Figure 3: Number of patients with drug–drug interaction/s wherein levetiracetam values were less than the therapeutic range when given with other anti-epileptic drugs (AEDs). These graphs (a, b, and c) show the number of patients in whom levetiracetam levels were less than the therapeutic range when co-administered with 1, 2, and 3 AEDs, respectively with maximum interaction seen with phenytoin, carbamazepine, and valproate