Medical Editor: John P. Cunha, DO, FACOEP
Plenaxis (abarelix) for Injectable Suspension inhibits gonadotropin releasing-hormone (GnRH) and is used in the palliative treatment of advanced prostate cancer. The brand name Plenaxis is discontinued but generic versions may be available. Common side effects of Plenaxis (abarelix) include:
- hot flashes
- sleep disturbances
- breast enlargement or pain
- nipple tenderness
- diarrhea or constipation
- swelling of extremities
- nausea
- dizziness
- headache
- fatigue
- changes with or difficulty urinating
- urinary tract infection or
- upper respiratory tract infection.
The recommended dose of Plenaxis is 100 mg administered intramuscularly to the buttock on Day 1 15 29 (week 4) and every 4 weeks thereafter. Plenaxis may interact with other drugs. Tell your doctor all medications and supplements you use. Plenaxis causes birth defects. Do not use this medication if you are pregnant or if you could become pregnant during treatment. This drug is not intended for use by women, therefore it is unlikely to be used while pregnant or breastfeeding; consult your doctor if you have questions.
Our Plenaxis (abarelix) for Injectable Suspension Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
SIDE EFFECTS
Immediate-Onset Systemic Allergic Reactions: See BOXED WARNINGS and WARNINGS
In the single study of Plenaxis™ conducted in men with advanced symptomatic prostate cancer, adverse events reported by ≥ 10% of patients are listed in Table 4. Adverse events are listed without regard to causality. Causality is often difficult to assess in elderly patients with multiple co-morbidities and prostate cancer.
Table 4: Adverse Events in ≥ 10% of Patients in the Advanced
Symptomatic Prostate Cancer Study (without regard for causality).
| Preferred Term | Plenaxis™ N=81 n (%) |
| Hot flushes* | 64 (79) |
| Sleep disturbance* | 36 (44) |
| Pain | 25 (31) |
| Breast enlargement* | 24 (30) |
| Breast pain/nipple tenderness* | 16 (20) |
| Back pain | 14 (17) |
| Constipation | 12 (15) |
| Peripheral edema | 12 (15) |
| Dizziness | 10 (12) |
| Headache | 10 (12) |
| Upper respiratory tract infection | 10 (12) |
| Diarrhea | 9 (11) |
| Dysuria | 8 (10) |
| Fatigue | 8 (10) |
| Micturition frequency | 8 (10) |
| Nausea | 8 (10) |
| Urinary retention | 8 (10) |
| Urinary tract infection | 8 (10) |
| * Pharmacological consequence of androgen deprivation | |
Changes in Laboratory Values
Clinically meaningful increases in serum transaminases were seen in a small percentage of patients in both treatment groups in each active-controlled Plenaxis™ study. In Study 1 and Study 2 combined, the percentage of Plenaxis™ patients reporting serum ALT > 2.5 times upper limit of normal or > 200 U./L was 8.2% and 1.8%, respectively. The percentage reporting serum AST > 2.5 times upper limit of normal or > 200 U/L was 3.1% and 0.8%, respectively. Similar results were reported for active comparators.
Slight decrease in hemoglobin, a pharmacological consequence of castration, were observed in patients receiving Plenaxis™ and active comparator. Mean increases in serum triglycerides of approximately 10% were seen in Plenaxis™ -treated patients.
Read the entire FDA prescribing information for Plenaxis (Abarelix)