MEDICAL DISCLAIMER: Educational research guidelines only. Lyophilized peptides are investigational chemical compounds and are NOT approved for human consumption, diagnosis, or therapy. Consult a licensed physician before any research application.
Buserelin Dosage Chart, Schedule & Reconstitution Protocol
Quickstart Highlights
Buserelin is a nonapeptide GnRH agonist (brand names Suprefact, Suprecur, Profact) used to suppress sex hormones in prostate cancer, endometriosis and uterine fibroids, and for pituitary down-regulation in IVF. A continuous dose first stimulates the pituitary, then desensitizes GnRH receptors so LH, FSH, testosterone and estradiol fall by about 95% within 1-3 weeks (Soloway, PMID 3133944). The licensed subcutaneous regimen is 500 mcg every 8 hours for 7 days, then 200 mcg once daily; the nasal spray is dosed at 400 mcg three times daily because intranasal bioavailability is only about 3%. In assisted reproduction, a single 500 mcg subcutaneous bolus can trigger ovulation instead of hCG. Subcutaneous injection is a genuine licensed route, so the reconstitution figures here mirror real prescribing. Buserelin is approved across the UK, EU, Canada and Australia but is not FDA-approved in the United States; this page is educational only and not medical advice.
Reconstitute: Add 2.5 mL bacteriostatic water → 2 mg/mL concentration.
Typical dose: 500 mcg q8h SC ×7 days, then 200 mcg/day SC
Easy measuring: At 2 mg/mL, 1 unit = 0.01 mL = 0.0200 mg (20 mcg) on a U-100 insulin syringe.
Storage: Lyophilized powder stored frozen at −20 °C. Reconstituted solution and the commercial 1 mg/mL injection are kept refrigerated at 2-8 °C, protected from light and not frozen; per the Suprefact SmPC an in-use injection vial should be discarded within about 14-15 days [5]. Nasal spray is stored below 25 °C.
Half-life: ~50-80 minutes subcutaneously and 1-2 hours intranasally; a 9.45 mg depot implant suppresses testosterone for ~224 days.
Route: Subcutaneous injection or intranasal spray (oral is inactive due to peptidase degradation); long-acting biodegradable SC depot implants also exist.
Status: Approved in the UK, EU, Canada and Australia (Suprefact/Suprecur/Profact); NOT FDA-approved in the US — presented here for education only.
About Buserelin
Buserelin dosage in the clinic follows a deliberate two-phase pattern that mirrors how GnRH agonists work: a high-frequency loading week to ride out the pituitary "flare," followed by a lower maintenance dose once receptor down-regulation suppresses LH, FSH, testosterone and estradiol [2][5]. For advanced hormone-dependent prostate cancer the licensed regimen is 500 mcg subcutaneously every 8 hours for 7 days, then 200 mcg once daily, or a switch to the intranasal spray at 400 mcg three times daily [5]. Endometriosis and uterine fibroids are usually treated with the nasal spray (400 mcg three times daily for up to 6 months); in IVF, buserelin is used for pituitary down-regulation in the long protocol, and a single 500 mcg subcutaneous bolus can substitute for hCG as an ovulation trigger [1][4][6].\n\nUnlike many compounds catalogued on this site, subcutaneous injection is a genuine, licensed route for buserelin, so the figures below mirror real prescribing rather than a route conversion; the intranasal route is equally common (nasal doses are larger because intranasal bioavailability is only about 3%). This guide models a 5 mg vial reconstituted with 2.5 mL of bacteriostatic water (2 mg/mL, 20 mcg per U-100 unit) so the 500 mcg loading dose lands at 25 units and the 200 mcg maintenance dose at 10 units.\n\nFrequency: Inject subcutaneously every 8 hours (three times daily) for the first 7 days, then once daily thereafter. Buserelin is approved outside the United States but is not FDA-approved; this reconstitution reference is educational only and not medical advice.
