Bit of a coincidence here. I am epileptic too. I suffer from Temporal Lobe Epilepsy rather than Tonic Clonic Epilepsy but I don't think that is relevant here. I have talked to a number of psychiatrists about seizure threshold over the years and they have tended to agree with each other. The tricyclics are probably worst for lowering the seizure threshold. I read a study of one of them, Imipramine, where
0.6 % of people taking it developed seizures and they didn't have epilepsy to start with. Probably a group to avoid. Fluoxetine, sertraline, fluvoxamine, trazodone,and the monoamine oxidase inhibitors, of which Moclobemide is one, have a lower seizure risk. The rest are somewhere between. I have read that the SNRI's Duloxetine and Venlafaxine are often recommended as a compromise. Maybe this was your GP's thinking when he put you on Duloxetine.
Seizure threshold isn't the only epilepsy relevant thing. There are P-450 isoenzyme problems. These are liver chemicals. Phenytoin, Carbamazepine, and Phenobarbitone can affect the breakdown of some anti-depressants so you can find yourself on a lower dose than you might expect from what you are swallowing. In the reverse direction fluvoxamine, fluoxetine, sertraline, and paroxetine can inhibit the breakdown of anti-epileptics and you could find yourself with higher antiepileptic levels than you are used to. Whether that matters I suppose depends on whether you are tolerating your antiepileptics. If you are, having a little more in your system might not matter much.
Persuading your GP to prescribe Moclobemide could be difficult. It is really a drug for psychiatrists in secondary care. The older members of the group had very severe food restrictions, revolving around Tyramine. Moclobemide was supposed to free of these restrictions but now people are advised to cut down on Tyramine containing foods rather than exclude them completely. I think that is more problematic than avoiding them completely. People did die on the older MAOI's through eating the wrong thing.
That might make choice of an anti-depressant a bit difficult. You aren't exactly swamped with alternatives. I would personally go for fluvoxamine, fluoxetine, or sertraline. It might be worth considering referral to your Community Mental Health Team. Their psychiatrist should be on top of P-450 problems in a way your GP is unlikely to be.
Love
Steve