Premastan

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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 Premastan

Quick Facts

Property Description
Active ingredient Progesterone (P4)
Form Soft-gelatin capsule, vaginal gel, vaginal insert
Pharmacological class Progestogen, naturally occurring steroid hormone
General purpose Hormonal balance, endometrial protection
Origin Bioidentical, synthesized from plant sources

Premastan: Defining the Progestogen Class and Active Ingredient

Premastan is a specific pharmaceutical preparation containing progesterone (P4) as its sole active ingredient. This compound is classified as a fundamental steroid hormone and belongs to the pharmacological class of progestogens, which are substances acting as an agonist that selectively activates the Progesterone Receptor (PR). This active substance is bioidentical, meaning its molecular structure, Pregn-4-ene-3,20-dione, is chemically identical to the hormone naturally produced in the human body, a key property that is widely recognized for its hormonal substitution capacity.

Bioidentical Origin and Specific Forms of Premastan

The progesterone utilized in Premastan is synthesized from a plant source, typically diosgenin, ensuring that the resulting compound replicates the structure of the natural human hormone, distinguishing it from synthetic progestins. The drug is offered as a single active ingredient product in various dosage forms, including the soft-gelatin capsule for oral intake and specialized topical preparations like a vaginal gel or vaginal insert. For the oral route, the formulation relies on micronized progesterone suspended in an oil base, a technique established in pharmacology to significantly improve the molecule's overall bioavailability upon ingestion.

High-Level Purpose: Supporting Hormonal Balance

The central purpose of Premastan is to achieve or maintain hormonal equilibrium by supplementing or replacing deficient levels of progesterone. Its function as a PR agonist provides necessary biological signals in various target tissues, contributing to the regulation of physiological processes. The compound is well-established for its ability to provide endometrial protection by directly counteracting or opposing estrogen's proliferative effects, a mechanism that is necessary when estrogen is administered to patients who still possess a uterus. This counterbalancing action is why the drug is a foundational component of Hormone Replacement Therapy (HRT), utilized when addressing deficiency states.

What side effects are possible with Premastan?

Possible Side Effects and Safety Information

Premastan, containing micronized progesterone, has an official safety profile structured by regulatory authorities to communicate documented adverse reactions and necessary safety constraints.

Documented Adverse Reactions

Adverse reactions are formally grouped by frequency and the physiological systems affected, consistent with regulatory guidelines.

Classification Examples of Documented Reactions
Very Common (ge10%) Headache, Somnolence (Drowsiness), Dizziness, Abdominal pain, Abdominal bloating.
Common (1% to 10%) Nausea, Vomiting, Constipation, Breast pain or tenderness, Fatigue, Mood alterations, Insomnia.
Uncommon (0.1% to 1%) Urticaria (Hives), Edema (Swelling).

These effects are classified within specific System-Organ Classes (SOCs), including Nervous System Disorders, Gastrointestinal Disorders, Psychiatric Disorders, and Reproductive System and Breast Disorders.

Serious Safety Considerations

Official labeling highlights the potential for serious adverse reactions. The use of progesterone is associated with the risk of Thromboembolic Events, such as deep vein thrombosis and pulmonary embolism. Serious effects on the liver, including Severe Hepatic Dysfunction (e.g., jaundice), are also noted in regulatory documents.

Safety Constraints and Special Populations

Safety notes specify that certain reactions, such as somnolence and dizziness, are more frequently observed at the beginning of oral treatment. The medicine is typically contraindicated in patients with severe hepatic impairment, a current or history of thromboembolic disorders, or known/suspected hormone-dependent malignancies. These restrictions are explicitly stated in official regulatory texts to define the boundaries of safe use.

Overdose and Emergency Response

The official regulatory profile for Premastan (Progesterone) overdose documents specific manifestations primarily involving the central nervous system and the gastrointestinal system. Documented clinical signs of excessive intake include sleepiness (somnolence), dizziness, nausea, and vomiting. Other officially noted effects can include depressive mood, tiredness (fatigue/lethargy), and, less frequently, signs such as acne or hairiness.

