Which of the following drug classes includes atorvastatin and simvastatin?

Atorvastatin and simvastatin belong to the class of drugs known as antihyperlipidemics. This class is specifically used to lower lipid levels in the blood, particularly cholesterol and triglycerides. These medications function by inhibiting HMG-CoA reductase, an enzyme involved in the synthesis of cholesterol, thereby reducing total and LDL cholesterol levels, which helps decrease the risk of cardiovascular diseases.

In the context of the other drug classes mentioned: Hormone Replacement Therapy focuses on replacing hormones that are deficient in the body, such as in menopausal women; Fibrinolytics are used to break down blood clots; and Anticoagulants are prescribed to prevent blood clot formation. None of these classes involve the mechanisms or therapeutic goals found in antihyperlipidemics, making the identification of atorvastatin and simvastatin as part of the antihyperlipidemic class the correct choice.