Quick Protocol Navigation
Reconstitution Instruction & Mixing Step-by-Step
Lyophilized powder must be reconstituted carefully. Agitating peptide chains can shear disulfide bonds and render the peptide biologically inert.
Draw 2.5 mL of bacteriostatic water into a sterile syringe.
Inject the water slowly down the inner glass wall of the 5 mg Buserelin vial; do not aim the stream directly at the powder and do not shake.
Gently swirl or roll the vial until the solution is completely clear; the result is a 2 mg/mL concentration (2,000 mcg/mL, or 20 mcg per U-100 insulin-syringe unit).
Store refrigerated at 2-8 °C and draw the prescribed number of units: 500 mcg loading dose = 25 units (0.25 mL); 200 mcg maintenance dose = 10 units (0.10 mL).
Educational note: subcutaneous injection and intranasal spray are buserelin's real licensed routes — rotate injection sites, discard the reconstituted vial within ~14 days, and remember this is not FDA-approved and not medical advice.
Interactive Buserelin Syringe Calculator
Currently visualizing the 5 mg vial reconstituted with 2.5 mL bacteriostatic water. Adjust the target dose to dynamically render syringe units.
Reconstitution Calculation: 5mg dry powder in 2.5mL water yields 2.00 mg/mL. To evaluate a 250mcg dose, pull to 12.5 units (13 syringe ticks).
U-100 Syringe Representation
Educational reference visual. Assumes standard U-100 insulin syringe where 1.0 mL volume = 100 units.
Titration & Dose Escalation Schedules
| Phase | Dose per injection | Units (per injection) |
|---|---|---|
| Days 1-7 — loading (500 mcg SC every 8 hours, ~1,500 mcg/day) | 500 mcg | 25 units (0.25 mL) |
| Day 8 onward — maintenance (200 mcg SC once daily) | 200 mcg | 10 units (0.10 mL) |
| IVF ovulation trigger — single SC bolus (alternative to hCG) | 500 mcg | 25 units (0.25 mL) |
Administration guidelines: Refer to guidelines | 2.5 mL Reconstitution
Research Supplies Quantity Planner
Scientific mathematical planning of syringes, bacteriostatic water and dry vials needed for extended research blocks using the 5 mg vial.
Peptide Vials (Buserelin, 5 mg each):
- check8-week course (loading week ~1,500 mcg/day, then 200 mcg/day) ≈ 20,300 mcg → about 5 vials, allowing for ~14-day reconstituted shelf life
- check12-week course ≈ 25,900 mcg → about 6 vials
- check16-week course ≈ 31,500 mcg → about 7 vials
Insulin Syringes (U-100):
- checkLoading week: 3 injections/day = 21 syringes; maintenance: 7 syringes/week
- check8 weeks ≈ 70 syringes
- check12 weeks ≈ 98 syringes
- check16 weeks ≈ 126 syringes
Bacteriostatic Water (10 mL bottles): Use 2.5 mL per vial for reconstitution.
- check8 weeks (~5 vials): 12.5 mL → 2 × 10 mL bottles
- check12 weeks (~6 vials): 15 mL → 2 × 10 mL bottles
- check16 weeks (~7 vials): 17.5 mL → 2 × 10 mL bottles
Alcohol Swabs: One for the vial stopper plus one for the injection site at every administration.
