Mephedrone, or 4-methylmethcathinone, is a recreational drug that got very popular in the UK in recent years, no doubt due to it being legal to sell and possess up until April of this year. There is not a tremendous amount known about the pharmacology of this drug at present, however we can deduce quite a bit about where we should start looking from user experiences. I am currently intrigued by the fact that if you look at online user forums you can get Ecstasy fans describing mephedrone as being sortof like Ecstasy...only not as good, or not quite the same. In addition, a recent paper which surveyed a certain subset of users found that many of them report intranasal mephedrone to be as good or better than intranasal cocaine. You will recall, of course, that I have a great deal of blog interest in discussing MDMA-related fatalities.
A Case Report that recently appeared in the Lancet helps us to connect up some dots. Sammler and colleagues report on the case of a 15 year old girl who presented to their emergency department one afternoon with "altered mental status, vomiting and nausea". She had been out drinking the night before and had also consumed a "white powdery substance". The clinical workup contained a few interesting clues:
-the cerebrospinal fluid (CSF) opening pressure during lumbar puncture in the lateral decubitus position was raised at 350 mm of water.
-Blood tests showed profound hyponatraemia at 118 mmol/L.
-Serum osmolality was low at 256 mmol/kg, whereas urine osmolality was high at 742 mmol/kg.
Well, well, well. Hyponatraemia is frequently reported in cases of MDMA-related medical emergency and death. This is very likely related to an effect on vasopressin / antidiuretic hormone release that would cause the kidneys to retain water, perhaps in combination with induced polydipsia (urge to drink) or intentional (albeit misguided) prophylactic strategies. This is likely driven by the serotonin transporter inhibition properties of MDMA, this indirect agonist effect perhaps working through the serotonin 3, 2C, 4 and/or 7 receptor subtypes to induce vasopressin release.
I have no good stats but there is a distinct impression from reading MDMA case reports that young women may be particularly liable to hyponatremia following MDMA. This is something I need to take up at some point- is there evidence for increased sensitivity of adolescent women to fluid balance dysregulation?
Returning to the topic at hand, is this just a case of MDMA-induced hyponatraemia?
Fortunately, the doctors ran the tox panels:
We suspected drug intoxication and did gas chromatography-mass spectroscopy of the patient’s urine; this was unequivocally positive for mephedrone metabolites, but was negative for opioids, methadone, barbiturates, cocaine, cannabinoids, alcohol, benzodiazepines, and amphetamines including ecstasy. Analysis of the white powder was consistent with mephedrone.
Interesting. This suggests to me, as it did to the authors, that there is a MDMA-like component to this mephedrone stuff. It may be a dopamine transporter inhibitor and/or dopamine releaser like cocaine, amphetamine, methamphetamine but the hyponatraemia suggests an additional (significant) serotonergic component of the pharmacological response to mephedrone. This would be consistent with those users who report it as being at least somewhat like Ecstasy.
As I discussed before, one prior paper reported on the subjective effects of several cathinone analog compounds using the drug-discrimination assay. The cathinone structure if very similar to amphetamine and supports parallel modifications. The question becomes whether the same modifications of the cathinone and amphetamine core structures convey similar changes in the pharmacology.
In very brief overview of the drug-discrimination procedure, you train rats to tell you if the drug you have just given it is similar to a reference drug such as amphetamine or MDMA. The prior paper found that methylenedioxycathinone (MDC) and methylenedioxymethcathinone (MDMC) fully substituted for MDMA at reasonably similar doses. MDMC also fully substituted for amphetamine whereas MDC did not; in both cases the potency was much lower-higher doses had to be employed for comparable effect to the reference amphetamine.
This is complicated, because if anything MDA is closer in subjective and behavioral effect to amphetamine than is MDMA. And if there are any data on the 4-Methylmeth modification of amphetamine, I am unaware of them. Nevertheless it provides some clue that we are not totally out of line to suspect that the 4-Methylmeth modification to cathinone adds on a serotonergic agonist component, very likely mediated by blockade of the serotonin transporter (with perhaps some releasing effect)...just like one sees with the methylenedioxymeth modification of amphetamine in the case of MDMA.
Final note: The 15 year old girl in this Case Report made a full recovery. That's a very good thing.
Sammler EM, Foley PL, Lauder GD, Wilson SJ, Goudie AR, & O'Riordan JI (2010). A harmless high? Lancet, 376 (9742) PMID: 20801405