Version July 2025
Endometriosis : Intranasal: 400 mcg (200 mcg into each nostril) 3 times daily; treatment duration is usually 6 months; maximum duration: 9 months.
Prostate cancer, advanced: Note: Administration of an antiandrogen agent beginning ~7 days prior to initiation of buserelin therapy and continuing for up to ~4 to 5 weeks with buserelin therapy is recommended.
SubQ:
Suprefact: Initial: 500 mcg every 8 hours for 7 days. Maintenance: 200 mcg once daily.
Suprefact Depot:
2-month: 6.3 mg implant every 2 months (dosage interval may be shortened or extended by a few days if needed).
3-month: 9.45 mg implant every 3 months (dosage interval may be shortened or extended by a few days if needed).
Intranasal: Maintenance: 400 mcg (200 mcg into each nostril) 3 times daily (after 7 days of initial SubQ treatment).
Missed doses: Non-depot formulations: If a dose is missed, administer as soon as remembered; if it is almost time for the next dose, skip the missed dose and continue with regular dosing schedule. Do not double doses to make up for a missed dose.
Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
There are no dosage adjustments provided in the manufacturer’s labeling.
There are no dosage adjustments provided in the manufacturer’s labeling.
Refer to adult dosing.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Reported adverse reactions are for adults. Adverse reaction profile differs based on indication (endometriosis and prostate cancer) and route of administration. Incidences are reported for intranasal administration, unless otherwise noted as subcutaneous (SUBQ) solution or depot implant administration.
>10%:
Endocrine & metabolic: Decreased libido (implant: 2%; intranasal: 12%), heavy menstrual bleeding (24%), hot flash (implant: 16%; intranasal/SUBQ: 66% to 72%), loss of libido (intranasal: 75%; SUBQ: 85%)
Gastrointestinal: Flatulence (15%)
Genitourinary: Impotence (males: implant: 2%; intranasal/SUBQ: 75% to 79%), vaginal dryness (29%)
Local: Injection-site reaction (implant: 1%; SUBQ: 12%; including irritation at injection site: 3%, pain at injection site: 5%, swelling at injection site: 3%, and urticaria at injection site: 2%)
Nervous system: Headache (20% to 29%)
Neuromuscular & skeletal: Back pain (28%)
Respiratory: Nasal mucosa irritation (13%)
1% to 10%:
Cardiovascular: Edema (implant: 1%; intranasal: 3% to 6%), hypertension (implant: 2%), palpitations (1%), peripheral edema (2%)
Dermatologic: Acne vulgaris (5%), diaphoresis (implant/intranasal: ≤2%), pruritus (implant/SUBQ: ≤1%), xeroderma (2%)
Endocrine & metabolic: Gynecomastia (males: implant: <1%; SUBQ: 3%), hirsutism (intranasal/SUBQ: ≤1%), menstrual disease (1%), weight gain (implant: <1%; intranasal: 3%), weight loss (implant: <1%; intranasal: 2%)
Gastrointestinal: Constipation (implant/intranasal: ≤1%), diarrhea (intranasal: 8%; SUBQ: <1%), dysgeusia (2%), gastrointestinal fullness (3%), nausea (implant/SUBQ: <1%; intranasal: 7%), sore throat (5%), vomiting (4%), xerostomia (2% to 3%)
Genitourinary: Dyspareunia (2%), mastalgia (females: 3%), vaginitis (2%)
Hematologic & oncologic: Purpuric disease (1%)
Infection: Infection (7%)
Local: Application site reaction (intranasal: 5% to 7%: including application-site irritation: 4%, application-site pain, and urticaria [application-site]: 2%)
Nervous system: Anxiety (1%), asthenia (implant: <1%; intranasal: 7%), depression (implant: 2%; intranasal: 8%), dizziness (9%), emotional lability (7%), hostility (1%), insomnia (implant: <1%; intranasal: 5%), malaise (8%), migraine (3%), nervousness (implant: <1%; intranasal: 2%), pain (implant/SUBQ: ≤2%), paresthesia (2%), sleep disorder (1%)
Neuromuscular & skeletal: Arthralgia (5%), limb pain (2%), myalgia (2%), neck stiffness (1%)
Respiratory: Dry nose (intranasal: 2%), rhinitis (2%), upper respiratory tract infection (1%)
<1%:
Cardiovascular: Heart failure (implant), syncope, tachycardia (implant), thrombophlebitis (implant), vasodilation
Dermatologic: Skin photosensitivity, skin rash (implant/intranasal)
Endocrine & metabolic: Exacerbation of diabetes mellitus (implant), feminization (males: SUBQ), hyperglycemia (implant)
Gastrointestinal: Abdominal pain, fecal incontinence (implant), gastrointestinal pain, increased appetite, oral mucosa ulcer
