It has been reported that, in some cases, the use of abarelix has resulted in serious allergic reactions. An allergic reaction may occur after any injection of the medication, including, but not limited to the first dose. Patients should be observed in the doctor’s office for at least 30 minutes following each dose so that immediate treatment of an allergic reaction can be obtained if needed.
Other, less serious side effects may be more likely to occur. Talk to your doctor if you experience the following side effects:
- hot flashes;
- sleep disturbances;
- breast enlargement or pain;
- diarrhea or constipation;
- fatigue; or
- changes with or difficulty urinating.
Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.
Side Effects That Affect Healthcare Professionals
Endocrine side effects have included hot flushes (79%), sleep disturbance (44%), breast enlargement (30%), and breast pain/nipple tenderness (20%) as pharmacological consequences of androgen deprivation.
General side effects including pain (31%) and fatigue (10%) have been reported.
Musculoskeletal side effects including back pain (17%) have been reported.
Physicians should carefully consider whether the risks of abarelix outweigh the benefits in patients with baseline QTc values >450 msec and in patients taking class IA or class III antiarrhythmic medications.
Cardiovascular side effects including peripheral edema (15%) and prolongation of the QT interval have been reported.
Gastrointestinal side effects including constipation (15%), diarrhea (11%), and nausea (10%) have been reported.
Nervous system side effects including dizziness (12%) and headache (12%) have been reported.
Respiratory side effects including upper respiratory tract infection (12%) have been reported.
Genitourinary side effects including dysuria (10%), micturition frequency (10%), urinary retention (10%), and urinary tract infection (10%) have been reported.
Hypersensitivity side effects including immediate-onset allergic reactions (3.7%), sometimes resulting in hypotension and syncope, have been reported to have occurred after administration of abarelix.
The allergic reaction included urticaria, pruritus, hypotension, and syncope.
Immediate-onset reactions have been reported to have occurred following any administration of abarelix, including the initial dose. The cumulative risk for such a reaction increases with the duration of treatment.
Following each injection of abarelix, patients should be observed for at least 30 minutes in the office. If an allergic reaction associated with hypotension and/or syncope does occur, supportive measures such as leg elevation, oxygen, IV fluids, antihistamines, corticosteroids, and epinephrine should be administered as needed.
Hepatic side effects including clinically meaningful increases in serum transaminases have been reported in a small percentage of patients.
Hematologic side effects including slight decreases in hemoglobin and mean increases in serum triglycerides of approximately 10% have been reported.