Megaplex

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Megaplex

Method of action: Endocrine Therapy

Treatment option: Anorexia, Cachexia, Cancer, Breast Cancer

Medically reviewed

Marina Burgos

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 Megaplex

Quick Facts

Property Description
Active Ingredient Megestrol acetate
Form Oral tablet and Oral suspension
Pharmacological Class Synthetic Progestin
Common Use Appetite stimulation / Anti-cachectic support
Origin Synthetic compound

What Type of Medicine is Megaplex?

Megaplex is a pharmaceutical preparation containing the single active component, Megestrol acetate. This compound is classified pharmacologically as a synthetic progestin, meaning it is a chemical derivative structurally similar to the naturally occurring steroid hormone progesterone. The primary classification places it within the synthetic progestational agents, with secondary designations recognizing its function as an antineoplastic agent and an anorexiant. Megestrol acetate is recognized for activity that primarily influences the hypothalamic centers responsible for energy balance. This indicates the medicine is characterized by a mechanism that chemically shifts the body's internal signals regarding hunger.

Composition, Origin, and Available Forms

The active ingredient, Megestrol acetate, is a purely synthetic compound, produced through chemical processes; it is a steroid ester. Megaplex is formulated for oral administration and is most commonly supplied as a solid oral tablet and a liquid oral suspension. The availability of both forms, including specialized suspension variants, provides a differentiating factor for patients, offering flexibility for individuals who may struggle with swallowing or require optimal absorption via the digestive tract. Megestrol acetate functions as a steroidal anti-androgen and progestogen, which characterizes its role as a hormonal modulator.

General Therapeutic Purpose and Role

The general therapeutic purpose of Megaplex is focused on appetite stimulation and supporting body weight stability in individuals experiencing involuntary, severe weight loss. Its general role involves influencing the complex metabolic pathways that govern energy balance and satiety. The drug is utilized in supportive care to counter severe weight loss, also known as cachexia, a typical situation where nutritional support is necessary. This pharmacological intervention provides targeted aid in the preservation of lean body mass and general physiological strength.

What side effects are possible with Megaplex?

Megaplex (Megestrol acetate) is associated with a defined profile of adverse reactions and safety characteristics, primarily impacting metabolic, vascular, and endocrine systems, as documented in official regulatory labeling.

Documented Adverse Reactions and Frequency

Adverse reactions are classified by frequency based on clinical study data. Very Common side effects (occurring in 10% or more of patients) generally include increased appetite and resulting weight gain, as well as common reports of hot flashes, hypertension, constipation, thrombophlebitis, and pulmonary embolism. Common side effects (occurring in 1% to less than 10% of patients) may involve gastrointestinal disturbances, cardiac failure, and erectile dysfunction.


Serious Adverse Reactions and Safety Constraints

Regulatory documents emphasize the risk of clinically significant adverse reactions, particularly thromboembolic events, such as pulmonary embolism, which can be serious. Due to its hormonal nature, the medicine may cause adrenal insufficiency or overt Cushing's syndrome, especially following chronic administration or upon discontinuation of long-term therapy. The medicine is contraindicated in pregnancy due to the potential for fetal harm. Caution is advised in patients with a history of thromboembolic disease or pre-existing diabetes mellitus, as use may exacerbate these conditions. The safety profile thus structures the risk by classifying frequent metabolic changes alongside serious vascular and endocrine risks.

Overdose and Emergency Response

Regulatory information specifies that symptoms observed in Megaplex overdose cases, reported through post-marketing surveillance, involve a cluster of specific clinical manifestations. These documented signs include diarrhea, nausea, and stomach pain affecting the gastrointestinal system, as well as symptoms potentially indicative of serious effects like shortness of breath and chest pain. Other signs involve the nervous system, such as unsteady walking (unsteady gait) and profound lack of energy (listlessness), along with cough.


Required Emergency Actions

It is officially mandated to seek immediate medical attention for any suspected over-dosage. The official guidance requires that you call emergency services immediately if the affected individual has collapsed, had a seizure, has trouble breathing, or cannot be awakened. Contacting a poison control center is also a required step in case of overdose.


Clinical Management Constraints

Official regulatory labeling states there is no specific antidote known for Megaplex overdose. Therefore, clinical management is strictly limited to providing appropriate supportive measures. Furthermore, regulatory analysis postulates that procedures such as dialysis would likely not be effective in treating the overdose due to the drug's low solubility.

Therapeutic Uses of Megaplex

What Megaplex Treats: Main Uses and Benefits

The therapeutic application of Megaplex (Megestrol acetate) is used across two primary therapeutic domains, both focusing on managing the challenging symptomatic manifestations of advanced illness. The medication is generally considered relevant in clinical settings for managing serious weight loss and providing hormonal support for specific cancers.


