Characteristics of patients positive for methamphetamine in the emergency department, and the influence of the co-administration of GHB

Abstract

The Emergency Department Admission Blood Psychoactive Testing (EDABPT) study surveyed blood taken from intoxicated ED patients at four metropolitan hospitals (Adelaide, South Australia). This report aims to describe the clinical, demographic and toxicological findings relating to MA and other drug detections in the blood of these patients. The study enrolled ED patients with symptoms of drug intoxication and for whom intravenous access was clinically required and 2 × 5 ml NaF/oxalate-preserved blood samples were collected (ethics approval CALHN HREC/17/RAH/439 R20171015). Limited demographic, symptomatic and clinical outcome data was recorded. The samples were analysed for alcohol (GC-FID), common pharmaceuticals, drugs of abuse and NPS (approx 600 compounds, supported liquid extraction followed by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF)), and gamma-hydroxybutyrate (GHB, acid cyclisation, liquid-liquid extraction) Quantification of 50 common drugs was conducted simultaneously. 1120 patients were enrolled in the program. Patient ages were 18-79yo with a median of 31yrs. 64% of patients were male. The most common symptoms observed across the cohort were central nervous system (CNS) depression (64%), CNS elevation (39%) and hypoventilation (20%). Overall, the main clinical outcomes recorded were: admitted to short stay ward 47%; discharged from ED 25%; and admitted to high dependency unit/intensive care unit 17%. The most common drugs detected were: MA 55%; alcohol 30%; GHB 28% and diazepam 19%. The average number of drugs detected MA positive samples was slightly higher than MA negative samples (3.2 cf. 2.6, excluding drug metabolites). Alcohol was less prevalent in MA positive patients (9%) compared to MA negative patients (54%). MA concentration median was 0.19 mg/L and the interquartile range was between 0.08 (Q1) and 0.38 mg/L (Q3). Analysis of the data by MA concentration quartile did not show significantly different observed symptom profiles. GHB was detected in 28% of patients overall. GHB was more prevalent in MA positive patients (42%) compared with MA negative patients (19%). 89% of GHB positive patients experienced CNS depression. 87% of GHB positive cases also contained MA. GHB prevalence increased from 26% in the first quartile of MA concentrations (up to 0.08 mg/L), to 44% in the interquartile range (0.081–0.38 mg/L), and to 54% in the highest quartile (0.39–3.2 mg/L). Compared to MA positive patients, patients with both MA and GHB had a higher prevalence of CNS depression (88% cf. 50%), hypoventilation (34% cf. 15%) and apnoea (18% cf. 7%). In the absence of GHB, MA positive patients had a greater prevalence of CNS elevation/agitation (47% cf. 27%), cardiovascular system (CVS) elevation (21% cf. 6%) and psychosis (26% cf. 3%). Although it was the most common drug detected in this cohort, it is apparent that the presence of MA does not necessarily result in expected stimulant-like symptoms, even in the high MA concentration quartile. This is likely due to the influence of poly-drug use in the cohort-particularly GHB, but also other depressant drugs unable to be discussed here. In general terms, GHB dominates the symptomatic profile regardless of MA concentration. Given the high incidence of GHB in the MA cohort and vice versa, a pattern of combined use is evident which is supported by interstate and local drugs in driver reports. It is not possible to say whether the patients in this study have miscalculated the deliberate combination of GHB and MA in the pursuit of a desired effect, or if one drug is administered in an attempt to reverse the undesirable effects of the other.