Although some high-affinity peptide drugs have been successfully marketed, including GLP-1 analogs for type 2 diabetes and PTH or PTHrP analogs for osteoporosis, they have many disadvantages such as inconvenient subcutaneous injection, expensive, and associated with side effects such as headache and nausea.2 Unlike injectable drugs, small-molecule drugs have better drug properties and easier for oral transmucosal delivery. Here, PTH is linked to osteoporosis.