# Inhalable Dry Powders from Lyophilized Sildenafil-Loaded Liposomes with Resveratrol or Cholesterol as a Bilayer Component

## TL;DR

Researchers developed inhalable dry powders using sildenafil-loaded liposomes with resveratrol, offering a new way to deliver drugs to the lungs.

## Contribution

This is the first use of resveratrol as a cholesterol substitute in sildenafil-loaded liposomes for pulmonary delivery.

## Key findings

- Resveratrol improves drug loading in liposomes compared to cholesterol.
- Lyophilized sildenafil liposomes can be made into inhalable powders suitable for pulmonary delivery.
- Mannitol and lactose are effective excipients for this formulation.

## Abstract

Pulmonary drug delivery represents a promising approach in the treatment of respiratory diseases, allowing for passive targeting and enhanced drug efficacy. Background/Objectives: The aim of the present study was to develop inhalable dry powders from lyophilized sildenafil citrate (SC)-loaded liposomes made from phosphatidylcholine and either cholesterol (CH) or resveratrol (RSV). Methods: Liposomes were prepared via a pH gradient method to increase drug entrapment efficiency and drug loading, and then the liposomes were lyophilized using different proportions of ethanol, mannitol, and lactose as excipients. The resulting dry cakes were converted into powders and evaluated for aerodynamic performance using a custom-designed air-blowing device. Notably, this is the first time that resveratrol has been used as a substitute for cholesterol in SC-loaded liposomes. Results: Our results demonstrate that RSV is a suitable liposome bilayer component and improves drug loading. Our findings prove that lyophilized cakes containing liposomes produce a dry powder that is suitable for aerosolization with potential application to pulmonary delivery of sildenafil citrate. The results suggest that RSV represents a potential alternative to traditional cholesterol-based liposomal formulations. Conclusions: This work presents a novel strategy for the pulmonary delivery of sildenafil, using biocompatible and FDA-approved mannitol and lactose for this administration route.