A hydrophobic complex between teriparatide and sodium dodecyl sulfate (SDS) was prepared. Teriparatide was dissolved in 1 mM HCl at a concentration of 1.7 mg/mL, to which an equal volume of SDS (1.008 mg/mL) was added dropwise. A white precipitate formed which was collected by centrifugation at 10,000 rpm for 15 min. The supernatant was removed, and the white pellet was dissolved in ethanol (to a theoretical concentration of 1.7 mg/mL). Teriparatide loaded liposomes were obtained by addition of ion-pair dispersion (0.1 mL) to the phospholipid mixture in ethanol prior to the thin-film rehydration procedure as described under Section 2.2. Liposomes were rehydrated to a concentration of 5 mg/mL total lipid and unentrapped peptide was initially removed by centrifugation using 50 kDa Amicon filters. For release experiments, more concentrated liposomes were prepared by adding 0.85 mL of the ethanolic ion pair dispersion to the phospholipids. Liposomes were prepared at 10 mg/mL in 100 mM phosphate buffer and further purified by dialysis using 100 kDa Float-A-Lysers (Repligen, US).