What Are The Side Effects Of Using Cocaine While On Levetiracetam, ( Kepra) Topiramate And Ziprasidone?

My son had a bilateral frontal TBI . He was taken home by his roommate and put to bed. 2 days later they called me because they could not wake him. He was in a coma. A craniotomy was not enough to release pressure so a lobectomy of the right frontal and temporal was done. He was in a coma about three weeks. He has grand Mal seizures. He takes leverteractam, toprimate, lamotrogine, venlafaxine , and ziprasidone. I just found where he has been skipping some of his levertaractam ( Kepra) toprimate and ziprasidone and hiding them .He told me he needed to have a bunch on hand so he could take before doing Cocaine if he got a chance. I am his guardian , mother and caregiver. I do not believe he would get a chance to find cocaine but am worried of interaction of these meds. I do keep prescriptions locked up and monitor him to the best of my ability. He does not drink alcohol as he knows it lowers his threshold for seizures. He does smoke cigarettes, seeks cafe in which I try to limit and uses medical marijuana.