Table 2.
Examples of Desirable and Undesirable AED Combinations
| Combination | Desirability | Rationale |
|---|---|---|
| Phenytoin or Carbamazepine, plus | ||
| Lamotrigine | – | EIAEDs decrease LTG, heightened pharmacodynamic neurotoxic adverse effects |
| Oxcarbazepine | – | EIAEDs decrease OXC, OXC inhibits CYP 2C19 and may increase PHT concentrations; increased neurotoxic adverse effects |
| Topiramate | – | EIAEDs decrease TPM, TPM inhibits CYP 2C19 and may increase PHT concentrations; increased neurotoxic adverse effects |
| Levetiracetam | + | Possible synergism with CBZ |
| Lamotrigine or Oxcarbazepine, plus | ||
| Gabapentin | ++ | Potential synergism |
| Pregabalin | ++ | Potential synergism |
| Levetiracetam | ++ | Potential synergism |
| Topiramate | + | Potential synergism |
| Zonisamide | +/– | Possible additive effects, similar principle MOA |
| Valproate or divalproex, plus | ||
| Phenytoin | – | Increased free PHT fraction and neurotoxic adverse effects; however, retrospective case series suggest synergism |
| Carbamazepine | – | Valproate increases CBZ-epoxide, similar principle MOA |
| Lamotrigine | +/– | Controlled clinical trial evidence for efficacy; however, increased risk of rash |
| Topiramate | +/– | Hypothetically may offset weight gain adverse effects; however, increase in neurotoxic adverse effects |
| Levetiracetam | ++ | Possible synergism |
| Zonisamide | + | Possible synergism |
+
Potentially desirable combination;
++
Desirable combination.
–
Potentially undesirable combination;
– –
Undesirable combination.
+/–
Data are conflicting.