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tasimelteon

Phase 3FDA approved

Insomnia Disorder | Small molecule | Psychiatry |Vanda Pharmaceuticals Inc.|Trials Updated: Oct 9, 2026

tasimelteon development status

FDA approval on record Jan 31, 2014
Approval holderVanda Pharms Inc
ApplicationNDA205677
Highest phase Phase 3
Registered trials 21 across 2 sponsors since Jun 2007

Label indication HETLIOZ is a melatonin receptor agonist. HETLIOZ capsules are indicated for the treatment of: Non-24-Hour Sleep-Wake Disorder (Non-24) in adults ( 1 ) Nighttime sleep disturbances in Smith-Magenis Syndrome (SMS) in patients 16 years of age and older ( 1 ) HETLIOZ LQ oral suspension is indicated for the treatment of: Nighttime sleep disturbances in SMS in pediatric patients 3 years to 15 years of age ( 1 ) 1.1… FDA label

tasimelteon target and mechanism

Molecular targetMTNR1A, MTNR1B
Target classAgonist
ModalitySmall molecule

Also known as Tasimelteon Oral Capsule, Tasimelteon Oral Suspension, Hetlioz, VEC-162, BMS-214778

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLED
Total Trials16
Total Enrollment2,643

FDA Designations

No designations recorded

tasimelteon clinical trials

tasimelteon · 16 trials · 18 indications

Phase 3 9Phase 2 4Phase 1 3
NCT06953869Evaluating the Effects of Tasimelteon vs. Placebo in Treating Pediatric InsomniaInsomnia Disorder
RECRUITING420 Analytics
NCT06701396Evaluating the Effects of Tasimelteon Vs. Placebo in Delayed Sleep-Wake Phase Disorder (DSWPD) and the CRY1Δ11 VariantSleep Wake Disorders
RECRUITING60 Analytics
NCT04652882Evaluating the Effects of Tasimelteon vs. Placebo in Delayed Sleep-Wake Phase Disorder (DSWPD)Sleep Wake Disorders
COMPLETED43 Analytics
NCT03373201Evaluating the Effects of Tasimelteon vs. Placebo on Jet Lag Type InsomniaJet Lag Type Insomnia
COMPLETED320 Analytics
NCT01429116Tasimelteon for the Treatment of Non-24-hour Sleep-Wake Disorder (N24HSWD) in Blind Individuals With no Light PerceptionNon-24-Hour Sleep-Wake Disorder
COMPLETED200 Analytics
NCT01430754Withdrawal Study to Demonstrate the Maintenance Effect in the Treatment of Non-24-Hour Sleep-Wake DisorderNon-24-Hour Sleep-Wake Disorder
COMPLETED20 Analytics
NCT01163032Efficacy and Safety of Tasimelteon Compared With Placebo in Totally Blind Subjects With Non-24-Hour Sleep-Wake DisorderNon-24-Hour Sleep-Wake Disorder
COMPLETED136 Analytics
NCT00548340VEC-162 Study in Adult Patients With Primary InsomniaPrimary Insomnia
COMPLETED322 Analytics
NCT00291187VEC-162 Study in Healthy Adult Volunteers in a Model of InsomniaInsomnia
COMPLETED411 Analytics
PHASE3RECRUITING
Evaluating the Effects of Tasimelteon vs. Placebo in Treating Pediatric Insomnia
Insomnia DisorderUnlock trial analytics
PHASE3RECRUITING
Evaluating the Effects of Tasimelteon Vs. Placebo in Delayed Sleep-Wake Phase Disorder (DSWPD) and the CRY1Δ11 Variant
Sleep Wake DisordersUnlock trial analytics
PHASE3COMPLETED
Evaluating the Effects of Tasimelteon vs. Placebo in Delayed Sleep-Wake Phase Disorder (DSWPD)
Sleep Wake DisordersUnlock trial analytics
PHASE3COMPLETED
Evaluating the Effects of Tasimelteon vs. Placebo on Jet Lag Type Insomnia
Jet Lag Type InsomniaUnlock trial analytics
PHASE3COMPLETED
Tasimelteon for the Treatment of Non-24-hour Sleep-Wake Disorder (N24HSWD) in Blind Individuals With no Light Perception
Non-24-Hour Sleep-Wake DisorderUnlock trial analytics
PHASE3COMPLETED
Withdrawal Study to Demonstrate the Maintenance Effect in the Treatment of Non-24-Hour Sleep-Wake Disorder
Non-24-Hour Sleep-Wake DisorderUnlock trial analytics
PHASE3COMPLETED
Efficacy and Safety of Tasimelteon Compared With Placebo in Totally Blind Subjects With Non-24-Hour Sleep-Wake Disorder
Non-24-Hour Sleep-Wake DisorderUnlock trial analytics
PHASE3COMPLETED
VEC-162 Study in Adult Patients With Primary Insomnia
Primary InsomniaUnlock trial analytics
PHASE3COMPLETED
VEC-162 Study in Healthy Adult Volunteers in a Model of Insomnia
InsomniaUnlock trial analytics

