Abiraterone and prednisone are frequently prescribed together in medical treatment. This combination therapy uses the unique actions of each drug to achieve a more comprehensive therapeutic effect. While abiraterone targets specific biological pathways, prednisone helps manage certain physiological responses that can arise from abiraterone’s activity. The combined approach aims to enhance treatment efficacy while mitigating potential adverse reactions.
What Abiraterone Is and How It Works
Abiraterone, often known by its brand name Zytiga, is a medication classified as an androgen biosynthesis inhibitor. Androgens are male hormones, such as testosterone, which can stimulate the growth of prostate cancer cells.
Abiraterone works by specifically blocking an enzyme called CYP17A1 (17α-hydroxylase/C17,20-lyase), which is involved in the production of androgens throughout the body. This inhibition occurs in various locations, including the adrenal glands, the testes, and within the prostate tumor itself. By reducing androgen levels across these sites, abiraterone effectively “starves” the cancer cells of the hormones they rely on for growth and survival, helping to slow the progression of prostate cancer that has become resistant to other forms of hormone therapy.
What Prednisone Is and Why It’s Used with Abiraterone
Prednisone is a synthetic corticosteroid, a type of steroid hormone that mimics the effects of cortisol, a natural hormone produced by the adrenal glands. It possesses broad anti-inflammatory and immunosuppressive properties, meaning it can reduce inflammation and suppress the immune system’s activity.
When abiraterone inhibits the CYP17A1 enzyme, it not only reduces androgen production but also affects the synthesis of cortisol. This can lead to an accumulation of precursor hormones that have mineralocorticoid activity, potentially causing side effects such as fluid retention, high blood pressure (hypertension), and low potassium levels (hypokalemia). Prednisone is prescribed alongside abiraterone primarily to mitigate these specific mineralocorticoid excess side effects, acting as a glucocorticoid replacement and signaling the body to reduce the production of adrenocorticotropic hormone (ACTH), which in turn helps to lower the levels of those problematic precursors. A typical dosage is 5 mg twice daily.
Treating Prostate Cancer with Abiraterone and Prednisone
The combination of abiraterone and prednisone is a standard treatment for certain stages of prostate cancer. It is particularly used for metastatic castration-resistant prostate cancer (mCRPC), which means the cancer has spread beyond the prostate and is no longer responding to treatments that lower testosterone levels. It can also be used in patients with de novo metastatic castration-sensitive prostate cancer. This therapeutic approach aims to slow the progression of the disease and improve patient outcomes, including overall survival. Clinical trials have demonstrated that abiraterone acetate plus prednisone can significantly extend median overall survival compared to placebo plus prednisone in chemotherapy-naïve patients with mCRPC.
Common Side Effects and Management
Side effects related to mineralocorticoid excess due to abiraterone’s action include hypertension (high blood pressure), hypokalemia (low potassium levels), and fluid retention. These effects are often managed by the co-administration of prednisone, as well as through regular monitoring of blood pressure and electrolyte levels.
Other side effects can stem from the prednisone itself, such as fatigue, muscle weakness, elevated blood sugar levels, and mood changes. Healthcare providers closely monitor patients for these symptoms through regular medical appointments and blood tests. Dietary adjustments, such as limiting sodium intake for fluid retention or managing blood sugar, may also be recommended to help mitigate these adverse effects.
Key Considerations During Treatment
Adherence to the prescribed regimen is important for patients taking abiraterone and prednisone. Abiraterone should typically be taken on an empty stomach, either one hour before or two hours after a meal, to ensure proper absorption. Consistent timing of medication intake each day is also important for maintaining stable drug levels.
Regular medical appointments are necessary for monitoring treatment effectiveness and managing any side effects. This includes routine blood tests to check liver function, electrolyte levels, and hormone levels. Patients should also inform their healthcare team about all other medications, supplements, or dietary changes, as potential drug interactions can occur, affecting the efficacy or safety of the treatment.