What is the preferred route of administration for Goserelin (LHRH agonist)?

Routes of Administration for Goserelin

Goserelin is administered subcutaneously, with the preferred injection site being the anterior abdominal wall (upper abdominal wall). 1, 2

Approved Administration Routes

Subcutaneous Administration (Primary Route)

• The FDA-approved route is subcutaneous injection into the upper abdominal wall 1
• The drug is formulated as a biodegradable depot containing 3.6 mg (monthly) or 10.8 mg (3-monthly) that releases goserelin continuously over the dosing period 2, 3
• Absorption is rapid following subcutaneous administration, with peak blood radioactivity occurring between 0.5 and 1.0 hours after dosing 1

Intramuscular Administration

• Intramuscular injection is an alternative route used in clinical practice, particularly with leuprolide formulations (7.5 mg IM every 4 weeks or 11.25-22.5 mg IM every 12 weeks) 4
• However, for goserelin specifically, the subcutaneous route is standard 1, 2

Specific Injection Technique

Site Selection

• Inject into the anterior abdominal wall (upper abdominal wall) 1, 5
• This site provides optimal absorption and minimal local reactions 5

Administration Considerations

• Some patients may require local anesthetic before injection 5
• Local reactions are minimal with proper technique 5
• The depot formulation should be administered every 28 days for the 3.6 mg dose or every 12 weeks for the 10.8 mg dose 1, 2

Routes NOT Used for Goserelin

Goserelin is NOT administered via:

• Oral route (not bioavailable) 2
• Intravenous route (not formulated for this use) 1
• Transdermal route (not available in this formulation) 1

Clinical Context Across Indications

Prostate Cancer

• Subcutaneous administration every 4 weeks with 3.6 mg depot 4, 6
• Alternative 3-month depot (10.8 mg) available for extended dosing intervals 3

Breast Cancer (Ovarian Suppression)

• Subcutaneous goserelin 3.6 mg every 4 weeks or 10.8 mg every 12 weeks 4
• Must be initiated appropriately relative to chemotherapy timing 4, 7

Endometriosis and Uterine Fibroids

• Same subcutaneous route, 3.6 mg every 4 weeks 2

Important Pharmacokinetic Note

Despite the subcutaneous depot releasing drug at varying rates (slower initially for first 8 days, then more rapid and continuous release), this route maintains therapeutic testosterone suppression in males and estradiol suppression in females throughout the 28-day dosing period 1, 3