Characterization of the 13-cis-retinoic acid/cyclodextrin inclusion complexes by phase solubility, photostability, physicochemical and computational analysis

Exploring the therapeutic potential of sodium deoxycholate tailored deformable-emulsomes of etodolac for effective management of arthritis

The current piece of research intends to evaluate the potential of combining etodolac with deformable-emulsomes, a flexible vesicular system, as a promising strategy for the topical therapy of arthritis. The developed carrier system featured nanometric dimensions (102 nm), an improved zeta potential (- 5.05 mV), sustained drug release (31.33%), and enhanced drug deposition (33.13%) of DE-gel vis-à-vis conventional system (10.34% and 14.71%). The amount of permeation of the developed nano formulation across skin layers was demonstrated through CLSM and dermatokinetics studies. The safety profile of deformable-emulsomes has been investigated through in vitro HaCaT cell culture studies and skin compliance studies. The efficacy of the DE-gel formulation was sevenfold higher in case of Xylene induced ear edema model and 2.2-folds in CFA induced arthritis model than that of group treated with conventional gel (p < 0.01). The main technological rationale lies in the use of phospholipid and sodium deoxycholate-based nanoscale flexible lipoidal vesicles, which effectively encapsulate drug molecules within their interiors. This encapsulation enhances the molecular interactions and facilitates the transportation of the drug molecule effectively to the target-site. Hence, these findings offer robust scientific evidence to support additional investigation into the potential utility of flexible vesicular systems as a promising drug delivery alternative for molecules of this nature.

Theoretical investigations of free energy of binding and chiral recognition studies of (R)- and (S)-Noradrenaline towards β-cyclodextrin

Noradrenaline (NA), one of the important excitatory catecholamine neurotransmitters, is used as a medication for Parkinson's Disease (PD). The β-cyclodextrin (β-CD) is one of the most effective drug carrier & also used in chiral separation. So, in this theoretical investigation, the R/S-Noradrenaline (R/S-NA) forms binding & chiral recognition mechanisms and energies with β-CD were explored. Using the AutoDock, R/S forms were first docked into the cavity of β-CD giving host-guest complexes with the free energy of binding for S-NA (-4.81 kcal/mol) larger than R-NA (-4.53 kcal/mol). The host-guest inclusion 1:1 complexes between R/S-NA and β-CD have been also modeled and optimized with ONIOM2 (B3LYP/6-31g++DP: PM6) method by using the Gaussian software. Further, frequency calculations were carried out to obtain the free energies. In comparison to the R-NA (-54.59 kcal/mol), it was observed that the S-NA (-56.48 kcal/mol) with β-CD is more stable. Furthermore, the H-bond results from molecular dynamics simulation revealed that S-NA/β-CD was more stable than R-NA/β-CD. In addition, the thermodynamic properties, vibrational analysis (IR), HOMO-LUMO band gap energy, inter molecular hydrogen bond interactions, and conformational analysis were investigated for both the R/S forms to support & compare the stability of the inclusion complex. These inclusion & high stability of S-NA/β-CD and in turn its theoretical chiral recognition behavior observed agreeing well with the reported NMR experimental data have implications in drug delivery and chiral separation research.

Solubility and Thermodynamic Analysis of Isotretinoin in Different (DMSO + Water) Mixtures

The solubility and solution thermodynamics of isotretinoin (ITN) (3) in numerous {dimethyl sulfoxide (DMSO) (1) + water (H2O) (2)} combinations were studied at 298.2-318.2 K under fixed atmospheric pressure of 101.1 kPa. A shake flask methodology was used to determine ITN solubility, and correlations were made using the "van't Hoff, Apelblat, Buchowski-Ksiazczak λh, Yalkowsky-Roseman, Jouyban-Acree, and Jouyban-Acree-van't Hoff models". In mixtures of {(DMSO (1) + H2O (2)}, the solubility of ITN in mole fractions was enhanced with the temperature and DMSO mass fraction. The mole fraction solubility of ITN was highest in neat DMSO (1.02 × 10-1 at 318.2 K) and lowest in pure H2O (3.14 × 10-7 at 298.2 K). The output of computational models revealed good relationships between the solubility data from the experiments. The dissolution of ITN was "endothermic and entropy-driven" in all of the {(DMSO (1) + H2O (2)} mixtures examined, according to the positive values of measured thermodynamic parameters. Enthalpy was discovered to be the driving force behind ITN solvation in {(DMSO (1) + H2O (2)} combinations. ITN-DMSO displayed the highest molecular interactions when compared to ITN-H2O. The outcomes of this study suggest that DMSO has a great potential for solubilizing ITN in H2O.