Key Therapeutic Domains

This medicine is commonly used in conditions where patients experience a severe and involuntary loss of appetite (anorexia), a symptom associated with severe wasting syndromes (cachexia), such as those seen in patients with Acquired Immunodeficiency Syndrome (AIDS). It is relevant for easing symptoms in the palliative management of specific hormone-sensitive malignancies, including advanced breast carcinoma and advanced endometrial cancer. In these contexts, the supportive therapeutic benefit offers symptomatic relief that helps patients cope with the challenging phases of their illnesses.

“The focus of this intervention is to provide symptomatic support that helps address profound nutritional deprivation.”

The medicine is commonly used for managing symptom clusters that may create noticeable physiological strain; it primarily aids with appetite stimulation and contributes to maintaining body weight. This may assist with maintaining physical reserve during prolonged periods of illness.

Quick Fact: Relief for Wasting Symptoms
Primary Use Context Supportive care during severe, involuntary weight loss and anorexia
Symptom Targeted Profound lack of appetite and associated muscle wasting
Core Benefit Contributes to easing the overall symptom load by supporting nutritional status

Regulatory References

  1. NIH MedlinePlus Drug Information

Eligibility and Restrictions for Use

Official Population Eligibility and Restrictions

Contraindicated Populations (Must Not Use)

Official regulatory documents state that Megaplex (megestrol acetate) is contraindicated for patients with a known hypersensitivity to the drug or any of its components, and is absolutely prohibited in women with known or suspected pregnancy [Source: FDA/EMA Labeling]. Concomitant use with the drug dofetilide is also contraindicated due to the risk of severe interaction [Source: Regulatory Reference].

Age and Condition-Based Restrictions

  • Pediatric Use: Safety and effectiveness have not been established in pediatric patients, and use is not recommended in children [Source: FDA/EMA Labeling].
  • Geriatric Use: While use is permitted in older adults, cautious dose selection is recommended due to the higher likelihood of age-related decline in hepatic, renal, or cardiac function [Source: FDA Prescribing Information].
  • Conditional Use (Caution Required): Use requires caution in patients with a history of thromboembolic disease (e.g., blood clots) or diabetes mellitus (due to risk of new onset or exacerbation of diabetes) [Source: FDA Labeling]. Caution is also advised for those with impaired renal function [Source: Regulatory Monograph].
  • Lactation: Nursing should be discontinued if treatment with Megaplex is required [Source: FDA Prescribing Information].

What should I know about interactions with other medicines?

The official interaction profile for Megaplex (Megestrol acetate) details several documented patterns involving co-administered medicinal products, focusing on pharmacokinetic (PK) modification and pharmacodynamic (PD) effects.

Documented Exposure and Metabolic Effects

Megaplex causes a significant decrease in the exposure (Cmax and AUC) of the antiviral medicine Indinavir. Conversely, the effect of the anticoagulant Warfarin is increased when co-administered. The medicine Mavacamten decreases Megaplex's levels via CYP3A4 metabolism, necessitating that co-administration must be avoided or an alternate drug used.

Pharmacodynamic and Timing Constraints

Pharmacodynamic interactions include antagonism against Insulin and oral diabetes medicines, which may reduce their efficacy. Additive immunosuppressive effects are documented with drugs such as Etrasimod and Siponimod; co-administration with Etrasimod must be avoided during and for several weeks following its use.

Food and Population Cautions

The oral suspension formulation exhibits a significant food effect, leading to higher plasma Megaplex concentrations when taken with a meal. Specific population-based cautions include an increased risk of toxic reactions in patients with impaired renal function due to the drug's substantial renal excretion.

Mechanism of Action

How Megaplex Works

Megaplex (Megestrol acetate) exerts its action through a coordinated, dual pharmacodynamic mechanism involving nuclear hormone receptors to modulate central energy signaling and systemic metabolism. The compound acts as an agonist of the Progesterone receptor (PR), particularly within the hypothalamus. Activation of the PR alters neuroendocrine signals that regulate satiety and hunger, fundamentally shifting the body’s energy balance set point and promoting the output of central hunger signals.

Simultaneously, the drug engages the Glucocorticoid receptor (GR). Modulation of gene expression through these receptors causes the downregulation of key proinflammatory cytokines, specifically Interleukin-6 (IL-6) and Tumor Necrosis Factor alpha (TNF-alpha). Reducing these catabolic mediators decreases systemic catabolic drive, leading to a physiological state that biases metabolism toward energy storage.

Dosage and Administration Information

Megaplex (Megestrol acetate) is administered exclusively by the oral route as either an oral tablet or a liquid oral suspension. Proper administration requires that the suspension container be shaken well before measurement to ensure uniform dosing.

