Metyrapone is a cytochrome P450 (CYP) inhibitor. Metyrapone inhibits 11β-hydroxylase (CYP11B1), a key enzyme involved in the final step of cortisol biosynthesis, with an IC50 value of 7.83 μM. Also, metyrapone inhibits other steroidogenic enzymes (e.g. cholesterol side chain cleavage enzyme) at high concentrations. Administration of metyrapone to man and animals (e.g. dogs and sheep) results in a decrease in circulating levels of cortisol. Thus, metyrapone has been used clinically for diagnostic and therapeutic purposes.

References:

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3. Asakura T, Shichi H. Cytochrome P450-mediated prostaglandin ω/ω-1 hydroxylase activities in porcine ciliary body epithelial cells. Experimental Eye Research, 1992, 55(2): 377-384.

4. JENKINS JS, MEAKIN JW, NELSON DH, et al. Inhibition of adrenal steroid 11-oxygenation in the dog. Science, 1958, 128(3322): 478-480.