Study Endpoints

Primary Endpoints

Change in sleep latency, as measured by daily sleep diary.
12 Weeks
Latency to Persistent Sleep, as measured by polysomnography.
Two Nights
Change in Sleep Onset over the treatment period, as measured by sleep diary.
28 days
Total Sleep Time in the First Two Thirds of the Night
1 Day

Total sleep time during the first 2/3 of the night following an 8-hour phase advance bedtime, as measured by PSG. This is representative of trans meridian travel across 8 time zones.

Number of participants with Treatment-Emergent Adverse Events (AEs)
24 months + 12 month optional extension

Treatment-emergent adverse events will be summarized by presenting the number and percentage of patients having any treatment-emergent AE, having an AE in each body system, and having each individual AE.

Maintenance of Entrainment (aMT6s) in Subjects With N24HSWD.
Approximately 12 weeks

Entrainment is a measure of synchronization of the master body clock to the 24-hour day. The circadian period (τ) was calculated using urinary aMT6s collected over four separate 48 hour periods, approximately 1 week apart, during the run-in and randomized phases of the trial. Maintenance of entrainment is defined as the proportion of subjects who become non-entrained to a 24 hour day after randomization to tasimelteon or placebo. Non-entrainment was defined as having a post-baseline τ value ≥ 24.1 or the lower bound of the 95% CI \>24.0.

Proportion of Patients Entrained as Assessed by Urinary aMT6
1 month

Entrainment is a measure of synchronization of the master body clock to the 24-hour day. The circadian period (τ) was calculated using urinary aMT6s collected over four 48 hour periods , collected approximately 1 week apart for 4 separate weeks, during the screening and month 1 of the randomization phase of the trial. Entrainment was defined as having a post-baseline τ value less than 24.1 and a 95% CI that included 24.0.

Proportion of Patients With a Clinical Response: Entrainment of aMT6 and Score of ≥ 3 on N24CRS
6 months

Clinical response is defined as the coincident demonstration of entrainment (aMT6) and a score ≥ 3 on the Non-24 Clinical Response Scale (N24CRS). N24CRS measures improvement in sleep-wake measures and overall functioning (LQ-nTST, UQ-dTSD, MoST and CGI-C). Each assessment is scored as a 1 or 0 depending on the pre-specified threshold (see below). LQ-nTST: \>45 minutes increase in average nighttime sleep duration; UQ-dTSD: \>45 minutes decrease in average daytime sleep duration; MoST: \>30 minutes increase and a standard deviation \<2 hours during double-masked phase (6 months); CGI-C: \<2.0 from the average of D112 and Day 183 compared to baseline For patients randomized to tasimelteon 20 mg and who also participated in the screening phase of Study 3203 (month 7 of treatment), the screening τ from Study 3203 was used if the patient did not become entrained in Study 3201 but did become entrained during the screening phase of Study 3203.

Average Change From Baseline - Latency to Persistent Sleep (LPS)
Baseline, Night 1, and Night 8 measurement

Average latency to persistent sleep is defined as the length of time elapsed between lights off and onset of persistent sleep (defined as the point at which 10 minutes of uninterrupted sleep has begun as determined by PSG) between Baseline and the average of nights 1 and 8.

Average Improvement of Latency to Persistent Sleep (LPS)
Night 1

The average improvement in Latency to persistent sleep (the number of minutes between Lights Off and the onset of at least 10 minutes of persistent sleep, as measured by polysomnography) is defined as the difference observed in the VEC-162 treated subjects compared with placebo treated subjects.

Total Sleep Time in the First Two-Thirds of the Night on the Night(s) Most Likely to be Disrupted
4 days

Measured using polysomnography (PSG) and analyzed as change from baseline. Examination of the observational phase baseline data demonstrated that Night 3 was the night most disrupted.

