Methods of delivering therapeutic agents by administering compositions including a bacterial collagen-binding polypeptide segment linked to the therapeutic agent to subjects in need of treatment with the therapeutic agent are provided. Methods of treating hyperparathyroidism, and hair loss using compositions comprising a collagen binding polypeptide and a PTH/PTHrP receptor agonist are provided. In addition, methods of reducing hair regrowth by administering a composition including a collagen binding polypeptide and a PTH/PTHrP receptor antagonist are provided.