Prostate cancer patients are often elderly with multiple comorbidities, increasing the risk of polypharmacy and drug-drug interactions. This study examined interactions between androgen receptor signaling inhibitors (ARSIs)—apalutamide, abiraterone, and enzalutamide—and concomitant medications in metastatic hormone-sensitive prostate cancer (mHSPC) patients.

From April 2018 to June 2024, 73 mHSPC patients treated with ARSIs at our institution were reviewed. Drug-drug interactions were assessed using Drugs.com®'s Interaction Checker and categorized as Major, Moderate, or Minor.

Median age and number of medications were 72.9 years and 4.3 drugs for apalutamide, 74.7 years and 3.2 drugs for abiraterone, and 72 years and 4.1 drugs for enzalutamide. Apalutamide had 6 Major, 12 Moderate, and 1 Minor interaction; abiraterone had 1 Major and 6 Moderate; enzalutamide had 2 Major and 7 Moderate.

Drug-drug interactions with ARSIs are a clinically significant issue. According to Drugs.com®, apalutamide, abiraterone, and enzalutamide have known interactions with 625, 408, and 655 medications, respectively. The results of this study indicate that major interactions are more frequently observed with apalutamide and enzalutamide, underscoring the need for careful management during treatment. Thorough and individualized drug management can lead to safer and more effective treatment outcomes.