Pharmacotherapeutic group: Psycholeptics, orexin receptor antagonists, ATC code: N05CJ03
Mechanism of action
Daridorexant is a dual orexin receptor antagonist, acting on both orexin 1 and orexin 2 receptors and equipotent on both. The orexin neuropeptides (orexin A and orexin B) act on orexin receptors to promote wakefulness. Daridorexant antagonises the activation of orexin receptors by the orexin neuropeptides and consequently decreases the wake drive, allowing sleep to occur, without altering the proportion of sleep stages (as assessed by electroencephalographic recording in rodents or polysomnography in patients with insomnia).
Clinical efficacy and safety
The efficacy of daridorexant was evaluated in two multicentre, randomised, double-blind, placebo-controlled, parallel-group, Phase 3 studies, Study 1 and Study 2, which were identical in design.
A total of 1854 subjects with insomnia disorder (dissatisfaction with sleep quantity or quality, for at least 3 months, with clinically significant distress or impairment in daytime functioning) were randomised to receive daridorexant or placebo once daily, in the evening, for 3 months. Study 1 randomised 930 subjects to daridorexant 50 mg (N = 310), 25 mg (N = 310), or placebo (N = 310). Study 2 randomised 924 subjects to daridorexant 25 mg (N = 309), 10 mg (N = 307), or placebo (N = 308). At baseline, the proportion of subjects with an Insomnia Severity Index (ISI) score between 8–14, 15–21, and 22–28, was 12%, 58%, and 30%, respectively.
At the end of the 3-month treatment period, both confirmatory studies included a 7-day placebo run-out period, after which subjects could enter a 9-month double-blind, placebo-controlled extension study (Study 3). A total of 576 subjects were treated with daridorexant for at least 6 months of cumulative treatment, including 331treated for at least 12 months.
In Study 1, subjects had a mean age of 55.4 years (range 18 to 88 years), with 39.1% of subjects ≥ 65 years of age, including 5.8% ≥ 75 years of age. The majority were female (67.1%).
In Study 2, subjects had a mean age of 56.7 years (range 19 to 85 years), with 39.3% of subjects ≥ 65 years of age, including 6.1% ≥ 75 years of age. The majority were female (69.0%).
Primary efficacy endpoints for both studies were the change from baseline to Month 1 and Month 3 in Latency to Persistent Sleep (LPS) and Wake After Sleep Onset (WASO), measured objectively by polysomnography in a sleep laboratory. LPS is a measure of sleep induction and WASO is a measure of sleep maintenance.
Secondary endpoints included in the statistical testing hierarchy with Type 1 error control were patient-reported Total Sleep Time (sTST), evaluated every morning at home using a Sleep Diary Questionnaire (SDQ), and patient-reported daytime functioning, assessed using the sleepiness domain of the Insomnia Daytime Symptoms and Impacts Questionnaire (IDSIQ), every evening at home. The IDSIQ total score, Alert/cognition, and Mood domain scores were also evaluated to complete the assessment of daytime functioning.
Effect of daridorexant on sleep and daytime functioning
Across the two studies, the efficacy of daridorexant increased with increasing dose on objective (LPS, WASO) and subjective (sTST) sleep variables as well as on daytime functioning as assessed by IDSIQ scores, both at Month 1 and Month 3.
In Study 1, the 50 mg dose showed statistically significant (p < 0.001) improvements compared to placebo on all primary and secondary endpoints. For the 25 mg dose, statistical significance was consistently achieved on WASO and sTST across both studies, and on LPS in Study 1. The 10 mg dose was not effective.
The efficacy of daridorexant was similar across subgroups based on age, sex, race and region.
