 14. Patients receiving ketoconazole, erythromycin, verapamil, diazepam, quinidine, diltiazem, rifampicin, carbamazepine, phenytoin, efavirenz, nevirapine, fluoxetine or gemfibrozil. Patients taking any of these drugs may qualify for treatment on this investigational study if they have been off the drug at least for 7 days. 