Leuprorelin 3.75 mg is formulated as a long‑acting sustained‑release microsphere. Its core advantage lies in the precise regulation of the endocrine axis, providing a convenient and effective therapeutic regimen for hormone‑dependent diseases. Approved by the FDA in 1985, the product has been widely and maturely used in clinical practice.
The product features a unique mechanism of action: through continuous stimulation, it desensitizes pituitary GnRH receptors, inhibits the release of gonadotropins, and subsequently reduces estradiol or testosterone levels, thereby achieving a medical castration effect. The effect is reversible, and the function of the pituitary‑gonadal system can be gradually restored after drug withdrawal.This dosage form is administered by intramuscular injection once a month. The product enables stable drug release, avoids fluctuations in plasma drug concentration, and improves therapeutic stability and patient compliance.
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Leuprorelin COA
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| Certificate of Analysis | ||
| Compound name | Leuprorelin | |
| Grade | Pharmaceutical grade | |
| CAS No. | 53714-56-0 | |
| Quantity | 65g | |
| Packaging standard | PE bag+Al foil bag | |
| Manufacturer | Shaanxi BLOOM TECH Co., Ltd | |
| Lot No. | 202512090051 | |
| MFG | Dec 9th 2025 | |
| EXP | Dec 8th 2028 | |
| Structure |
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| Item | Enterprise standard | Analysis result |
| Appearance | White or almost white powder | Conformed |
| Water content | ≤5.0% | 0.93% |
| Loss on drying | ≤1.0% | 0.51% |
| Heavy Metals | Pb≤0.5ppm | N.D. |
| As≤0.5ppm | N.D. | |
| Hg≤0.5ppm | N.D. | |
| Cd≤0.5ppm | N.D. | |
| Purity (HPLC) | ≥99.0% | 99.90% |
| Single impurity | <0.8% | 0.24% |
| Total microbial count | ≤750cfu/g | 95 |
| E. Coli | ≤2MPN/g | N.D. |
| Salmonella | N.D. | N.D. |
| Ethanol (by GC) | ≤5000ppm | 613ppm |
| Storage | Store in a sealed, dark, and dry place below -20°C | |
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| Chemical Formula | C59H84N16O12 | |
| Exact Mass | 1208.65 | |
| Molecular Weight | 1209.42 | |
| m/z | 1208.65(100.0%), 1209.65(63.8%), 1210.65(20.0%), 1209.64(5.9%), 1211.66(4.1%), 1210.65(3.8%), 1210.65(2.5%), 1211.65(1.6%), 1211.65(1.2%) | |
| Elemental Analysis | C,58.59; H,7.00; N,18.53; O,15.87 | |
Clinical Applications in Uterine Fibroids
Based on its pharmacological properties and clinical practice, Leuprorelin 3.75 mg is mainly used for preoperative pretreatment, symptomatic relief, and conservative treatment in special populations of patients with uterine fibroids.
Preoperative Pretreatment
Preoperative pretreatment is the most important application of the product in uterine fibroids, especially for patients with large fibroids, severe symptoms, anemia, or high surgical complexity.Its core purpose is to reduce fibroid volume, improve the patient's general condition, lower surgical risks, and enhance surgical outcomes.
In patients with fibroid diameter ≥10 cm or markedly enlarged uterus (e.g., corresponding to ≥12 weeks of gestation),3–6 months of preoperative treatment with it can reduce fibroid volume by an average of 48%–50% and significantly decrease uterine size.This reduces intraoperative bleeding, lowers the risk of injury to adjacent organs (e.g., bladder, rectum), and facilitates surgical procedures, especially minimally invasive surgeries such as laparoscopy and hysteroscopy, thus reducing surgical trauma and shortening postoperative recovery time.
A multicenter randomized controlled trial showed that compared with the progestogen lynestrenol, 16 weeks of preoperative treatment with it reduced mean fibroid diameter by 26.5%, which was significantly higher than 7.3% in the lynestrenol group.The decrease in hemoglobin at 48 hours postoperatively was also smaller, indicating better improvement of preoperative anemia and less intraoperative bleeding.
