Table 3.
Clinical Symptoms for Patients with Elevated Lamotrigine and Levetiracetam Drug Levelsa.
| Presenting Signs and Symptoms | Patients with Lamotrigine level > 14 mg/L (n = 293) | Patients with Levetiracetam level ≥ 80 mg/L (n = 106) |
|---|---|---|
| n (%) | n (%) | |
| Agitation/aggression | 10 (3.4 %) | 5 (4.7 %) |
| Altered mental statusb | 34 (11.6 %) | 16 (15.1 %) |
| Asymptomatic | 162 (55.3 %) | 48 (45.3 %) |
| Ataxiab | 42 (14.3 %) | 2 (1.9 %) |
| Cardiac | 2 (0.7 %) | 0 (0.0 %) |
| Dizziness | 35 (11.9 %) | 2 (1.9 %) |
| Dysarthria | 2 (0.7 %) | 0 (0.0 %) |
| Fatigue | 7 (2.4 %) | 1 (0.9 %) |
| Headache | 5 (1.7 %) | 1 (0.9 %) |
| Known ingestion | 6 (2.0 %) | 2 (1.9 %) |
| Muscle weakness | 5 (1.7 %) | 3 (2.8 %) |
| Nausea/vomiting | 15 (5.1 %) | 0 (0.0 %) |
| Nystagmus | 3 (1.0 %) | 1 (0.9 %) |
| Paranoia | 2 (0.7 %) | 0 (0.0 %) |
| Psychosisb | 4 (1.4 %) | 0 (0.0 %) |
| Respiratory distress | 2 (0.7 %) | 0 (0.0 %) |
| Seizures | 41 (14.0 %) | 33 (31.1 %) |
| Serotonin syndrome | 3 (1.0 %) | 0 (0.0 %) |
| Tremors, twitches, or jerksb | 15 (5.1 %) | 0 (0.0 %) |
| Unknown (presence or absence of symptoms not documented) | 23 (7.8 %) | 2 (1.9 %) |
| Vision changes | 15 (5.1 %) | 0 (0.0 %) |
| Miscellaneous (n = 1 each only for lamotrigine) | Coma, drooling, dry mouth, dysarthria, night sweats, paresthesia, weight loss | None |
The table summarizes the main two clinical symptoms and signs (if present) documented at time that drug level was obtained.
"Altered mental status" was defined as a general change in brain function from the baseline for the patient, encompassing symptoms such as amnesia, confusion, loss of alertness, disorientation, and disruptions in perception. "Ataxia" describes a lack of muscle control or coordination of voluntary movements, such as walking or picking up objects. “Muscle weakness" (reduced muscle strength) was defined by inability to produce normal muscle contraction despite full effort. “Psychosis” referred to situations where patient showed psychiatric symptoms with loss of touch with reality that seemed causally connected with drug toxicity. “Tremors, twitches, or jerks” were unintentional muscle movements involving one or more parts of the body and classified as a single combined group given widely varying documentation of symptoms in the electronic medical record even though different mechanisms likely underlie these effects. This category encompasses cases where these effects seem distinct from the baseline seizure disorder.