Relugolix
Overview
Relugolix is a small-molecule gonadotropin-releasing hormone receptor antagonist that suppresses the release of luteinizing hormone and follicle-stimulating hormone from the pituitary gland. This leads to a rapid and sustained reduction in testosterone production, which is essential for controlling hormone-dependent prostate cancer. Unlike GnRH agonists, relugolix does not cause an initial testosterone surge, allowing immediate hormone suppression without flare-related complications. It is administered orally once daily, offering a non-injectable alternative for androgen deprivation therapy. Relugolix plays an important role in modern prostate cancer management by providing effective hormonal control with a predictable pharmacologic profile when used under specialist supervision.
Background and Date of Approval
Relugolix was developed to provide oral androgen deprivation through direct GnRH receptor blockade. It received approval from the United States Food and Drug Administration in 2020 for the treatment of adult patients with advanced prostate cancer requiring testosterone suppression. Approval was based on clinical trial data demonstrating high rates of sustained castration-level testosterone suppression and favorable cardiovascular outcomes compared with injectable hormonal therapies. Regulatory evaluations in other regions have followed similar evidence standards. Relugolix has also been studied in other hormone-dependent conditions, although oncology use focuses on the single-agent formulation.
Uses
Relugolix is indicated for the treatment of adult men with advanced hormone-sensitive prostate cancer where androgen deprivation therapy is clinically required. It is used to achieve and maintain low testosterone levels as part of prostate cancer treatment strategies. Therapy is initiated and monitored by oncology or urology specialists, with patient selection based on disease stage, treatment goals, and overall clinical profile.
Administration
Relugolix is administered orally as tablets. Treatment typically begins with a loading dose on the first day to rapidly suppress testosterone levels, followed by a maintenance dose taken once daily at approximately the same time each day. The medication may be taken with or without food. Tablets should be swallowed whole. If therapy is interrupted for an extended period, re-initiation with a loading dose may be required. Dose modification may be necessary in the presence of significant adverse reactions or interacting medications.
Side Effects
Common side effects of relugolix are primarily related to testosterone suppression and include hot flushes, fatigue, musculoskeletal pain, diarrhea, constipation, and decreased libido. Metabolic changes such as increased blood glucose or lipid levels and mild liver enzyme elevations may also occur. These effects vary among patients and are generally manageable with routine clinical monitoring and supportive care.
Warnings
Serious adverse events associated with relugolix include potential cardiac rhythm disturbances, particularly QT interval prolongation, which may increase the risk of arrhythmias in susceptible patients. Severe hypersensitivity reactions, including swelling of the face or airway, have been reported. Relugolix can cause embryo-fetal harm, and effective contraception is required for patients with partners of reproductive potential. Patients with significant cardiovascular disease should be monitored closely during treatment.
Precautions
Before starting relugolix, clinicians should assess cardiovascular history, electrolyte balance, and liver function. Ongoing monitoring is recommended to detect metabolic changes and cardiac effects. Relugolix may interact with medications that affect cardiac conduction or alter drug metabolism, and a thorough medication review is advised before and during therapy. Patients should be counselled regarding fertility effects and the importance of contraception during and after treatment.
Expert Tips
Ensure patients understand the importance of the initial loading dose and strict adherence to daily oral therapy to maintain consistent testosterone suppression. Counsel patients on expected hormonal side effects and emphasize early reporting of cardiac symptoms such as palpitations or dizziness. Regularly review laboratory values and cardiovascular status, especially in patients with preexisting risk factors. Coordinate care across oncology, urology, and pharmacy teams to optimize safety and long-term disease control.