To determine the efficacy of tasimelteon administered daily compared to placebo, as measured by improvement in sleep parameters
9 Weeks
Change From Baseline to Endpoint at Week 8 Using the Total Score of the Hamilton Depression Rating Scale (HAM-D)
8 weeks

Hamilton Rating Scale for Depression (HAM-D) assesses the range of symptoms that are most frequently observed in subjects with major depressive disorder (MDD) on a scale from 0 to 52. Higher HAM-D scores indicate more severe levels of depressive symptoms, thus, a negative change from baseline indicates a reduction (or improvement) in depressive symptoms.

Circadian Phase Shift
Night 3 and Night 4

Exposure response to VEC-162 on induction of circadian phase shift as measured by Dim Light Melatonin Onset (DLMO) was defined as the time change between Night 3 and Night 4 when melatonin production reached 25% of the maximum melatonin concentration. Samples below LOQ of the melatonin assay were assigned 5 pg/ml.

Mean Sleep Efficiency
Night 4 and Night 2

Exposure response was measured by comparing the change in sleep efficiencies of VEC-162 and placebo treated subjects upon a sleep schedule phase advance. Sleep efficiency (total time asleep divided by the time allowed as an opportunity for sleep in a period multiplied by 100%, where time allowed for sleep was 8 hours or 480 minutes) was measured objectively by overnight polysomnographic recordings. Sleep efficiency was also compared in parts of the night by dividing the full night into thirds.

Area under the curver (AUC) of tasimelteon and its metabolites
Pre-dose, 15 minutes post dose, 30 minutes post dose,1 hour post dose, 2 hours post dose, 4 hours post dose
Maximum concetration (Cmax) of tasimelteon and its metabolites
Pre-dose, 15 minutes post dose, 30 minutes post dose,1 hour post dose, 2 hours post dose, 4 hours post dose
Steady-state concentration (Css) of tasimelteon and its metabolites
Pre-dose, 15 minutes post dose, 30 minutes post dose,1 hour post dose, 2 hours post dose, 4 hours post dose
Half-life of tasimelteon and its metabolites
Pre-dose, 15 minutes post dose, 30 minutes post dose,1 hour post dose, 2 hours post dose, 4 hours post dose
Trough concentration (Ctrough) of tasimelteon and its metabolites
Pre-dose, 15 minutes post dose, 30 minutes post dose,1 hour post dose, 2 hours post dose, 4 hours post dose
Safety and tolerability of tasimelteon as measured by spontaneous reporting of adverse events (AEs)
Day 1
Safety and tolerability of tasimelteon as measured by Pediatric Adverse Event Reporting System (PAERS)
Day 1
Tasimelteon pharmacokinetic parameters (AUC, Cmax, Tmax)
Predose, 0.25, 1, 1.5, 2, 4, 6, 8, 12, 24, 30, and 36 hours post-dose
Plasma concentrations and PK of tasimelteon
36 hours

To assess plasma concentrations and pharmacokinetics of tasimelteon in subjects with mild or moderate hepatic impairment compared to healthy subjects with normal hepatic function.

Secondary Endpoints

Change in nighttime subjective sleep parameters, such as sleep quality, as measured by sleep diary.
12 Weeks
Change in nighttime subjective sleep parameters, such as sleep time, as measured by sleep diary.
12 Weeks
Change in daytime functioning, as measured by questionnaire.
12 Weeks
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
TasimelteonEXPERIMENTAL -
PlaceboPLACEBO_COMPARATOR -
VEC-162 20 mgEXPERIMENTALVEC-162 (tasimelteon) 20 mg capsules PO daily for five weeks
VEC-162 50 mgEXPERIMENTALVEC-162 (tasimelteon) 50 mg capsules PO daily for five weeks
20 mg VEC-162EXPERIMENTAL20 mg taken orally 30 minutes prior to bedtime.
50 mg VEC-162EXPERIMENTAL50 mg taken orally 30 minutes prior to bedtime.
100 mg VEC-162EXPERIMENTAL100 mg taken orally 30 minutes prior to bedtime.
Pharmacokinetic DosingEXPERIMENTALSingle-dose pharmacokinetics of tasimelteon
End Stage Renal Disease, dialysisEXPERIMENTALeGFR \<15 ml/min/1.73m\^2
Severe renal impairmentEXPERIMENTALeGFR \< 29 ml/min/1.73m\^2
Healthy controlsEXPERIMENTALeGFR \> 80 mL/min/1.73m\^2 Matched to renally impaired subjects by age, gender, BMI, and smoking status
Moderate Hepatic ImpairmentEXPERIMENTAL -
Mild Hepatic ImpairmentEXPERIMENTAL -
Healthy VolunteersEXPERIMENTAL -

