A Novel Approach to the Pulmonary Delivery of Liposomes in Dry Powder Form to Eliminate the Deleterious Effects of Milling


  1. Desai, T.R.
  2. Wong, J.P.
  3. Hancock, R.E.W.
  4. Finlay, W.H.
Corporate Authors
Defence R&D Canada - Suffield, Ralston ALTA (CAN)
The effect of lyophilization and jet-milling on Liposome integrity was investigated as a function of their ability to retain the encapsulated model drug on reconstitution of the dry products. The encapsulation efficiencies of the lyophilized and jet-milled formulations were determined at various concentrations of lactose. Lyophilization resulted in considerble leakage of the model drug at lower concentrations of lactose, and jet-milling further augmented the leakage for all the lyophilized formulations, with optimum retention obtained for formulations contaiing at least 10-1 molar ratio of lactose/lipid. In an attempt to overcome the deleterious effects of lyophilization and jet-milling, the feasibility of formulating phospholipid-based powders that result in spontaneous formation of liposomes in an aqueous environment has been investigated. Partitioning of three model drugs (viz., ciprofloxacin, CM3 peptide, and salbutamol sulfate) between the aqueous phase and spontaneously formed liposomes was determined. in terms of encapsulation efficiency. The effects of several parameters, including lactose concentration, lipid compositions, and lipid concentration on the encapsulation efficiency of these model drugs were investigated. The spontaneous formation of liposomes on dispersion of phosphollid-based powder formulations was further evidenced by freeze-fracture scanning electron microscopy. TRUNCATED
Drug delivery;Inhalation therapy;Liposome powders;Lyophilized liposomes;Jet milling;Freeze-fracture scanning electron microscopy;Ciprofloxacin;Salbutamol sulfate;Cationic peptide
Report Number
DRDC-SUFFIELD-SL-2002-123 — Scientific Literature
Date of publication
18 Jan 2002
Number of Pages
Reprinted from
Journal of Pharmaceutical Sciences, vol 91, no 2, 2002, p 482-491

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