The functionality of the formulated teriparatide was determined using the HEK293-PTH1R cell line, by measuring and comparing intracellular cAMP levels after cellular binding of native and processed teriparatide. Release of the formulated peptide was obtained by incubating 1mL of the liposomal formulations overnight at 45 °C. The liposomal formulation (1 mL) was then dialysed against 5 mL phosphate saline buffer (PBS) with 100 kDa Float-A-Lysers for approximately 24 h. Teriparatide concentration in the dialysate was quantified by HPLC. A teriparatide stock was prepared in induction buffer (PBS containing 500 µM isobutyl-1-methylxanthine and 100 µM 4-(3-butoxy-4methoxybenzyl) imidazolidinone). A total of five samples at concentrations in the range of 0.2 pM -1.8 nM were prepared in induction buffer for all released teriparatide samples, as well as for the native peptide.