Scientists at the University of Kentucky have altered a certain bacterial enzyme to eat cocaine in the human body. The bacterium, known as Stenotrophomonas maltophilia, naturally produces the enzyme cocaine esterase. This enzyme eats cocaine, breaking it down into carbon and nitrogen. The bacterium was originally discovered at a pharmaceutical plant that processed cocaine. If necessary, the enzyme can survive exclusively on cocaine.
The properties of cocaine esterase have made researchers hopeful that it can be used to treat cocaine overdoses and perhaps even to help people in recovery avoid relapses. Until recently, the search for drugs to treat cocaine abuse has drawn very few results. In contrast, various drugs have come on the market that show promise for treating opioid addiction.
Alteration Prolongs Enzyme Activity
However, the potential of cocaine esterase has been limited by one major factor: the cocaine-eating activity of cocaine esterase is temperature sensitive, and the conditions found in the human body are not ideal for it.
At normal human body temperature, the pairs that the enzyme needs to form in order to function – known as dimers – are unable to remain together for very long. As a result, cocaine esterase is only able to consume cocaine at human body temperature for an average of 12 minutes.
The University of Kentucky researchers were able to carefully alter cocaine esterase so that is survives and functions longer in humans. They were able to create a strain that will survive and consume cocaine at normal human body temperature for more than 100 days.
Extra-Long Lifespan Has Promise for Relapse Prevention
The new version of cocaine esterase is the second successful attempt by the Kentucky scientists to prolong the active life of the enzyme. However, the previous alteration allowed cocaine esterase to survive for only six hours at human body temperature.
This change was enough to make cocaine esterase a possible option for reversing cocaine overdoses. This version of the enzyme has proceeded to clinical testing, and is currently undergoing a phase II randomized, double-blind, placebo-controlled trial to test its efficacy at eliminating a dose of cocaine that has been introduced into the system.
However, an enzyme that eats cocaine for only six hours would not be effective at helping recovering cocaine users stay clean. As a result, the researchers were highly motivated to continue experimenting until they were able to produce a version of cocaine esterase that would remain active for a much longer period of time.
Drug Treatment Approaches to Substance Abuse
Some drugs, like methadone or Suboxone, treat opioid addiction by serving as replacements; they satisfy the body’s opioid craving without producing a high and remain in the system for a long time. Other drugs, like the opioid overdose drug naloxone, bind to the same receptors as abused drugs and prevent them from taking effect. Finally, there are drugs that actually eliminate other drugs from the body.
Any drugs that eventually come on the market and employ cocaine esterase will use the last approach. Cocaine esterase could be made available to law enforcement and the public in an effort to save the lives of people who have overdosed on cocaine. It could also be prescribed to people in cocaine addiction recovery, so that if they do relapse, the drug will be consumed by the enzyme before it can take effect.
So far, the new enzyme has only been tested in isolation and on mice. On its own, the enzyme was able to survive and consume cocaine for over 100 days. The researchers also tested the enzyme’s effectiveness at reversing cocaine overdose in mice, and they found that mice were able to survive for three days on doses of cocaine that were 180 times higher than a typical human dose.