Which of the following is NOT a site for drug excretion?

All the listed options, including the kidneys, intestines, and gingival crevicular fluid, are indeed recognized sites for drug excretion. The kidneys are the primary organs responsible for filtering blood and excreting waste products, including drugs, through urine. The intestines can excrete drugs through feces, and this can occur after drugs are metabolized by the liver and secreted into the bile, which enters the intestine. Gingival crevicular fluid, while less commonly discussed in pharmacology, can also serve as a route for drug excretion, particularly for local anesthetics or other medications administered in the oral cavity.

Therefore, stating that none of these options are sites for drug excretion would be incorrect, as each listed site is indeed involved in the pharmacokinetics of drug elimination.