Which of the following is a common androgen synthesis inhibitor?

The common androgen synthesis inhibitor among the provided options is abiraterone acetate. This medication works by inhibiting the enzyme CYP17, which plays a crucial role in the synthesis of androgens in the adrenal glands and testes. By reducing androgen levels, it can help in the treatment of hormone-sensitive prostate cancer and other conditions dependent on androgens.

Ketoconazole, while also mentioned, is an antifungal medication that has been found to have some effects on inhibiting androgen synthesis as a secondary effect; however, it is primarily used for its antifungal properties rather than as a first-line treatment for androgen inhibition in the context of prostate cancer. Its use for this purpose is limited and not as specifically targeted as with abiraterone acetate.

Fulvestrant and raloxifene are primarily estrogen receptor antagonists and modulators. They do not have a significant role in inhibiting androgen synthesis and are used mainly in the treatment of conditions like breast cancer that are driven by estrogen rather than androgens. This distinction highlights why abiraterone acetate is correctly identified as the specific medication used in androgen synthesis inhibition.