For patients with moderate-to-severe anemia (hemoglobin ≤8 g/dl), the product can inhibit endometrial hyperplasia, reduce menstrual flow, and promote the recovery of bone marrow hematopoietic function,gradually increasing hemoglobin levels to correct anemia, avoiding preoperative blood transfusion, reducing transfusion-related risks, and creating favorable conditions for surgery.Clinical data show that after 3 months of treatment with the product, hemoglobin and serum iron levels are significantly increased, and anemia is effectively improved, ensuring safe surgery.
Efficacy Evaluation of Leuprorelin in Uterine Fibroids
The efficacy of the product in the treatment of uterine fibroids is mainly evaluated from three aspects: changes in fibroid volume, symptom improvement, and recovery of laboratory parameters.Based on clinical research data, its efficacy is definite and rapid, as detailed below:
(1) Changes in Fibroid Volume
Clinical studies show that after 3 months of treatment with the product, uterine fibroid volume is reduced by an average of 48%–50%,which is comparable to that of other GnRH agonists (e.g., triptorelin 3.75 mg) with no significant difference.
A multicenter randomized controlled trial involving 125 patients with uterine fibroids showed that after 3 months of treatment with the product,the median reduction rate of the largest fibroid volume was 48%, and the median reduction rate of uterine volume was 49%,which were not statistically different from 50% and 51% in the triptorelin group, confirming reliable efficacy in reducing fibroid volume.
For large fibroids (diameter ≥10 cm), the volume reduction rate can exceed 50% after 6 months of treatment.Some patients achieve a fibroid volume suitable for minimally invasive surgery or even avoid surgery.In addition, Leuprorelin 3.75 mg shows good volume reduction effects on different types of uterine fibroids (e.g., intramural fibroids, subserosal fibroids),with a slightly weaker effect on submucosal fibroids. The treatment plan should be adjusted according to fibroid type.
(3) Recovery of Laboratory Parameters
In patients with anemia, hemoglobin levels gradually increase after treatment with it.Usually after 3 months of treatment, hemoglobin returns to the normal range (110–150 g/L), and serum iron levels also return to normal, eliminating the need for blood transfusion.
Meanwhile, estrogen levels decrease to postmenopausal levels (estradiol <183 pmol/L), and progesterone levels are also significantly reduced,supporting fibroid shrinkage and symptom relief.Clinical studies show that serum estradiol levels decrease to below 183 pmol/L in 94% of patients after treatment, creating a favorable endocrine environment for fibroid regression.
The research and development of the product originated from in-depth studies on GnRH. In 1971, researchers successfully isolated and chemically characterized GnRH, confirming it as a polypeptide hormone secreted by the hypothalamus, which regulates the release of pituitary gonadotropins and further affects hormone secretion by the ovaries and testes. This laid the theoretical foundation for the subsequent synthesis of GnRH analogs.Based on this discovery, many pharmaceutical companies and research institutions launched projects to develop highly potent GnRH agonists, among which the research team of Japan's Takeda Pharmaceutical Company made the first breakthrough.
Synthesis and Patent Protection of Leuprorelin (1973–1974)
Around 1973, the team at Takeda Pharmaceutical successfully synthesized the product. Its chemical name is:5-oxo-L-prolyl-L-histidyl-L-tryptophyl-L-seryl-L-tyrosyl-D-leucyl-L-leucyl-L-arginyl-N-ethyl-L-prolinamide acetate.It is a synthetic peptide analog of native GnRH, with higher potency and longer half-life than natural GnRH.In 1974, Takeda applied for patents for the compound and its synthetic process in Japan, Germany, the United States and other countries, providing legal protection for later formulation development and clinical application.
