Scripps: Scientists at The Scripps Research Institute (TSRI) have
found using animal models that the new recreational drug alpha-PVP
(“flakka”) seems equivalently potent as a stimulant, and therefore as
addictive, as its chemical cousin MDPV (“bath salts”). News stories in recent months have blamed flakka for
incidents of extreme violence, paranoid psychoses, compulsive nudity,
zombie-like behavior and even “superhuman strength.” One man, allegedly
high on the drug, tried to break into a police station. Another ran
naked through Fort Lauderdale traffic. “There have been assertions that flakka is somehow worse
than MDPV, but this study shows that the two are very similar,” said
Michael A. Taffe, an associate professor at TSRI.
TSRI Associate Professor Tobin J. Dickerson, who was
co-senior author of the study with Taffe, added, “That doesn’t mean that
flakka use is ‘safe’—our data show that flakka is as potent as MDPV,
making it a very good stimulant, arguably with worse addiction liability
than methamphetamine.”
The team’s findings were published online ahead of print in the journal Psychopharmacology.
Potent and Cheap
Alpha-PVP (α-pyrrolidinopentiophenone) is a synthetic
stimulant; the street drug supply is reportedly made in laboratories in
China, India and Pakistan. It was designed to be slightly different,
chemically, from MDPV, which has been illegal in the U.S. since 2011.
The new drug’s chemical difference, the lack of a cluster of atoms known
as the 3,4-methylenedioxy motif, is the same as the one that
distinguishes methamphetamine from MDMA (“Ecstasy”).
Alpha-PVP was legal until the U.S. Drug Enforcement
Administration put a ban on it early in 2014—a temporary ban that is
almost certain to become permanent. Nevertheless, the drug is so potent
and so cheap—reportedly as low as $5 per dose—that its use has grown in
certain parts of the country, prompting concerns among police and health
officials.
For the study, the research team used a standard animal
model of addiction potential in which rats are trained to press a lever
to infuse themselves intravenously with small doses. As expected for an
addictive stimulant, the rats tended to press the drug-delivery lever
more and more in each one-hour session as 20 daily sessions progressed.
When the researchers increased the number of lever presses required to
get another dose, the animals kept pressing—for up to hundreds of
presses per dose.
In a head-to-head test of self-administration of
alpha-PVP against MDPV, alpha-PVP showed an almost identical potency to
induce lever presses. The drugs also showed approximately the same
ability to induce two classic stimulant effects, boosting physical
activity and disrupting body temperature.
Although the results suggest that scare stories over
alpha-PVP may be somewhat overblown, the fact that it is comparable to
MDPV makes it a highly dangerous drug. MDPV is already widely considered
one of the worst-ever drugs in terms of addiction potential. In a study
reported in 2013, for example, the Taffe and Dickerson labs showed that
MDPV induced far more drug-seeking lever presses in rats than crystal
meth. “Animals will self-administer MDPV like no drug I have ever seen,”
said Dickerson.
Overshadowing Other Pleasures
In a related study, also published online ahead of print in Psychopharmacology, the TSRI researchers set up a test of MDPV’s ability to supplant other rewarding behaviors.
“We commonly think of drug addiction as making the drug
more important than anything else in the user’s life, but we haven’t had
good rodent models of that,” said Taffe. “The animals will almost
always respond more to food and tasty flavors, for example, than drugs.”
The team decided to get around this problem by testing
the ability of MDPV to supplant a pleasurable but less fundamental
behavior for rats, wheel running. The researchers found that as the
animals self-administered more MDPV per session, their use of the wheel
declined significantly, indicating that the drug had made this normally
rewarding behavior seem much less appealing.
Remarkably, a subset of the rats didn’t increase their
MDPV intake gradually, but went from occasional sampling to bingeing on
as much as they could get during the session. “That was when they
stopped using the wheel—that very day they binged,” said Taffe. “In
subsequent sessions, the bingers’ intake would stay high and they
wouldn’t run much on the wheel. We think it’s a good model of the ways
in which—and the speed with which—drugs can supplant other rewarding
things we normally do.”
Taffe and his colleagues also suspect that initial
bingeing may be a predictor of individual liability for addiction, which
normally affects only a minority of people who try a drug.
MDPV is related to cathinone, a natural stimulant found in the khat
leaves traditionally chewed in Northeast Africa and Arabian Peninsula
regions, but it also shares structural similarity to methamphetamine and
MDMA. Originally developed as a potential pharmaceutical stimulant by
Boehringer Ingelheim chemists in the 1960s, MDPV re-emerged as a
recreational drug within the past decade. The fact that it enjoyed legal
status for a time has led to the development of variants—also briefly
legal—such as alpha-PVP.
In this rapidly evolving recreational drug “market,”
obtaining high-purity drug for laboratory research can be a challenge.
In this collaboration, Dickerson designed the synthesis of drugs from
precursor compounds prior to scheduling, when they are not available
from research supply companies.
“There are now dozens of substituted cathinones out
there that could become popular, and what we’re trying to do is to study
these drugs as they emerge, using our animal models, and hopefully come
up with general principles for predicting their effects,” said Taffe.
“These drugs are not made in garages anymore,” said
Dickerson. “They’re made by sophisticated chemistry labs that are
producing not just one drug, but also analogs of that drug, so as soon
as one drug gets banned, here comes the next one, and the next one—and
there’s no evidence of any kind of safety testing prior to their release
into the drug user population.”