Somnol

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Somnol

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Method of action: Hypnotic

Treatment option: Insomnia

Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Somnol

What is Somnol? Definition and Classification

Property Description
Active ingredient Zopiclone
Form Oral tablets
Pharmacological class Nonbenzodiazepine Sedative-Hypnotic
Common use Insomnia and sleeping difficulties
Origin Synthetic organic compound

Somnol is a commercial brand name for the prescription-only medication containing the active ingredient Zopiclone. This compound is a synthetic organic compound chemically classified as a cyclopyrrolone derivative. Zopiclone belongs to the distinct pharmacological class of nonbenzodiazepine hypnotic agents, colloquially known as a "Z-drug." This classification is clinically recognized for its function as a sedative-hypnotic designed specifically to help manage sleeping difficulties and is typically indicated for the short-term treatment of insomnia.

Zopiclone: Mechanism, Composition, and Purpose

The medication is a single-ingredient product, supplied most commonly as oral tablets for oral route administration. The primary purpose of Zopiclone is to promote a state conducive to sleep, facilitating both sleep initiation and continuity for individuals experiencing persistent inability to fall asleep.

Zopiclone's mechanism of action involves enhancing the effects of the brain's main calming neurotransmitter, gamma-aminobutyric acid (GABA). Specifically, it functions as a positive allosteric modulator at the GABA-A receptor complex, which leads to a targeted decrease in central nervous system excitability. This interaction is designed to reinforce the body's natural processes for slowing down brain activity to achieve rest. The compound is manufactured as a racemic mixture of its R- and S-stereoisomers, which is a key compositional feature.

Regulatory References

  1. EMA Assessment Report (Zopiclone Jubilant)

What side effects are possible with Somnol?

Possible side effects and safety information

The safety profile of Somnol, which contains the active ingredient Zopiclone, is derived strictly from official government regulatory classifications, which organize adverse reactions by frequency and affected body system.


Officially Documented Adverse Reactions

The most frequently reported effects, generally classified as Common in regulatory documents, include a lingering dysgeusia (a bitter or metallic taste), somnolence (daytime drowsiness), headache, dizziness, and dry mouth or nausea. Less common effects, often classified as Uncommon or Rare, include psychiatric disturbances such as agitation, nightmares, confusion, and a transient loss of memory known as amnesia.

Serious Safety Patterns and Contraindications

Official regulatory warnings focus on rare but clinically significant risks. These include the potential for complex sleep behaviors, such as sleepwalking or sleep-driving, for which the patient has no recall, and which may lead to serious injury. Severe allergic reactions, including anaphylaxis and angioedema (swelling of the face or throat), are also officially documented. The drug is contraindicated in conditions like severe respiratory failure, severe sleep apnoea syndrome, and severe hepatic insufficiency.

Population and Duration Safety Constraints

The regulatory profile specifies that the risk of dependence and subsequent severe withdrawal symptoms (including rebound insomnia) increases with the duration of treatment, particularly if use extends beyond four weeks. Special caution is documented for older adults, where there is an officially stated increased risk of falls due to impaired motor and cognitive function. Furthermore, the safety and effectiveness of Zopiclone have not been established in the pediatric population (under 18 years of age).

Overdose and Emergency Response

Overdose and when to seek help

Suspected overdose of Somnol (Zopiclone) requires immediate medical attention. Regulatory authorities uniformly mandate that individuals contact emergency services without delay, regardless of the severity of the symptoms observed.

Documented Manifestations and Severe Outcomes

The official prescribing information describes the clinical presentation of Zopiclone overdose as a spectrum of central nervous system (CNS) depression. Initial signs may include somnolence, lethargy, confusion, ataxia, and hypotension. In severe overdose scenarios, the CNS depression can escalate to life-threatening outcomes such as respiratory depression and coma. The risk of these severe consequences, including death, is significantly increased when Zopiclone is ingested along with alcohol or other CNS depressants (poly-drug ingestion). Furthermore, specific official warnings note that elderly patients and those with existing hepatic or respiratory impairment may experience a greater severity of effects.

Official Management and Monitoring

Regulatory documents confirm that the standard approach to overdose management is providing symptomatic and supportive treatment. This often includes procedures such as maintaining a patent airway and monitoring cardiorespiratory function in a hospital setting. While specific management procedures like gastric lavage and activated charcoal are noted as potential supportive measures, the primary action is securing urgent hospital care. The use of Flumazenil, a specific GABA-A receptor antagonist, is mentioned as a conditional agent that medical professionals may consider.

