Serum Hydroxyzine Concentrations and Toxic Symptom in Acute Intoxication Patients.

The serum drug concentrations in 6 cases of acute hydroxyzine intoxication patients were measured by HPLC. The patients were admitted about 1-10 hours after ingesting from 200 to 15000mg hydroxyzine. The serum hydroxyzine levels were within a range of 0.12-1.70μg/mL. The elimination half-lives were within a range of 4.7-111 hours during treating the patients by forced diuresis. The serum hydroxyzine levels associated with drowsiness was>0.51μg/mL, while that associated with vomiting was >0.51μg/mL and that with is miosis was> 1.40μg/mL. Only one fetal case was encountered. However, the fetal case could possibly have been due to trazodone rather than hydroxyzine because the concentration of hydroxyzine was 0.12μg/mL.