Can Naltrexone Help Recovery From Crystal Meth Addiction?

The use of amphetamine and its more powerful cousin methamphetamine (crystal meth; otherwise known as "ice," "crank" or "Tina") can become addictive. Crystal meth impairs judgment and can lead users to engage in unprotected sex, which can result in the transmission of HIV.

Recently, neuroscientists at Sweden's Karolinska Institutet conducted a placebo-controlled clinical trial of naltrexone to assess its effect on reducing dependence on amphetamines. The results are promising and have implications for research with people addicted to crystal meth.

Study Details

Researchers recruited 80 HIV negative people addicted to amphetamine who did not have any other major health conditions or addictions (except to nicotine). All participants were interested in breaking free from their addiction to amphetamine. Before the trial started, potential participants were extensively interviewed and urine samples were collected to assess the presence of illicit substances. Once in the study, participants visited the Institute's clinic on a weekly basis to do the following:

• have further interviews
• receive study drugs
• undergo neuropsychiatric assessment
• have counselling that focused on relapse prevention
• deposit fresh urine samples under supervision

Participants were mostly male (80%), smoked tobacco daily and preferred to inject amphetamine (70%) than take it in other ways.

All participants were randomly assigned by computer to receive capsules of one of the following interventions:

• naltrexone 50 mg per day
• fake naltrexone (placebo) daily

The 12-week trial was double blind; that is, neither the study team nor participants knew who received naltrexone until the study ended and the trial was unblinded.

Results -- Recovery

Based on the assessment of urine samples, participants who received naltrexone were more likely to stay away from amphetamine compared to those on placebo. This difference was statistically significant; that is, not likely due to chance alone. Moreover, people who received naltrexone took twice as long to relapse than people on placebo.

However, there are indications that naltrexone is not 100% effective. For instance, by the end of the study, 50% of naltrexone users and 30% of people on placebo continued to abstain from amphetamine use.

According to the study team, "participants who received naltrexone experienced a greater reduction in [amphetamine] craving ... compared with the placebo group, and this was evident from week 4 onward."

Safety

A total of 14 participants in the naltrexone group reported side effects such as the following:

• headache
• lack of energy
• gastrointestinal discomfort

They noted that these symptoms were mild.

Dropouts

Although 80 participants entered the study, only 55 people (69%) completed it. There were no statistically significant differences between dropouts in people assigned to placebo compared to people assigned to naltrexone. People generally dropped out of the trial because of an inability to regularly visit the study clinic.

Key Findings

The Swedish scientists note that their findings suggest the following:

• Adherence to naltrexone was an important part of the effort to reduce consumption of amphetamine.
• Naltrexone appears to reduce the craving for amphetamine. With reduced craving, participants were less likely to relapse.
• Participants did not attempt to compensate for the lost high from amphetamine abstinence by bingeing on other drugs such as alcohol. Previous research has found that naltrexone can be used to help people recover from alcohol addiction.
• Having a diagnosis of ADHD (attention deficit hyperactivity disorder) did not affect recovery from amphetamine addiction.
• Relapse-prevention counselling was an essential part of the recovery process.

Surprising Findings in Urine

In Sweden, like much of Scandinavia, the use of amphetamine is more common than methamphetamine. However, this appears to be changing. Indeed, urine analysis revealed that 16% of study participants were taking methamphetamine. Previous studies in animals addicted to methamphetamine suggested that naltrexone might be useful in helping them recover from addiction. The Swedish researchers suggest that the results from the present study support further research with naltrexone in people addicted to crystal meth (Johan Franck, MD, PhD, Karolinska Institutet, personal communication).

Stories of Addiction and Recovery

The Swedish team generously included the perspective of two study participants and their experience of addiction and the study.

Story 1

Ms. L was a 54-year-old woman whose history of amphetamine addiction began at age 14. Her father and paternal grandfather had suffered from alcohol addiction. She married at age 18, had four children and then divorced. Since then she has lived alone in a trailer. Significant periods of being drug-free occurred during her four pregnancies. The impetus for her seeking change came from her youngest daughter, who gave her an ultimatum: she could only attend her daughter's 20th birthday party if she had started treatment.

Before entering the study, Ms. L used between 1.0 and 1.5 grams of amphetamine daily. During the study she received naltrexone and after her 4th week she decided to "test" the effect of amphetamine by taking a dose. She reported: "I just did not get high from my usual dose of amphetamine. Suddenly, I felt free." She attributed this reaction to diminished craving for amphetamine and the skills she had learned as a result of counselling. Ever since the study and escaping from the grip of amphetamine, Ms. L reported a greater interest in self-care; her diet is more nutritious and she enjoys better relations with family and friends.

Story 2

Mr. S was 45 years old and sought help because his amphetamine use was leading to feelings of exhaustion and difficulty concentrating. His entrée to the drug world began in the factory where he worked. His co-workers often used amphetamine, which helped sustain their energy and made bearable the monotony of factory life. His father was addicted to alcohol.

Interestingly, in a glimpse of how amphetamine use can make it difficult for some people to recognize their addiction and its destructive impact, Mr. S claimed that he did not view amphetamine use as problematic because none of his co-workers or friends "experienced him as different while on drugs." Yet he conceded that his prolonged drug use was a major factor in his divorce.

He also received naltrexone in the study and said: "I have never considered my drug use a problem and had no intention of stopping, but now I don't feel like taking amphetamine -- I don't even think about it."

At the end of the study he also felt the need to "test" the effect of amphetamine and reported that "the nice feeling" was gone. He then requested a prescription for more naltrexone to help keep him amphetamine-free.

There are limitations to this study, such as the low proportion of women and the lack of people with serious co-existing health conditions such as major depression and HIV. Moreover, the study only lasted three months. Hopefully, future studies will explore these issues.

Bear in mind that the Swedish study is merely the first step in what will likely be many more studies on the potential role of different doses of oral naltrexone in assisting recovery from amphetamine and methamphetamine. Intensive counselling is sure to be part of those studies.

References

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