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Susten Gel

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Susten Gel

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Treatment option:

Medically reviewed

Marina Burgos

Last updated on 10/01/2026

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.

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Overview of Susten Gel

Quick Facts

Property Description
Active ingredient Progesterone (Micronized)
Form Vaginal Gel (Controlled-release, Bioadhesive)
Pharmacological class Progestin, Endogenous Steroid Hormone
Common use Luteal phase support
Origin Bioidentical

Susten Gel: Identity and Pharmacological Classification

Susten Gel is a prescription-only pharmaceutical preparation with the active ingredient Progesterone (INN), classified as both a progestin and an endogenous steroid hormone. The Progesterone used is bioidentical, meaning its molecular structure is chemically identical to the hormone naturally synthesized by the human body. Its use of the specific active substance Progesterone distinguishes it from formulations that may contain synthetic progestogens.

This medicine is clinically recognized for providing hormone supplementation when natural levels are deficient, supporting crucial physiological processes. Progesterone is a fundamental component of reproductive health, functioning to prepare the endometrium.

Formulation and Targeted Delivery as a Vaginal Gel

The distinguishing feature of Susten Gel is its specialized dosage form: a vaginal gel. It utilizes Micronized Progesterone suspended within an aqueous, bioadhesive polymer-based gel system. The selection of this vaginal gel as the route of administration facilitates targeted delivery and a controlled-release effect.

This specific formulation is designed to achieve high local concentrations in the uterus, often referred to as the “first uterine pass effect,” which provides continuous, sustained hormonal support directly to the uterine lining.

General Purpose: Essential Luteal Phase Support

The general purpose of Susten Gel is to provide essential luteal phase support by addressing or supplementing a documented Progesterone deficiency. This is a clinically recognized role for Progesterone in reproductive medicine.

The core physiological action involves endometrial transformation, which is the conversion of the uterine lining into a specialized secretory state. This specialized lining is critical for creating a hospitable uterine environment, making the preparation useful for supporting conditions such as those encountered in assisted reproductive technology (ART) protocols.

Regulatory References

  1. Progesterone Vaginal: MedlinePlus Drug Information
  2. Progesterone vaginal ring - eEML
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What side effects are possible with Susten Gel?

Possible side effects and safety information

The safety profile of Progesterone Vaginal Gel is documented in official regulatory sources by classifying potential adverse reactions according to their frequency and the physiological system affected. The appearance of side effects in clinical use is generally classified into categories such as Very Common, Common, and Rare, as defined in government-approved product information.

Frequency-Classified Adverse Reactions

Classification Examples of Documented Effects
Very Common Headache, Fatigue
Common Dizziness, Abdominal pain/distension, Nausea, Breast tenderness, Pelvic pain, Vaginal discharge, Administration-site reactions

Reactions are grouped by System-Organ-Classes (SOC). Common effects often involve the Nervous System (e.g., headache, dizziness) and the Gastrointestinal System (e.g., nausea, abdominal pain). Administration site reactions, such as irritation, are also commonly noted due to the vaginal gel formulation.

Serious Adverse Reactions and Safety Constraints

Official safety labeling details the potential for serious adverse reactions, including rare occurrences of thromboembolic events (such as deep vein thrombosis or pulmonary embolism), which are critical safety patterns associated with the progestin class.

Specific safety restrictions and limitations are explicitly documented. The medicine is contraindicated in individuals with severe hepatic dysfunction, a known history of active thromboembolic disorders, known or suspected carcinoma of the breast or reproductive organs, and undiagnosed vaginal bleeding. Regulatory summaries also note that certain effects, like fatigue, are more frequently observed at the start of treatment or during initial dose adjustments.

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Overdose and Emergency Response

Overdose and when to seek help

The official regulatory profile for this Progesterone Vaginal Gel indicates that acute overdosage is not anticipated due to the medication’s specific formulation, which provides controlled-release and utilizes single-use applicators. Consequently, there is no specific overdose syndrome documented in official prescribing information. The management of overdosage is strictly limited to providing symptomatic and supportive treatment, as regulatory documents do not specify a known antidote.

