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Bioequivalence Study of 80 mg Lavender Oil Gastro‑Resistant Capsule Compared with Soft Capsule in Healthy Volunteers

Registered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study involves adults who are in good health and will receive a soft, oral capsule that contains lavender oil under the brand name Silexan at a dose of 80 mg. Two different versions of the same capsule are being compared: one that dissolves quickly in the stomach (the reference) and one that is designed to resist stomach acid and release the ingredient later (the test).

The purpose of the trial is to demonstrate bioequivalence between the two formulations, meaning that both versions should provide the same amount of the active component to the body. Participants will take one type of capsule, then after a short break will take the other type, while blood samples are collected to see how much of the lavender oil ingredient, called linalool, reaches the bloodstream. The total amount of drug exposure over time is measured as AUC, and the highest level reached in the blood is called Cmax; both help determine if the two capsules behave the same way.

Throughout the study, volunteers are checked for any unwanted effects, vital signs such as blood pressure and heart rate, and overall well‑being. Any side effects that occur are recorded and evaluated, and participants can stop the study at any time if needed.

The research process

The trial runs in 8 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment and consent

    After you join the study you will receive written information about what will happen and you will be asked to sign a consent form confirming that you understand the procedures.

  2. Step 2

    Baseline health checks

    The study staff will measure your vital signs such as blood pressure and heart rate, and will perform a physical examination to confirm that you are a healthy volunteer.

  3. Step 3

    First dose administration

    You will take one silexan 80 mg capsule (the test formulation) or one lavender oil 80 mg capsule (the reference formulation) by mouth. the dose is a single soft capsule containing 80 milligrams of lavender oil. the capsule is taken once and no other study medication is taken at this time.

  4. Step 4

    Blood sampling after first dose

    After the first dose a series of blood samples will be taken at scheduled times to measure the amount of lavender oil in your blood. these measurements are used to assess how the drug is absorbed and cleared, which is needed to compare the two formulations.

  5. Step 5

    Washout period

    A washout period will follow, during which you will not take any study medication. this period allows the first capsule to leave your body before the next dose is given.

  6. Step 6

    Second dose administration

    You will take the other capsule that you did not receive in the first period. this will be a single oral dose of 80 milligrams of lavender oil, either the silexan 80 mg test capsule or the lavender oil 80 mg reference capsule.

  7. Step 7

    Blood sampling after second dose

    A second series of blood samples will be collected at the same scheduled times as after the first dose. these samples are used to compare the two formulations.

  8. Step 8

    Final health checks and study completion

    At the end of the study the staff will repeat the vital signs and physical examination to ensure that you remain healthy. you will then be thanked for your participation and the trial will be closed for you.

Who can join the trial?

9 criteria

  • You must be a healthy person as shown by a physical exam, an ECG (a quick heart test), normal vital signs (such as blood pressure and heart rate), and routine lab safety tests.
  • You must be male or female and at least 18 years old but not older than 55 years when you sign the study consent.
  • Your body mass index (BMI), a measure of weight relative to height, must be between 18 and 30, and you must weigh at least 50 kg at screening and the day before the study starts.
  • Your vital signs must be in the normal range at screening and the day before the study; any out‑of‑range readings must be judged by the doctor as not a serious health problem.
  • Your physical examination must not show any important health problems, as confirmed by the doctor at screening and the day before the study.
  • You must sign an informed consent form, which means you understand the study and agree to take part, before any other study steps begin.
  • You must agree to follow the study plan, which includes staying in the clinic when required, attending scheduled visits, taking the medication as directed, and allowing clinical laboratory tests and other study procedures, including any lifestyle rules.
  • You must be connected to a Social Security System (or similar national health coverage).
  • You must be able to speak, read, and understand the local language used in the study.

Who cannot join the trial?

