A 2008 "British Medical Journal" article highlights that the combination of some macrolides and statins (used for lowering cholesterol) is not advisable and can lead to debilitating myopathy. This is because some macrolides (clarithromycin and erythromycin, not azithromycin) are potent inhibitors of the cytochrome P450 system, particularly of CYP3A4. Macrolides, mainly erythromycin and clarithromycin, also have a class effect of QT prolongation, which can lead to torsades de pointes. Macrolides exhibit enterohepatic recycling; that is, the drug is absorbed in the gut and sent to the liver, only to be excreted into the duodenum in bile from the liver. This can lead to a buildup of the product in the system, thereby causing nausea. In infants the use of erythromycin has been associated with pyloric stenosis.