**6.4 Liposomes**

Enhanced pulmonary absorption of protein or peptide therapeutics (e.g., insulin) has been shown using the Liposome (discussed in Section 2.7) as a carrier. Intratracheal administration of insulin liposomes led to increased pulmonary uptake of insulin [167]. The ability of liposome to promote pulmonary insulin absorption depends on the concentration, charge, and acyl chain length of the phospholipid [168].