- checkLoading week ≈ 42 swabs; maintenance ≈ 14 swabs/week
- check8 weeks ≈ 140 swabs
- check12 weeks ≈ 196 swabs
- check16 weeks ≈ 252 swabs → 2-3 × 100-count boxes
Mechanism of Action (MOA)
Buserelin is a synthetic nonapeptide analog of gonadotropin-releasing hormone (GnRH, also called LHRH) with the sequence pyroGlu-His-Trp-Ser-Tyr-D-Ser(tBu)-Leu-Arg-Pro-ethylamide (molecular formula C60H86N16O13, ~1,239 Da). Substituting D-serine(tert-butyl) at position 6 and replacing the C-terminal glycinamide with an ethylamide makes the molecule resistant to enzymatic degradation and far more potent and longer-acting at the pituitary GnRH receptor than native GnRH [2].\n\nEndogenous GnRH is secreted in pulses every 60-120 minutes, and this pulsatility is essential: gonadotrope cells respond to intermittent stimulation but are silenced by continuous exposure. Buserelin exploits both behaviors. On first administration it acts as a potent agonist and triggers a surge of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) — the clinical "flare" — which transiently raises testosterone in men and estradiol in women and is deliberately harnessed as a single-bolus ovulation trigger in IVF [6]. With continued daily (or intranasal multi-daily) dosing, GnRH receptors are occupied continuously, internalize and down-regulate; the gonadotrope is desensitized and LH/FSH output collapses over roughly 1-3 weeks. Sex-steroid production then falls to castrate levels in men and menopausal levels in women — testosterone and estradiol each drop by about 95% — producing a reversible "medical castration" used to treat hormone-dependent prostate cancer, endometriosis, uterine fibroids and central precocious puberty [1][2][3].\n\nPharmacokinetics: because buserelin is a peptide it is destroyed by gastrointestinal peptidases and is not orally active. It is given subcutaneously (about 70% bioavailable), intranasally (only ~2.5-3.3% bioavailable, which is why nasal doses are roughly double the subcutaneous ones — 400 mcg versus 200 mcg), or as a biodegradable depot implant (6.3 mg or 9.45 mg) that releases drug over 2-3 months. Plasma protein binding is about 15%. The elimination half-life is short — roughly 50-80 minutes after subcutaneous injection and 1-2 hours intranasally — so immediate-release dosing must be repeated frequently (q8h loading, then daily), whereas a 9.45 mg depot implant maintains castrate testosterone for around 224 days [3][5]. Buserelin is inactivated by peptidases in the liver, kidney and gut and is excreted in urine and bile, with roughly half the dose recovered unchanged in urine [5].\n\nBecause the same molecule both stimulates (acutely/pulsatile) and suppresses (chronically) the hypothalamic-pituitary-gonadal axis, the dosing strategy entirely determines the effect: the continuous regimens on this page are designed to suppress, while the single-bolus trigger is the opposite use. Buserelin is approved in the UK, EU, Canada, Australia and many other markets but has never been FDA-approved in the United States, where related agonists (leuprolide, goserelin, triptorelin) fill the same niche [5].
Clinical Trial Efficacy Highlights
- starSoloway (1988, Am J Clin Oncol) reported that subcutaneous buserelin reliably reduced serum testosterone to castrate levels (<100 ng/dL) by week 4 in 95% of men with advanced prostate cancer, with mean testosterone of about 29 ng/dL at 4 and 12 months on the subcutaneous route, and showed no significant difference in response or progression versus historical controls treated with diethylstilbestrol or orchiectomy [2].
- starPettersson and colleagues (2006, Eur Urol) followed men with localized prostate cancer given a single 9.45 mg biodegradable buserelin implant and found testosterone suppressed below the castration limit (0.58 ng/mL) for a median of 224 days (range 139-309), demonstrating the depot's long-acting, sustained suppression [3].
- starDonnez and colleagues (1989, Fertil Steril) compared intranasal buserelin with a subcutaneous buserelin implant in 100 infertile patients with ovarian endometriosis; both routes lowered serum estradiol to menopausal levels, but the subcutaneous implant produced more profound and consistent pituitary-ovarian suppression and a greater reduction in endometriotic lesion scores and cyst diameter [1].
- starTarlatzis and colleagues (1993, Hum Reprod) randomized 527 assisted-reproduction cycles to short versus long buserelin/HMG/HCG protocols; the long (down-regulation) protocol yielded significantly more follicles (9.1 vs 7.7), oocytes (8.4 vs 6.5) and embryos (6.3 vs 4.0), with a numerically higher pregnancy rate per transfer (25.8% vs 19.4%) [4].
