Co-exposure to gamma-hydroxybutyrate is associated with attenuated neuropsychiatric and stimulant effects of metamfetamine

Figures & data

Table 1. Comparison of baseline characteristics between groups defined by analytical detections.

Comparison groups	Median age in years (Interquartile range, 95% confidence interval)	Sex (% female)	Median blood metamfetamine concentration in mg/L (Interquartile range, 95% confidence interval)	Median blood gamma-hydroxybutyrate concentration in mg/L (Interquartile range, 95% confidence interval)
Lone metamfetamine versus	33 (24–39, 28–35)	40.0	0.1 (0.05–0.21, 0.09–0.18)	Not applicable
metamfetamine plus benzodiazepine	30 (25–40, 27–33)	32.8	0.1 (0.06–0.20, 0.08–0.20)	Not applicable
metamfetamine plus gamma-hydroxybutyrate	32 (28–38, 31–33)	36.2	0.2* (0.10–0.32, 0.20–0.23) P = 0.0001	110 (82–140, 100–120)
metamfetamine plus gamma-hydroxybutyrate plus benzodiazepine	30 (24–36, 28–31)	48.1	0.2* (0.10–0.30, 0.20–0.30) P = 0.0004	Not applicable
Metamfetamine plus gamma-hydroxybutyrate versus	32 (28–38, 31–33)	36.2	0.2* (0.10–0.32, 0.20–0.23) P < 0.0001	110 (82–140, 100–120)
metamfetamine plus benzodiazepine	30 (25–40, 27–33)	32.8	0.1 (0.06–0.20, 0.08–0.20)	Not applicable
Metamfetamine plus gamma-hydroxybutyrate versus	32 (28–38, 31–33)	36.2	0.2 (0.10–0.32, 0.20–0.23)	110 (82–140, 100–120)
metamfetamine plus gamma-hydroxybutyrate plus benzodiazepine	30 (24–36, 28–31)	48.1* P = 0.039	0.2 (0.10–0.30, 0.20–0.30)	133* (92–191, 120–150) P = 0.0004
Metamfetamine plus benzodiazepine versus	30 (25–40, 27–33)	32.8	0.1 (0.06–0.20, 0.08–0.20)	Not applicable
metamfetamine plus benzodiazepine plus gamma-hydroxybutyrate	30 (24–36, 28–31)	48.1* P = 0.033	0.2* (0.10–0.30, 0.20–0.30) P = 0.0002	133 (92–191, 120–150)

* Statistically significant difference with P value.

Figure 1. Median, interquartile range and range of metamfetamine blood concentrations at the time of hospital admission for each analytically defined exposure groups. *Median metafetamine blood concentration in groups with gamma-hydroxybutyrate detections was significantly greater than groups without gamma-hydroxybutyrate detected (P < 0.0004).

Figure 2. Median, interquartile range and range of gamma-hydroxybutyrate blood concentrations at the time of hospital admission for the analytically defined exposure groups. *Median gamma-hydroxybutyrate blood concentration was significantly greater in the metamfetamine plus gamma-hydroxybutyrate plus benzodiazepine group compared to the metamfetamine plus gamma-hydroxybutyrate group (P = 0.0004).

Figure 3. Median, interquartile range and range of presenting heart rates (beats per minute) for each analytically defined exposure group. *Median presenting heart rate in the gamma-hydroxybutyrate groups was significantly lower than groups without co-detection of gamma-hydroxybutyrate (P < 0.0001).

Table 2. Comparison of clinical effects recorded at the time of hospital presentation between groups defined by analytical detections.

Comparison groups	Median heart rate beats per minute (interquartile range plus 95% confidence interval))	Median systolic blood pressure mmHg (interquartile range)	Median diastolic blood pressure mmHg (interquartile range)	Median temperature degrees Celsius (interquartile range)	Per cent of cases with Glasgow Coma Scale <9	Per cent of cases with agitation
Metamfetamine versus	110 (87–131, 93–120)	130 (120–149, 127–140)	80 (71–92, 78–87)	36.5 (35.8–37.1, 36.2–36.7)	15	58
metamfetamine plus benzodiazepine	84* (73–98, 80–90) P < 0.0001	120* (109–132, 116–124) P < 0.001	77 (69–87, 73–80)	36.2* (35.7–36.6, 36.0–36.4) P = 0.017	27	29* P < 0.0003
metamfetamine plus gamma-hydroxybutyrate	72* (63–86, 70–78) P < 0.0001	130 (117–141, 125–132)	80 (70–90, 77–84)	35.8* (35.0–36.2, 35.6–35.9) P < 0.0001	63* P < 0.0001	34* P = 0.0004
metamfetamine plus gamma-hydroxybutyrate plus benzodiazepine	72* (60–83, 68–76) P < 0.0001	124* (110–137, 120–129) P = 0.001	78 (70–85, 75-80)	35.7* (35.0–36.2, 35.6–35.8) P < 0.0001	72* P < 0.0001	17* P < 0.0001
Metamfetamine plus gamma-hydroxybutyrate versus	72* (63–86, 70–78) P < 0.0001	130 (117–141, 125–132)	80 (70–90, 77–84)	35.8* (35.0–36.2, 35.6–35.9) P = 0.0001	63* P < 0.0001	34
metamfetamine plus benzodiazepine	84 (73–98, 80–90)	120* (109–132, 116–124) P = 0.003	77 (69–87, 73–80)	36.2 (35.7–36.6, 36.0–36.4)	27	29
Metamfetamine plus gamma-hydroxybutyrate versus	72 (63–86, 70–78)	130 (117–141, 125–132)	80 (70–90, 77–84)	35.8 (35.0–36.2, 35.6–35.9)	63	34
metamfetamine plus gamma-hydroxybutyrate plus benzodiazepine	72 (60–83)	124 (110–137, 120–129)	78 (70–85, 75–80)	35.7 (35.0–36.2)	72	17* P = 0.0007
Metamfetamine plus benzodiazepine versus	84 (73–98, 80–90)	120 (109–132, 116–124)	77 (69–87, 73–80)	36.2 (35.7–36.6, 36.0–36.4)	27	29
metamfetamine plus benzodiazepine plus gamma-hydroxybutyrate	72* (60–83, 68–76) P < 0.0001	124 (110–137, 120–129)	78 (70–85, 75–80)	35.7* (35.0–36.2, 35.6–35.8) P < 0.0001	72* P < 0.0001	17

* Statistically significant difference with P value. The median Poison Severity Score for all groups was 3.

Figure 4. Median, interquartile range and range of presenting temperature (degrees Celsius) for each analytically defined exposure group. *Median presenting temperature in the gamma-hydroxybutyrate groups was significantly lower than groups without co-detection of gamma-hydroxybutyrate (P ≤ 0.0001).

Figure 5. Reported incidence of agitation on hospital presentation for each analytically defined exposure group. *Incidence of agitation in groups with co-detection of gamma-hydroxybutyrate or benzodiazepines was significantly lower compared to the lone metamfetamine group (P ≤ 0.0004).