Levetiracetam-associated hyponatremia

Seizure (2008) 17, 389—390

www.elsevier.com/locate/yseiz

LETTER TO THE EDITOR Levetiracetam-associated hyponatremia KEYWORDS Levetiracetam; Side effects; Hyponatremia

Hyponatremia has been associated with several antiepileptic drugs (AEDs), such as carbamazepine, oxcarbazepine, and occasionally with valproate and lamotrigine.1,2 To date, there is only a report of hyponatremia associated with levetiracetam in a 65-year-old patient predisposed to the development of syndrome of inappropriate antidiuretic hormone secretion (SIADH).3 We recently observed a patient developing hyponatremia following two challanges with levetiracetam in absence of any evident predisposition to SIADH. This 76-year-old man suffered from complex partial seizures, occasionally followed by secondarily generalization, started 4 months before. Initial treatment with phenobarbital (100 mg daily) was soon discontinued due to diurnal somnolence and replaced with levetiracetam (1000 mg twice daily). Six months later the man was admitted to our Neurology Clinic due to a tonic—clonic seizure. His previous medical history included hypertension and anxiety for which he was receiving amlodipine and lorazepam. At admission, an EEG revealed lateralized temporal epileptiform activity. Brain MRI and chest CT scan were unremarkable. Haematological tests showed serum sodium level of 127 mM (normal, 135—145) and osmolality of 290 mOsm/kg (normal, 280—300). Urine sodium and osmolality were 6 mM (normal,