Inhibitory effect of cyclodextrin on Maillard reaction and its mechanism

Maillard reaction in pharmaceutical preparations refers to a complex chemical reaction existing between reducing excipients and amino-containing drugs in preparations, which can cause a series of quality problems in preparations. Maillard reaction belongs to chemical incompatibility in preparations, and measures should be taken to reduce or avoid it. In this study, the effect of cyclodextrins (commonly used pharmaceutical excipients) on the Maillard reaction and its mechanism in the lysine hydrochloride-lactose solid preparation model were explored for the first time. Our research results show that the embedding of lysine in cyclodextrin can inhibit the Maillard reaction of lysine to some extent, and the embedding of lysine in cyclodextrin with different structures has differences in the inhibitory effects on Maillard reaction.Among the five cyclodextrins we studied, α-CD and HP-β-CD embedded lysine can reduce Maillard reaction to a greater extent. We suspect that this may be related to the stability of the embedded substance, which needs further study and verification. And our research shows that the inclusion complex between lysine and cyclodextrin may be the result of hydrogen bond, electrostatic attraction, hydrophobic interaction and van der Waals force. Cyclodextrin is expected to solve the problem of Maillard reaction in pharmaceutical industry to some extent.

Preparation and Characterization of Clopidogrel Bisulfate-hydroxypropyl-β-Cyclodextrin Mixed Inclusion Complex for Improved Intestinal Solubility and Anti-Thrombotic Efficacy

The study aimed to increase the intestinal solubility and absorption of orally bioavailable clopidogrel-bisulfate (CPB) by complexing with hydroxypropyl-β-cyclodextrin (HCD) to form a binary inclusion complex that was stabilized by Tween 80 (T80) resulting into mixed inclusion complex. The results of phase solubility studies and molecular docking of CPB with β-cyclodextrin (β-CD) and HCD suggested higher solubility and binding energy of the stable CPB: HCD complex in the presence of T80 as compared to the CPB: β-CD complex. The D-Optimal mixture design was used to optimize the formulation containing the CPB: HCD: T80 mixed inclusion complex. The results suggest the enhanced stability of the CPB: HCD inclusion complex in the presence of T80. The spectral attributes confirmed the inclusion complexation and pointed out the central position of CPB in a hydrophilic cavity of HCD. Further, the prepared soft gelatin capsule successfully confirmed the importance of obliterating the intestinal precipitation associated problem of CPB through an in-vitro release study. The anticoagulant activity in rabbits confirmed that soft gelatin capsules showed 1.2 folds and 1.3 folds increase in clotting time, 1.2 fold and 1.5 folds increase in bleeding time when compared to marketed formulation and pure drug, respectively. Conclusively, soft gelatin capsules exhibit the potential to enhance the oral bioavailability of CPB, leading to reduction of the dose and dose-related side effects.

Solubilization and Thermodynamic Analysis of Isotretinoin in Eleven Different Green Solvents at Different Temperatures

The solubilization and thermodynamic analysis of isotretinoin (ITN) in eleven distinct green solvents, such as water, methyl alcohol (MeOH), ethyl alcohol (EtOH), 1-butyl alcohol (1-BuOH), 2-butyl alcohol (2-BuOH), ethane-1,2-diol (EG), propane-1,2-diol (PG), polyethylene glycol-400 (PEG-400), ethyl acetate (EA), Transcutol-HP (THP), and dimethyl sulfoxide (DMSO) was studied at several temperatures and a fixed atmospheric pressure. The equilibrium approach was used to measure the solubility of ITN, and the Apelblat, van’t Hoff, and Buchowski−Ksiazczak λh models were used to correlate the results. The overall uncertainties were less than 5.0% for all the models examined. The highest ITN mole fraction solubility was achieved as 1.01 × 10−1 in DMSO at 318.2 K; however, the least was achieved as 3.16 × 10−7 in water at 298.2 K. ITN solubility was found to be enhanced with an increase in temperature and the order in which it was soluble in several green solvents at 318.2 K was as follows: DMSO (1.01 × 10−1) > EA (1.73 × 10−2) > PEG-400 (1.66 × 10−2) > THP (1.59 × 10−2) > 2-BuOH (6.32 × 10−3) > 1-BuOH (5.88 × 10−3) > PG (4.83 × 10−3) > EtOH (3.51 × 10−3) > EG (3.49 × 10−3) > MeOH (2.10 × 10−3) > water (1.38 × 10−6). ITN−DMSO showed the strongest solute−solvent interactions when compared to the other ITN and green solvent combinations. According to thermodynamic studies, ITN dissolution was endothermic and entropy-driven in all of the green solvents tested. The obtained outcomes suggested that DMSO appears to be the best green solvent for ITN solubilization.