Genitourinary: Breast atrophy, breast hypertrophy, ejaculatory disorder (implant), genital pain (male: implant), genitourinary disease (implant), pelvic pain, urinary retention (SUBQ), vaginal hemorrhage
Hematologic & oncologic: Myelofibrosis (implant)
Hypersensitivity: Hypersensitivity reaction
Local: Bleeding at injection site (implant)
Nervous system: Abnormality in thinking, altered sense of smell, amnesia, drowsiness, hyperalgesia (implant), suicidal tendencies (implant), tremor, vertigo
Neuromuscular & skeletal: Muscle cramps (implant), myopathy (implant)
Ophthalmic: Accommodation disturbance, dry eye syndrome, transient blindness (one eye: implant)
Otic: Otalgia, tinnitus
Respiratory: Dyspnea (implant), epistaxis, pharyngitis (implant)
Miscellaneous: Fever (implant/SUBQ)
Frequency not defined (any route of administration): Endocrine & metabolic: Increased plasma estradiol concentration (transient), increased testosterone level (transient; with potential clinical flare: 1%)
Postmarketing (any route of administration):
Cardiovascular: Lower extremity edema, prolonged QT interval on ECG, thrombosis
Dermatologic: Allergic skin reaction, eczema, hypertrichosis, loss of body hair, loss of scalp hair, onychia sicca
Endocrine & metabolic: Changes in serum lipids, decreased glucose tolerance, increased thirst, pituitary neoplasm
Gastrointestinal: Gastrointestinal pseudo-obstruction (Ohlsson 2007)
Genitourinary: Lactation (female), ovarian cyst (during initial phase of therapy), testicular atrophy
Hematologic & oncologic: Leukopenia, thrombocytopenia
Hepatic: Increased serum bilirubin, increased serum transaminases
Hypersensitivity: Anaphylactic shock, nonimmune anaphylaxis
Nervous system: Fatigue, lack of concentration, memory impairment, mood changes
Neuromuscular & skeletal: Arthritis, decreased bone mineral density
Ophthalmic: Eye disease, eye irritation, sensation of eye pressure, visual disturbance (including blurred vision)
Respiratory: Rhinorrhea
Known hypersensitivity to buserelin or any component of the formulation; patients who do not present with hormone-dependent prostate cancer; patients who have undergone orchiectomy.
Nasal solution: Additional contraindications: Undiagnosed abnormal vaginal bleeding; pregnancy; breastfeeding.
Concerns related to adverse effects:
• Anemia: Testosterone suppression is associated with the development of anemia.
• CNS effects: May cause dizziness, which may impair physical or mental abilities; patients must be cautioned about performing tasks that require mental alertness (eg, operating machinery or driving). Patients with a history of depression should be monitored for mood changes and managed appropriately.
• Decreased bone density: [Canadian Boxed Warning]: Prolonged use of a luteinizing hormone releasing hormone (LHRH) agonist may cause decreased bone mineral density and possibly lead to osteoporosis and increased risk of skeletal bone fracture. Fracture risk increases with duration of therapy. Use of buserelin for >6 months or in association with other risk factors may contribute to additional bone loss. Some clinical trial data suggest a partial reversibility of bone mineral loss following therapy discontinuation. Patients at risk for reduced bone density include those with chronic alcohol and/or tobacco use, family history of osteoporosis, and chronic treatment with antiseizure medications or corticosteroids. The benefits and risks of potential buserelin therapy should be considered before treatment is initiated.
• Disease flare: [Canadian Boxed Warning]: A transient (usual duration <10 days) exacerbation of the signs and symptoms of the disease process may be observed with the initiation of therapy. Prostate cancer patients may experience worsening or new onset bone pain, neuropathy, hematuria, ureteral or bladder outlet obstruction, hydronephrosis, lymphostasis, or thrombosis with pulmonary embolus; cases of spinal cord compression possibly contributing to paralysis with or without complications have also been reported. Caution and close monitoring should be used in patients with vertebral metastases who are at risk for lesion exacerbation with possible spinal cord compression; Most buserelin studies were conducted without concomitant antiandrogen therapy, although in some studies, antiandrogen therapy was initiated 7 days prior to beginning buserelin and continued for 4 to 5 weeks with buserelin.
