Clarithromycin

Indications

Clarithromycin is used for: Respiratory tract infections, Skin and soft tissue infections, Leprosy, peptic ulcer disease, pharyngitis, tonsillitis, acute maxillary sinusitis, acute bacterial exacerbation of chronic bronchitis, pneumonia, legionellosis, Helicobacter pylori, lyme disease, Community-Acquired Pneumonia, Acne.

Adult Dose

Oral Acute Exacerbation of Chronic Bronchitis 250-500 mg PO q12hr for 7-14 days Extended release: 1000 mg PO once daily for 7 days Mycobacterial Infection Prophylaxis and treatment 500 mg PO q12hr for 7-14 days Use with antimycobacterial drugs such as rifampin and ethambutol Peptic Ulcer Disease 500 mg PO q8-12hr for 10-14 days Administer as part of 2- or 3-drug combination regimen with bismuth subsalicylate, amoxicillin, H2 receptor antagonist, or proton pump inhibitor Pharyngitis, Tonsillitis 250 mg PO q12hr for 10 days Community-Acquired Pneumonia, Skin/Skin Structure Infection 250 mg PO q12hr for 7-14 days Extended release: 1000 mg PO once daily for 7 days Endocarditis Prophylaxis 500 mg PO 30-60 minutes before surgical procedure Intravenous Respiratory tract infections; Skin and soft tissue infections ; Susceptible infections Adult: 500 mg bid for 2-5 days. Infuse over 60 min using a 0.2% soln. Revert to oral therapy whenever possible. Topical Apply a thin layer to the affected area once daily.

Child Dose

Child: PO 15 mg/kg/day, max 1 g/day q12h

Renal Dose

Renal impairment: CrCl (ml/min) <30 Half the dosage or double dosing interval.

Administration

Standard release tab & oral susp: May be taken with or without food. XL & MR tab: Should be taken with food. Swallow whole, do not chew/crush.

Contra Indications

Hypersensitivity. Patients receiving terfenadine, astemizole, pimozide, cisapride and ergot derivatives. Pregnancy; history of acute porphyria.

Precautions

Renal and hepatic impairment; macrolide cross-resistance; lactation, children. Lactation: Drug is excreted in breast milk; use with caution

Pregnancy-Lactation

Interactions

Reduced efficacy w/ CYP3A inducers (e.g. phenytoin, carbamazepine). Strong inducers of CYP450 system (e.g. efavirenz, rifampicin) may accelerate metabolism, thus lower plasma levels of clarithromycin. Inhibition of metabolism w/ ritonavir. Torsades de pointes may result from concomitant quinidine or disopyramide. Increased phosphodiesterase inhibitor exposure w/ sildenafil, tadalafil or vardenafil. Increased risk of digoxin toxicity. Decreased concentration of zidovudine. Concomitant use w/ atazanavir, itraconazole or saquinavir may result to bi-directional drug interactions. Hypotension, bradyarrhythmias, and lactic acidosis may result when taken w/ verapamil. Increased risk of myopathy, including rhabdomyolysis w/ HMG-CoA reductase inhibitors. Increased risk of hypoglycaemia w/ oral hypoglycaemic drugs (e.g. pioglitazone) and insulin. Risk of serious haemorrhage and elevation of INR and prothrombin time w/ oral anticoagulants. Increased ototoxicity w/ aminoglycosides. Increased and prolonged sedation w/ triabenzodiazepines (e.g. midazolam). Potentially Fatal: Concurrent use w/ ergot alkaloids (e.g. ergotamine or dihydroergotamine) is associated w/ acute ergot toxicity characterised by vasospasm and ischaemia of the extremities. Concomitant use w/ astemizole, cisapride, pimozide and terfenadine may result in QT prolongation or ventricular cardiac arrhythmia.

Adverse Effects

Side effects of Clarithromycin : >10% Gastrointestinal (GI) effects, general (13%) 1-10% Abnormal taste (adults, 3-7%),Diarrhea (3-6%),Nausea (adults, 3-6%),Vomiting (adults, 1%; children, 6%),Elevated blood urea nitrogen (BUN; 4%),Abdominal pain (adults, 2%; children, 3%),Rash (children, 3%),Dyspepsia (2%),Heartburn (adults, 2%),Headache (2%),Elevated prothrombin time (PT; 1%) <1% Anaphylaxis,Anorexia,Anxiety,Clostridium difficile colitis,Dizziness,Dyspnea,Elevated liver function tests,Glossitis,Hallucinations,Hepatic dysfunction,Hepatitis,Hypoglycemia,Increased alkaline phosphatase,Increased aspartate aminotransferase,Increased bilirubin,Increased serum creatinine,Jaundice,Leukopenia,Manic behavior,Neuromuscular blockade,Neutropenia,Pancreatitis,Psychosis,QT prolongation,Seizures,Stevens-Johnson syndrome,Thrombocytopenia Topical: Dryness, irritation, itching, peeling, redness, swelling of the skin. Potentially Fatal: Pseudomembranous colitis, anaphylaxis, Stevens-Johnson syndrome.

Mechanism of Action

Clarithromycin inhibits protein synthesis by binding to 50s ribosomal subunits of susceptible organisms. It has activity against susceptible streptococci and staphylococci as well as other species including B. catarrhalis, L. spp, C. trachomatis and U. urealyticum.