Predicted time to reach steady state in patients without impaired clearance mechanisms
| Drug | tss (days) |
| Carbamazepine | 7* |
| Clonazepam | 6 |
| Ethosuximide | 10 |
| Gabapentin | 2 |
| Lamotrigine | 5† |
| Methylphenobarbitone | |
| Phenobarbitone | 20 |
| Phenytoin | 5 |
| Primidone | |
| Tsagabine | 1–1.5 |
| Topiramate | 4–6 |
| Valproate | 2–3 |
| Vigabatrin | 2 |
↵* This value is calculated from the half-life. In practice the value may be appreciably shorter because of autoinduction of metabolism or longer with new therapy as autoinduction progresses over 2–3 weeks.
↵† Longer in persons co-medicated with valproate, shorter in those co-medicated with microsomal enzyme-inducing antiepileptic drugs, for example phenytoin.