Therapeutic Uses of Somnol

What Somnol Treats: Main Uses and Benefits

Somnol is a medication applied within therapeutic domains where short-term symptomatic assistance is needed for sleep disturbances. It is considered relevant in conditions presenting with acute episodes of insomnia, helping to ease symptoms that create noticeable interference with daily functioning. Zopiclone is indicated for the short-term treatment of severe insomnia.

The medication is relevant for easing symptom clusters related to difficulty falling asleep (prolonged sleep latency), frequent nocturnal awakenings, and waking too early without the ability to return to rest. It is generally applied during phases when symptoms become more noticeable and assists with maintaining functional stability.

This supportive relief contributes to improved comfort during periods of heightened symptoms. The patient benefit is often framed as a temporary respite: “This supportive relief may help patients cope more steadily with symptom fluctuations when the symptoms are most disruptive.”


Quick Fact: Relief for Sleep Initiation Failure

The medication is applied in addressing the symptom of taking too long to fall asleep, a key component of insomnia that interferes with daily comfort.

Eligibility and Restrictions for Use

Who Can and Cannot Use Somnol (Zopiclone)?

Eligibility for Somnol is defined by specific population restrictions, contraindications, and cautionary guidelines established in regulatory documents. The medication is approved for use in adults (18 years and older) for the short-term treatment of severe insomnia.


Contraindicated Populations (Must Not Use)

Category Exclusion Condition
Age Children and adolescents under 18 years of age (safety/efficacy not established).
Comorbidity Myasthenia gravis, severe hepatic insufficiency (severe liver failure), or severe respiratory insufficiency (severe breathing problems).
Adverse History Patients who have previously experienced complex sleep behaviors (e.g., sleepwalking) after taking zopiclone or a similar 'Z-drug'.

Use with Restriction or Caution

Use is allowed but requires special consideration in specific patient groups, often involving a lower mandatory starting dose:

  • Elderly Patients (65+ years): Treatment must be initiated with a lower dose due to increased sensitivity.
  • Organ Impairment: Patients with mild-to-moderate hepatic or renal insufficiency (kidney problems) require a lower starting dose.
  • Vulnerability: Extreme caution is required for patients with a history of alcohol or drug abuse.

Pregnancy and Lactation

Somnol is not recommended during pregnancy or lactation. Use during the last three months of pregnancy or labor is restricted to strict medical indication.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Official regulatory information for Somnol (Zopiclone) establishes constraints based on the substance's metabolism and its effects on the central nervous system (CNS).

Pharmacokinetic Interactions (Exposure Modification)

Zopiclone is primarily cleared via the CYP3A4 enzyme system in the liver. Interactions are documented for substances that alter this clearance:

Interacting Product Category Official Effect on Zopiclone Concentration
Potent CYP3A4 Inhibitors (e.g., Ketoconazole, Erythromycin) Increases plasma levels (exposure), with up to a 2.2-fold increase officially reported with Ketoconazole.
Potent CYP3A4 Inducers (e.g., Rifampicin, St. John's wort) Decreases plasma levels (exposure), with up to an 80% reduction officially reported with Rifampicin.

Pharmacodynamic and Substance Interactions

Interaction classifications document additive CNS effects and associated restrictions:

  • Central Nervous System (CNS) Depressants: Co-administration with substances such as opioids, other hypnotics, antidepressants, and antihistamines may result in additive CNS depressant effects, including profound sedation and respiratory depression, according to regulatory warnings.
  • Alcohol: Concomitant use with alcohol is formally listed as a contraindication in certain international regulatory data sheets due to the risk of dangerously enhanced sedative effects.
  • Food: Ingestion with a high-fat/heavy meal is documented to reduce the maximum concentration (Cmax) and delay absorption (Tmax), which may mitigate the intended effect on sleep onset.

Population-Specific Notes

  • Patients with Severe Hepatic Impairment are noted in regulatory information to have reduced Zopiclone clearance, leading to increased exposure and higher potential for interaction severity.

Mechanism of Action

How Somnol Works: Mechanism of Action

Targeting Central Sleep-Regulating Receptors

Somnol works by acting as an agonist on the Melatonin Receptor Type 1 ( MT1) and Type 2 ( MT2) receptors, which are G protein-coupled receptors primarily found in the brain. This action initiates a molecular cascade that reduces the intracellular signaling mediator cyclic adenosine monophosphate ( cAMP).