27 criteria

  • Cannot take part if you are already involved in another clinical study or have recently finished one before the screening visit.
  • Cannot take part if you have a history of malignancy (any type of cancer, such as lymphoma, leukaemia or skin cancer).
  • Cannot take part if you have any other active illness that could affect how the study drug is absorbed, distributed, or eliminated, including acute or chronic infections.
  • Cannot take part if you have used any prescription medicines within the past 4 weeks, or any over‑the‑counter drugs or supplements (such as vitamins, herbal products, St. John’s wort, or dietary supplements) within the past 5 days (or 14 days for drugs with a long half‑life). A small amount of paracetamol is allowed only if the investigator permits up to three 500 mg doses per day.
  • Cannot take part if your screening blood tests show abnormal results (for example, abnormal complete blood count, clotting tests, infection serology, or chemistry values) that the investigator considers clinically important.
  • Cannot take part if you test positive for HIV antibodies, hepatitis B surface antigen, or hepatitis C antibodies during screening.
  • Cannot take part if blood is found in your urine at screening or on the day before dosing, unless it is due to menstrual bleeding in a female participant and the investigator does not consider it clinically significant.
  • Cannot take part if your 12‑lead ECG (electrocardiogram) shows significant abnormalities, such as a prolonged QTc interval (QTc ≤ 450 ms for men or ≤ 470 ms for women is considered normal).
  • Cannot take part if you have had any surgery (including dental surgery) within one month before randomisation, or if you plan to have any operation during the trial period.
  • Cannot take part if you have had a clinically significant illness within the 14 days before randomisation.
  • Cannot take part if you have smoked any type of tobacco in the past three months.
  • Female participants cannot take part if they are pregnant or breastfeeding.
  • Cannot take part if you regularly drink more than five cups of coffee (or equivalent caffeine‑containing drinks) per day.
  • Cannot take part if you regularly consume large amounts of alcohol (more than about 24 g of pure alcohol per day for men, or more than about 12 g per day for women; 12 g is roughly one standard drink).
  • Cannot take part if a urine drug test or breath‑alcohol test is positive at screening or on the day before dosing.
  • Cannot take part if you are a member of the trial staff or a first‑degree relative (parent, sibling, or child) of an investigator.
  • Cannot take part if you have donated more than 450 mL of blood or plasma within the 28 days before the first dose.
  • Cannot take part if you are considered unreliable, unwilling, or unable to follow the study rules and restrictions.
  • Cannot take part if you are a vulnerable individual (for example, a person who is detained).
  • Cannot take part if the investigator believes any of your conditions could make participation unsafe.
  • Female participants who could become pregnant must use reliable contraception; those who do not use adequate birth‑control methods are excluded.
  • Cannot take part if a pregnancy test is positive.
  • Cannot take part if you have gastrointestinal disorders that may prevent proper absorption of oral medicines, such as partial or total removal of the stomach or intestines, inflammatory bowel disease, celiac disease, significant lactose intolerance, or chronic diarrhoea.
  • Cannot take part if you have a known allergy or hypersensitivity to the active ingredient of Silexan, any of its inactive components, or if you have impaired liver (hepatic) function.
  • Cannot take part if you have hereditary conditions that affect sugar metabolism, such as galactose intolerance, lactase deficiency, or glucose‑galactose malabsorption.
  • Cannot take part if you have a history of significant allergic reactions (atopic allergy, hypersensitivity, or drug‑related allergies).
  • Cannot take part if you have a clinically important disorder of the kidneys, liver, heart, blood, lungs, nervous system, metabolism, or a serious psychiatric condition, or if you have a history of drug or alcohol abuse, or any allergic disease other than mild seasonal allergies.
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Investigated drugs

  • Silexan

    is a capsule that contains lavender oil. In this study it is the test product, meaning it is the version being evaluated for how it behaves in the body. The capsule is made to resist breaking down in the stomach, so the lavender oil is released later in the digestive system. This design helps researchers see whether the timing and amount of lavender oil that reaches the bloodstream is the same as with the standard formulation.

  • Lavender oil soft capsule

    is a soft gelatin capsule that also contains lavender oil. It serves as the comparator, or reference product, in the trial. This capsule is not protected against stomach acid, so the lavender oil is released quickly after the capsule is swallowed. By comparing this product with Silexan, the study can determine if the two formulations deliver the same amount of lavender oil to the body.

What is already known about the treatment

  • HUILE ESSENTIELLE DE LAVANDE SCHWABE capsule molle

    This medication is taken by mouth as a soft gelatin capsule containing 80 mg of lavender oil. It is an over‑the‑counter herbal product that has been used for many years and is described in several medical articles. It is mainly used to help with mild anxiety, stress, and occasional sleep problems. The oil works by gently calming the brain’s activity, likely through a mild effect on the GABA system, and it is classified as an herbal anxiolytic/sedative.

  • Silexan 80 mg

    This drug is also taken orally as a gastro‑resistant soft capsule delivering 80 mg of lavender oil. It is a licensed, prescription‑grade preparation that has been examined in numerous clinical studies and is listed in drug reference guides. It is used to reduce symptoms of anxiety and to improve sleep quality in adults. The lavender oil in Silexan acts in a similar gentle way on brain pathways that control calmness, and it belongs to the class of herbal anxiolytics.

Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase ITrial ID2023-503647-34-00Protocol codeD.01.01.2.03Estimated enrolment92 patientsSponsorDr. Willmar Schwabe GmbH & Co. KG

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