Liposomes et peau : passé, présent, futur

Nanovesicles for Nanomedicine: Theory and Practices

Lipid-based nanovesicles such as liposomes, niosomes, and ethosomes are now well recognized as potential candidates for drug delivery and theranostic applications. Some of them have already stepped forward from laboratory to market. The property to entrap lipophilic drugs in their bilayers and hydrophilic drugs in the aqueous milieu makes them a unique carrier for drug delivery. Delivery of drugs/diagnostics to various organs/tissues/cells via nanovesicles is considered to be a topic of long-standing interest with new challenges being posed to formulation scientists with new developments. The key challenge in this context is the physiological and pathological conditions, which make the delivery of drugs extremely difficult at the disease locus and makes their precise delivery ineffective. This chapter gives an insight into the role of novel nanovesicles in the field of drug delivery. We present an overview of the formulation and characterization and role of diverse nanovesicles. A comprehensive update about their application and current as well as potential challenges have also been discussed.

Electroporation-delivered transdermal neostigmine in rats: equivalent action to intravenous administration

Purpose

Transdermal electroporation has become one of the most promising noninvasive methods for drug administration, with greatly increased transport of macromolecules through the skin. The cecal-contracting effects of repeated transdermal electroporation delivery and intravenous administration of neostigmine were compared in anesthetized rats.

Methods

The cecal contractions were detected with implantable strain gauge sensors, and the plasma levels of neostigmine were followed by high-performance liquid chromatography.

Results

Both intravenously and EP-administered neostigmine (0.2–66.7 μg/kg) increased the cecal contractions in a dose-dependent manner. For both the low doses and the highest dose, the neostigmine plasma concentrations were the same after the two modes of administration, while an insignificantly higher level was observed at a dose of 20 μg/kg after intravenous administration as compared with the electroporation route. The contractile responses did not differ significantly after the two administration routes.

Conclusion

The results suggest that electroporation-delivered neostigmine elicits action equivalent to that observed after intravenous administration as concerning both time and intensity. Electroporation permits the delivery of even lower doses of water-soluble compounds through the skin, which is very promising for clinical practice.

Ultrasonic spectroscopy and differential scanning calorimetry of liposomal-encapsulated nisin

The thermal stability of phosphatidylcholine (PC) liposomes (colloidal dispersions of bilayer-forming polar lipids in aqueous solvents) in the presence and absence of the antimicrobial polypeptide nisin was evaluated using differential scanning calorimetry (DSC) and low-intensity ultrasonic spectroscopy (US). PC liposome mixtures with varying acyl chain lengths (C16:0 and C18:0) were formed in buffer with or without entrapped nisin. Gel-to-liquid crystalline phase transition temperatures (T(M)) of liposomes determined from DSC thermograms were in excellent agreement with those determined by ultrasonic velocity and attenuation coefficient measurements recorded at 5 MHz. The dipalmitoylphosphatidylcholine (DPPC) T(M) measured by DSC was approximately 41.3 and approximately 40.7 degrees C when measured by ultrasonic spectroscopy. The T(M) of distearoylphosphatidylcholine (DSPC) and DPPC/DSPC 1:1 liposomes was 54.3 and 54.9 degrees C and approximately 44.8 and approximately 47.3 degrees C when measured by DSC and US, respectively. The thermotropic stability generally increased upon addition of nisin. Analysis of the stepwise decrease in ultrasonic velocity with temperature indicated an increased compressibility corresponding to a loss of structure upon heating.