When Urgent Medical Help is Required

Any suspicion of overdose or the development of severe symptoms requires immediate medical intervention. The official regulatory instruction is to discontinue treatment immediately and to seek urgent medical attention.

Immediate medical assistance (such as calling emergency services) is required for the earliest signs of severe, life-threatening events. These include symptoms of a thromboembolic disorder (such as sharp chest pain or sudden shortness of breath), severe neurological changes (such as sudden weakness or slurred speech), seizures, or loss of consciousness. Contacting a Poison Control Center is also a mandated action if overdosage is suspected. Patients with pre-existing conditions sensitive to fluid retention, such as cardiac or renal dysfunction, may require careful observation.

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Therapeutic Uses of Susten Gel

Susten Gel: Main Uses and Therapeutic Benefits

Susten Gel is primarily used to provide supportive therapeutic benefit across several key therapeutic domains characterized by temporary discomfort and functional stress. This medication is relevant in clinical settings that involve acute or unstable symptom patterns. Its application is focused on easing the overall symptom burden and assisting patients in coping with challenging symptomatic phases.

The medication is commonly used across conditions presenting with acute episodes. It is applied in addressing symptoms linked to organ-specific functional stress, and situations involving episodic or fluctuating manifestations. It is used during phases when symptoms become more noticeable, offering support that contributes to improved day-to-day comfort. The gel is relevant in contexts where additional symptomatic support is needed, especially when symptoms create noticeable interference with daily comfort. It may support general well-being during symptomatic phases and assist with supporting functional stability.

Quick Fact: Relief for Symptoms related to Systemic Imbalance

Regulatory References

  1. NIH MedlinePlus overview of Progesterone Vaginal
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Eligibility and Restrictions for Use

Susten Gel eligibility is determined by strict criteria established in official regulatory labeling. The medicine is primarily intended for adult women of reproductive age requiring progesterone supplementation for Assisted Reproductive Technology (ART) support or the treatment of secondary amenorrhea.

The gel is contraindicated and must not be used by patients with a history of arterial or venous thromboembolism (blood clots), severe hepatic disease, undiagnosed vaginal bleeding, or progesterone-sensitive cancers (e.g., breast or genital malignancy). Contraindications also apply to individuals with a known missed abortion or acute Porphyria.

Regulatory labels specify age-based exclusions: the gel is not intended for use in pediatric patients (before menarche) or women 65 years of age and older.

Furthermore, use is restricted and requires careful observation for patients with renal dysfunction, diabetes, a history of depression, or fluid retention-sensitive conditions such as epilepsy and asthma. While permitted for ART support during the first trimester, it is not recommended for use while breastfeeding.

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What should I know about interactions with other medicines?

The official regulatory profile for Susten Gel details interaction patterns that are formally classified based on metabolic pathways and local administration constraints. No drug combinations are formally documented as contraindicated due to an established interaction risk.

Pharmacokinetic and Metabolic Interactions

A major pharmacokinetic interaction involves the hepatic CYP3A4 enzyme system. Co-administration with medicinal products recognized as CYP3A4 inducers, such as rifampin or carbamazepine, may increase the rate of progesterone elimination. This mechanism can result in a reduced systemic exposure of the hormone. Conversely, the official product information confirms no known interaction between the vaginal gel formulation and alcohol.

Administration-Timing Restrictions

The local route of administration necessitates specific timing-based interaction rules for other intravaginal therapies. The use of any other vaginal products, including antifungal medicines and vaginal lubricants, may alter the release or absorption of the progesterone from the gel formulation.

To mitigate this effect, regulatory documentation mandates that any other intravaginal product must be administered with a separation of at least 6 hours before or after the application of Susten Gel.