⏱️ Modulating the Circadian Rhythm

The drug's targeted effect on the MT receptors primarily affects the neurons of the Suprachiasmatic Nucleus ( SCN), the central biological regulator of circadian timing. By suppressing the SCN's firing rate, Somnol directly influences the central signaling pathways that regulate the sleep-wake cycle.

Initiating Physiological Sleep Onset

This specific modulation of the circadian machinery promotes the physiological processes associated with the initiation of sleep. The resulting physiological effects include a promotion of drowsiness and a reduction in core body temperature, leading to the initiation of sleep as the final system-level consequence.

Dosage and Administration Information

Official Administration Guidelines

The administration of Somnol (Zopiclone) is strictly governed by official labeling and is intended for the oral route only, using the available film-coated tablets. The tablet must be swallowed whole with water and should not be crushed or chewed. It is administered as a single intake per night, taken immediately before bedtime when a full seven to eight hours of uninterrupted sleep is possible; the dose must not be readministered during the same night.

Dosing and Duration Principles

The standard adult dose is typically 7.5 mg once daily, which is also the maximum dose and should not be exceeded. However, treatment must always be initiated with the lowest effective dose.

A reduced starting dose of 3.75 mg is mandated for specific populations, including older adults (geriatric patients) and individuals with hepatic (liver) or renal (kidney) impairment. For these groups, the maximum dose is generally restricted to the reduced dose to align with official usage protocols. The overall duration of use must be for the shortest time possible, generally limited to a maximum of four weeks in total, including any dose tapering period necessary for discontinuation.

While Somnol may be taken with or without food, the administration should not occur immediately after a heavy, high-fat meal, as this condition may reduce the drug's absorption rate. If a single nightly dose is missed, it should be skipped entirely, and the next dose should be taken at the scheduled time the following night.

Recent Clinical Evidence

Research evidence / Overview of studies for Somnol

Evidence for use in Short-Term Insomnia

The foundational evidence structure for Zopiclone in short-term sleeping difficulties is based on Randomized Controlled Trials (RCTs). These studies were conducted to compare Zopiclone against an inactive substance (placebo) or sometimes against active comparators. Research has primarily explored measurements of Sleep Latency (the time taken to fall asleep) and Total Sleep Time (the duration of sleep) in patients receiving Zopiclone, over short periods, typically lasting only a few nights up to four to six weeks.

Short-term trials explored how symptoms changed over time, with studies monitoring measurements related to sleep initiation and maintenance in the groups receiving Zopiclone. These findings describe patterns observed in the studies and contribute to the broader evidence landscape by providing insight into short-term changes in sleep metrics for the groups studied. While research provides insight into short-term changes, evidence for how long any observed changes may last remains limited. Follow-up durations were limited in the main controlled studies. Research describes that some studies monitored participants after stopping the medication and observed patterns of temporary worsening sleep (sometimes called rebound insomnia).


Long-Term Follow-up and Chronic Use Studies

Research was conducted to evaluate prolonged administration, but the body of evidence focusing on Zopiclone's administration for chronic insomnia (lasting many months or years) is different from the short-term trials. Studies exploring extended or long-term administration are primarily based on Observational Studies. These studies monitored how symptoms evolved in the observed populations during periods of increased symptom activity and chronic usage.

Data show patterns related to measured sleep patterns, which were observed in some studies of chronically administered medication to be comparable to those of individuals with chronic insomnia who were not using any sleep medication. Data are still emerging, and certainty remains low regarding sustained changes over the long term. Scientific reviews and regulatory guidance often emphasize that administration should be limited to short-term periods because the evidence base is insufficient to fully characterize the sustained effects and potential for tolerance and dependence development over extended periods.


Evidence in Special Populations

Specific research has explored how Zopiclone was studied for different patient groups, most notably in older adults. Additionally, Zopiclone was evaluated in research settings involving patients with insomnia co-occurring with certain other conditions, such as advanced cancer. However, results apply only to the populations studied, and data for certain groups remain insufficient. For instance, data are still emerging regarding sustained outcomes or administration in other specific groups, like pregnant or breastfeeding populations, where evidence is limited and certainty remains low.

Frequently Asked Questions (FAQ)

Common questions about Somnol (FAQ)


Q: How quickly does Somnol typically start to work?

A: Official information from pharmacokinetic studies indicates that Somnol reaches its highest concentration in the bloodstream relatively quickly, typically between 1.5 to 2 hours after administration. This time frame aligns with the drug's purpose of facilitating sleep initiation.

Q: How long do the effects of Somnol usually last after a single dose?