• Hypersensitivity: Hypersensitivity reactions (including pruritus, rash, urticaria, allergic asthma with dyspnea, and local erythema) have been observed; anaphylactic/anaphylactoid shock have been reported rarely. Removal of buserelin depot implant may be necessary for severe reactions.
• Hypogonadism: Hypogonadism is an anticipated effect of androgen deprivation therapy; reversal of hypogonadism induced by therapy has not been established in this patient population.
• Pituitary adenoma: The development of pituitary adenomas may rarely be seen with long-term therapy.
Disease related concerns:
• Cardiovascular disease: Androgen-deprivation therapy may increase the risk for cardiovascular disease (Levine 2010). Androgen deprivation may increase the QT interval (on ECG); avoid use in patients with congenital long QT syndrome; consider risk:benefit ratio in patients with concomitant antiarrhythmic therapy, electrolyte imbalances or heart failure. Correct electrolyte imbalances prior to initiation of therapy. Discontinue therapy if QT interval prolongation occurs. Increases in blood pressure (including hypertensive crisis) may occur in patients with preexisting hypertension; monitor blood pressure regularly.
• Diabetes: Reduced glucose tolerance and loss of blood glucose control have been noted in rare cases. Use caution in patients with diabetes; monitor blood glucose.
• Endometriosis: A transient exacerbation of the signs/symptoms may be associated with the initiation of therapy (worsening clinical condition may require discontinuation or surgical intervention). Oral contraceptives should be discontinued prior to starting therapy; use of a nonhormonal contraceptive is recommended.
• Urinary obstruction: In patients with prostate cancer, a transient increase in patient symptoms may occur early in therapy. Monitor for signs of urinary obstruction or retention.
Other warnings/precautions:
• Experienced physician: [Canadian Boxed Warning]: Should be prescribed by a physician experienced in the use of hormonal therapy in endometriosis and prostate cancer, and administered under the supervision of a health care provider.
Not available in the US
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Implant, Subcutaneous:
Suprefact Depot 2 Months: 6.6 mg (1 ea)
Suprefact Depot 3 Months: 9.45 mg (1 ea)
Solution, Nasal:
Suprefact: 1 mg/mL ([DSC]) [contains benzalkonium chloride]
Solution, Subcutaneous:
Suprefact: 5.5 mg/5.5 mL (5.5 mL) [contains benzyl alcohol]
Intranasal: Administer at equal time intervals; before first application, pump bottle several times in upright position until a uniform mist is released; priming may need to be repeated after storing between uses.
SubQ: Rotate injection sites; administer at equal time intervals.
Depot formulation: Administer into lateral abdominal wall; a local anesthetic may be administered to injection site prior to implantation.
This medication is not on the NIOSH (2024) list; however, it may meet the criteria for a hazardous drug. Buserelin may cause carcinogenicity, teratogenicity, reproductive toxicity, and has a structural or toxicity profile similar to existing hazardous agents.
Use appropriate precautions for receiving, handling, storage, preparation, dispensing, transporting, administration, and disposal. Follow NIOSH and USP 800 recommendations and institution-specific policies/procedures for appropriate containment strategy (NIOSH 2023; NIOSH 2024; USP-NF 2020).
Note: Facilities may perform risk assessment of some hazardous drugs to determine if appropriate for alternative handling and containment strategies (USP-NF 2020). Refer to institution-specific handling policies/procedures.
Note: Not approved in the US.
Endometriosis: Nasal solution: Treatment of endometriosis in patients who do not require surgical intervention as first-line therapy (length of therapy is usually 6 months and should not exceed 9 months).
Prostate cancer, advanced: Injection, nasal solution: Palliative treatment of hormone-dependent advanced prostate cancer (stage D).
Buserelin may be confused with goserelin, nafarelin, triptorelin.
Suprefact may be confused with Suprane.
The Institute for Safe Medication Practices (ISMP) includes this medication among its list of drugs (contraindicated in pregnancy [nasal solution]) which have a heightened risk of causing significant patient harm when used in error (High-Alert Medications in Community/Ambulatory Care Settings).
ALERT: Canadian Boxed Warning: Health Canada-approved labeling includes a boxed warning. See Warnings/Precautions section for a concise summary of this information. For verbatim wording of the boxed warning, consult the product labeling.
