Cyclodextrins (CDs), a group of oligosaccharides formed by glucose units bound together in a ring, show a promising ability to form complexes with drug molecules and improve their physicochemical properties without molecular modifications. The stoichiometry of drug/CD complexes is most frequently 1:1. However, natural CDs have a tendency to self-assemble and form aggregates in aqueous media. CD aggregation can limit their solubility. Through derivative formation, it is possible to enhance their solubility and complexation capacity, but this depends on the type of substituent and degree of substitution. Formation of water-soluble drug/CD complexes can increase drug permeation through biological membranes. To maximize drug permeation the amount of added CD into pharmaceutical preparation has to be optimized. However, solubility of CDs, especially that of natural CDs, is affected by the complex formation. The presence of pharmaceutical excipients, such as water-soluble polymers, preservatives, and surfactants, can influence the solubilizing abilities of CDs, but this depends on the excipients’ physicochemical properties. The competitive CD complexation of drugs and excipients has to be considered during formulation studies.

Purpose.: To test the safety and efficacy of topical 1.5% dexamethasone aqueous eye drops with cyclodextrin microparticles for diabetic macular edema (DME). Methods.: Nineteen eyes of 19 consecutive patients with DME were administered dexamethasone-cyclodextrin eye drops three or six times a day for 4 weeks and then observed for 4 weeks without treatment. Visual acuity, intraocular pressure, and spectral domain optical coherent tomography–measured central macular thickness recordings at weeks 0 (baseline), 4, and 8. These parameters were compared using Bonferroni-corrected paired t-tests. Results.: At weeks 0, 4, and 8, logMAR visual acuity (mean ± SD) was 0.52 ± 0.41, 0.37 ± 0.40 (P = 0.0025 vs. baseline), and 0.45 ± 0.41, respectively; central macular thickness (μm) was 512 ± 164, 399 ± 154 (P = 0.0016 vs. baseline), and 488 ± 172 (P = 0.0116 versus week 4), respectively; and intraocular pressure (mm Hg) was 15.2 ± 3.1, 17.4 ± 4.2 (P = 0.0015 vs. baseline) and 15.8 ± 4.0, respectively. At week 4, in 12 (63%) of 19 eyes, central macular thickness had decreased more than 10%, and the mean change was −20% (−65% to +10%). In 14 of 19 eyes (74%) visual acuity (logMAR) had improved more than 0.1 at week 4. No subjects showed severe adverse effects related to the eye drops. Conclusions.: Based on this short pilot study, topical dexamethasone-cyclodextrin eye drops are well tolerated, decrease central macular thickness, and improve visual acuity in DME. The results encourage comparative studies between dexamethasone cyclodextrin microparticle eye drops and other treatments for DME. (http://www.umin.ac.jp/ctr number, UMIN000001790.)

Amphotericin B (AmB) is one of the most effective systemic antifungal agents, but its use is circumscribed by the dose-limiting toxicity of the conventional micellar dispersion formulation, Fungizone®. Significantly lesser toxicity is obtained when AmB incorporated into the aqueous dispersion of lipid nanoparticles. The aim of this study was to develop and characterize AmB loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs). NLC differed from SLN by the presence of liquid lipid, glyceryl tri(caprylate/caprate) in the lipid matrix. Various surfactants i.e., tween 20, cremophor RH40, poloxamer 407 (P407) and Myrj 52 were used to stabilize SLN and NLC. The effect of phospholipid incorporated in those lipid dispersions was also determined. Among surfactants tested, only P407 could stabilize AmB lipid dispersions. There was no chemical reaction occurred between AmB and other components that confirmed by Fourier transform infrared spectroscopy (FT-IR) spectra. The differential scanning calorimetry (DSC), hot-stage microscopy (HSM), powder X-ray diffractometry (PXRD) data showed that AmB was molecularly dispersed or in amorphous form in the lipid matrix. The proton nuclear magnetic resonance (¹H-NMR) results showed that in the presence of phospholipid oil clusters within the lipid matrix are formed. These results indicate that SLN and NLC stabilized by P407 and/or phospholipid as the colloidal carrier for AmB were successfully developed.