How does cannabis use affect antipsychotics



The use of cannabis is relatively common and widespread around the world. The need for treatment for cannabis users has increased in most parts of the world. Measures to decriminalize or legalize cannabis use in some countries are likely to cause this trend to continue. There are currently no drugs specifically designed to treat cannabis use. The aim of this review was to assess the effectiveness and safety of drugs used to treat cannabis addiction.

Research date

We reviewed the scientific literature in March 2018.

Study characteristics

We found 21 randomized controlled trials (clinical trials in which people were randomly assigned to one of two or more treatment groups) of 909 participants on active medication and 846 participants on placebo (a dummy treatment). Main characteristics of drug addiction are compulsive use, loss of control over use, and withdrawal symptoms when use is stopped. This review includes studies in which participants were described as dependent or likely to be dependent due to cannabis use several days a week or daily.

The average age of participants in each study was between 22 and 41, with the exception of three studies that targeted young people. Most (75%) of the study participants were male. Most (16) of the studies were conducted in the United States, three in Australia, one in Canada, and one in Israel. The studies looked at a wide range of drugs that reduce symptoms of cannabis withdrawal and promote cessation or reduction in cannabis use.

Four studies received the study drugs from manufacturing pharmaceutical companies, but none were funded by pharmaceutical companies. One study did not report the funding or the origin of the drugs.

Main results

The endpoint of abstinence at the end of treatment were Δ9-Tetrahydrocannabinol (THC, the main ingredient in cannabis) preparations probably ineffective. Antidepressants called selective serotonin reuptake inhibitors, mixed-acting antidepressants, a drug called buspirone, and a drug called N-acetylcysteine ​​may also have been ineffective. We are also unsure about the effects of anti-epileptic drugs and mood stabilizers.

THC supplements, mixed-acting antidepressants, anti-epileptic drugs, and mood stabilizers may not have been effective by the endpoint of completing the planned duration of treatment. We were unsure about the effects of SSRI antidepressants, and N-acetylcysteine ​​likely did not aid completion of treatment. The use of anti-epileptic drugs and mood stabilizers could have increased the likelihood that people stopped taking treatment prematurely.

The likelihood of side effects was probably no higher with THC supplements and N-acetylcysteine ​​than with placebo. Mixed antidepressants and buspirone may not have been more likely to cause side effects than placebo, and we were unsure about SSRI antidepressants.

According to the current state of research, all drugs should still be classified as experimental.

Quality of the evidence

The quality of the evidence for many of the endpoints in this review was low or very low because each drug was examined by a small number of studies (from one to four), each study had a small number of participants, and there was inconsistent results and there was a risk of bias from study participants leaving treatment.