Vaccine May Lessen The Human Tragedy of America’s Meth Epidemic
A vaccine that could block the effects of methamphetamine – one of the world’s most addictive and toxic drugs – has shown promise in pre-clinical studies, researchers say. It’s an important advance that could break the cycle of addiction for meth users who are committed to recovery.
The vaccine works by producing antibodies (large proteins in the bloodstream) that bind to the ingested meth — making it too big to cross the blood-brain barrier. And when meth fails to reach the brain, the user gets no satisfaction or euphoric rush. There’s less chance of relapse, since the physical high is extinguished.
“The animal studies have gone very well with no toxicities and very good efficacy in preventing methamphetamine from getting into the brain,” says Thomas Kosten, M.D., one of several scientists conducting vaccine studies funded by the National Institute on Drug Abuse (NIDA). Kosten is Director of Alcohol and Addiction Psychiatry at Baylor College of Medicine in Houston, where he also serves as a professor and the Waggoner Chair in the Menninger Department of Psychiatry and Behavioral Services.
In the last decade, the science of addiction recovery has rapidly evolved (Kosten has pioneered several breakthroughs – including a cocaine vaccine now being tested in human clinical trials). But unlike options for alcohol and opiate addiction, there are no medications to treat people hooked on meth. Some users recover with behavioral therapies and incentive-based interventions.
“Since we have no FDA-approved medications for methamphetamine addiction, these vaccines can be very helpful in helping prevent relapse in patients who become abstinent and want to stay that way,” Kosten says. The Baylor studies will go to the FDA for approval in mid-2016, he says, to test the vaccine in humans.
User Motivation is Key
Only drug users who are determined to quit using meth would be good candidates for the vaccine, according to Kosten. If a person tries to “override” the vaccine and ingests a large amount of meth, the toxic effect on the body would be magnified. Users could suffer organ damage, severe paranoia or other serious health risks.
Vaccine candidates must also commit to booster shots, which keep the antibodies at high levels to prevent meth from rapidly entering the brain. “The vaccine will require a booster about every 2-3 months to remain effective, so the patient must be motivated to want to stop (meth use),” Kosten says.
In addition to Kosten’s research, meth vaccine studies are also underway at InterveXion Therapeutics, a pharmaceutical company in Little Rock, Arkansas; and at The Scripps Research Institute in La Jolla, California.
“We think our vaccine shows great promise since we are focused on technology to safely increase the amount and duration of the anti-METH antibodies generated by the vaccination. Low immune responses was a significant weakness in earlier generation anti-addiction vaccines,” says Michael Owens, Chief Scientific Officer of InterveXion Therapeutics and the Mills Endowed Chair in Alcohol and Substances Abuse Prevention at the University of Arkansas for Medical Science in Little Rock.
The Scripps Research Institute has been working on a meth vaccine since 2008, according to Michael Taffe, Ph.D., Associate Professor for Scripps’ Committee on the Neurobiology of Addictive Disorders. In Taffe’s studies, vaccinated rats showed less preference for meth, as measured by how often they pressed a lever to self-administer the drug. The vaccinated rats also were less sensitive to its stimulating effects.
“The vaccine reduced the degree to which methamphetamine caused the rats to increase their movements around the cage and use of an activity wheel,” Taffe says. “It also reduced the degree to which methamphetamine changed their body temperature.”
One potential – and controversial – implication of a meth vaccine would be a population-wide preventative effect, Taffe says. “But this would require broad scale vaccination of adolescents, akin to what is being accomplished with Gardasil (the HPV vaccine).”
“The field has shied away from considering a prophylactic (preventative) approach,” Taffe says. “This is despite the fact that most addictions are established with adolescent exposure and that the probability of a life-long problem goes down the longer you keep an individual from taking the drug. I think we should be talking more seriously about the potential use of anti-drug vaccines in a preventative manner.”
Whether a meth vaccine is ultimately used for prevention, or therapeutic treatment of drug-addicted users, the next step is to seek FDA approval for human studies.
“Given the pre-clinical research successes, it is likely the case that the major factor will be the willingness of private enterprise to invest in the necessary clinical trials,” Taffe says.
A Stronger Meth, A Faster Addiction
Abuse of methamphetamine – a powerful central nervous system stimulant – has ravaged many U.S. communities. Today, experts are concerned about a more potent form of the drug, P2P meth, that’s cheap and readily available. Made in Mexico’s “super labs” with the chemical phenyl-2-proponone, P2P meth is smuggled into the United States and converted into rock-like crystal meth (“ice”).
“One of the problems with the P2P meth is the potency and the quicker addiction,” says Jane Maxwell, Ph.D., a research professor at the University of Texas who has been tracking drug trends for 44 years.
“You can’t cook it up in the country somewhere. It’s being made in very good chemical labs in Mexico,” Maxwell says. She notes that P2P meth is testing “at 95 percent potency” compared with 50 percent potency for meth made with pseudoephedrine, the over-the-counter cold medicine used by home meth cooks (these methods produce only a tiny fraction of the meth available in today’s illicit drug market).
Maxwell says the problem is especially acute in Texas, where P2P meth is flooding the southwest border.
“We are seeing more cases of human exposure and adverse events reported by Texas poison control centers, more treatment admissions, more items being identified by Texas laboratories as methamphetamine, more reports of individuals becoming addicted sooner with cases of psychosis,” Maxwell says.
Available And On The Rise
While more than 12 million Americans have tried methamphetamine, the number of regular users is about 569,000, according to the 2014 National Survey on Drug Use and Health. This represents about 0.2 percent of the population ages 12+ – similar to the percentages of monthly users since 2008.
However, meth use appears to be on the rise according to the Drug Enforcement Administration (DEA), which notes in its 2014 National Drug Threat Assessment Summary:
“Seizure data, law enforcement reporting and localized treatment information all indicate methamphetamine trafficking and abuse continues to increase throughout the nation.”
The drug is “highly available,” especially in the Western United States, the DEA says. An estimated 40.6 percent of law enforcement agencies report that meth can be readily found in their communities.
“Meth use is still a phenomenon in the West, but now it’s traveling East,” Maxwell says. “My colleagues are reporting that meth is a major problem drug in Los Angeles, Denver, Texas and Atlanta – and it’s growing in Miami.”
Meth was ranked as the single greatest drug threat in the Denver metro area (meth treatment admissions there increased to a high of 2,127 in year 2014, compared with 1,475 in 2011). In Los Angeles, meth accounted for “the largest percentage of drugs identified from law enforcement seizures” and 24.6 percent of admissions to substance abuse treatment programs, up from 20.1 percent in 2013. And in Texas, meth is the top drug threat in Dallas and the drug most often identified in forensic labs.
Meth use in Atlanta is the highest of any major U.S. city east of the Mississippi, and has reached its highest levels there since the drug peaked in 2005, according to the National Drug Early Warning System (NDEWS), which monitors emerging drug trends. In 2014, Fulton County, Georgia reported 19 deaths with methamphetamine present, compared with four deaths that indicated meth in toxicology reports in 2012.
Nationwide, emergency room visits related to meth use rose 52 percent between 2007 and 2011, the most recent data available from the Substance Abuse and Mental Health Services Administration (SAMHSA). There were 67,954 meth-related ER visits in 2007 vs. 102,961 in 2011, according to SAMHSA. A majority of these visits (62 percent) also involved other drugs such as marijuana or alcohol.
“We know that the problem is getting worse. We really need to get better treatment resources,” Maxwell says.
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