- starHumaidan and colleagues (2005, Hum Reprod) showed that in GnRH-antagonist IVF/ICSI cycles a single 0.5 mg (500 mcg) subcutaneous buserelin bolus could trigger final oocyte maturation and ovulation in place of hCG, exploiting the agonist flare to generate an endogenous LH surge and reduce ovarian hyperstimulation risk [6].
- starAcross the licensed indications captured in the Suprefact SmPC — advanced hormone-dependent prostate cancer, endometriosis, uterine fibroids, pituitary down-regulation for assisted reproduction and central precocious puberty — efficacy depends on transitioning patients off the initial high-frequency loading schedule onto maintenance dosing once receptor desensitization has suppressed gonadotropin output, with anti-androgen cover recommended during the prostate-cancer flare [5].
Side Effects & Tolerability Profile
Clinical subjects transiently report mild side effects. Slowly escalating the titration dose represents the single most effective intervention to limit side effects.
- warningInitial flare: the first days of treatment transiently raise testosterone/estradiol, which in prostate cancer can cause tumor flare with worsening bone pain, urinary obstruction or, rarely, spinal cord compression; co-administration of an anti-androgen during the loading week is recommended to blunt this [2][5].
- warningHypogonadal/hypoestrogenic effects from sustained suppression are the most common adverse events: hot flushes (reported in about 72% of men by Soloway), reduced libido, erectile dysfunction, vaginal dryness and atrophy, and menstrual changes [2][5].
- warningProlonged use (generally beyond 6 months) causes loss of bone mineral density and osteoporosis risk; this is why endometriosis courses are usually capped at 6 months and add-back therapy is considered [5].
- warningMood effects, including an increased risk of depression that may be severe, emotional lability, headache and dizziness, are recognized GnRH-agonist class effects flagged in the buserelin SmPC; patients should be counseled accordingly [5].
- warningRoute-specific effects: subcutaneous injection-site reactions occurred in about 12% of patients in Soloway's series, and the nasal spray can cause nasal irritation, dryness, epistaxis or altered smell/taste [2][7].
- warningContraindications and cautions include pregnancy and breastfeeding, undiagnosed abnormal vaginal bleeding, hypersensitivity to GnRH analogs, and hormone-independent prostate cancer or prior surgical castration (no benefit); rare hypersensitivity/anaphylaxis has been reported.
- warningRegulatory/research status: Buserelin is NOT FDA-approved in the United States (it is approved in the UK, EU, Canada and Australia); any use as post-cycle therapy or for performance is off-label and unproven, and the figures here are educational only, not medical advice.
Subcutaneous Injection Technique
Most research peptides require subcutaneous injection into fatty tissue. Never inject directly into a blood vessel or deep muscle tissue unless clinically detailed.
1. Site Selection
Common locations include the abdomen (2 inches from navel), outer upper arms, or thighs.
2. Sanitization
Thoroughly clean the selected site, stopper and vial top using 70% isopropyl alcohol prep swabs.
3. Angle & Push
Pinch the skin and insert the needle at a 45 to 90-degree angle. Depress plunger smoothly.
4. Site Rotation
Rotate injection sites continuously to avoid lipodystrophy or tissue scarring.
Frequently Asked Questions
What is the typical Buserelin dosage?expand_more
For advanced hormone-dependent prostate cancer the licensed Buserelin dosage is 500 mcg subcutaneously every 8 hours (three times daily) for the first 7 days, then 200 mcg subcutaneously once daily, or a switch to the intranasal spray at 400 mcg three times daily. Endometriosis and uterine fibroids use the nasal spray at 400 mcg three times daily for up to 6 months. In IVF, buserelin is used for pituitary down-regulation, and a single 500 mcg subcutaneous bolus can trigger ovulation. These are clinical reference figures, not a personal prescription.