Table 2 : Efficacy on sleep variables and daytime functioning – Study 1
| | 50 mg N = 310 | 25 mg N = 310 | Placebo N = 310 |
| WASO (wake after sleep onset, min): sleep maintenance, assessed objectively by PSG |
| Baseline | Mean (SD) | 95 (38) | 98 (39) | 103 (41) |
| Month 1 | Mean (SD) | 65 (35) | 77 (42) | 92 (42) |
| Change from baseline LSM (95% CL) | -29 [-33, -25] | -18 [-22, -15] | -6 [-10, -2] |
| Difference to placebo LSM (95% CL) | -23 [-28, -18] | -12 [-17, -7] | |
| Month 3 | Mean (SD) | 65 (39) | 73 (40) | 87 (43) |
| Change from baseline LSM (95% CL) | -29 [-33, -25] | -23 [-27, -19] | -11 [-15, -7] |
| Difference to placebo LSM (95% CL) | -18 [-24, -13] | -12 [-17, -6] | |
| LPS (latency to persistent sleep, min): sleep onset, assessed objectively by PSG |
| Baseline | Mean (SD) | 64 (37) | 67 (39) | 67 (40) |
| Month 1 | Mean (SD) | 34 (27) | 38 (32) | 46 (36) |
| Change from baseline LSM (95% CL) | -31 [-35, -28] | -28 [-32, -25] | -20 [-23, -17] |
| Difference to placebo LSM (95% CL) | -11 [-16, -7] | -8 [-13, -4] | |
| Month 3 | Mean (SD) | 30 (23) | 36 (34) | 43 (34) |
| Change from baseline LSM (95% CL) | -35 [-38, -31] | -31 [-34, -27] | -23 [-26, -20] |
| Difference to placebo LSM (95% CL) | -12 [-16, -7] | -8 [-12, -3] | |
| sTST (subjective total sleep time, min): patient-reported |
| Baseline | Mean (SD) | 313 (58) | 310 (60) | 316 (53) |
| Month 1 | Mean (SD) | 358 (74) | 345 (66) | 338 (65) |
| Change from baseline LSM (95% CL) | 44 [38, 49] | 34 [29, 40] | 22 [16, 27] |
| Difference to placebo LSM (95% CL) | 22 [14, 30] | 13 [5, 20] | |
| Month 3 | Mean (SD) | 372 (79) | 358 (72) | 354 (73) |
| Change from baseline LSM (95% CL) | 58 [51, 64] | 48 [41, 54] | 38 [31, 44] |
| Difference to placebo LSM (95% CL) | 20 [11, 29] | 10 [1, 19] | |
| IDSIQ sleepiness domain score (daytime functioning): patient-reported |
| Baseline | Mean (SD) | 22.5 (7.2) | 22.1 (6.9) | 22.3 (6.9) |
| Month 1 | Mean (SD) | 18.6 (7.8) | 19.4 (7.1) | 20.3 (6.9) |
| Change from baseline LSM (95% CL) | -3.8 [-4.3, -3.2] | -2.8 [-3.3, -2.2] | -2.0 [-2.6, -1.5] |
| Difference to placebo LSM (95% CL) | -1.8 [-2.5, -1.0] | -0.8 [-1.5, 0.0] | |
| Month 3 | Mean (SD) | 16.5 (8.1) | 17.3 (7.6) | 18.5 (7.8) |
| Change from baseline LSM (95% CL) | -5.7 [-6.4, -5.0] | -4.8 [-5.5, -4.1] | -3.8 [-4.5, -3.1] |
| Difference to placebo LSM (95% CL) | -1.9 [-2.9, -0.9] | -1.0 [-2.0, 0.0] | |
CL = confidence limits; IDSIQ = Insomnia Daytime Symptoms and Impacts Questionnaire; LSM = least squares mean; PSG = polysomnography; SD = standard deviation.
