Targinact can be used as a second-line treatment for patients with severe or very severe RLS who have failed to respond adequately to, lost response to, or experienced unacceptable tolerability or augmentation with dopaminergic therapy. RLS symptoms should be present for at least 4 days per week.
Patients should be reviewed every 3 months during treatment and gradual withdrawal should be attempted after 1 year to ascertain whether continued use is necessary.
The combination tablets contain naloxone to counteract opioid-induced constipation by blocking the action of oxycodone at opioid receptors in the gut.
Evidence of the efficacy of prolonged-release oxycodone/naloxone in the treatment of RLS comes from a conducted in 306 patients with symptoms for at least 6 months and an International RLS Study Group severity rating scale sum score of at least 15.
Participants received twice-daily doses of either oxycodone 5mg/naloxone 2.5mg, increased as necessary to a maximum of oxycodone 40mg/naloxone 20mg, or placebo.
After 12 weeks of treatment, the mean change in International RLS Study Group rating scale sum score was −16.5 in the oxycodone/naloxone group and −9.4 in the placebo group (mean between-group difference 8.15, 95% CI 5.46–10.85; p<0.0001). The difference translated into an improvement from an average rating of 'very severe' to 'moderate'.
Patients who entered a 40-week open-label extension phase had a final mean International RLS Study Group rating scale sum score of 9.7, compared with a mean starting score of 15.4.
The safety profile of oxycodone/naloxone was as expected, with treatment-related adverse events occurring during the double-blind phase in 73% of patients compared with 43% of those in the placebo group. During the extension phase, 57% of patients experienced treatment-related adverse events. No augmentation was observed.
Very common adverse effects of the combination include somnolence, increased or decreased blood pressure, constipation and hyperhidrosis.