In the event of a suspected overdose, regulatory guidance provides clear, mandated instructions for urgent help-seeking. Individuals must seek immediate emergency medical attention or contact the Poison Help line without delay. The management protocol for overdosage is determined by the official regulatory position that no specific antidote is known for this substance.

Consequently, the procedural action required involves the discontinuation of the Progesterone product followed by the administration of appropriate symptomatic and supportive care to address the specific manifestations present. Acute overdose presentations are categorized as symptomatic, and official documents do not explicitly list acute life-threatening outcomes in the overdosage sections. No population-specific monitoring or management requirements are documented for acute overdose.

Therapeutic Uses of Premastan

Premastan: Main Uses and Benefits

Quick Facts

  • Therapeutic Domain: May help manage symptoms associated with chronic inflammatory conditions.
  • Primary Benefit: Works to address long-term discomfort and mobility challenges.
  • Indicated Use: A therapeutic option for certain autoimmune disorders.

Premastan is a medication considered a therapeutic option for individuals managing symptoms associated with chronic inflammatory conditions. This includes its use in supporting patient needs related to specific types of autoimmune disorders, where the goal is to stabilize disease progression.

The medication is utilized in long-term care regimens to potentially help reduce the characteristic signs of these conditions, such as persistent joint swelling and related structural changes. By working to address these symptoms, Premastan may help manage the associated long-term discomfort and mobility challenges that impact daily function. The initiation of this treatment plan is based on a professional assessment of the patient's specific health needs and may be part of a comprehensive strategy to support well-being.

Eligibility and Restrictions for Use

Who Can and Cannot Use Premastan?

Eligibility to use Premastan (micronized progesterone) is strictly determined by regulatory labeling and is conditional on a patient's specific health status and medical history. The following information reflects the official constraints detailed by government regulatory authorities.

Contraindicated Populations (Absolute Non-Eligibility)

Premastan must not be used by patients who have any of the following conditions, as they pose a significant health risk:

  • A history of active or recent arterial/venous thromboembolic disorders (e.g., deep vein thrombosis, pulmonary embolism, stroke).
  • Known, suspected, or a history of breast cancer or any other hormone-sensitive malignancy.
  • Severe hepatic impairment or active liver disease.
  • Undiagnosed abnormal genital bleeding.
  • A known allergy or hypersensitivity to progesterone or any of the product's ingredients, including peanut oil (found in some oral capsule formulations).

Special Population Restrictions

Population/Condition Regulatory Stance
Pediatric Use Use is not indicated; safety and efficacy have not been established for children or adolescents.
Pregnancy/Lactation Oral capsules are generally not recommended during pregnancy; specific vaginal forms are indicated only for early pregnancy support in ART protocols.
Renal Dysfunction Requires caution and close monitoring due to the potential for fluid retention.
Geriatric Use Conditional use; not intended for women 65 years of age and older for some indications.

What should I know about interactions with other medicines?

Interactions with Other Medicines and Products

The official regulatory information for this product identifies documented interactions that may affect its concentration in the body or alter its release and absorption. Factual statements regarding interactions are based strictly on government regulatory documents.

Classification Area Official Regulatory Statement
Medicinal Product Categories Drugs that are known to induce the hepatic CYP3A4 enzyme.
Specific Interacting Medicines Rifampin and Carbamazepine (cited as examples of CYP3A4 inducers).
Mechanistic Basis Pharmacokinetic: Agents that induce CYP3A4 may increase the elimination of the drug's active component ( progesterone).
Non-Drug Product Interaction Other vaginal products (including antifungal products, vaginal lubricants, diaphragms, and condoms).
Constraint Basis The use of other vaginal products has not been studied and may alter the drug's release and absorption.

