Rx Update: September 2004
Joan Murhammer, R.Ph., Mary Ross, R.Ph., M.B.A., Kevin Bebout,
R.Ph.
Peer Review Status: Internally Reviewed
Telithromycin
Telithromycin (Ketek®) is in a new class of antibiotics (ketolides) which are structurally similar to macrolide antibiotics (e.g., erythromycin, clarithromycin, azithromycin) with activity against gram-positive, gram-negative, and atypical organisms. It is indicated for the treatment of mild to moderate severity community-acquired pneumonia, acute bacterial sinusitis, and acute exacerbation of chronic bronchitis.
Telithromycin should not be used in patients who have had a hypersensitivity reaction to telithromycin or macrolide antibiotics. Due to the potential for prolongation of the QTc interval with telithromycin therapy, it should not be used in patients with proarrhythmic conditions, significant bradycardia, congenital prolongation of the QTc interval, and those who are receiving Class IA (e.g., procainamide, quinidine) or Class III (e.g., dofetilide) antiarrhythmic agents. Exacerbations of myasthenia gravis have been reported in patients using telithromycin and it should be avoided in these patients.
Telithromycin is a strong inhibitor of the cytochrome P450 3A4 system and displays drug interactions similar to macrolide antibiotics. Co-administration of telithromycin and drugs metabolized by the cytochrome P450 3A4 enzyme system (e.g., cisapride, pimozide, simvastatin, lovastatin, atorvastatin, midazolam, or triazolam) may result in elevation of serum levels of these drugs. As a result, increases or prolongation of the therapeutic and/or adverse effects of the concomitant drug may be observed. Acute ergot toxicity (e.g., severe peripheral vasospasm and dysesthesia) has been reported when macrolide antibiotics were co-administered with ergot alkaloid derivatives (e.g., ergotamine or dihydroergotamine); therefore, the co-administration of telithromycin and these drugs is not recommended. Moderate increases in digoxin and theophylline concentrations have been reported with concomitant telithromycin therapy. Administration of theophylline should be separated by at least one hour from telithromycin to minimize gastrointestinal effects. Concomitant administration of CYP 3A4 inducers (e.g., rifampin, phenytoin, carbamazepine, or phenobarbital) with telithromycin is likely to result in subtherapeutic levels of telithromycin and loss of effect.
The most common adverse events with telithromycin therapy are diarrhea (10.8%), nausea (7.9%), headache, dizziness, and vomiting. Visual disturbances (such as blurred vision, diplopia, and difficulty focusing) have been documented and usually occur with the first few doses. Most events were mild to moderate; however, severe cases have been reported. Patients should be cautioned about the potential effects of these visual disturbances on driving a vehicle, operating machinery, or engaging in other potentially hazardous activities.
The recommended dose of telithromycin is 800 mg orally once daily for 5 days for acute sinusitis and acute exacerbation of chronic bronchitis. The dose for community-acquired pneumonia is 800 mg orally once daily for 7 to 10 days. Telithromycin can be taken regardless of meals. Dosage adjustments are not required in patients with hepatic impairment, but may be required in patients with severe renal impairment (creatinine clearance < 30 mL/min). Telithromycin is available in 400 mg tablets.
Emergency Medication Kits
Medications are readily available at UIHC for use in emergency situations. Nursing units that would like to assemble a kit of medications to have available for potential emergency situations (for which an Emergency Drug Tray does not meet the need) should contact a representative from the Department of Pharmaceutical Care for assistance. The list of medications should be standardized and approved by an appropriate physician associated with the patient care area. Pharmacy staff will assemble the kits and secure them with a numbered, breakaway lock. The kits must be stored in a secure location, and area personnel must check the integrity of the kits daily and record the lock number on a log. If a kit is opened or expired, area personnel should immediately return it to Pharmacy for exchange for an unopened kit. If the kit contains non-medication supplies, area personnel should restock the kit before returning it to Pharmacy.