Alcohol metabolism of local Chinese in Hong Kong: a statistical determination on the effects of various physiological factors.

A study was designed to examine the elimination rate of alcohol from the body of the local Chinese after consumption of different types of alcoholic drinks. The breath alcohol of 184 healthy volunteers was determined and converted into blood alcohol levels after they finished drinking. Information on the type and volume of alcoholic drinks consumed, age group, sex, drinking habit, and drinking on empty stomach or with/after meal was recorded for each participant. The results show that the elimination rate of an individual can be explained in terms of physiological variables including sex and drinking habit. The determined elimination rates allow forensic toxicologists to back calculate the blood alcohol concentration (BAC) of the drivers at the time of accident in drunk driving cases. The elimination rates of blood alcohol at 95% prediction intervals for male and female are in the range of 9.5-23.8 mg/100 ml/h and 11.1-37.1 mg/100 ml/h, respectively.

An epidemiological study on alcohol/drugs related fatal traffic crash cases of deceased drivers in Hong Kong between 1996 and 2000.

This study is designed to evaluate the correlation between fatal vehicle crashes (FVC) and consumption of alcohol and/or drugs among drivers. Between 1996 and 2000 in Hong Kong, a total of 197 FVC cases of deceased drivers were investigated. The blood and/or urine samples of the victims were examined for the presence of alcohol and drugs. The 197 cases were then classified into two groups: single-vehicle crashes (SVC) and multiple-vehicle crashes (MVC). Out of the 106 cases for the latter group, alcohol and/or drugs were detected in 22 cases (21%) while the remaining 84 cases (79%) were regarded as no significant finding. As for the 91 cases in SVC group, 51 cases (56%) were positive for alcohol and/or drugs. The findings indicate that a driver consuming alcohol and/or drugs has a higher risk of being involved in a FVC. The most frequently detected drugs for SVC group (11 cases) were: 46% central nervous system (CNS) stimulants (including designer drugs like MDMA); 36% cannabis; 18% benzodiazepines and 9% ketamine. The detected drug for the only case in the MVC group was a CNS stimulant. The number of cases with ketamine, methamphetamine and MDMA detected has increased in recent years as these party drugs have gained popularity in Hong Kong.

Widmark factors for local Chinese in Hong Kong. A statistical determination on the effects of various physiological factors.

The Widmark formula has been widely adopted in forensic applications to drink driving cases for the last 70 years. It is known that the amount of alcohol consumed and the body weight of the drinkers are important information for the estimation of blood alcohol concentration (BAC). However, the direct application of the Widmark factors derived from Caucasian to the calculation of BAC for the Chinese population often encounters serious challenges. Owing to this inherent weakness, a thorough analysis to determine the theoretical Widmark factors for the Chinese population, r(0) at the start of drinking and the practical factors, r(peak), at peak BAC was conducted. In the present study, other factors such as gender, stomach condition and other physiological conditions are taken into account. The determined theoretical Widmark factors, r(0,) for local Chinese male and female are 0.68 and 0.59 (with BAC in the units of weight/volume), respectively, demonstrating the applicability of the Widmark formula to the Chinese population. The practical factors at peak BAC, r(peak), were also determined to serve the forensic purpose of refuting the "hip-flask" defence in drink driving cases. Findings show that gender and stomach condition are the key factors that could statistically explain the variability of both r(0) and r(peak).

Rapid determination of ketamine in urine by liquid chromatography-tandem mass spectrometry for a high throughput laboratory.

In recent years, the abuse of ketamine had gained popularity in rave parties in Hong Kong. The Urinalysis Unit of the Government Laboratory of Hong Kong faced a tremendous increase in workload for ketamine analysis. The number of tests performed rose from 10 in 1999 to 15,000 in 2002. As a fully validated immunoassay test for ketamine was not available in the market, most laboratories analyzed ketamine by chromatographic techniques after liquid-liquid extraction. However, these methods reported in the literature are not suitable for high throughput laboratories. Hence, a rapid screening/confirmation method for ketamine by liquid chromatography-tandem mass spectrometry (LC-MS-MS) with a detection limit of 5 ng/ml was developed. After automated solid-phase extraction (SPE), the urine extract was analyzed for ketamine by a 2.5-min chromatographic run, the estimated recovery was 89% and the precision was 11% R.S.D. at 20 ng/ml. With the aid of an in-house developed computer program, the results were presented in spreadsheet format for easy checking. The method has been applied to our laboratory for routine ketamine analysis and a maximum of 200 samples per day can be achieved.