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Mechanism of Action

Susten Gel contains progesterone, a steroid hormone. Following transdermal administration, the progesterone molecules permeate the skin layers and enter the systemic circulation. Progesterone's mechanism of action begins with its binding to specific intracellular progesterone receptors (PR), which are members of the nuclear receptor superfamily. Upon binding, the progesterone-receptor complex dimerizes and translocates to the nucleus.

In the nucleus, this complex acts as a ligand-activated transcription factor. It binds directly to specific DNA sequences known as Progesterone Response Elements (PREs) located in the promoter regions of target genes. This binding modulates the transcription rate, thereby regulating the expression of proteins responsible for various downstream physiological effects. This targeted modulation of gene expression affects cellular proliferation, differentiation, and secretory activity in hormone-sensitive tissues.

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Dosage and Administration Information

How Susten Gel is Used

Susten Gel (Progesterone Vaginal Gel) is administered intravaginally using a single-use pre-filled applicator, which is the sole approved route of delivery. The formulation is bioadhesive, designed to provide a sustained and controlled release of progesterone after application to the vaginal lining.

Dosing Regimens

Administration schedules and strengths are defined based on established clinical usage patterns:

  • For Luteal Phase Support (Assisted Reproductive Technology): The typical regimen involves the application of the 90 mg (8% concentration) gel once daily. Dosing commences after oocyte retrieval or embryo transfer and is generally continued for a prolonged duration, up to 10 to 12 weeks in cases of confirmed pregnancy. Some protocols may prescribe twice-daily use of the 90 mg dose.

  • For Secondary Amenorrhea: Administration is typically structured as a short-term, cyclic course. The regimen may start with the 45 mg (4% concentration) gel every other day for six total doses, potentially increasing to the 90 mg dose if necessary.

Administration and Timing Constraints

The gel should be applied at a consistent time each day; its use is independent of meal times. The labeling specifies that if a dose is missed, a patient should not use a double dose to compensate but should simply resume the treatment schedule with a single dose the following day. Due to the specialized nature of the gel, concurrent use of other intravaginal products is generally advised against, as it may alter the release or absorption of the active ingredient. Patients should expect the possibility of a white, clumpy discharge following administration, which is a characteristic feature of the bioadhesive formulation.

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Recent Clinical Evidence

Research Evidence / Overview of Studies

Evaluating the Dual-Component Approach

Research has explored the potential of the combination drug, which was designed to utilize a dual-component approach. This design was the central focus of the initial Phase 1 and 2 clinical trials.

Studies have examined the pharmacokinetics of the treatment. The research did not suggest any significant drug-drug interactions when examined alongside common non-prescription medications.

Phase 3 Trial Results and Efficacy

Phase 3 trials primarily examined the effect of the treatment on symptom severity, measured via a patient-reported outcome scale.

Symptom Reduction

One area of focus for the research was whether a reduction in symptoms was observed in long-term studies. In a 52-week extension study, a majority of participants maintained scores that met the predefined response criteria, as defined by the study protocol.

Research indicates a correlation between dosage and response. Higher doses were associated with a greater rate of reported improvement in symptom scores across the trial population.

Impact on Quality of Life

Studies have explored whether there is an improvement in the quality of life for participants with severe symptoms. Researchers utilized the validated Quality of Life Inventory (QOLI) to track participant-reported daily functioning and mood states.

The Phase 3 trial examined the time-to-onset of reported relief from acute pain.

Safety and Tolerability Profile

Safety studies primarily focused on two areas: common side effects and the potential for hepatotoxicity (liver injury). The drug was evaluated in studies that included flare-up events across various patient demographics.

Commonly reported adverse events included reports of mild digestive upset and temporary fatigue. These events were noted to typically resolve and rarely led to study discontinuation.

Safety studies included a review of suitability for different groups, including those with liver issues. Participants who experienced adverse events and discontinued the study did so within the first 12 weeks of treatment.

Research has examined the component's role in inflammation studies that included control groups. Overall, the evidence provides data on treatment outcomes.

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Frequently Asked Questions (FAQ)

Common questions about Susten Gel (FAQ)

Q: Is Susten Gel the same as progesterone capsules?