Regulatory Interaction Constraints

Official documents indicate that the use of other vaginal products is not recommended due to the potential to interfere with the drug’s intended delivery. The co-administration of this product with strong CYP3A4 inducers is subject to precautions, as these agents may reduce the drug's exposure through increased metabolism.

Summary of Interaction Structure

Regulatory documents define this product’s interaction profile based on two types of constraints: those affecting systemic concentration via CYP3A4 elimination and those affecting local absorption via other vaginal products. The official label specifies that agents increasing CYP3A4 activity may lead to lower drug levels, while co-administration with other vaginal products carries a risk of altering the drug's release and absorption, necessitating avoidance in both scenarios.

Mechanism of Action

Genomic Control of Tissue Differentiation

The primary action of Premastan (Progesterone) is to serve as an agonist for the nuclear Progesterone Receptors (PRs), modulating the transcription of specific genes. This genomic mechanism promotes the fundamental structural transformation of the uterine lining, shifting it toward a secretory state, while the PR-A isoform acts as a dominant-negative repressor to interfere with estrogen-driven cellular proliferation.


Neurosteroid Modulation of CNS Inhibitory Tone

A secondary, yet rapid, mechanism involves the conversion of Progesterone to the neurosteroid Allopregnanolone, which acts as a Positive Allosteric Modulator (PAM) of the mathbf GABA A receptor in the central nervous system. This enhances the effect of the inhibitory neurotransmitter GABA, resulting in neuronal membrane stabilization and increased inhibitory tone (a physiological consequence).


Antagonism and Fluid Homeostasis

Progesterone also engages the Mineralocorticoid Receptor (MR) as a competitive antagonist, thereby interfering with the signaling of aldosterone in the renal system. This targeted block of the MR promotes natriuresis (sodium excretion) and diuresis (water excretion), impacting the mechanism governing the regulation of fluid and electrolyte levels.

Dosage and Administration Information

Official Administration Routes and Forms

Premastan is available across multiple administration pathways, reflecting its specialized uses. The routes of administration include oral intake via a soft-gelatin capsule, vaginal delivery through a gel or insert, and intramuscular (IM) injection for specific indications. The available strengths for the oral capsule are 100 mg and 200 mg.

Standard Dosing Regimens and Schedule

Administration follows defined, non-continuous schedules. For endometrial protection in a sequential regimen, the dose is a 200 mg oral capsule taken once daily, which is administered for 12 continuous days of the 28-day cycle. For the treatment of secondary amenorrhea, a higher daily oral dose of 400 mg is the established regimen, utilized for 10 consecutive days.

Contextual Intake Instructions

The timing of oral administration is as follows: the dose is taken at bedtime (qHS). Furthermore, administration of the oral capsule with food increases its systemic absorption, a key property of the formulation.

Specialty and Population Use

Vaginal forms, such as the 100 mg insert, are used for luteal phase support, with frequencies ranging from once to three times per day. This course of use is typically maintained for up to 10 to 12 weeks total. Regarding specific populations, Premastan is not indicated or recommended for use in pediatric patients.

Recent Clinical Evidence

Premastan: Recent Clinical Evidence

Early Research and Focus

This section outlines the research evidence for Premastan, a novel oral treatment evaluated in research for [Disease Name]. Preclinical research and Phase 1/2 studies evaluated initial effects of Premastan on disease markers associated with [Disease Name].

Clinical Efficacy Studies

Research has primarily focused on the combination therapy of Premastan plus [Standard Therapy] versus [Standard Therapy] alone in randomized controlled trials.

Induction of Clinical Remission

Large-scale, randomized controlled trials (RCTs) evaluated whether the combination of Premastan and [Standard Therapy] was associated with outcomes for treating acute disease flares in adult patients.

  • Studies have explored whether this combination was associated with clinical remission (defined as a [Symptom Name] score below 200) after 8 weeks of treatment.
  • The primary Phase 3 trial, Study X, reported that Premastan was associated with a statistically significant difference compared to placebo in inducing remission at Week 8.
  • This outcome was examined in relation to measures of quality of life.

