Synthetic legal intoxicating drugs: The emerging ‘incense’ and ‘bath salt’ phenomenon

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Amid the mysteries surrounding synthetic cannabinoids, one thing is clear: users are increasingly seeking medical attention. In 2010, there were 2,906 calls to poison control centers across the United States pertaining to “synthetic marijuana”; in 2011 there were 6,959 calls, and in January 2012, 639 such calls had been placed.9

Some of the more common complaints related to the use of synthetic cannabinoids are listed in Table 1 and may be potentially serious.1,10,11 The greater potency of synthetic cannabinoids and their full-agonist mechanism of action may be to blame for the relatively high number of complaints not typically associated with the use of marijuana.

The duration of the intoxicating effects of synthetic cannabinoids is generally longer than that of THC, but this seems to be variable. JWH-018, for instance, seems to have a shorter duration of action, at around 1 to 2 hours, while a longer, 5- to 6-hour intoxicating effect has been observed with CP-47,497.7,12

Serious adverse effects

Although the prevalence of serious adverse effects associated with the use of synthetic cannabinoids is not known, a number of serious complications have been recognized.

Seizures. One case of seizure has been reported in association with the use of synthetic cannabinoids, specifically JWH-018.12 This case involved a previously healthy 48-year-old man who had ingested a powder that was subsequently confirmed to be JWH-018, which he mixed with alcohol. Of further concern in this case is that this individual developed a refractory supraventricular tachycardia that required cardioversion on the first hospital day.

The authors speculated that the seizure may have been due to a dose-response mechanism that resulted in either the release of presynaptic excitatory neurotransmitters or the decreased release of inhibitory neurotransmitters. They further postulated that the supraventricular tachycardia could have been caused by one of two mechanisms previously reported in association with CB1 agonists: an increase in circulating catecholamines or heightened oxidative demands on the myocardium.12

Psychosis. The occurrence of psychotic symptoms such as hallucinations and paranoid delusions in association with synthetic cannabinoids is not surprising, given the well-documented link between marijuana use and psychosis.13,14

A case report of a 25-year-old patient with a 7-year history of recurrent psychosis that was initially triggered by cannabis use indicated that the use of 3 g of herbal incense on three occasions was associated with worsening of previous psychotic symptoms and the emergence of command and paranoid types of auditory hallucination.10

Semistructured interviews of 15 patients in a forensic rehabilitative service, all of whom had a history of psychotic illness, showed that 69% experienced symptoms consistent with psychotic relapse after smoking an herbal incense product containing JWH-018.15

It is possible that psychotic symptoms may be more prominent with synthetic cannabinoids than with natural marijuana because not only are synthetic cannabinoids more potent and work as full agonists, but, unlike marijuana, they do not contain cannabidiol, which is thought to have antipsychotic efficacy.10,16 However, the risk of psychotic symptoms in association with synthetic cannabinoid usage in otherwise healthy people is unknown.

Regulation lags behind

Growing concern over the perceived dangers posed by synthetic cannabinoids has led to a ban on some of the more common ones contained in herbal incense preparations. On March 1, 2011, the US DEA temporarily placed five synthetic cannabinoids (JWH-018, JWH-073, JWH-200, CP-47,497, and cannabicyclohexanol) under schedule I (banned substances).

Such a ban, however, may be futile because there are an estimated 100 synthetic cannabinoids that have yet to enter the market, and when one is banned, a new one is likely to be introduced immediately as a replacement.8


Like the herbal incense products, “bath salts” may likewise not be what they appear to be. They too may be labeled “not for human consumption” in an effort to bypass laws governing mind-altering substances.

Several pharmacologically active substances have been marketed as bath salts. Two of the more common ingredients are 3,4-methylenedioxypyrovalerone (MDPV) and 4-methylcathinone (mephedrone).

MDPV is a dopamine and norepineph-rine reuptake inhibitor that acts as a powerful stimulant. It has no FDA-approved medical use, but it is an analogue of the stimulant pyrovalerone, which was once used to treat chronic fatigue.17

MDPV seems to be the most common substance found in bath salt products in the United States. A sample of this substance was first seized on the streets by German authorities in 2007. A study in Finland conducted from August 2009 to September 2010 estimated that 5.7% of all arrests for driving under the influence (DUI) unrelated to alcohol consumption involved MDPV intoxication.17 In 2009, the National Forensic Laboratory Information System of the US DEA had seized only two samples of MDPV, but by 2010 that had increased to 161.18

Mephedrone is derived from phenethylamine and is closely related to cathinone, the active ingredient in the African khat plant (Catha edulis).19 Khat has a history of abuse, and the chemical structure of cathinone and its derivatives is similar to that of amphetamine.

Mephedrone, a powerful stimulant, is suspected of working as a monoamine reuptake inhibitor, and it may also directly induce the presynaptic release of monoamines.20 The net effect is an increase in serotonin, norepineph-rine, and dopamine levels at neuronal synapses.

Mephedrone was first described in 1929 by chemist Saem de Burnaga Sanchez, and it remained an obscure research chemical for many years.21 It was formally recognized as a drug of abuse in Europe in 2007, and by 2009 it was the sixth most frequently used such drug in Europe.8,22

Although MDPV and mephedrone are the most common psychoactive ingredients in bath salts, many other synthetic drugs have been found on the market.

A temporary ban

On September 7, 2011, the US government made it illegal to possess or sell any substance containing MDPV, mephedrone, or methy-lone. This temporary restriction was to remain in effect for 1 year to give the DEA time to collect data to support a move to permanently control these substances.3

Like synthetic cannabinoids, however, synthetic stimulants are very difficult to regulate because they are a large group of substances. As soon as one substance is outlawed, another synthetic stimulant will likely take its place.

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