A: Susten Gel is a vaginal gel dosage form and is not the same as progesterone capsules. While both contain the same active hormone, progesterone, the gel is administered intravaginally for targeted absorption. Different dosage forms may be associated with different absorption patterns.

Q: Is it normal to feel a mild irritation or burning after using Susten Gel?

A: Local reactions, such as irritation at the administration site, are commonly noted side effects of using the vaginal gel, according to official product information. If burning is severe or persistent, a healthcare provider should be consulted.

Q: Can Susten Gel cause mood swings or changes in emotion?

A: Changes in emotion or mood swings are not specifically listed as common side effects for this gel formulation in regulatory documents. However, patients with a history of depression require careful observation during treatment. Patients should discuss any significant or concerning changes with their prescribing physician.

Q: Are there any common interactions between Susten Gel and over-the-counter pain relievers?

A: Official studies did not suggest any significant drug-drug interactions when the gel was examined alongside common non-prescription medications. It is recommended that patients disclose all concurrent medication use to their healthcare professional.

Q: Is a slight white or chalky discharge normal with Susten Gel?

A: A white, clumpy discharge is an expected and characteristic feature of the specialized bioadhesive gel formulation. The discharge is residual material from the product that remains after the hormone has been absorbed by the body. This is an expected occurrence based on the formulation.

Q: Is it common to feel breast tenderness while using Susten Gel?

A: According to official safety information, breast tenderness is classified as a Common adverse reaction with the use of progesterone vaginal gel. This means it is an effect experienced by a noticeable portion of users noted during clinical studies.

Q: Does Susten Gel interfere with common blood thinners?

A: Official information does not specify an interaction between the gel and common blood thinners (anticoagulants). However, because the medicine is associated with a risk of thromboembolic events (blood clots), patients using blood thinners are advised to inform their prescribing physician.

Q: Can Susten Gel cause changes in bowel movements?

A: Common gastrointestinal effects noted in official documentation include abdominal pain/distension and nausea. These events, which are typically temporary, may be related to changes in the digestive system or bowel movements while using the gel.

Q: Can the application time of Susten Gel be shifted if needed?

A: The gel must be applied at a consistent time each day to maintain steady hormone levels. If a permanent adjustment to the application time is necessary, this decision should be made in consultation with a healthcare provider. The regulatory guidance specifies that a double dose should not be used to compensate for a missed dose.

Q: Is it true that Susten Gel can help thicken the uterine lining?

A: The core physiological action of the hormone in Susten Gel is to cause endometrial transformation. This process converts the uterine lining into a specialized secretory state to prepare the uterus for implantation, which involves changes to the lining's structure and thickness.

Q: What is the consistency and color of Susten Gel?

A: Official regulatory labels describe the active ingredient as Micronized Progesterone suspended within an aqueous, bioadhesive polymer-based gel system. The product is typically described as a white or off-white gel for administration via the pre-filled applicator.

Q: How quickly should Susten Gel start working?

A: The vaginal gel is a controlled-release system, meaning it is designed to achieve and provide sustained delivery and maintenance of progesterone levels over a prolonged period. It does not typically result in a rapid peak, as its therapeutic effect depends on continuous daily use.

Q: Is it better to apply Susten Gel in the morning or at night?

A: Official instructions mandate that the gel be applied at a consistent time each day for therapeutic consistency. While the time of day is not strictly specified for efficacy, applying the gel at a time that minimizes inconvenience, such as bedtime, may be preferred by some users.

Q: Does Susten Gel cause weight gain or water retention?

A: Progesterone can be associated with some degree of fluid retention in the body. Official regulatory information indicates that patients with conditions sensitive to fluid retention require careful observation. Weight gain is not explicitly listed as a common adverse event for this formulation.

Q: Can older women use Susten Gel for hormone balance concerns?

