Ion-pair amphiphiles (IPAs) are neoteric pseudo-double-tailed compounds with potential as a novel substitute of phospholipid. IPA, synthesized by stoichiometric/equimolar mixing of aqueous solution of hexadecyltrimethylammonium bromide (HTMAB) and sodium dodecyl sulfate (SDS), was used as a potential substituent of naturally occurring phospholipid, soylecithin (SLC). Vesicles were prepared using SLC and IPA in different ratios along with cholesterol. The impact of IPA on SLC was examined by way of surface pressure (π)-area (A) measurements. Associated thermodynamic parameters were evaluated; interfacial miscibility between the components was found to depend on SLC/IPA ratio. Solution behavior of the bilayers, in the form of vesicles, was investigated by monitoring the hydrodynamic diameter, zeta potential, and polydispersity index over a period of 100 days. Size and morphology of the vesicles were also investigated by electron microscopic studies. Systems comprising 20 and 40 mol % IPA exhibited anomalous behavior. Thermal behavior of the vesicles, as scrutinized by differential scanning calorimetry, was correlated with the hydrocarbon chain as well as the headgroup packing. Entrapment efficiency (EE) of the vesicles toward the cationic dye methylene blue (MB) was also evaluated. Vesicles were smart enough to entrap the dye, and the efficiency was found to vary with IPA concentration. EE was found to be well above 80% for some stable dispersions. Such formulations thus could be considered to have potential as novel drug delivery systems.

This study aimed to investigate the effect of hydrocarbon chain length of nonionic surfactants, Tween 40 and Tween 60, on the physicochemical properties of nanostructured lipid carriers (NLCs). Two local anaesthetics, lidocaine (LIDO) and procaine hydrochloride (PRO$HCl), were incorporated in the NLCs.NLC formulations were prepared using sorbitantristearate (Span 65), soy lecithin (SLC) and stearic acid (SA) in a 2 : 2 : 1 mole ratio employing the hot homogenization technique. The systems were characterized by combined dynamic light scattering (DLS), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and spectroscopic studies. The formulations were found to be stable up to 60 days when kept at 4 C. NLCs stabilized by Tween 60 were superior to the corresponding Tween 40 based formulations. A spherical morphology with smooth surfaces was evidenced by TEM measurements. DSC and polarity studies indicated that LIDO altered the crystallinity of the lipid matrices as it could insert into the core of the NLC. Entrapment efficiency (EE) and loading content (LC) studies revealed that Tween 60 stabilized NLCs have better drug loading capability than the Tween 40 based formulation. Controlled and prolonged drug release was experienced by Tween 60 stabilized drug loaded NLCs as studied by in vitro release kinetics. The developed NLCs could thus be considered to have prospects as novel drug carriers for controlled/sustained release to improve the time duration of anaesthesia, especially for topical application.

No abstract

Proposed model of NSAID loaded and polymer coated NLC alongwith its dependence of size ( ), PDI ( ), release rate ( ) and absorption maxima ( ) as well as its morphology and antibacterial activity ARTICLE This journal is Nanostructured lipid carriers (NLCs), with potential drug delivery capabilities, were formulated using soylecthin (SLC), tristearin (TS) and palmitic acid (PA) in the absence and the presence of two antiinflammatory drugs, diclofenac sodium (DNa) and indomethacin (IMC). Tween 60 was used as stabilizer separetely in combination with sodium carboxymethyl cellulose (NaCMC, anionic), polyethylene glycol (PEG, nonionic) and N, N, dimethyl-N-dodecyl derivative of hydroxyethyl cellulose (LM200, cationic). Both DNa and IMC substantially decreased size and increased polydispersity index (PDI) of the NLCs. Hydrodynamic parameter, viz., size, zeta potential and polydispersity index as well as the thermal behaviour of the NLCs depended on the type and charge of the added polymers. Weak interactions between drug and lipid matrices in the bulk mixtures were established through FT-IR studies. NLC formulations exhibited lower entrapment efficiency and loading content in case of DNa compared to IMC due to the higher ionic nature of the former drug. Polymers influenced the entrapment efficiency and loading ability of the NLCs in case of both DNa and IMC. 85% of the entrapped DNa was released from the NLC, compared to 54% release in case of IMC; the drug release rate were higher for PEG and NaCMC coated systems. LM200 delayed the drug release process with respect to NaCMC and PEG. Both DNa and IMC loaded NLCs inhibited the growth of gram positive bacteria, Bacillus amyloliquefaciens. It was concluded that the physicochemical properties of NLCs could effectively be modified by using polymers; thus the biomimetic characteristics of lipids and architectural advantage of polymers can be combined to yield a superior drug delivery system.