<qa>  What is the main drug that is well known in prolonging QTc?- QTc450 msec. Common drugs that are well known in prolonging QTc include azithromycin, citalopram, escitalopram, fluconazole, and pentamidine. Baselines EKG will be obtained in each patient and if QTc 450 msec, then they will be excluded from the trial. 