Pen Peptide
Bulking Stack | YK-11, RAD140, MK677 & OTR AC - 290mg/3ml
Bulking Stack | YK-11, RAD140, MK677 & OTR AC - 290mg/3ml
Pre-Mixed Stabilized Pen
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- 🥇 The first peptide brand with Pre-Mixed Pen stabilized formulations
- 📦 We ship with DHL Express in thermo-insulated packaging
- 💳 Secure payment by card or bank transfer
- 🧪 Purity ≥98% for precise research protocols
✅ Proper storage
✅ Proper storage
To ensure the optimal quality of our products, we pay special attention to the delivery and storage of peptides. All our shipments are sent in special cooling boxes that maintain the required temperature during transportation. This guarantees that the products will reach you in perfect condition.
After receiving the peptides, it is important to store them properly to preserve their stability and effectiveness. We recommend storing them at a temperature between 2°C and 8°C in a refrigerator. This ensures that the peptides retain their properties throughout their shelf life.
✅ Order and Delivery
✅ Order and Delivery
At Pen Peptide, we ensure fast and secure delivery of your order with DHL Express, maintaining the highest quality and reliability throughout the process.
How we process your order:
Once your payment is confirmed via bank transfer or debit/credit card, we dispatch your order on the next business day.
Orders are carefully packaged in temperature-controlled cooling boxes to ensure product integrity during transportation.
Delivery timeframe:
Standard delivery time within the Europe & UK: 1 to 3 business days (typically 1-2 business days for most locations).
Deliveries are handled exclusively by DHL Express, providing a fast and reliable shipping experience.
Tracking & order confirmation:
After your payment has been successfully processed, you will receive an email confirmation with your tracking number.
You can use the provided tracking link to monitor your shipment’s progress and estimated delivery time.
With Pen Peptide, you can trust that your order will arrive quickly and in perfect condition, ensuring a seamless and efficient experience.
✅ How does the pen work?
✅ How does the pen work?
The peptide pen is an innovative and easy-to-use device, designed for precise dosing of the substance in research settings. It is a pre-mixed pen (Pre-Mixed Pen), which means it contains an already dissolved peptide in an optimal concentration, ready for use.
Key features of the pen:
- Precision – Each pen is pre-dosed, ensuring accurate and consistent application.
- Ease of Use – No dilution or additional preparation is required.
- Sterility and Safety – Each product is manufactured in controlled laboratory conditions and sterile-packaged to guarantee its purity and effectiveness.
How to use the pen?
- Attach the needle by placing it onto the pen and twisting until fully secured.
- Set the desired dose – use the dosage dial by rotating the regulator to the corresponding number, which represents the selected units. The numbers displayed range from 0 to 60, indicating the units for dosing.
- Administer the dose according to the requirements of your research.
- Store the pen properly – in a refrigerator at a temperature between 2°C and 8°C to maintain the stability of the peptide.
With the pre-mixed pen from Pen Peptide, the process is simplified, efficient, and safe, ensuring optimal results for your research.
✅ Why choose Pen Peptide?
✅ Why choose Pen Peptide?
If you are looking for peptides of the highest quality with over 98% purity, Pen Peptide is one of the best places where you can easily and securely order online. At Pen Peptide, we specialize in the synthesis of highly purified peptides intended exclusively for Research & Development Use Only.
Our peptides are produced in certified GMP laboratories, adhering to strict standards of quality, safety, and control. Each product undergoes rigorous testing for purity and stability to ensure you receive research materials with verified origin and maximum effectiveness.
We understand how important fast and reliable service is for our customers. That’s why we offer express delivery within 1 to 3 business days. All shipments are securely packaged to maintain product quality during transportation.
✅ Molecular Structure Stabilization Process Technology (MSSPT)
✅ Molecular Structure Stabilization Process Technology (MSSPT)
The Molecular Structure Stabilization Process Technology (MSSPT) focuses on preserving the structural integrity and functionality of molecules under harsh conditions and during prolonged storage periods. This process may involve modification of the molecule itself, optimization of storage conditions, or the use of auxiliary components that protect the molecules from degradation.

Key stages of the process:
1. Molecular modification:
Chemical and genetic engineering: Involves altering the structure or composition of the molecule to make it more resistant to degradation. For example, protein cross-linking can prevent unfolding, or modification can reduce susceptibility to chemical reactions.
Chemical modification: The introduction of protective groups or changes to reactive sites can prevent unwanted chemical reactions and degradation.
2. Optimization of storage conditions:
Lyophilization (freeze-drying): This method removes water from the sample, helping to preserve structure and prevent degradation during storage.
Storage in specialized containers: Using containers that protect from light and oxygen can safeguard molecules from photodegradation or oxidation.
Controlled-release systems: These systems provide a steady concentration of the therapeutic molecule, but introduce additional challenges related to stabilizing molecules over extended release periods.
3. Use of auxiliary components:
Buffers: Buffers help maintain stable pH levels, which are crucial for many chemical reactions and biological processes.
Antioxidants: These additives can prevent or reduce oxidative degradation, which is a common cause of molecular instability.
Stabilizing agents: These help prevent aggregation, precipitation, or other forms of degradation.
4. Understanding molecular interactions:
Thermodynamic equilibrium: A fundamental understanding of the interactions between a molecule and its environment is essential for developing effective stabilization strategies.
Detergents for membrane proteins: Specialized detergents, such as those developed to stabilize membrane proteins, help maintain their structure in solution.