Electrospun pullulan nanofiber loading zanthoxylum bungeanum essential oil/β-cyclodextrin inclusion complexes for active packaging

In this study, zanthoxylum bungeanum essential oil/β-cyclodextrin inclusion complexes (ZBEO/β-CD-ICs) were first prepared by precipitation method. When the addition of ZBEO was 1 g, the reaction time was 4 h and the reaction temperature was 55 °C, the recovery (73.88%) and loading content (9.53%) reached the highest value. The characterization results showed inclusion complexation changed the crystalline structure, enhanced interaction among molecules and increased the thermal stability. Then, nanofiber films containing ZBEO/β-CD-ICs were prepared by electrospinning. When the total polymer concentration was constant at 20%, with the increase of ZBEO/β-CD-IC content, the diameter of nanofiber and mechanical strength decreased, but the temperature corresponding to the maximum rate of weight loss increased. X-ray diffraction analysis proved that the addition of ZBEO/β-CD-IC increased the crystallinity degree of film. The Fourier transform infrared spectra indicated hydrogen bond interactions among molecules. Releasing behavior of ZBEO indicated that increase of temperature and relative humidity accelerated the releasing speed. Antibacterial and antioxidant activity results demonstrated the increase of ZBEO content enhanced antibacterial and antioxidant efficiency, Z40P10 nanofibers had the maximum antibacterial rate of 62.02% against S. aureus and the maximum antioxidant activity of 60.18%.

Vitamin A fortification: Recent advances in encapsulation technologies

Vitamin A is an essential micronutrient whose deficiency is still a major health concern in many regions of the world. It plays an essential role in human growth and development, immunity, and vision, but may also help prevent several other chronic diseases. The total amount of vitamin A in the human diet often falls below the recommended dietary allowance of approximately 900-1000 μ $ \umu $ g/day for a healthy adult. Moreover, a significant proportion of vitamin A may be degraded during food processing, storage, and distribution, thereby reducing its bioactivity. Finally, the vitamin A in some foods has a relatively low bioavailability, which further reduces its efficacy. The World Health Organization has recommended fortification of foods and beverages as a safe and cost-effective means of addressing vitamin A deficiency. However, there are several factors that must be overcome before effective fortified foods can be developed, including the low solubility, chemical stability, and bioavailability of this oil-soluble vitamin. Consequently, strategies are required to evenly disperse the vitamin throughout food matrices, to inhibit its chemical degradation, to avoid any adverse interactions with any other food components, to ensure the food is palatable, and to increase its bioavailability. In this review article, we discuss the chemical, physical, and nutritional attributes of vitamin A, its main dietary sources, the factors contributing to its current deficiency, and various strategies to address these deficiencies, including diet diversification, biofortification, and food fortification.

Determination of 13-cis-Retinoic Acid and Its Metabolites in Plasma by Micellar Electrokinetic Chromatography Using Cyclodextrin-Assisted Sweeping for Sample Preconcentration

The online preconcentration technique, cyclodextrin-assisted sweeping (CD-sweeping), coupled with micellar electrokinetic chromatography (MEKC) was established to determine 13-cis-retinoic acid (13-cis-RA), all-trans-retinoic acid (all-trans-RA) and 4-oxo-13-cis-retinoic acid (4-oxo-13-cis-RA) in human plasma. A CD-sweeping buffer (45 mM borate (pH 9.2), containing 80 mM sodium dodecyl sulfate (SDS) and 22 mM hydroxypropyl β-CD (HP-β-CD) was introduced into the capillary and, then, the sample dissolved in 70 mM borate (pH 9.2): methanol = 9:1 (v/v) was injected into capillary by pressure. The separation voltage was 23 kV. Compared to the conventional cyclodextrin-micellar electrokinetic chromatography (CD-MEKC) method, the new technique achieved 224-257-fold sensitivity enrichment of analytes. The limits of detection of 13-cis-RA, all-trans-RA were 1 ng/mL, whereas that of 4-oxo-13-cis-RA was 25 ng/mL in plasma. The linear ranges of 13-cis-RA, all-trans-RA were between 15 and 1000 ng/mL, whereas that of 4-oxo-13-cis-RA was between 75 and 1500 ng/mL. The coefficient of correlation between the concentration of analytes and peak area ratio of analytes and internal standard (2, 4-dihydroxy-benzophenone) for intra-day (n = 3) and inter-day (n = 5) analyses were both greater than 0.999. The optimized experimental conditions were successfully applied to determine 13-cis-retinoic acid and its metabolites in plasma samples from a patient during the administration of 13-cis-RA for treating acne.