Interventions

NameTypeDescription
Tasimelteon Oral SuspensionDRUGSingle daily dose, weight-based liquid suspension formulation.
PlaceboDRUGPlacebo comparator.
TasimelteonDRUGOral capsule
VEC-162 20 mgDRUG20 mg VEC-162 (tasimelteon) capsules, PO daily for five weeks
VEC-162 50 mgDRUG50 mg VEC-162 (tasimelteon) capsules, PO daily for five weeks
20 mg VEC-162DRUG20 mg VEC-162
50 mg VEC-162DRUG50 mg VEC-162
100 mg VEC-162DRUG100 mg VEC-162
VEC-162DRUG -
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Eligibility Criteria

Age Range2 Years to 17 Years
SexALL
Healthy VolunteersNo
Study Sites35

Inclusion Criteria: * Ability and acceptance to provide written informed consent of the participant or legal guardian (and assent as required). * Confirmed clinical diagnosis of insomnia disorder * Males and Females between 2 and 17 years, inclusive. * The sleep disturbance must not be a result of ...

Countries:United StatesGermanyPolandUnited KingdomTurkey (Türkiye)Austria
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Competitive Landscape -Insomnia and Sleep Disorders 22 trials (matched to "Insomnia Disorder")

Top 2 of 6 competitors

CompanyTickerTrialsLead PhaseDrugs
Merck & Co., Inc.MRK1PHASE3Suvorexant
Vanda Pharmaceuticals Inc.VNDA2PHASE3tasimelteon
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Recent Changes (Last 90 Days)

HIGHOct 9, 2026NCT04652882Status: ACTIVE_NOT_RECRUITING → COMPLETED
HIGHOct 9, 2026NCT04652882Status: ACTIVE_NOT_RECRUITING → COMPLETED
MEDIUMJul 27, 2026NCT04652882Status: RECRUITING → ACTIVE_NOT_RECRUITING
MEDIUMJul 27, 2026NCT04652882Status: RECRUITING → ACTIVE_NOT_RECRUITING
MEDIUMJul 27, 2026NCT04652882Status: RECRUITING → ACTIVE_NOT_RECRUITING

Frequently asked questions about tasimelteon

What is tasimelteon used for?

Tasimelteon is being studied for circadian rhythm sleep disorders, including delayed sleep-wake phase disorder and jet lag type insomnia, as well as insomnia disorder, jet lag disorder, major depressive disorder, and hepatic impairment. It is an investigational small molecule developed by Vanda Pharmaceuticals Inc. (VNDA).

How does tasimelteon work?

Tasimelteon is an agonist of the melatonin receptors MTNR1A and MTNR1B. By activating these receptors, it is designed to influence circadian timing and sleep regulation. This mechanism underlies its investigation in circadian rhythm sleep disorders and related sleep conditions.

Who makes tasimelteon?

Tasimelteon is developed by Vanda Pharmaceuticals Inc., which trades under the ticker VNDA. Vanda is the sponsor of the clinical trials evaluating tasimelteon across circadian rhythm sleep disorders, insomnia disorder, jet lag disorder, and major depressive disorder.

What phase is tasimelteon in?

Tasimelteon is in clinical development, with Phase 3 trials in delayed sleep-wake phase disorder, jet lag type insomnia, and pediatric insomnia. It is investigational and has not been established as approved for these uses based on the available development information.

What clinical trials is tasimelteon in?

Tasimelteon trials include NCT06953869, a recruiting Phase 3 study in pediatric insomnia; NCT06701396, a recruiting Phase 3 study in delayed sleep-wake phase disorder and the CRY1Δ11 variant; NCT04652882, a completed Phase 3 DSWPD study; and NCT03373201, a completed Phase 3 study in jet lag type insomnia.

Is tasimelteon the same as Tasimelteon Oral Capsule or Tasimelteon Oral Suspension?

Yes. Tasimelteon Oral Capsule and Tasimelteon Oral Suspension are alternative names for tasimelteon, the same active drug developed by Vanda Pharmaceuticals Inc. (VNDA). The different names reflect the capsule and suspension formulations rather than distinct therapeutic agents.