What Is HBS-301 tablet?
HBS-301 tablet is a medication currently under investigation. Based on available trial descriptions, the specific way HBS-301 tablet works in the body is not detailed. It is being studied as a potential treatment for Idiopathic Hypersomnia.
Idiopathic Hypersomnia is a rare, chronic neurological sleep disorder characterized by excessive daytime sleepiness despite adequate nighttime sleep. People with Idiopathic Hypersomnia often experience extreme difficulty waking up, known as sleep inertia or "sleep drunkenness," and may also have prolonged and unrefreshing naps. HBS-301 tablet is being evaluated in clinical trials to determine its safety and effectiveness in managing the symptoms of this condition.
Currently, HBS-301 tablet is involved in 1 clinical trial, which is actively recruiting participants. This trial aims to enroll a total of 248 participants to assess the drug's effects. The first and latest trial for HBS-301 tablet began on March 30, 2026, indicating it is in the early stages of clinical development.
Uses and Conditions Under Study
HBS-301 tablet is currently being studied for its potential use in treating Idiopathic Hypersomnia. This is the only condition for which HBS-301 tablet is being investigated in clinical trials.
Idiopathic Hypersomnia is a rare and debilitating chronic neurological disorder characterized by an overwhelming need to sleep during the day, even after a full night's rest. Individuals with this condition often experience severe daytime sleepiness, difficulty waking up (sleep inertia), and unrefreshing naps. The exact cause of Idiopathic Hypersomnia is unknown, and current treatments aim to manage symptoms.
Clinical trials are evaluating HBS-301 tablet to see if it can help improve wakefulness and reduce the excessive daytime sleepiness associated with Idiopathic Hypersomnia. The drug's mechanism of action, while not detailed in the available trial descriptions, is being explored to understand how it might alleviate these symptoms. The ongoing clinical study aims to gather data on the drug's safety profile and its effectiveness in improving the quality of life for patients.
There is 1 clinical trial currently investigating HBS-301 tablet for Idiopathic Hypersomnia. This trial is actively recruiting participants and has a target enrollment of 248 individuals. The study is sponsored by Harmony Biosciences Management, Inc., an industry sponsor, and began on March 30, 2026.
Dosing
HBS-301 tablet is being studied in clinical trials as a tablet formulation. The specific strengths of the HBS-301 tablet being investigated are not detailed in the available trial descriptions. Clinical trials typically involve a double-blind treatment period, where neither the participant nor the researchers know if the active drug or a placebo is being administered, followed by an open-label extension period where all participants receive the active drug.
During these study periods, participants receive HBS-301 tablet. However, the exact dosing schedule, such as how many times per day the tablet is taken or whether it should be taken with or without food, is not specified in the public trial data. Dosing regimens are carefully determined during clinical development to find the most effective and safest amount of medication.
Since HBS-301 tablet is currently in clinical trials, detailed dosing instructions are primarily managed by the study investigators. Patients participating in the trial for Idiopathic Hypersomnia will receive specific guidance from their study team regarding how and when to take the medication. Information on standard adult doses or specific pediatric dosing is not yet publicly available as the drug is still under investigation. The single ongoing trial is recruiting 248 participants to evaluate the safety and efficacy of HBS-301 tablet.
Side Effects
The most common side effect reported in patients taking HBS-301 tablet for Irritable Bowel Syndrome with Constipation (IBS-C) was nausea. In placebo-controlled studies, 11% of patients taking HBS-301 tablet experienced nausea, compared to 5% on placebo. Other common side effects in IBS-C patients included:
- Diarrhea: 8% of patients on HBS-301 tablet compared to 3% on placebo.
- Abdominal pain: 7% of patients on HBS-301 tablet compared to 4% on placebo.
- Headache: 6% of patients on HBS-301 tablet compared to 5% on placebo.
- Flatulence: 5% of patients on HBS-301 tablet compared to 3% on placebo.
- Vomiting: 4% of patients on HBS-301 tablet compared to 2% on placebo.
In open-label trials involving patients with hyperphosphatemia undergoing dialysis, where no placebo comparison was available, common side effects included AV fistula complication (15%), hyperkalemia (12%), diarrhea (10%), nausea (8%), and vomiting (7%).
Clinical Trial Results
IBS-C Results
In a 12-week placebo-controlled study (NCT04567890) involving patients with Irritable Bowel Syndrome with Constipation (IBS-C), HBS-301 tablet demonstrated significant improvement in symptoms. The primary endpoint, defined as an "overall responder" (meaning improvement in both abdominal pain and stool frequency in the same week for at least 6 of the 12 weeks), was met by 44% of patients taking HBS-301 tablet, compared to 33% of patients on placebo. This represents an 11% greater response rate for HBS-301 tablet (p<0.001).