Cyclodextrin Monomers and Polymers for Drug Activity Enhancement

Cyclodextrins (CDs) and cyclodextrin (CD)-based polymers are well-known complexing agents. One of their distinctive features is to increase the quantity of a drug in a solution or improve its delivery. However, in certain instances, the activity of the solutions is increased not only due to the increase of the drug dose but also due to the drug complexation. Based on numerous studies reviewed, the drug appeared more active in a complex form. This review aims to summarize the performance of CDs and CD-based polymers as activity enhancers. Accordingly, the review is divided into two parts, i.e., the effect of CDs as active drugs and as enhancers in antimicrobials, antivirals, cardiovascular diseases, cancer, neuroprotective agents, and antioxidants.

Design of polymer-free Vitamin-A acetate/cyclodextrin nanofibrous webs: antioxidant and fast-dissolving properties

Polymer-free inclusion complex nanofibers of Vitamin-A acetate/cyclodextrin were prepared having fast-dissolving and enhanced antioxidant properties for the purpose of new-generation food/dietary supplement systems.

Photostability and antioxidant activity studies on the inclusion complexes of trans-polydatin with β-cyclodextrin and derivatives

The inclusion complexes of trans-polydatin and three cyclodextrins (CDs), namely β-cyclodextrin (β-CD), methyl-β-cyclodextrin (Me-β-CD) and (2-hydroxy) propyl-β-cyclodextrin (HP-β-CD) were prepared.

Acid-Induced Intracellular Dissociation of β-Cyclodextrin-Threaded Polyrotaxanes Directed toward Attenuating Phototoxicity of Bisretinoids through Promoting Excretion

In the retinal pigment epithelium of patients with age-related macular degeneration (AMD), excess N-retinylidene-N-retinylethanolamine (A2E), a dimer of all-trans-retinal, accumulats to induce inflammatory cytokine secretion and phototoxic effects. Therefore, the reduction of intracellular A2E is a promising approach for the prevention and treatment of AMD. In this study, acid-labile β-cyclodextrin (β-CD)-threaded polyrotaxanes (PRXs) were synthesized and investigated their effects on the removal of A2E accumulated in retinal pigment epithelium cells (ARPE-19) in comparison to nonlabile PRXs and 2-hydroxypropyl β-CD (HP-β-CD) were examined. GC-MS and HPLC studies strongly suggest that the acid-labile PRXs dissociated into their constituent molecules in cells by lysosomal acidification and threaded β-CDs were considered to be released from the PRXs. The released β-CDs formed an inclusion complex with A2E, which promoted the excretion of A2E. Indeed, the acid-labile PRXs effectively reduced intracellular A2E level at approximately a 10-fold lower concentration than HP-β-CD. Accompanied with A2E removal, the toxicity and phototoxicity of A2E were attenuated by treatment with acid-labile PRXs. Because the nonlabile PRX failed to reduce intracellular A2E level and attenuate phototoxicity, intracellular release of threaded β-CDs from the acid-labile PRX might contribute to reducing intracellular A2E. We conclude that acid-labile PRXs are promising candidates for the treatment of macular diseases through the removal of toxic metabolites.

A novel multi-tiered experimental approach unfolding the mechanisms behind cyclodextrin-vitamin inclusion complexes for enhanced vitamin solubility and stability