Is Buserelin FDA approved?expand_more
No. Buserelin is not approved by the U.S. FDA. It is, however, approved and widely marketed in the United Kingdom, European Union, Canada, Australia and many other countries under brand names such as Suprefact, Suprecur and Profact. In the United States, clinicians use other GnRH agonists in the same class (leuprolide, goserelin, triptorelin). Because it lacks U.S. approval, the protocol on this page is provided strictly for education and is not medical advice.
How do you reconstitute Buserelin and measure a dose?expand_more
In this educational model a 5 mg vial is reconstituted with 2.5 mL of bacteriostatic water, giving 2 mg/mL (2,000 mcg/mL, or 20 mcg per U-100 insulin-syringe unit). Add the water slowly down the vial wall, swirl gently until clear, and refrigerate. A 500 mcg loading dose is then 25 units (0.25 mL) and a 200 mcg maintenance dose is 10 units (0.10 mL). Subcutaneous injection is a genuine licensed route for buserelin, so these figures mirror real prescribing rather than a route conversion.
What is Buserelin's half-life?expand_more
Buserelin has a short plasma elimination half-life of roughly 50-80 minutes after subcutaneous injection and about 1-2 hours after intranasal dosing, which is why immediate-release dosing is given every 8 hours during loading and then daily. Subcutaneous bioavailability is about 70% versus only ~2.5-3.3% intranasally. A long-acting biodegradable depot implant (6.3 mg or 9.45 mg) sidesteps this by releasing drug over 2-3 months and can suppress testosterone for around 224 days.
Why does Buserelin cause an initial flare, and is it used for PCT or stacking?expand_more
Buserelin is a GnRH agonist, so its first doses overstimulate the pituitary and cause a transient surge in LH, FSH, testosterone and estradiol — the flare — before continuous exposure desensitizes and down-regulates the receptors and suppresses the axis. This dual behavior is why a single bolus is used to trigger ovulation in IVF while continuous dosing is used for medical castration. Some bodybuilders speculate about using the flare for post-cycle therapy (PCT) or stacking it with other agents, but this is off-label, unstudied for that purpose, and risks profound suppression with continued use; it is not an evidence-based PCT strategy.
Related Guides & Tools
Step-by-step references for reconstituting, measuring, and storing Buserelin, plus the universal dosing calculator.
Academic References & Study Citations
Donnez J, Nisolle-Pochet M, Clerckx-Braun F, Sandow J, Casanas-Roux F. Administration of nasal Buserelin as compared with subcutaneous Buserelin implant for endometriosis. Fertil Steril. 1989;52(1):27-30. View Scientific Paper →
Soloway MS. Efficacy of buserelin in advanced prostate cancer and comparison with historical controls. Am J Clin Oncol. 1988;11 Suppl 1:S29-32. View Scientific Paper →
Pettersson B, Varenhorst E, Petas A, Sandow J. Duration of testosterone suppression after a 9.45 mg implant of the GnRH-analogue buserelin in patients with localised carcinoma of the prostate: a 12-month follow-up study. Eur Urol. 2006;50(3):483-489. View Scientific Paper →
Tarlatzis BC, Pados G, Bontis J, et al. Ovarian stimulation with buserelin/HMG/HCG: prospective randomized study of short versus long protocol. Hum Reprod. 1993;8(6):807-812. View Scientific Paper →
Suprefact 1 mg/ml solution for injection — Summary of Product Characteristics (SmPC). Electronic Medicines Compendium (emc), Cheplapharm. View Scientific Paper →
Humaidan P, Ejdrup Bredkjaer H, Bungum L, et al. GnRH agonist (buserelin) or hCG for ovulation induction in GnRH antagonist IVF/ICSI cycles: a prospective randomized study. Hum Reprod. 2005;20(5):1213-1220. View Scientific Paper →
Buserelin 150 micrograms Nasal Spray Solution — Patient Information Leaflet. Electronic Medicines Compendium (emc). View Scientific Paper →