough, flatulence, rash, bicarbonate decreased, CPK increased ,seg neutrophils increased, dyspnea, pruritus/urticaria, insomnia.

Other adverse reactions - Abnormal stools, allergic reaction (not further defined) amblyopia, anorexia, anxiety, constipation, dehydration, depression, dry mouth, dysmenorrhea, edema, epistaxis, eye disorder (not further defined)

Fever, flu syndrome, gastritis, gastroenteritis, hemoptysis, hyperventilation, malaise, mouth ulceration, myalgia, neck pain, nervouseness, palpitation, paresthesia, peripheral edema, somnolence, sweating, syncope, taste perversion, thirst, tinnitus, urinary frequency, vaginal moniliasis, vagintits, vasodilation

Other laboratory reactions- decreased- albumin, chloride, hemotocrit, hemoglobin, esg neutrophils, phosphorus, platelet count and total protein increased- alkaline phosphatase, ALT, AST, bands, basoiphils, total bilirubin, creatinine, GGT, leukocyte count, lymphocytes, monocytes, phosphorus and uric acid.

Hypersensitivity to dirithromycin, erythromycin or any other antibiotics

Special precautions-

Superinfection- Use of antibiotics(especially prolonged or repeated therapy) may result inbacterial or fungal overgrowth of nonsusceptible organisms. Such over growth may lead to a secondary infection.

Drug/Food interaction- Dirithromycin should be administerd with food or within an hour of having eaten Dietary fat had little or no effect on the bioavailability of dirithromycin.

Warnings-

Terfenadine drug sensitivity- serious cardiac dysrhythmias some resulting in death have occured in patients receiving terfenadine concomitantly with other macrolide antibiotics. In addition,most macrolides are contraindicated in patients receiving terfenedine therapy who have preexisting cardiac abnormalities (eg,. arrhythmias, bradycardia,

QT interval prolongation, ischemic heart disease, congestive heart failure) or electrolyte disturbances. It is prudent to monitor the terfenadine levels when dirithromycin and terfenadine are coadministered.

Bacteremias- dirithromycin should not be used in patients with known , suspected or potential bacteremias as serum levels are inadequate to provide antibacterialcoverage of the blood stream.

Respiratory infections- because of safety and efficacy of dirithromycin in the treatment of respiratory disease secondary to H influenzae have not been demonstrated ,dirithromycin is NOT indicated for the empiric treatment of acute bacteial exacerbations of chronic or secondary bacterial infections of acute bronchitis.

Skin/structure infections- because the safety and efficacy of dirithromycin in the treatment of uncomplicated skin and skin structure infections due to S pyogenes have not been demonstrated , dirithromycin is NOT indicated for the empiric treatment of uncomplicated skin and structure infections

 Pseudomembranous colitis- has been reported with nearly all bacterial agents including dirithromycin ,and may range in severity to mild life threatening. Therefore it is important to consider this diagnosis in patients who present with diarrhea and subseqent to the adminisatrationof antibacterial agents.

Renal function impairment- no dosage adjustment should be necessary in patients with impaired renal function, including dialysis patients.

Hepatic function impairment- no dosageadjusment should be necessary in patients with mildly impaired function.

Elderly- Based on results of studies available, no dosage adjustments shouldbe necesary in elderly patients.

Pregnancy- use during pregnancy, only if the potential benefit justifies the potential risk to fetus.

Lactation- use caution when administering to a nursing woman

Children- safety and efficacy in children< 12 years of age have not been established

Approved by FDA in June 1995

Indication-

Susceptible infections

Dosage:

Administer with food within 1 hour of having eaten. Do not cut, crush or chew the tablets Dosage- (> 12 years of age) 500mg once daily for 7 days

Missed dose-

1. If you miss a dose of this medicine, take it as soon as possible.

2. However, if it is almost time for next dose, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

1. Take dirithromycin with food or within an hour of having eaten.

2. Do not cut, chew or crush the tablets

3. Allergies- Tell your doctor if you have ever had any unusual or allergic reactions to dirithromycin or other related medicines. Also tell your doctor if youn are allergic to any other substances such as foods, preservatives or dyes.

4. Pregnancy- before taking this medicine make sure your doctor knows if you are pregnant or if you become pregnant

5. Breast feeding- mothers who are taking this medicine and who wish to breast feed should discuss this with their doctor.

6. Children- no specific information comparing use of dirithromycin in children with other age groups

7. Elderly- signs and symptoms of overdose may be especialy likely to occur in elderly patients

8. Other medicines- tell your doctor if you are taking any of the following- other non prescription or OTC medicines

9.Other medical problems- tell your doctor if you have any other medical problems- Liver disease - patients with moderate to severe disease may have an increased chance of side effects

10. Missed dose- If you miss a dose of this medicine take it as soon as possible. However if it is almost time for your next dose go back to your regular dosing schedule. Do not double doses.

Pharmacology

Dirithromycin, a semi-synthetic macrolide antibiotic is a pro-drug converted non-enzymatically during intestinal absorption into the microbiologically active moiety erythromycylamine, which exert its activity by binding 50S ribosomal subunits of susceptible microorganisms resulting in inhibition of protein synthesis it activity

Pharmacokinetics-

Dirithromycin is rapidly absorbed and conveted by nonenzymatic hydrolysis to the microbiologically active compound erythromycylamine. The absolute bioavailability of the oral formulation is app 10%. The mean plasma half-life of erythromycylamine was estimated to be about 8 hr, while mean urinary terminal elimination half-lfe isf about 44hr.

Dirithromycin should be administered with food or within an hour of having eaten

Pregnancy:

No adequate and well controlled studies in pregnant women. Use during pregnancy only if the potential benefits outweigh the potential risks to the fetus.

Lactation:

Use caution when administering to a nursing woman Children- Safety and efficacy in children < 12 years of age have not been established