Dizziness primidone

Levetiracetam Action on synaptic protein SV2A Well absorbed orally not bound to plasma proteins metabolized to 3 inactive metabolites ty2 6-11 h Generalized tonic-clonic seizures, partial seizures, generalized seizures Toxicity Nervousness, dizziness, depression, seizures Interactions Phenobarbital, phenytoin, carbamazepine, primidone... 

Primidone, a deoxybarbiturate, is partly metabolized to phenobarbital, which is responsible for most of its pharmacological effects. During chronic dosing, the adverse effects of primidone are identical to those of phenobarbital. However, at the start of treatment, primidone can cause a transient intolerance reaction with malaise, dizziness, nausea, vomiting, headache, and other symptoms. 

The optimal therapeutic concentration of primidone has been established as 5 to 12 U,g/mL. Because phenobarbital is an active metabolite of primidone, concurrent analysis of phenobarbital is required for complete result interpretation. The previously defined therapeutic range for phenobarbital applies to adequate primidone therapy. The phenobarbital concentrations rise gradually over a period of 1 to 2 weeks after therapy is initiated. Toxicity due to accumulation of primidone occurs at serum concentrations in excess of 15 llg/mL and is usually associated with symptoms of sedation, nausea, vomiting, diplopia, dizziness, ataxia, and a phenobarbital concentration greater than dOpg/mL. Specimen collection is dictated by the same rules that apply to phenobarbital the trough concentration is most useful. 

Comparative studies In an open prospective comparison of valproate and primidone in 136 patients with partial epilepsy unresponsive to carbamazepine significantly more of those who took valproate (51%) achieved a greater than 50% seizure reduction than those who took primidone (34%) [231 ]. One patient withdrew from valproate because of dizziness and three because of nausea. Of those who took primidone, three withdrew because of dizziness, three patients because of drowsiness, and one because of gastrointestinal complaints. Adverse effects in other patients were mild and gradually disappeared during treatment. 

---