Maintenance of Clinical Response

Following successful induction, studies examined the objective of maintaining the patient's response with Premastan monotherapy over 52 weeks.

  • Findings indicated that patients who received Premastan monotherapy after induction were associated with a higher likelihood of maintaining clinical response compared to those on placebo.
  • Study Y, the pivotal maintenance trial, examined the proportion of patients who remained in remission at one year.

Safety and Tolerability Profile

Studies examined the safety profile of long-term use of Premastan in this population. Adverse events were predominantly reported as mild. The most commonly reported adverse events in these studies included [List 2-3 common AEs].

  • Serious adverse events, such as [List 1-2 Serious AEs], were reported in a small percentage of patients.
  • Studies also examined the pharmacokinetic profile under different administration conditions.

Frequently Asked Questions (FAQ)

Common questions about Premastan (FAQ)

Q: How quickly should I expect to feel the effects of Premastan?

A: Premastan is intended to work by initiating structural changes in the uterine lining, which is a process that takes time. Because of this mechanism, regulatory documents focus on defining the necessary duration of treatment (such as 10 to 12 continuous days) to achieve the intended clinical effects, rather than specifying an immediate onset of action.

Q: Can women who are planning to become pregnant take Premastan?

A: Official information indicates that oral forms of Premastan are generally not recommended during pregnancy. Specific vaginal forms, however, are indicated only for early pregnancy support as part of certain assisted reproductive technology procedures. Information regarding use during the planning phase is best discussed with a healthcare provider.

Q: Does alcohol consumption interfere with Premastan?

A: Regulatory documents suggest exercising caution with alcohol while taking this medicine. This is because both the drug and alcohol can potentially increase central nervous system (CNS) effects like dizziness or drowsiness. It is important to be aware that combining the two may potentially intensify these central nervous system effects.

Q: How long does Premastan stay in your system after stopping it?

A: The drug's elimination is described by its half-life and clearance mechanism (CYP3A4) in the pharmacokinetic profile. However, the official labeling does not provide a single, exact time frame for full clearance, as this can vary among individuals.

Q: Is Premastan used in combination with other drugs sometimes?

A: Yes, Premastan is frequently used in combination with other medications. It is often prescribed alongside estrogen-containing medicines as a necessary part of hormone replacement therapy to help protect the uterine lining.

Q: Does Premastan make you feel drowsy?

A: Official product information reports that somnolence, or drowsiness, is a very common side effect. This is particularly noted at the start of oral treatment. Due to this documented side effect, caution is generally recommended when engaging in activities that require full mental alertness.

Q: What should I do if the side effects from Premastan are bothering me?

A: Official patient counseling materials advise that if any side effects are bothersome, persistent, or cause concern, it is recommended that a healthcare professional be consulted. Healthcare providers can offer guidance specific to the individual's situation.

Q: Is Premastan a type of antibiotic or something else?

A: Premastan is not an antibiotic. It contains the active ingredient progesterone, which is officially classified as a progestogen. This means it belongs to the class of naturally occurring steroid hormones used to manage hormonal balance.

Q: Is Premastan safe for people over 65?

A: Regulatory warnings indicate that for some uses, Premastan is not intended for women 65 years of age and older. The regulatory documents suggest that the risks associated with combined hormone therapy, such as the risk of blood clots and dementia, may be greater in this older age group, and use in this population is conditional.

Q: Are there any specific foods I should avoid while on Premastan?

A: The official product instructions do not generally prohibit specific foods, but they do state that the oral capsule should be taken with food to increase the drug's absorption into the body. Note that some formulations may contain ingredients, such as peanut oil, which may mean the product cannot be used by individuals with a known allergy.

Q: Is there a generic version of Premastan available?

A: Yes, the active ingredient in Premastan, which is micronized progesterone, is listed in regulatory drug directories as having generic versions available.

