Intoxication is a frequent cause of calls to emergency medical services (EMS) in Norway, with most of these poisonings being self-inflicted [1,2,3]. Primarily these cases involve alcohol and opioids, particularly heroin [4, 5]. However, in recent years, Scandinavia has experienced overdoses due to so-called “club drugs” (gamma-hydroxybuturate (GHB) and gamma-butyrolactone (GBL)) [6,7,8,9].
Gamma-hydroxybutyrate is found naturally occurring in many tissues of the body, and is closely related to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) . The sodium salt of gamma-hydroxybutyric acid is called gamma-hydroxybuturate (GHB). It is likely that GHB has its own GHB receptor, and when in high doses works to activate GABA B receptors, including dopamine release in the brain [11, 12]. GABA-B receptors are likely activated both in the pre- and post-synapses, which may explain many of the different effects of GHB intoxication .
The drug was originally developed in the 1960s in an attempt to create a GABA analog that would cross the blood-brain barrier . When the compound proved to have strong sedative properties, it was then considered for its use as an anesthetic agent. Given the narrow therapeutic interval, combined with large individual differences in tolerance, today the drug has a very limited medicinal use [14, 15]. The calming and euphoric effects of GHB in low doses (20–30 mg/kg) have given the drug the nickname “liquid ecstasy” . Since the drug is both inexpensive and easy to ingest, it has been popular as a “party drug.”
The oral absorption of GHB is relatively fast, with peak concentrations in plasma after 20–45 min, and half-life of 20–30 min . At higher doses (> 50 mg/kg), the hypnotic effects are more prominent, and at doses >60 mg/kg coma, convulsions, and respiratory depression can occur . The clinical hallmark of GHB poisoning is rapid onset of coma, with respiratory depression, hypoventilation and bradycardia [11,12,13]. Combination with alcohol potentiates these effects, especially respiratory depression and hypotension [10, 18].
GHB is a metabolic precursor to gamma-butyrolactone (GBL) and 1.4-butanediol (1.4 BD). GBL is used in the chemical industry, and is relatively easily acquired via the internet. Therefore, it has been imported to Norway in large quantities, predominately from Eastern Europe (personal communication, Hordaland Police District). The drug may be either “cooked” into GHB by the addition of caustic soda, or ingested directly, since after oral ingestion the substance is rapidly converted to GHB . GBL appears to be more potent than GHB, as animal studies have shown that the substance at equimolar oral doses gave both a faster and longer-lasting effect than GHB, as well as a higher peak plasma concentration [20, 21]. Increasing occurrences of fatal poisonings and deaths in which GBL was probably involved, as well as more international focus on this drug was the reason that also GBL was classified as a narcotic and therefore prohibited in Norway in March 2010 .
The intoxicating effects of GHB are well known, and it has been reported to be involved in varying rates of fatal poisonings [8, 23, 24]. In Norway, opioids are most commonly taken parenterally and are significantly more costly, lending to a lower threshold to try the innocent appearing “soda caps” with GHB. GHB is often used recreationally as a party drug, with typical users viewing the drug as relatively non-toxic and harmless, comparable to alcohol .
Ambulance records have been used to investigate epidemiological trends for a variety of issues [26,27,28]. Population level monitoring of GHB use is limited , and the indirect information provided by ambulance records can provide a current overview of GHB overdoses in the city. This information can give insight into distinct user groups and patterns of use, which can in turn be used to monitor and guide treatment and prevention interventions. Further, an investigation into temporal patterns may shed light on what role the GBL restriction had on overdoses. Therefore, the aims of this study were to investigate characteristics and temporal trends of GHB/GBL ambulance attended overdoses in Bergen from 2009 to 2015.