buserelin

REMS

SC: Initial and maintenance palliative treatment of advanced hormone-dependent prostate cancer (usually in combination with an antiandrogen).
Maintenance palliative treatment of advanced hormone-dependent prostate cancer (usually in combination with an antiandrogen).
Nonsurgical treatment of endometriosis.

Action ⬆ ⬇

Acts as a synthetic analog of endogenous gonadotropin-releasing hormone (GnRH/LHRH). Chronic use results in inhibited secretion of gonadotropin release and gonadal steroid production. The overall effect is due to downregulation of pituitary LHRH receptors. In men, testosterone synthesis and release are ↓. In women, secretion of estrogen is ↓.

Therapeutic effects:

Decreased spread of advanced prostate cancer.
Decreased sequelae of endometriosis (pain, dysmenorrhea).

Pharmacokinetics ⬆ ⬇

Absorption: SUBQ: 70%; intranasal: 1–3%; implant: drug is slowly absorbed over 2–3 mo.

Distribution: Accumulates in liver, kidneys and anterior pituitary lobe.

Metabolism/Excretion: Metabolized in liver and kidneys and by enzymes on membranes in the pituitary gland.

Half-Life: SUBQ: 80 min; intranasal: 1–2 hr; implant: 20–30 days.

Time/Action Profile ⬆ ⬇

ROUTE	ONSET	PEAK	DURATION
prostate cancer ‡	7 days	4 mo	until discontinuation
endometriosis ‡(intranasal)	unknown	unknown	duration of treatment

‡↓in testosterone concentrations.

‡Symptom improvement.

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Nonhormonal-dependent prostate cancer or previous orchiectomy;
Women with undiagnosed vaginal bleeding;
OB: Pregnancy;
Lactation: Lactation.

Use Cautiously in:

Prostate cancer with urinary tract obstruction or spinal lesions;
Pedi: Safety and effectiveness not established in children (injection contains benzyl alcohol).

Adv. Reactions/Side Effects ⬆ ⬇

CV: edema, hypertension

Derm: hot flashes, acne

EENT: nasal irritation (nasal spray)

Endo: glucose intolerance, gynecomastia, testosterone flare

GI: constipation, nausea

GU: ↓libido, menorrhagia, vaginal dryness, impotence, suppression of ovulation

Hemat: anemia

Local: injection site reactions

MS: bone pain, osteoporosis

Neuro: headache (nasal spray), insomnia, weakness, depression, dizziness

Misc: transient exacerbation of metastatic prostate cancer or endometriosis

Interactions ⬆ ⬇

Drug-drug:

Risk of serious arrhythmias may be ↑ by amiodarone, disopyramide, dofetilide, flecainide ibutilide, propafenone quinidine, sotalol, antipsychotics, antidepressants (including amitriptyline and nortriptyline), methadone, macrolides, fluoroquinolones, azole antifungals, 5-HT3 antagonists, beta-2 receptor agonists, pentamidine, and quinine.

Route/Dosage ⬆ ⬇

Prostate cancer

SC (Adults ): Initial treatment: 500 mcg every 8 hr for 7 days; Maintenance treatment: 200 mcg once daily.
(Adults ): Maintenance treatment: 400 mcg (200 mcg in each nostril) 3 times daily.

Endometriosis

(Adults ): 400 mcg (200 mcg in each nostril) 3 times daily. Treatment is usually continued for 6 mo; not to exceed 9 mo.

Availability ⬆ ⬇

Solution for SUBQ injection (contains benzyl alcohol): 1000 mcg/mL
Intranasal solution: 1000 mcg/mL (delivers 100 mcg/actuation)

Assessment ⬆ ⬇

Cancer: Monitor patients with vertebral metastases for ↑ back pain and ↓ sensory/motor function.
Monitor intake and output and assess for bladder distention in patients with urinary tract obstruction during initiation of therapy.
Endometriosis: Assess for signs/symptoms of endometriosis before and periodically during therapy. Amenorrhea usually occurs within 8 wk of initial administration and menses usually resume 8 wk after completion.

Lab Test Considerations:

Verify negative pregnancy test before starting therapy.
- Monitor serum testosterone concentrations every 3 mo during treatment in men. When treatment begins, testosterone concentrations can temporarily markedly ↑, and patients may need another medication to ↓ concentrations.
- Monitor blood glucose in patients with diabetes frequently; may affect blood glucose.

Implementation ⬆ ⬇

Prostate Cancer

SC: Only use syringes that come with kit for accurate dose. Inject into fatty tissue of abdomen, arm, or leg 3 times/day for 7 days; then once daily during maintenance.
When used as maintenance, begin nasal spray in each nostril 3 times daily. If patient also receives decongestant nasal spray, wait 30 min to give buserelin spray before or after the decongestant.

Endometriosis

Administer one spray in each nostril 3 times daily for 6–9 mo.

Patient/Family Teaching ⬆ ⬇

Explain purpose and side effects of medication to patient. Advise patient to read Patient Information before starting therapy.
Advise patient to notify health care provider of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care provider before taking other medications.
Advise men that they may experience breast swelling and tenderness, ↓ libido, hot flashes and sweats, impotence, and weight gain. Notify health care provider if these symptoms occur.
Advise women that they may experience ↓ libido, constipation, painful sexual intercourse, menopausal symptoms, and changes in hair growth. Notify health care provider if these symptoms occur.
SC: Advise patient in proper technique for self-injection and care and disposal of equipment. Use only syringes included in kit. Instruct patients that syringes may only be used once and then discarded.
Advise patient on proper nasal spray technique. Prime pump before use.
Advise patient that the nasal spray can cause nose bleeds and may change smell and taste senses.
Rep: May cause fetal harm. Advise women of reproductive potential to notify health care provider if pregnancy is planned or suspected or breastfeeding. Oral contraceptives should be discontinued before starting therapy; patients should employ a nonhormonal method of contraception during therapy. Advise men and women to use contraception while taking this drug.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