Opioids appeared to be efficacious for treating symptoms of restless leg syndrome (RLS) but there is no definitive evidence regarding the issue of safety, a study published in Cochrane Database of Systematic Reviews concluded.

Symptoms of RLS start with the patient at rest and follow a pattern with increases during the evening or at night. Pharmacologic treatment is available for RLS including L-dopa and dopaminergic agonists, anticonvulsants, benzodiazepines, and opioids. Dopaminergic agents are the most commonly used treatments for RLS but some patients show inadequate response and need other medication. Opioids are recommended for patients with severe symptoms and are associated with adverse events such as constipation, tolerance, and dependence. 

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Researchers aimed to assess the effects of opioid vs. placebo for RLS in adults. They searched various databases up to April 2016 for randomized controlled clinical trials of treatment with opioids for adults with idiopathic RLS. 

One randomized clinical trial where 276 of the 304 randomized patients was included for analysis. The study evaluated prolonged release oxycodone/naloxone vs. placebo. After 12 weeks, RLS symptoms had improved more in the drug treatment arm vs. the placebo group (IRLSSS mean difference [MD] –7.0, 95% CI: –9.69 to –4.31; CGI MD –1.11, 95% CI: –1.49 to –0.73). Also, more patients in the drug arm were responders vs. the placebo arm (IRLSSS risk ratio [RR] 1.82, 95% CI: 1.37–2.42; CGI RR 1.92, 95% CI: 1.49–2.48). 

A higher proportion of remitters was seen in the drug arm vs. placebo (RR 2.14, 95% CI: 1.45–3.16) and the quality of life scores also improved more in this group vs. placebo (MD –0.73, 95% CI: –1.1 to –0.36). There was a greater improvement in the quality of life sleep in the drug group as measured by sleep adequacy (MD –0.74, 95% CI: –1.15 to –0.33) and sleep quantity (MD 0.89, 95% CI: 0.52–1.26). 

Study authors noted no difference for daytime somnolence, difficulty staying awake during the day, or naps during the day between the two groups. The oxycodone/naloxone arm also reported more adverse events (RR 1.22, 95% CI: 1.07–1.39). The evidence for this study was rated as moderate quality. 

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