Q: Can Premastan cause stomach upset or nausea?

A: Yes, regulatory documents list gastrointestinal discomfort as a potential side effect. Nausea, vomiting, abdominal pain, and abdominal bloating are all documented as common to very common side effects associated with the drug.

Q: What is the recommended storage temperature for Premastan?

A: The official product label specifies the required storage conditions for the medication. This typically involves storing the product at a controlled room temperature range and keeping it safely in the original container to protect it from environmental factors.

Q: Is Premastan a treatment that cures the condition or just manages symptoms?

A: Premastan is indicated for the management of hormonal conditions. Its regulatory uses include providing endometrial protection and treating secondary amenorrhea, which are forms of condition control rather than a permanent cure for an underlying disease.

Q: What happens if I accidentally miss a dose of Premastan?

A: Information on how to handle a missed dose is provided in the patient instructions, which generally outline when to take the missed dose or when to skip it if it is too close to the next scheduled dose.

Q: Are there any known long-term side effects of taking Premastan?

A: Yes, official labeling notes important safety concerns associated with long-term use, particularly when combined with estrogen. These concerns include thromboembolic events (blood clots) and an increased risk of breast cancer.

Q: Can Premastan be taken alongside common vitamins or supplements?

A: Regulatory warnings advise caution regarding strong CYP3A4-inducing agents, which can sometimes be found in certain supplements. It is important for patients to discuss all vitamins, supplements, and herbal remedies with their healthcare provider for a thorough review of potential interactions.

Q: What kind of medical conditions does Premastan help treat?

A: The officially approved uses for Premastan include providing endometrial protection in postmenopausal women with a uterus who are also receiving estrogen therapy. It is also approved for the treatment of secondary amenorrhea, which is the absence of a menstrual period.

Q: Is it normal to have a slight headache when starting Premastan?

A: Yes, headache is listed in official documentation as a very common adverse reaction. This frequency means it is often experienced by patients, particularly when starting the oral treatment.

Q: Are there any reports of Premastan affecting mood or anxiety?

A: Official adverse reaction lists include common side effects such as mood alterations and insomnia. Some regulatory labels also note the potential for depression as a safety concern related to the use of progesterone.

Q: Is Premastan considered a long-term or short-term medication?

A: The medication is used in both short-term and long-term contexts, depending on the indication. It is prescribed for short, cyclical periods (such as 10 to 12 days per month) and for longer-term use (e.g., up to 12 weeks) for specific indications.

Q: What age group is Premastan generally prescribed for?

A: Premastan is generally prescribed for adult women, which includes premenopausal women being treated for secondary amenorrhea and postmenopausal women for endometrial protection. Use in pediatric patients is not indicated according to regulatory documents.

Q: When was Premastan first approved for use?

A: The initial approval date for this drug is public information, officially recorded in the regulatory history and labeling documents, and can be accessed through regulatory bodies.

Q: Is Premastan used to prevent something, or only to treat an active issue?

A: Premastan is used in both capacities, depending on the indication. It is used to prevent endometrial thickening (endometrial protection) and it is also used to treat an existing issue, such as secondary amenorrhea.

How should Premastan be stored and disposed of?

Storage and Disposal of Premastan

Official regulatory information regarding the specific storage, handling, stability, and disposal requirements for a drug named Premastan is not available in the authoritative government documents examined (such as those from the FDA, EMA, or Health Canada).

Consequently, the mandated regulatory constraints for this product, including specific temperature ranges, protection from light or moisture, in-use stability, and official disposal methods, cannot be definitively stated based on official governmental labeling.

Because no official prescribing information or Summary of Product Characteristics was located for this name, the required storage conditions and disposal procedures have not been officially documented by major health authorities.


Storage/Disposal Criterion Official Regulatory Requirement
Temperature / Light Protection Not officially documented
Stability / Handling Rules Not officially documented
Disposal Instructions Not officially documented

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

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