A preliminary study to predict the ingested dose of doxylamine from its plasma concnetration in the Korean patients with doxylamine intoxication

Abstract

Background: Doxylamine succinate, over-the-counter antihistamine, is commonly used as a nighttime sleep-aid and is world-wide ingested in overdoses when one attempts a suicide because of its easy accessibility. The objective of this study was aimed to find out models to predict the ingested amount of doxylamine from its blood concentrations of thirty Korean patients with doxylamine intoxication. Method: Thirty patients who were admitted to two emergency centers through Jul, 2006 to Jul, 2008 due to doxylamine overdose were recruited. In all patients, demographic information and clinical variables, arrival time to the hospital after doxylmamine overdose, amount of doxylamine ingested, and vomiting were evaluated. Results: Of these thirty patients, average ingestion amount of doxylamine was 750 mg (range, 200~2500 mg). The mean arrival time to the hospital after the doxylamine ingestion was 4.5 h (range, <1.0~24 h) and its mean blood level at arrival time was 3.15 μg/mL (range, 0.64~11.31 μg/mL). Ingested doxylamine dose was predicted by determining the coefficient of plasma drug concentration using stepwise regression analysis. The linear regression formula calculated was: y=241.769(x)+217.117 (y=ingested doxylamine dose, x=its plasma concentration, p=0.001). Conclusion: Close clinical observation, laboratory follow-up and analysis of blood doxylamine concentration were required for patients, who intoxicated doxylamine and admitted emergency department, to estimate ingested dose and time of doxylamine, and to prevent the clinical toxicity. We suggested that recommended sampling time for analysis of plasma doxylamine concentration was 1~3 h after the ingestion, and its plasma level at the arrival time was a statistically significant factor to predict the ingested dose of doxylamine in the 30 Korean patients with doxylamine intoxication.