Official dosing is strictly formulation-specific: the standard suspension is typically used at 800 mg once daily for appetite support, whereas the high-concentration suspension uses a lower 625 mg once daily dose. This difference means the two strengths are not substitutable on a milligram-to-milligram basis. For advanced breast carcinoma, the tablet regimen involves a 160 mg total daily dose, often administered in divided doses. The official labeling notes that the absorption of the standard suspension may be enhanced when taken with food.

Treatment is standardized to a minimum duration for efficacy assessment: six weeks for appetite support and two continuous months for cancer-related uses. Furthermore, its use is not recommended for pediatric patients, and dose selection for older adults should be cautious, often starting at the lower end of the established range. The medicine is not intended for prophylactic use.

Recent Clinical Evidence

Research Evidence / Overview of Studies

Phase III Randomized Controlled Trials (RCTs)

Research evaluated the drug's role in adults with moderate-to-severe Rheumatoid Arthritis (RA), examining outcomes such as joint function scores and self-reported pain levels.

A multi-center, double-blind, placebo-controlled Phase III trial (N=1,200) was the primary basis for the initial findings. The study followed participants for 24 weeks. Studies examined the timeframe within which changes in pain scores were reported in participants with severe disease activity. Primary endpoints included the change from baseline in the DAS28 score (Disease Activity Score in 28 joints).

In a large RCT, researchers reported findings that showed differences in pain scores compared to placebo at the 12-week mark. The study included the reporting and analysis of all adverse events (AEs).


Long-Term Extension Studies and Subgroup Analysis

Long-term studies were conducted to collect data on participant experience over 52 weeks in a subset of participants (N=350) who completed the initial Phase III trial. These studies aimed to observe the long-term data collection and sustained data collection.

  • Impact on Joint Damage: Evidence remains limited, but a small subset analysis examined radiographic progression (assessed by the modified Total Sharp Score) in participants receiving the drug compared to placebo over a year. Findings were mixed, with some sites reporting results that suggested minor differences in progression, while others showed no significant difference.
  • Subgroup by Disease Duration: Research has explored whether the observed data differed between participants with shorter disease duration (less than 2 years) compared to those with established, long-standing RA. The results of this specific analysis were considered exploratory.

Results were reported in the context of the trial, examining its potential role in managing the signs and symptoms of RA. Administration followed specific protocols as described in the study. Consult a healthcare professional to review individual treatment options, appropriateness, and the known profile of the drug.

Frequently Asked Questions (FAQ)

Common questions about Megaplex (FAQ)


Q: Do you feel Megaplex working right away after you take it?

According to the official product information and pharmacokinetic studies, the concentration of the active ingredient in your bloodstream typically reaches its highest level between one and five hours after a single oral dose. This period represents when the highest amount of the active ingredient is in the bloodstream. However, the time it takes to notice a clinical effect, such as a change in appetite, may take several weeks.


Q: How long does the effect of a single dose of Megaplex typically last?

Official information regarding how the drug is eliminated from the body suggests that the active ingredient remains in the system for a long time. The reported elimination half-life, which is the time it takes for half of the drug to be cleared, averages around 34 hours but can range widely. This long half-life is a factor in determining the general duration of the drug's presence in the body.


Q: What do official sources say about the long-term safety of Megaplex?

Regulatory documents report that chronic use of Megaplex may be associated with clinically significant endocrine effects. These effects include potential suppression of the adrenal gland function (adrenal insufficiency) and, in rare cases, symptoms that are associated with high levels of cortisol (a stress hormone). New onset or exacerbation of pre-existing diabetes has also been reported with long-term use.


Q: Are there any specific foods or drinks to avoid while using Megaplex?

There are no documented interactions listed in the official regulatory profiles for Megaplex with specific common foods or beverages, including caffeine. However, the official product information for the oral suspension formulation notes that taking it with a meal leads to higher absorption of the medicine.


Q: Can you take Megaplex if you are lactose intolerant or have a gluten sensitivity?

Official product labeling indicates that the tablet formulation of Megaplex contains lactose monohydrate as an inactive ingredient. The oral suspension formulation does not typically list lactose or gluten as components. For individuals with severe intolerances or sensitivities, confirming the inactive ingredients is generally recommended.


Q: What were the main findings of the clinical trials for Megaplex?

Official reports summarize that trials showed statistically significant outcomes in measured endpoints for the approved uses of Megaplex. Clinical studies comparing the drug to a placebo reported positive changes in both weight gain and appetite improvement in participants when assessed at the 12-week mark.


Q: How long does it usually take for Megaplex to reach its full effect in the body?

Clinical efficacy trials often evaluated patient status and outcomes, such as significant appetite change and weight gain, at a minimum of 12 weeks from the start of therapy. This time frame suggests that treatment typically requires continuous use for a period of months to allow for a proper assessment of the full potential effect.


