Next Article in Journal
Towards Non-Degenerate Quantum Lithography
Previous Article in Journal
Towards Enhanced Performance of Neural-Network-Based Fault Detection Using an Sequential D-Optimum Experimental Design
Previous Article in Special Issue
Nanostructured Lipid Carriers as Promising Delivery Systems for Plant Extracts: The Case of Silymarin
Article Menu
Issue 8 (August) cover image

Export Article

Open AccessArticle
Appl. Sci. 2018, 8(8), 1291;

Sildenafil Citrate Liposomes for Pulmonary Delivery by Ultrasonic Nebulization

Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Salamanca, 37007 Salamanca, Spain
Institute of Biopharmaceutical Sciences of the University of Salamanca (IBSAL), 37007 Salamanca, Spain
CPIRN-IPG-Center of Potential and Innovation of Natural Resources, Polytechnic Institute of Guarda, 6300-559 Guarda, Portugal
CICS-UBI-Health Sciences Research Centre, University of Beira Interior, 6201-001 Covilha, Portugal
LAQV, REQUIMTE, Department of Chemical Sciences, Laboratory of Applied Chemistry, Faculty of Pharmacy, Porto University, 4050-313 Porto, Portugal
Author to whom correspondence should be addressed.
Received: 26 June 2018 / Revised: 12 July 2018 / Accepted: 19 July 2018 / Published: 2 August 2018
Full-Text   |   PDF [3010 KB, uploaded 21 August 2018]   |  


Technological advances in lipid vesicles facilitate optimization of their properties to achieve therapeutic goals and promote alternative drug administration routes. Sildenafil citrate (SC) is orally administered for the treatment of pulmonary hypertension, but local release would be advantageous in terms of efficacy and safety. In the present study, liposomes from egg phosphatidylcholine and cholesterol loaded with SC, with and without d-α-tocopheryl polyethylene glycol 1000 succinate (Vit E TPGS), were prepared by sonication of the components. A transmembrane pH gradient was applied for active loading of liposomes, and the size, zeta potential, and entrapment efficiency (EE%) were determined. The liposomes were lyophilized and then nebulized. The nebulized samples were collected and the EE% was determined. The transmembrane pH gradient produced a significant increase in the EE% (from 17.68 ± 4.25% to 89.77 ± 7.64%) and, after lyophilization, the EE% remained the same as that of the originals, but the size and zeta potential were modified. EE% of liposomes decreased upon nebulization, particularly for those with Vit E TPGS. Thus, the additives used for lyoprotection reduced the impact of nebulization. Additional studies are essential, but according to these results, SC-loaded liposomes can be considered as suitable and safe carriers for the local release of sildenafil in the pulmonary system. View Full-Text
Keywords: liposomes; pulmonary delivery; sildenafil; local drug release; transmembrane pH gradient; solvent-free pharmaceutical procedures liposomes; pulmonary delivery; sildenafil; local drug release; transmembrane pH gradient; solvent-free pharmaceutical procedures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

de Jesús Valle, M.J.; Gil González, P.; Prata Ribeiro, M.; Araujo, A.R.T.S.; Sánchez Navarro, A. Sildenafil Citrate Liposomes for Pulmonary Delivery by Ultrasonic Nebulization. Appl. Sci. 2018, 8, 1291.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Appl. Sci. EISSN 2076-3417 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top