Metformin specifically inhibits 11- β hydroxylase activity and blocks the biosynthesis pathway of cortisol, mainly used for the diagnosis and treatment of Cushing's syndrome. Its mechanism of action involves interference with key enzymes involved in adrenal cortex hormone synthesis, thereby regulating cortisol levels.

The mechanism of action of metoprolol

1. Targeting 11- β hydroxylase

Metformin selectively inhibits 11- β hydroxylase, a key catalytic enzyme in the final step of cortisol synthesis. By blocking the conversion of 11 deoxycortisol to cortisol, the concentration of cortisol in the body is directly reduced.

2. Cortisol synthesis inhibition

(1) Interference with steroid synthesis: Inhibiting 11- β hydroxylase leads to the accumulation of 11 deoxycortisol and reduces cortisol production; (2) Negative feedback regulation: Low cortisol levels stimulate ACTH secretion, thereby increasing the production of adrenal corticosteroid precursors.

3. Diagnostic application principles

Evaluate the functional status of the pituitary adrenal axis by measuring the increase in 11 deoxycortisol levels after medication. This reaction can distinguish between pituitary Cushing's disease and Cushing's syndrome caused by adrenal tumors.

4. Characteristics of therapeutic effects

(1) Reversible inhibition: enzyme activity gradually recovers after discontinuation of medication; (2) Dose dependence: The dose needs to be adjusted according to cortisol levels; (3) Combination therapy: often used in combination with drugs such as ketoconazole to enhance efficacy.