None known.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Antidiabetic Agents: Hyperglycemia-Associated Agents may decrease therapeutic effects of Antidiabetic Agents. Risk C: Monitor
Choline C 11: Luteinizing Hormone-Releasing Hormone Analogs may decrease therapeutic effects of Choline C 11. Risk C: Monitor
Corifollitropin Alfa: Luteinizing Hormone-Releasing Hormone Analogs may increase adverse/toxic effects of Corifollitropin Alfa. Risk X: Avoid
Flotufolastat F18: Coadministration of Androgen Deprivation Therapy Agents and Flotufolastat F18 may alter diagnostic results. Management: Androgen deprivation therapy (ADT) may result in changes in the uptake of flotufolastat F18 in prostate cancer. The impact of ADT on the performance of flotufolastat F18 is unknown, but use of alternative agents should be considered. Risk D: Consider Therapy Modification
Gallium Ga 68 PSMA-11: Androgen Deprivation Therapy Agents may decrease therapeutic effects of Gallium Ga 68 PSMA-11. Management: Androgen deprivation therapy (ADT) may result in changes in the uptake of gallium Ga 68 PSMA-11 (gozetotide) in prostate cancer. The impact of ADT on the performance of gallium Ga 68 PSMA-11 is unknown, but use of alternative agents should be considered. Risk D: Consider Therapy Modification
Haloperidol: QT-prolonging Agents (Indeterminate Risk - Caution) may increase QTc-prolonging effects of Haloperidol. Risk C: Monitor
Indium 111 Capromab Pendetide: Coadministration of Luteinizing Hormone-Releasing Hormone Analogs and Indium 111 Capromab Pendetide may alter diagnostic results. Risk X: Avoid
Piflufolastat F18: Coadministration of Androgen Deprivation Therapy Agents and Piflufolastat F18 may alter diagnostic results. Management: Androgen deprivation therapy (ADT) may result in changes in the uptake of piflufolastat F18 in prostate cancer. The impact of ADT on the performance of piflufolastat F18 is unknown, but use of alternative agents should be considered. Risk D: Consider Therapy Modification
QT-prolonging Agents (Highest Risk): QT-prolonging Agents (Indeterminate Risk - Caution) may increase QTc-prolonging effects of QT-prolonging Agents (Highest Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor
Evaluate pregnancy status prior to initiation. To exclude preexisting pregnancy, begin treatment on the first or second day of menses; if there is doubt, a pregnancy test is recommended. Ovulation may occur with a missed dose; in the event a patient conceives, therapy should be discontinued. Oral contraceptives should be discontinued prior to starting therapy; patients should employ a nonhormonal method of contraception during therapy.
Buserelin is contraindicated in pregnant women.
Buserelin is contraindicated in breastfeeding women.
Small amounts of buserelin can be detected in breast milk. Contains benzyl alcohol, which has been associated with gasping syndrome in premature infants.
Monitor blood glucose levels (baseline then periodically thereafter in patients with diabetes). Monitor BP (regularly in hypertensive patients); monitor for mood changes or signs/symptoms of depression.
Prostate cancer: Monitor serum testosterone levels (4 to 6 weeks after initiation of therapy and every 3 months thereafter), prostate-specific antigen, prostatic acid phosphatase, bone scan, signs/symptoms of obstructive uropathy (if indicated consider CT scan, IV pyelogram, or ultrasound); digital rectal exam; ECG (in patients at risk for QT prolongation); serum electrolytes (calcium, magnesium and potassium; baseline and then as indicated); cardiovascular risk assessment (prior to treatment).
Endometriosis: Monitor serum estradiol levels.
Synthetic peptide analog of gonadotropin hormone releasing hormone (GnRH) with a magnified GnRH agonist effect and an extended duration of activity. Following an initial rise in the pituitary gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH), chronic administration of buserelin results in a sustained suppression of LH and FSH and interferes with the production of ovarian and testicular steroids. Eventually, a decline in gonadal steroids to castration levels is observed.
Onset: 3-month depot implant: Mean time until testosterone reached castrate levels: 10 days
Protein binding: ~15%
Metabolism: Via peptidase to inactive metabolites
Bioavailability: SubQ: 70% (non-depot formulation); Intranasal: 1% to 3%
Half-life elimination: SubQ: Immediate release: 80 minutes; Depot implants: 20 to 30 days; Nasal: 1 to 2 hours
Time to peak, plasma: 3-month depot: <1 day
Excretion: Urine (~50% as unchanged drug); Feces