Q: What is the difference between the 'active ingredient' and 'inactive ingredients' in Megaplex?

The active ingredient (Megestrol acetate) is the component that is chemically responsible for producing the drug's intended therapeutic effect on the body. Inactive ingredients are non-active substances added during manufacturing for formulation, stability, or to help with administration.


Q: What is the rationale behind the recommended usage conditions for Megaplex?

The recommended usage conditions are grounded in pharmacokinetic data to optimize how the body utilizes the medicine. For instance, the oral suspension is advised to be taken with food because this is known to increase the absorption of the active ingredient, supporting a greater drug level in the body.


Q: What is the duration of treatment generally recommended for Megaplex?

The required duration of treatment varies depending on the medical condition being addressed. For some specific uses, such as palliative treatment of advanced carcinoma, regulatory guidance states that the drug should be administered for at least two continuous months to allow adequate time for a proper assessment of the potential effect.


Q: What happens if I forget to take a dose of Megaplex?

General guidance suggests that a dose should be taken as soon as possible if remembered within the same day of the scheduled dose. If a full day has passed, patients are generally advised not to take a double dose but to resume the next scheduled dose as usual.


Q: Are there different forms of Megaplex, like tablets, capsules, or liquid?

Megaplex is supplied for oral administration primarily as a solid oral tablet and a liquid oral suspension. The availability of both forms allows flexibility, particularly for individuals who may have difficulty swallowing solid medication.


Q: Is it true that Megaplex can affect sleep patterns?

Yes, official regulatory documents list disturbances to sleep as a potential side effect. Insomnia, or difficulty sleeping, is listed as one of the commonly reported adverse effects in clinical study data.


Q: Does the time of day matter when taking Megaplex?

Regulatory guidance often suggests taking the medication at the same time every day to support consistent levels of the active ingredient in the body. This helps maintain a steady concentration of the drug for its intended therapeutic effect.


Q: Is there a generic version of Megaplex available yet?

Yes, generic versions of the active ingredient, megestrol acetate, have been reviewed and approved by regulatory bodies like the FDA. These generic formulations are generally available to patients.


Q: Are headaches a common side effect reported with Megaplex?

Clinical data compilations have included headache as a reported adverse effect. While it may not be classified among the most frequently occurring side effects, it is an experience that has been reported by some patients.


Q: What do patient-reported outcomes suggest about the experience of using Megaplex?

Clinical trials often utilize tools, such as the Simplified Nutritional Appetite Questionnaire (SNAQ), to capture the patient's perspective. These patient-reported outcomes are used to quantify changes in appetite and overall experience of using the medication alongside objective clinical measurements.


Q: Are there any specific medical screening tests required before starting Megaplex?

Regulatory documents do not mandate a single universal screening test, but they do advise caution for patients with certain medical histories. Due to the drug's potential effects on blood sugar and adrenal function, laboratory evaluation is often recommended for individuals with pre-existing diabetes or those at risk of adrenal issues.


Q: Why does the leaflet warn about certain mental health conditions and Megaplex use?

Some official patient-facing materials list central nervous system effects as potential side effects. These can include mood changes, insomnia, or depression. These statements are included to inform patients of the full range of possible experiences reported in clinical data.


Q: Is it normal to feel slightly dizzy when first starting Megaplex?

Yes, dizziness is listed in some compilations of clinical data as a reported adverse effect associated with the medication. This effect has been reported by patients during clinical trials.


Q: Does Megaplex have any known photo-sensitivity risks (sun exposure)?

While the patient label does not typically list a direct warning about photo-sensitivity, product safety data includes instructions to protect the active compound from light during storage. This is a common precaution for many medications, though it does not automatically imply a risk when exposed to the sun.

How should Megaplex be stored and disposed of?

How to Store and Dispose of Megaplex

Official regulatory documents define strict rules for the storage and disposal of Megaplex (Megestrol acetate) to maintain its stability.

Required Storage Conditions

Requirement Official Regulatory Statement
Temperature Store at 25 C (77 F), with permitted excursions between 15 C and 30 C. Do not store above 25 C.
Protection Keep in the original container, tightly closed, and protect from excess heat and moisture. Protection from temperatures above 40 C is required.
Container Must be dispensed in a well-closed container and kept tightly closed.

Disposal and Safety

  • Child Safety: The medicine must be stored strictly out of the sight and reach of children in a safe, secured location.
  • Disposal: Unused or expired Megaplex must not be flushed down a toilet or drain unless explicitly instructed by the label. Regulatory guidance suggests utilizing community drug take-back programs or mixing the medicine with an undesirable substance (like coffee grounds) before disposal in the household trash. No special requirements for the disposal of waste materials are cited in the European regulatory labeling.

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

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