Molecular simulations: Techniques such as molecular dynamics can provide valuable insights into the stability and behavior of molecules.
5. Examples of stabilization techniques:
Protein stabilization: Strategies include forming disulfide bonds, using stabilizing agents or chaperones, and introducing stabilizing mutations.
Polymer stabilization: Methods include the addition of antioxidants or the use of modified clay minerals that prevent polymer degradation.
Propellant stabilization: Stabilizers are essential to prevent the decomposition of propellants and ensure their safe and reliable performance.
Pen Peptide – Proven Molecular Stabilization
Our peptide pens are developed with a strong focus on preserving the biological activity and structural stability of the active compounds. Thanks to thoroughly researched stabilization processes—including optimization of storage environments and precise modification of molecular structure—we achieve long-term durability and reliability of the peptides under appropriate storage conditions.
The MSSPT (Molecule Structure Stabilization Process Technology) we use incorporates various approaches to maintain molecular integrity, including the use of suitable buffers, antioxidants, and stabilizing agents. The MSSPT technology allows for the integration of multiple active molecules into a compact volume without compromising their structural integrity or biological effectiveness. Additional optimization of storage conditions—such as pH control and prevention of photodegradation and oxidation—ensures maximum stability and bioactivity of the peptides.
These precise measures guarantee that the final product remains effective and stable even after extended storage periods, making it a secure and reliable option for use in various research protocols.
Pen Content: YK-11 – 80mg, RAD-140 – 80mg, MK-677 – 80mg, OTR-AC – 50mg
What is the Bulking Stack?
Bulking Stack is a stabilized, pre-formulated subcutaneous pen containing four synergistic compounds: YK-11, RAD-140 (Testolone), MK-677 (Ibutamoren), and OTR-AC. This combination is designed for research protocols focused on maximizing muscle mass, strength, recovery, and regeneration—without directly affecting classical hormonal axes.
It contains a total of 290mg of active ingredients in 3ml, formulated for high bioavailability when used subcutaneously for scientific purposes, ensuring stability and accurate dosing in experimental conditions.
Key Components and Mechanism of Action:
YK-11 is a unique SARM structurally based on DHT, with potential myostatin inhibition via increased follistatin expression. This makes it particularly valuable in research protocols aiming for hypertrophy beyond physiological limits. YK-11 exhibits partial androgenic activity combined with gene activation related to cellular growth and may support rapid and pronounced muscle mass gains.
RAD-140 (Testolone) is a potent selective androgen receptor modulator that activates receptors in skeletal muscle tissue without affecting other hormone-sensitive tissues. RAD-140 has been studied for its ability to stimulate protein synthesis, increase strength, and enhance recovery following high physical loads. Its combination with YK-11 provides a comprehensive anabolic response.
MK-677 (Ibutamoren) is a ghrelin receptor agonist and GH–IGF-1 axis activator that increases growth hormone and IGF-1 secretion without suppressing the androgenic axis. MK-677 supports nitrogen retention, enhances tissue repair, improves sleep quality, and aids regeneration—making it an essential component in protocols focused on long-term muscle building.
OTR-AC complements the stack with targeted action on muscle density and definition without fluid retention. It shows high selectivity toward muscle tissue and is suitable for enhancing outcomes under deficit or low-recovery conditions, without estrogenic activity.
Synergistic Effect of the Bulking Stack:
The combination of YK-11 and RAD-140 delivers a highly potent anabolic stimulus, while MK-677 supports hormonal and cellular regeneration. OTR-AC contributes to visual muscle density and the preservation of results under various metabolic conditions. This formula is aimed at maximizing muscle mass, strength, and structural integrity, delivering a balanced response between androgenic activation and hormonal support.
The synergy between the four compounds allows for reduced individual dosages while enhancing overall effectiveness, making it ideal for advanced research protocols with a strong anabolic focus.
Scientifically Supported Potential Benefits:
The Bulking Stack formula is designed to deliver pronounced hypertrophy supported by hormonal and receptor regulation. The stack addresses key objectives in scientific protocols focused on growth, density, and functional recovery.
- Creates conditions for optimized muscle growth through enhanced anabolic stimulation
- Supports accelerated regeneration and tissue repair
- Maintains an anabolic environment via IGF-1 and GH pathways
- Improves sleep quality and recovery, essential for long-term muscle development
- Stimulates visual density and dry muscle definition without water retention
- Suitable for intensive lab cycles assessing muscle growth capacity and metabolic adaptation
Dosage and Use in Research Protocols:
Recommended research protocol: 10 units once daily, for a duration of 4–8 weeks, followed by a rest period of 3–5 weeks.
Total pen content: 300 units
Maintaining optimal dosage and monitoring application duration play a crucial role in limiting the manifestation of side effects.
Possible Side Effects:
Currently, there is insufficient published clinical data regarding long-term usage profiles. In laboratory settings, tolerability is generally good, but as with any compound administered subcutaneously, individual reactions cannot be excluded.
Potential local effects related to the application method may include redness, sensitivity, discomfort, or mild swelling at the injection site. In longer cycles and higher doses, some models have explored possible effects on endogenous hormonal regulation, which may vary depending on dosage, duration, and individual sensitivity.
Strict monitoring of both dosage and duration is recommended for all research protocols.
For laboratory purposes and personal observation only.
For laboratory purposes and personal observation only.
The information has been collected from numerous studies and analyses conducted over the years and is not intended for diagnosing, treating, or preventing any diseases.
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