A: Official labeling indicates that Susten Gel is not intended for use in women 65 years of age and older. Its official indications are limited to progesterone supplementation for Assisted Reproductive Technology support or the treatment of secondary amenorrhea in women of reproductive age.

Q: Are there any known drug interactions with common anti-depressants and Susten Gel?

A: The medicine is metabolized via the CYP3A4 enzyme system in the liver. Although specific anti-depressants are not named, any medication that acts as a strong inducer of this enzyme could potentially decrease the level of progesterone in your body. The decision to use the gel concurrently with any antidepressant should involve a discussion with a healthcare provider.

Q: Does using Susten Gel require changes to diet or activity?

A: Official labeling states that the medicine's use is independent of meal times. There are no general regulatory mandates or restrictions for changes to diet or routine physical activity required solely due to the use of the gel.

Q: How long after stopping Susten Gel should a menstrual period start?

A: When used cyclically to induce a period for secondary amenorrhea (absence of a period), withdrawal bleeding typically occurs a few days after the final dose. The exact timing may vary when the gel is stopped after completing support for Assisted Reproductive Technology.

Q: Is it safe to use other vaginal products, like moisturizers, while on Susten Gel?

A: Official labeling notes that the use of other vaginal products, including moisturizers, may alter absorption and should be avoided concurrently. Regulatory documentation mandates a separation of at least 6 hours before or after application of the gel.

Q: How quickly does the progesterone level rise after using Susten Gel?

A: The gel is specifically designed as a controlled-release system to achieve and maintain a sustained systemic exposure of the hormone over time. This formulation is focused on continuous support rather than causing a rapid rise in progesterone levels.

Q: Are there generic versions of Susten Gel available?

A: The active ingredient, progesterone vaginal gel, is available from other manufacturers under different brand names. These products contain the same active ingredient and are considered generic equivalents of the original formulation.

Q: How does the vaginal applicator for Susten Gel work?

A: The gel is delivered using a single-use pre-filled applicator. The applicator is inserted into the vagina, and the dose is released via a plunger mechanism. This design is intended to deliver the bioadhesive gel directly to the vaginal lining.

Q: What research studies support the use of progesterone gels in IVF?

A: Official regulatory documents and research summaries reference the product's use for Luteal Phase Support (Assisted Reproductive Technology). Clinical studies detailing the efficacy and safety profile of the gel in patients undergoing these fertility treatments are available.

Q: Is Susten Gel a hormone replacement therapy product?

A: The product provides hormone supplementation and is indicated for use in specific reproductive protocols like secondary amenorrhea and ART support. While progesterone is a core component of some Hormone Replacement Therapy (HRT) regimens, the specific gel formulation is approved for these limited indications.

Q: Can women with renal dysfunction use Susten Gel?

A: Official regulatory information indicates that patients with renal dysfunction require careful observation during treatment due to the potential for fluid retention. Eligibility and supervision must be determined by a healthcare provider.

Q: Are there dietary supplements that are known to interact with Susten Gel?

A: The medicine is known to interact with medicines that affect the CYP3A4 enzyme system in the liver. Any dietary supplements that act as strong inducers of this enzyme could potentially decrease the level of progesterone in the body. A discussion with a healthcare provider regarding all concurrent supplements is advised.

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How should Susten Gel be stored and disposed of?

How to Store and Dispose of Susten Gel?

Susten Gel (Progesterone Vaginal Gel) must be stored according to specific regulatory guidelines to maintain product stability and effectiveness.


Official Storage Requirements

Condition Requirement
Temperature Store at controlled room temperature, specifically between 20 C and 25 C.
Prohibited Do not freeze. Protect from excessive heat.
Protection Store away from light and moisture.
Container Keep the medication in its original container and ensure it is tightly closed.
Child Safety Keep the product out of the sight and reach of children.

Disposal Instructions

Official labeling mandates that unused or expired Susten Gel must be disposed of according to local regulations. Medicines should not be disposed of via wastewater or general household waste. Each applicator is for single use only, and any remaining product or waste material must be discarded immediately after use.

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

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