Development of Long-Acting Sustained-Release Formulation and Birth of the 3.75 mg Strength (1980s)
The early synthesized Leuprorelin 3.75 mg was only available as a daily injection, which was inconvenient and limited its clinical use.Therefore, Takeda Pharmaceutical collaborated with Abbott Laboratories (US) to focus on the development of a long-acting sustained-release formulation. Using biodegradable polylactic acid/glycolic acid copolymer (PLGA) and polylactic acid (PLA) as carriers, microsphere sustained-release preparations were developed to achieve stable drug release.In 1989, the long-acting, once-monthly injectable formulation was approved, giving rise to the 3.75 mg strength. This strength allows once-monthly intramuscular administration, provides sustained hormonal suppression, greatly improves patient compliance, and meets the therapeutic needs of various hormone-dependent diseases.
Expansion and Global Popularization of the 3.75 mg Strength (After 1985)
In 1985, it was first approved by the U.S. FDA for the treatment of advanced prostate cancer. Later, its indications were gradually expanded to include endometriosis, uterine fibroids and other conditions.With the advantages of long-acting convenience and stable efficacy, Leuprorelin 3.75 mg strength became the preferred clinical formulation, widely used in preoperative pretreatment, symptomatic relief and other scenarios.With the deepening of clinical research, the population eligible for this strength has been continuously expanded, and its safety and efficacy have been recognized by the global medical community.The product is now marketed in many countries and has become one of the most widely used strengths among GnRH agonists, promoting the upgrading of treatment models for hormone-dependent diseases.
Identification: Verification of Drug Authenticity
Identification is mainly performed by a combination of High-Performance Liquid Chromatography (HPLC)and Thin-Layer Chromatography (TLC).
HPLC confirms consistency of the main peak by comparing the retention time of the test solution with that of the reference standard, showing high specificity.
TLC involves applying the test solution and reference standard onto a silica gel G thin-layer plate, developing with a specified mobile phase, and comparing the position and color of the spots after visualization. It is simple and rapid for preliminary screening of drug authenticity.
Combination of the two methods improves the accuracy of identification.
Assay: Accurate Determination of Active Ingredient
The assay is mainly performed by Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC).
As a peptide compound with relatively strong polarity, a C18 column is used, with acetonitrile–phosphate buffer as the mobile phase under gradient elution, and the detection wavelength is set at 220 nm.
The content of leuprorelin acetate in the test solution is calculated by the external standard method. The sustained-release microspheres must first be dissolved and the active ingredient extracted to eliminate interference from excipients.
This method provides excellent resolution and high accuracy, allowing precise determination of the active ingredient content in the 3.75 mg strength, in compliance with pharmacopoeial standards.
Related Substances Test: Control of Impurity Levels
RP-HPLC with gradient elution is used to separate related substances such as degradation products and synthetic intermediates in the test preparation.
By adjusting the mobile phase ratio, complete separation between the main peak and impurity peaks is achieved. The content of related substances is calculated by the self-reference method, with strict limits on impurities.
In addition, residual solvents (e.g., methanol, acetonitrile) are determined by Gas Chromatography (GC) to ensure that residual levels meet safety standards and prevent impurities from affecting efficacy or causing adverse reactions.
FAQ
1.What is leuprolide 3.75 mg injection used for?
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Leuprolide Depot 3.75mg Injection belongs to the class of synthetic hormones used in the treatment of prostate cancer in men, endometriosis, and hormone-responsive breast cancer in women. Also, Leuprolide Depot 3.75mg Injection is used to treat premature puberty in children.
2.How long is a typical LUPRON DEPOT 3.75 treatment?
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The duration of therapy with LUPRON DEPOT is limited to 3 months. The symptoms associated with fibroids will return after stopping therapy. Your doctor may consider a 1-month trial of iron alone, as some women will respond to iron alone.
3.Is leuprolide 3.75 safe for long term use?
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Maximum Treatment Duration
3Treatment should not exceed 12 months due to concerns about adverse impact on bone mineral density. The recommended dosage of LUPRON DEPOT 3.75 mg is one IM injection every month for up to three months.
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