The stability of teriparatide in different aqueous-ethanolic, aqueous-methanolic and aqueous acetonitrile solutions as well as in the pure solvent was assessed to identify the optimal solvents/mixtures. Aqueous-organic solutions were prepared at 20, 40, 60, and 80% (v/v) of each solvent. Teriparatide was initially prepared at 10 mg/mL in dH2O before diluting 100-fold in the above solutions. Further, a dilution in pure dH2O (control) and pure solvent was prepared. The final concentration of teriparatide within the solutions was 0.1 mg/mL. The samples were incubated for 10 min at room temperature before analysis by HPLC. The analysis of the teriparatide samples entailed determination of the retention time, quantification, and observation of the peak shape in HPLC.