Table 3 : Efficacy on sleep variables and daytime functioning – Study 2
| | 25 mg N = 309 | Placebo N = 308 |
| WASO (wake after sleep onset, min): sleep maintenance, assessed objectively by PSG |
| Baseline | Mean (SD) | 106 (49) | 108 (49) |
| Month 1 | Mean (SD) | 80 (44) | 93 (50) |
| Change from baseline LSM (95% CL) | -24 [-28, -20] | -13 [-17, -8] |
| Difference to placebo LSM (95% CL) | -12 [-18, -6] | |
| Month 3 | Mean (SD) | 80 (49) | 91 (47) |
| Change from baseline LSM (95% CL) | -24 [-29, -19] | -14 [-19, -9] |
| Difference to placebo LSM (95% CL) | -10 [-17, -4] | |
| LPS (latency to persistent sleep, min): sleep onset, assessed objectively by PSG |
| Baseline | Mean (SD) | 69 (41) | 72 (46) |
| Month 1 | Mean (SD) | 42 (39) | 50 (40) |
| Change from baseline LSM (95% CL) | -26 [-31, -22] | -20 [-24, -16] |
| Difference to placebo LSM (95% CL) | -6 [-12, -1] | |
| Month 3 | Mean (SD) | 39 (37) | 49 (46) |
| Change from baseline LSM (95% CL) | -29 [-33, -24] | -20 [-24, -15] |
| Difference to placebo LSM (95% CL) | -9 [-15, -3] | |
| sTST (subjective total sleep time, min): patient-reported |
| Baseline | Mean (SD) | 308 (53) | 308 (52) |
| Month 1 | Mean (SD) | 353 (67) | 336 (63) |
| Change from baseline LSM (95% CL) | 44 [38, 49] | 28 [22, 33] |
| Difference to placebo LSM (95% CL) | 16 [8, 24] | |
| Month 3 | Mean (SD) | 365 (70) | 347 (65) |
| Change from baseline LSM (95% CL) | 56 [50, 63] | 37 [31, 43] |
| Difference to placebo LSM (95% CL) | 19 [10, 28] | |
| IDSIQ sleepiness domain score (daytime functioning): patient-reported |
| Baseline | Mean (SD) | 22.2 (6.2) | 22.6 (5.8) |
| Month 1 | Mean (SD) | 18.7 (6.5) | 19.8 (6.3) |
| Change from baseline LSM (95% CL) | -3,5 [-4.1, -2.9] | -2.8 [-3.3, -2.2] |
| Difference to placebo LSM (95% CL) | -0.8 [-1,6, 0.1] | |
| Month 3 | Mean (SD) | 17.0 (7.0) | 18.4 (6.6) |
| Change from baseline LSM (95% CL) | -5.3 [-6.0, -4.6] | -4.0 [-4.7, -3.3] |
| Difference to placebo LSM (95% CL) | -1.3 [-2.2, -0.3] | |
CL = confidence limits; IDSIQ = Insomnia Daytime Symptoms and Impacts Questionnaire; LSM = least squares mean; PSG = polysomnography; SD = standard deviation.
Rebound insomnia
The potential for rebound insomnia was assessed during the placebo run-out period after 3 months of treatment with daridorexant in Study 1 and Study 2, looking at the change from baseline to the run-out period in LPS, WASO and sTST. At the recommended dose of 50 mg, for all three endpoints, the mean values at run-out were improved compared to baseline (–15, –3 and 43 min for LPS, WASO and sTST, respectively), indicating that no sign of rebound insomnia was observed upon treatment discontinuation.
Middle of the night safety
The effect of daridorexant on middle of the night safety was evaluated in a randomised, placebo-controlled trial in 18 healthy adult (< 65 years) and 18 healthy elderly (≥ 65 years) subjects. Postural stability measured by assessing body sway using a body sway meter approximately 5 min after awakening was assessed following a scheduled awakening 4 hours after administration of 25 or 50 mg daridorexant. The ability to awaken in response to a sound stimulus and cognitive function (memory) were also evaluated.
In the subgroup of healthy adults (< 65 years), nighttime dosing of daridorexant 25 mg and 50 mg resulted in increased body sway, with differences in least squares mean (95% CI) of 64.8 mm (16.0, 113.7) and 97.3 mm (48.4, 146.1), respectively, as compared to placebo.
Paediatric population
The European Medicines Agency has deferred the obligation to submit the results of studies with daridorexant in one or more subsets of the paediatric population in insomnia (see section 4.2 for information on paediatric use).