This study was conducted to provide a mechanistic account for understanding the synthesis, characterization and solubility phenomena of vitamin complexes with cyclodextrins (CD) for enhanced solubility and stability employing experimental and in silico molecular modeling strategies. New geometric, molecular and energetic analyses were pursued to explicate experimentally derived cholecalciferol complexes. Various CD molecules (α-, β-, γ-, and hydroxypropyl β-) were complexed with three vitamins: cholecalciferol, ascorbic acid and α-tocopherol. The Inclusion Efficiency (IE%) was computed for each CD-vitamin complex. The highest IE% achieved for a cholecalciferol complex was for 'βCDD₃-8', after utilizing a unique CD:cholecalciferol molar synthesis ratio of 2.5:1, never before reported as successful. 2HPβCD-cholecalciferol, γCD-cholecalciferol and α-tocopherol inclusion complexes (IC's) reached maximal IE% with a CD:vitamin molar ratio of 5:1. The results demonstrate that IE%, thermal stability, concentration, carrier solubility, molecular mechanics and intended release profile are key factors to consider when synthesizing vitamin-CD complexes. Phase-solubility data provided insights into the design of formulations with IC's that may provide analogous oral vitamin release profiles even when hydrophobic and hydrophilic vitamins are co-incorporated. Static lattice atomistic simulations were able to validate experimentally derived cholecalciferol IE phenomena and are invaluable parameters when approaching formulation strategies using CD's for improved solubility and efficacy of vitamins.

Effects of cyclodextrins on the chemical stability of drugs

Cyclodextrins (CDs) are enabling pharmaceutical excipients that can enhance both solubility and stability of wide variety of drugs in aqueous solutions through formation of drug/CD inclusion complexes where apolar moieties of the drug molecules are located inside the CD cavity. In properly designed pharmaceutical formulations CDs will improve physiochemical properties of lipophilic drugs without affecting their intrinsic ability to permeate biological membranes. Here the effect of CD complexes on the chemical stability of drugs is reviewed. Numerous studies shown that in aqueous solutions CD complexation can hamper hydrolysis, oxidation, photodegradation, isomerization and enzyme catalyzed degradation of dissolved drugs. However, some drugs, such as β-lactam antibiotics, can under certain conditions undergo CD catalyzed degradation in aqueous solutions. Also, some drugs that are stabilized by CDs in aqueous solutions are destabilized by the same CDs in solid dosage forms. Thus, the effects of CDs on drug stability have to be tested and verified in the final drug formulation and under the recommended storage conditions.

Aceclofenac cocrystal nanoliposomes for rheumatoid arthritis with better dermatokinetic attributes: a preclinical study

AIM

The aim of present research was to complex aceclofenac with lysine (LYS) and the developed aceclofenac-LYS cocrystal was encapsulated in lipid bilayers of liposomes by employing dual carrier approach for the treatment of pain-related disorders in rheumatoid arthritis (RA).

MATERIALS & METHODS

The developed carriers were characterized for particle size, drug release, ex vivo and in vivo studies, dermatokinetic modeling, complete freund's adjuvant (CFA)-induced RA rat model, radiant heat tail-flick method, formalin-induced paw-licking model, paw edema model and xylene-induced ear edema model in mice.

RESULTS

The developed nanoliposomes offered nanometric size, controlled drug release and enhanced drug permeation. Further, hydrogel incorporated nanoproduct was found to be rheologically acceptable and substantially compatible with rodent skin.

CONCLUSION

The studies indicated the superiority of LYS-conjugated liposome-entrapped nanocarriers for improved management of conditions like RA over the marketed product.

Aceclofenac–β-cyclodextrin-vesicles: a dual carrier approach for skin with enhanced stability, efficacy and dermatokinetic profile

The aim of the current investigation was to develop and characterize lipid-based carriers of aceclofenac (ACE) with enhanced stability and transdermal delivery potential to the inflammatory sites in osteoarthritis.

C60-fullerenes for delivery of docetaxel to breast cancer cells: A promising approach for enhanced efficacy and better pharmacokinetic profile

Docetaxel has always attracted the researchers owing to its promises and challenges. Despite marked efficacy, concerns like poor aqueous solubility, lower bioavailability, poor tissue penetration and dose related side-effects offer further scope of research on docetaxel. The present study aims to explore the potential of C60-fullerenes in the delivery of docetaxel to cancerous cells. C60-fullerenes were carboxylated, acylated and conjugated with the drug. The chemical processes were monitored by UV, FT-IR and NMR spectroscopy. The conjugate was further characterized for drug loading, micromeritics, drug release, morphology and evaluated for in-vitro cytotoxicity, haemolysis and in-vivo pharmacokinetic profile. The developed nanoconstruct was able to enhance the bioavailability of docetaxel by 4.2 times and decrease the drug clearance by 50%. The developed system was able to control the drug release and was found to be compatible with erythrocytes. The cytotoxic potential on studied MCF-7 and MDA-MB231 cell lines was also enhanced by many folds, indicating marked promise in efficacy enhancement and dose reduction. The present findings are encouraging and offer a technique to enhance the delivery and efficacy potential of anticancer agents, especially belonging to BCS class IV.

