Usage
- Buserelin is primarily prescribed for hormone-responsive conditions like prostate cancer, endometriosis, uterine fibroids, and central precocious puberty. It’s also used in assisted reproduction for female infertility.
- Pharmacological Classification: Gonadotropin-releasing hormone (GnRH) agonist.
- Mechanism of Action: Buserelin initially stimulates the pituitary gland to release gonadotropins (luteinizing hormone (LH) and follicle-stimulating hormone (FSH)). However, continuous administration leads to downregulation of GnRH receptors, resulting in suppressed LH and FSH release, effectively creating a hypogonadal state (similar to castration). This reduces the production of sex hormones like testosterone and estrogen.
Alternate Names
How It Works
- Pharmacodynamics: Buserelin mimics the action of GnRH, initially causing a surge in LH and FSH. Chronic administration desensitizes the pituitary gland, suppressing gonadotropin and sex hormone production. This effect leads to reduced growth of hormone-dependent tissues like prostate tissue in prostate cancer and endometrial tissue in endometriosis.
- Pharmacokinetics:
- Absorption: Varies depending on the route of administration. Subcutaneous injection has high bioavailability (around 70%), while nasal administration has lower bioavailability (1-3%).
- Metabolism: Metabolized by peptidases in the liver, kidneys, GI tract, and pituitary gland.
- Elimination: Primarily eliminated through renal excretion, with some biliary excretion.
Dosage
Standard Dosage
Adults:
- Prostate Cancer (Subcutaneous): 500 mcg three times daily for one week, followed by 200 mcg once daily.
- Endometriosis (Nasal): 150 mcg/spray into each nostril three times daily. Treatment duration is typically six months but can extend up to nine months.
- Ovulation Induction (Subcutaneous/Intranasal): 200-500 mcg daily, adjusted according to individual patient response. Up to 500 mcg twice daily may be necessary. Once pituitary downregulation is achieved (serum estradiol < 180 pmol/L and progesterone < 3 nmol/L), gonadotropin stimulation is initiated alongside continued Buserelin administration.
Children (Central Precocious Puberty):
- Nasal: Initial dose of 1200 mcg/day, divided into several administrations. The dose may be adjusted or switched to subcutaneous administration as needed.
Special Cases:
- Elderly Patients: Close monitoring recommended due to increased risk of adverse effects. Dose adjustments may be needed.
- Patients with Renal Impairment: Careful monitoring is necessary. Dose adjustment based on creatinine clearance may be required.
- Patients with Hepatic Dysfunction: Close monitoring is necessary; dose adjustment might be required.
Clinical Use Cases
Buserelin is primarily used in outpatient or specialist clinic settings, not typically in acute care situations like intubation, surgical procedures, mechanical ventilation, or emergency situations. Its use is centered around managing chronic conditions like prostate cancer and endometriosis or in assisted reproduction.
Side Effects
Common Side Effects:
- Hot flashes
- Decreased libido
- Vaginal dryness
- Mood changes
- Headache
- Injection site reactions (pain, swelling, itching)
Rare but Serious Side Effects:
- Allergic reactions (rash, breathing difficulties, swelling)
- Pituitary apoplexy
- Osteoporosis (with long-term use)
- Ovarian hyperstimulation syndrome (OHSS) (in women undergoing assisted reproduction)
Contraindications
- Hypersensitivity to buserelin or GnRH analogues.
- Pregnancy and breastfeeding.
- Undiagnosed vaginal bleeding.
- Non-hormone-dependent prostate cancer.
- Prior orchiectomy (surgical removal of testicles).
Drug Interactions
- Drugs that affect pituitary or gonadal function.
- Concomitant use with hormonal contraceptives can diminish the efficacy of Buserelin.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: X (contraindicated).
- Buserelin is contraindicated during pregnancy due to the risk of fetal harm.
- Breastfeeding is contraindicated as Buserelin passes into breast milk.
Drug Profile Summary
- Mechanism of Action: GnRH agonist, initially stimulating and then suppressing gonadotropin and sex hormone release.
- Side Effects: Hot flashes, decreased libido, mood changes, headache, injection site reactions.
- Contraindications: Hypersensitivity, pregnancy, breastfeeding, undiagnosed vaginal bleeding.
- Drug Interactions: Drugs affecting pituitary or gonadal function.
- Pregnancy & Breastfeeding: Contraindicated.
Popular Combinations
- In assisted reproduction, Buserelin is used in combination with gonadotropins (FSH and LH) for ovulation induction.
Precautions
- General Precautions: Assess for allergies and pre-existing conditions. Confirm negative pregnancy test before initiating treatment in women of reproductive age.
- Specific Populations: Caution is advised in patients with renal or hepatic impairment. Buserelin is contraindicated in pregnancy and breastfeeding.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Buserelin?
A: Dosage varies depending on the indication and route of administration. See detailed dosage guidelines above.
Q2: How long does it take for Buserelin to work?
A: Pituitary downregulation typically occurs within 1-3 weeks of continuous administration. Clinical effects vary depending on the condition being treated.
Q3: What are the common side effects of Buserelin?
A: Common side effects include hot flashes, decreased libido, mood changes, vaginal dryness, and headache.
Q4: Can Buserelin be used during pregnancy?
A: No, Buserelin is contraindicated in pregnancy due to the risk of fetal harm.
Q5: What should patients be advised about while taking Buserelin?
A: Patients should be advised about potential side effects, the importance of adherence to the prescribed regimen, and the need for contraception if appropriate.
Q6: What monitoring is recommended during Buserelin treatment?
A: Monitor hormone levels (testosterone, estrogen, LH, FSH) as appropriate for the indication. Bone mineral density should be monitored with long-term use.
Q7: Are there any drug interactions with Buserelin?
A: Drugs that affect pituitary or gonadal function can interact with Buserelin. Concomitant use with hormonal contraceptives can reduce its effectiveness.
Q8: How is Buserelin administered?
A: Buserelin can be administered subcutaneously by injection or intranasally via a nasal spray, depending on the indication and formulation.
Q9: What should be done if a dose of Buserelin is missed?
A: Administer the missed dose as soon as remembered, unless it is almost time for the next dose. Do not double the dose to catch up.
Q10: What is the role of Buserelin in assisted reproduction?
A: Buserelin is used to suppress the natural production of LH and FSH, allowing for controlled ovarian stimulation with exogenous gonadotropins. This helps prevent premature ovulation and improves the chances of successful IVF.
