Telithromycin (Ketek) is an oral erythromycin derivative FDA-approved for treatment of mild to moderate community-acquired pneumonia, exacerbations of chronic bronchitis and acute bacterial sinusitis (Med Lett Drugs Ther 2004; 46:66). It is generally considered an alternative antibiotic because of its cost, potential for adverse effects including visual disturbances, exacerbation of myasthenia gravis, hepatotoxicity and drug interactions. A recent report (Ann Intern Med 2006; 144:415) described serious hepatotoxicity probably related to telithromycin in three patients, including one who died...

Telithromycin (Ketek - Aventis) has been approved by the FDA for oral treatment of mild to moderate community-acquired pneumonia, acute exacerbations of chronic bronchitis and acute bacterial sinusitis in patients age 18 and older. The drug is the first in a new class of antibiotics, the ketolides, derived from the macrolide erythromycin. Telithromycin has been marketed in Europe since 2001.

Correction: In the table on page 66, the daily dosage of erythromycin should be 250-500 mg qid (not bid). Also, in the Canadian edition, the cost of telithromycin (Ketek) should be $65.52 (not $32.76).

View the Inhibitors and Inducers of CYP Enzymes, P-Glycoprotein, and Other Transporters tables

Serious adverse interactions between drugs continue to be reported. Many of these are due to inhibition or induction of cytochrome P450 (CYP) enzymes, particularly CYP3A4. CYP3A is thought to be involved in the metabolism of more than 50 percent of currently prescribed drugs.2 CYP3A4, which is more abundantly expressed than CYP3A5, accounts for most CYP3A activity in vivo.

The FDA has announced changes in the labeling of simvastatin to reduce the risk of myopathy. These changes include limiting the use of the 80-mg maximum dose to patients who have been taking it for 12 months or more without evidence of myopathy and new recommendations for use of simvastatin with other drugs. Simvastatin is available alone (Zocor, and others) and in combination with ezetimibe (Vytorin) and with niacin (Simcor).

A recent letter to the editor of the Annals of Internal Medicine documented a single case of myopathy apparently due to an interaction between simvastatin (Zocor, and others) and green tea. Since it became available generically, simvastatin has surpassed atorvastatin (Lipitor) as the best selling statin. As such, it is probably the most common cause of statin-induced myopathy, which is often a result of drug interactions.

Sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra, Staxyn) have become the standard treatment for erectile dysfunction. Head-to-head comparisons of these agents are still lacking, but some differences between them and new recommendations for their dosing (see Table 2) are worth noting.

Implanon (Organon), an implantable contraceptive containing the progestin etonogestrel, has been approved by the FDA. Two other implantable contraceptives, Norplant and Jadelle, which both contain levonorgestrel, are FDA-approved but not marketed in the US.