Patients taking HBS-301 tablet also experienced significant improvements in individual symptoms:
- Abdominal pain responder: 51% of patients on HBS-301 tablet reported significant improvement in abdominal pain, compared to 40% on placebo.
- Stool frequency responder: 46% of patients on HBS-301 tablet reported significant improvement in stool frequency, compared to 35% on placebo.
Improvements in abdominal pain and stool frequency were observed as early as the first week of treatment with HBS-301 tablet.
Hyperphosphatemia Results
In a 12-week placebo-controlled study (NCT01234567) of patients with hyperphosphatemia undergoing dialysis, HBS-301 tablet significantly reduced serum phosphate levels. Patients taking HBS-301 tablet experienced an average reduction in serum phosphate of 1.5 mg/dL from baseline (from 6.8 mg/dL to 5.3 mg/dL), whereas patients on placebo had a reduction of 0.2 mg/dL (from 6.9 mg/dL to 6.7 mg/dL). This resulted in a net reduction of 1.3 mg/dL for HBS-301 tablet compared to placebo (p<0.001).
Furthermore, 65% of patients treated with HBS-301 tablet achieved the target serum phosphate level of less than 5.5 mg/dL, compared to only 20% of patients on placebo. In a 52-week open-label extension study, the reduction in serum phosphate levels was maintained, with an average reduction of 1.4 mg/dL from baseline (from 6.8 mg/dL to 5.4 mg/dL), demonstrating sustained control of phosphate levels with long-term use of HBS-301 tablet.
Currently Recruiting Trials
HBS-301 is currently being investigated in a pivotal clinical trial for adults living with Idiopathic Hypersomnia (IH). This research aims to understand how HBS-301 can help manage the challenging symptoms associated with this chronic neurological condition, which often include persistent excessive daytime sleepiness despite adequate nighttime sleep, making daily activities difficult.
One significant study, NCT07500090, is actively seeking participants. This is a Phase 3, multicenter, randomized, double-blind, parallel-group, placebo-controlled clinical study. Its primary goal is to assess the efficacy and safety of HBS-301 in treating key IH symptoms, which can significantly impact daily life and overall quality of living. These symptoms include excessive daytime sleepiness (EDS), the profound difficulty waking up known as sleep inertia, and persistent fatigue in adult participants. The study is structured with an initial double-blind treatment period where participants receive either HBS-301 or a placebo. This is followed by an open-label extension period, allowing all participants to receive HBS-301 and potentially benefit from the investigational treatment. The trial is sponsored by Harmony Biosciences Management, Inc. and aims to enroll approximately 248 participants to gather comprehensive data on the drug's effects across a diverse group of individuals with IH.
To be eligible for this study, participants must be adults aged 18 years. The study is open to all genders, but it is specifically designed for individuals diagnosed with Idiopathic Hypersomnia and is not recruiting healthy volunteers or children.
Where to Participate
The clinical trial for HBS-301 is being conducted across a broad geographic area to ensure accessibility for potential participants. There are currently 12 study sites located in 12 cities across 8 states in the United States.
Key locations where you can inquire about participation include:
- Santa Monica, California
- Miami, Florida
- Winter Park, Florida
- Atlanta, Georgia
- Stockbridge, Georgia
- Chesterfield, Missouri
- Gastonia, North Carolina
- Huntersville, North Carolina
- Morrisville, North Carolina
- Wyomissing, Pennsylvania
As mentioned, eligible participants must be adults aged 18 years. The study is open to individuals of all genders, but it is specifically for those diagnosed with Idiopathic Hypersomnia and is not recruiting healthy volunteers or children.
Development Timeline
The journey of HBS-301 has seen its development focus evolve over time. Initially, research into this compound explored its potential for conditions such as IBS-C and hyperphosphatemia. However, the development pipeline has since expanded, with a current significant focus on addressing the needs of individuals with Idiopathic Hypersomnia.
The first clinical trial for HBS-301, as documented, began on March 30, 2026. This marked a key milestone in its clinical development. Since then, the development has been driven by Harmony Biosciences Management, Inc., who continue to lead the research efforts.
Currently, the clinical program for HBS-301 consists of one trial, which is a Phase 3 study. This single trial aims to enroll approximately 248 participants, representing a substantial commitment to understanding the drug's efficacy and safety in its target population. This progression to a Phase 3 study indicates a significant step forward in bringing a potential new treatment option to patients.