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abarelix (a-ba-re-lix)



Therapeutic: antineoplastics

Pharmacologic: gonadotropin-releasing hormone (GnRH) antagonists


Advanced prostate cancer when luteinizing hormone–releasing hormone (LHRH) agonists are inappropriate or surgical castration is refused and there is risk of neurologic compromise from metastatic disease, ureteral/bladder obstruction due to local/metastatic disease, or severe metastatic bone pain unresponsive to adequate opioid analgesia.


Directly and competitively blocks pituitary GnRH receptors, thereby suppressing production of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This results in decreased production of testosterone by the testes, which is not accompanied by an initial increase in testosterone. Therapeutic Effects: Suppressed spread of metastatic prostate cancer, with decreased neurologic complications, bladder outlet obstruction, and need for opioid analgesics.

Adverse Reactions/Side Effects

CNS: dizziness, fatigue, headache, sleep disturbances. CV: peripheral edema, prolonged QTc interval. GI: constipation, diarrhea, nausea, increased transaminases. GU: dysuria, urinary frequency. Derm: hot flushes. Endo: breast enlargement/nipple tenderness. MS: back pain. Misc: allergic reactions, decreased bone mineral density.


Examination and Evaluation

  • Assess heart rate, EcG, and heart sounds, especially during exercise (See Appendices G, H). Report any rhythm disturbances or symptoms of increased arrhythmias, including palpitations, chest discomfort, shortness of breath, fainting, and fatigue/weakness.

  • Assess peripheral edema using girth measurements, volume displacement, and measurement of pitting edema (See Appendix N). Report increased swelling in feet and ankles or a sudden increase in body weight due to fluid retention.

  • Monitor signs of allergic reactions, including pulmonary symptoms (tightness in the throat or chest, wheezing, dyspnea, cough) or skin reactions (rash, pruritus, urticaria). Notify physician or nursing staff immediately if these reactions occur.

  • Assess dizziness and drowsiness that might affect gait, balance, and other functional activities (See Appendix C). Report balance problems and functional limitations to the physician and nursing staff, and caution the patient and family/caregivers to guard against falls and trauma.

  • Assess any back pain to rule out musculoskeletal pathology; that is, try to determine if pain is drug induced rather than caused by anatomic or biomechanical problems.


  • For patients who are medically able to begin exercise, implement appropriate resistive exercises and aerobic training to maintain muscle strength and aerobic capacity during cancer chemotherapy, or to help restore function after chemotherapy.

  • Institute weight-bearing and resistance exercises as tolerated to maintain or increase bone mineral density.

  • Because of possible changes in cardiac excitation (prolonged QTc interval), use caution during aerobic exercise and endurance conditioning. Assess exercise tolerance frequently (blood pressure, heart rate, fatigue levels), and terminate exercise immediately if any untoward responses occur (See Appendix L).

Patient/Client-Related Instruction


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