β-Endorphin (1-27) (human) is an opioid antagonist that binds μ-, δ-, and κ-opioid receptors with Kis of 5.31, 6.17, and 39.82 nM, respectively. β-Endorphin (1-27) (human) inhibits β-Endorphin-induced and etorphine-induced analgesia.

Citric Acid Monohydrate is a tricarboxylic acid found in citrus fruits. Citric acid is used as an excipient in pharmaceutical preparations due to its antioxidant properties. It maintains stability of active ingredients and is used as a preservative.

Levothyroxine, the major hormone derived from the thyroid gland, is the agonist of Thyroid hormone receptor alpha and beta.evothyroxine (L-T(4))can upregulate the expression of P-gp mRNA and protein in LS180 cells, but only L-T(4) and L-T(3) can produce the same effect in Caco-2 cells, which are relatively lacking in PXR.