A: The duration of the drug's presence in the body is generally described by its elimination half-life. Regulatory documents state this half-life is approximately 5 hours, although the range can vary among individuals. The stated half-life helps determine how long the effects may be present in the body, typically seeking to reduce residual effects the following morning.

Q: Is Somnol classified as a controlled substance in the U.S.?

A: Yes, in the United States, the active ingredient in Somnol, Zopiclone, is classified by the Drug Enforcement Administration (DEA) as a Schedule IV controlled substance. This classification places restrictions and controls on how the drug is prescribed and dispensed due to the official acknowledgment of its potential for dependence and abuse.

Q: Which official health agencies have approved Somnol for use?

A: Official product information for Zopiclone has been established and reviewed by many regulatory bodies globally. These include major organizations such as Health Canada and the European Medicines Agency (EMA). Agencies such as these are responsible for reviewing and authorizing drug use based on regulatory data on quality, safety, and efficacy.

Q: How does the purpose of Somnol compare to other prescription medications for similar conditions?

A: Regulatory descriptions classify Somnol as a non-benzodiazepine hypnotic agent, often referred to as a 'Z-drug.' Official product monographs note that while Somnol is chemically unique, regulatory documents state its pharmacological profile is similar to that of the benzodiazepines, although it is chemically distinct.

Q: Is Somnol considered a new or novel type of medication?

A: Official documents describe Zopiclone as a cyclopyrrolone derivative, which is a unique chemical structure compared to older medications for sleep. While structurally different from benzodiazepines, regulatory classifications confirm its function as a sedative-hypnotic agent intended for the short-term management of sleeping difficulties.

Q: What should a patient generally know about identifying a serious side effect from Somnol?

A: Official patient information indicates that if specific serious side effects occur, the medication should be discontinued and medical help should be sought immediately. This includes any manifestation of complex sleep behaviors (such as sleepwalking or sleep-driving with no recall) or signs of a severe allergic reaction, such as swelling of the face or throat, or difficulty breathing.

Q: Does Somnol interact with grapefruit or other common foods and beverages?

A: Official labeling documents that the drug is metabolized in the body by the CYP3A4 enzyme system. Because certain components in grapefruit and similar foods can inhibit this enzyme, regulatory documentation indicates this could potentially increase the concentration of Somnol in the bloodstream.

Q: Are there any general warnings about operating heavy machinery while taking Somnol?

A: Official warnings specifically caution patients against engaging in activities that require complete mental alertness or motor coordination. Patients are generally advised to avoid operating heavy machinery or driving a motor vehicle for at least 12 hours following the administration of a dose.

Q: What is Somnol's legal status (e.g., prescription-only) in major regulatory regions outside the US?

A: In major regulatory regions worldwide, including Canada and countries within the European Union, Zopiclone is strictly classified as a prescription-only medicine (POM). This status indicates that the drug is restricted and may only be obtained and used with the authorization of a licensed healthcare professional.

Q: Does Somnol have any described effects on blood pressure or heart rate?

A: Cardiovascular effects are not commonly documented in the side effect profile during typical use. However, official safety documentation notes that in cases of overdose, the combination of excessive sedation and respiratory depression can potentially lead to symptoms associated with low blood pressure.

Q: Can Somnol be taken with other vitamins or mineral supplements?

A: Official guidance includes the recommendation that patients disclose to their healthcare provider or pharmacist all other substances being used. This includes any herbal remedies, vitamins, or mineral supplements, as these may interact with how the body processes the medication.

Q: Where can a patient find the complete, official regulatory labeling for Somnol?

A: The comprehensive official details and safety information for Zopiclone are available in documents such as the Summary of Product Characteristics (SmPC) or the Patient Information Leaflet (PIL). These documents are generally accessible through the respective national regulatory websites for the drug.

How should Somnol be stored and disposed of?

Somnol, which contains Zopiclone, must be stored under specific conditions to maintain its effectiveness and must be disposed of safely as pharmaceutical waste.

Storage Conditions

Requirement Official Instruction
Temperature Store below 25 C or 30 C in a dry place.
Protection Keep the tablets in the original blister in the outer carton to protect from light and moisture.
Safety Keep this medicine out of the sight and reach of children (mandatory).
Shelf-Life Do not use the medicine after the expiry date (EXP) stated on the packaging.

Disposal Instructions

Expired or unused Somnol must not be thrown away via wastewater or household waste. Disposal must be done in accordance with local requirements. The official method is to return any unused medicine to a pharmacist or utilize an authorized drug take-back program for proper pharmaceutical waste management.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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