Summary

Abiraterone and prednisone are commonly prescribed together for metastatic prostate cancer treatment. While this combination is therapeutically beneficial, it requires careful monitoring due to potential interactions affecting drug metabolism and increased risk of corticosteroid-related side effects.

Introduction

Abiraterone acetate is an androgen biosynthesis inhibitor used primarily in the treatment of metastatic castration-resistant prostate cancer. It works by blocking CYP17A1, an enzyme crucial for androgen production. Prednisone is a synthetic corticosteroid that mimics cortisol and is used to manage inflammation and suppress immune responses. In prostate cancer treatment, prednisone is often prescribed alongside abiraterone to help manage mineralocorticoid excess caused by abiraterone's mechanism of action.

Mechanism of Interaction

The interaction between abiraterone and prednisone is primarily pharmacodynamic rather than pharmacokinetic. Abiraterone inhibits CYP17A1, which not only blocks androgen synthesis but also affects cortisol production, leading to increased ACTH levels and subsequent mineralocorticoid excess. This can result in hypertension, hypokalemia, and fluid retention. Prednisone helps counteract these effects by providing exogenous corticosteroid activity, suppressing ACTH release, and reducing mineralocorticoid-related side effects.

Risks and Symptoms

The primary risks of this drug combination include enhanced corticosteroid effects leading to increased susceptibility to infections, delayed wound healing, osteoporosis, hyperglycemia, and mood changes. Patients may experience elevated blood pressure, electrolyte imbalances (particularly hypokalemia), and fluid retention. Long-term use increases the risk of adrenal suppression, cardiovascular complications, and metabolic disorders. Additionally, the combination may mask signs of infection due to prednisone's immunosuppressive effects.

Management and Precautions

Regular monitoring is essential when using abiraterone and prednisone together. Healthcare providers should monitor blood pressure, serum potassium levels, liver function tests, and blood glucose levels at baseline and regularly throughout treatment. Patients should be assessed for signs of infection, cardiovascular complications, and bone health. Dose adjustments may be necessary based on individual patient response and tolerance. Gradual tapering of prednisone is required when discontinuing to prevent adrenal insufficiency. Patients should be counseled on infection prevention, dietary modifications, and the importance of medication compliance.

Prednisone interactions with food and lifestyle

Prednisone should be taken with food or milk to reduce stomach irritation and gastrointestinal upset. Alcohol consumption should be limited or avoided while taking prednisone, as both can increase the risk of stomach ulcers and gastrointestinal bleeding. Patients should also limit sodium intake and increase calcium and vitamin D consumption, as prednisone can cause sodium retention and bone loss. Grapefruit and grapefruit juice should be avoided as they may increase prednisone levels in the blood. Live vaccines should be avoided during prednisone treatment due to immunosuppression.