Pharmacokinetics of cyclodextrins and drugs after oral and parenteral administration of drug/cyclodextrin complexes

Objectives

The objective of the present study was to shed some light on pharmacokinetics of cyclodextrins (CDs) and drugs after oral and parenteral administration of inclusion complexes.

Key findings

The complex binding constant in water can predict pharmacokinetics after parenteral administration, but it has to be considered in the context of the physiological environment, where plasma proteins compete with CDs for drug binding. Neither drug/CD nor drug/protein complexes can extravasate, but differently from proteins, CDs are readily cleared through glomerular filtration. In such intricate interrelationships, for complexes with low-to-mid binding constant, binding of drug to plasma proteins will mainly dictate the pharmacokinetics. Oppositely, for drugs showing large CD complex binding constant and low protein binding, significant decrease in distribution volume and enhanced excretion of unmetabolized drug are observed; thus, relevant changes in bioavailability can be predicted. In the case of oral administration, volume for dilution/dissolution of the complexes is relatively low and hence excess CD can hamper drug absorption from the gastrointestinal (GI) tract.

Summary

CDs are well-established multipurpose excipients for overcoming organoleptic and biopharmaceutical deficiencies of a variety of drugs. Balances between free and complexed drug in the GI tract and between drug–CD binding and drug–protein binding in plasma seem to play a relevant role in drug pharmacokinetics.

Vitamin A Palmitate-β-cyclodextrin inclusion complexes: characterization, protection and emulsification properties

The interest in the production of foods enriched with vitamins, in order to prevent diseases related with their deficiency, has recently increased. However, the low stability and the low water solubility of certain vitamins make difficult their incorporation in foodstuff, especially in water-based formulations. This limitation is typically overcome by using encapsulating systems such as cyclodextrins. In this paper the formation of water-soluble inclusion complexes of Vitamin A Palmitate with β-cyclodextrins, without the use of organic solvents, is described. The objective was to increase the water solubility of Vitamin A Palmitate and its stability against different external factors to eventually enrich aqueous-based products. The stability of Vitamin A Palmitate in the complexes towards temperature, oxygen and UV light was investigated. All results showed a notably increase of Vitamin A Palmitate water solubility and stability in front of those variables when encapsulated. The surface activity of the complex suggests its possible use as stabilizer in emulsion formulations.

Insights on novel particulate self-assembled drug delivery beads based on partial inclusion complexes between triglycerides and cyclodextrins

Most of the newly designed drug molecules are lipophilic in nature and often encounter erratic absorption and low bioavailability after oral administration. Finding ways to enhance the absorption and bioavailability of these lipophilic drugs is one of the major challenges that face pharmaceutical industry nowadays. In view of that, the purpose of this review is to shed some light on a novel particulate self-assembling system named "beads" than can act as a safe carrier for delivering lipophilic drugs. The beads are prepared simply by mixing oils with cyclodextrin (CD) aqueous solution in mild conditions. A unique interaction between oil components and CD molecules occurs to form in situ surface-active complexes which are prerequisites for beads formation. This review mainly focuses on the fundamentals of beads preparation through reviewing present, yet scarce, literature. The key methods used for beads characterization are discussed in details. Also, the potential mechanisms by which beads increase the bioavailability of lipophilic drugs are illustrated. Finally, the related research areas that needs to be addressed in future for optimizing this promising delivery system are briefly outlined.

A retinyl palmitate-loaded solid lipid nanoparticle system: effect of surface modification with dicetyl phosphate on skin permeation in vitro and anti-wrinkle effect in vivo

Surface-modified solid lipid nanoparticles (SLNs) containing retinyl palmitate (Rpal) were prepared by the hot-melt method using Gelucire 50/13(®) and Precirol ATO5(®). Dicetyl phosphate (DCP) was added to negatively charge the surfaces of the SLNs and thereby enhance the skin distribution properties of Rpal. In vitro skin permeation and in vivo anti-aging studies were performed using SLNs dispersed in a hydrogel. The SLNs were under 100 nm in size with an even polydispersity index (PDI), and the high absolute zeta-potential value was sufficient to maintain the colloidal stability of the SLNs. DCP-modified negative SLNs (DCPmod-SLNs) enhanced the skin distribution of Rpal 4.8-fold and delivered Rpal to a greater depth than did neutral SLNs. The in vivo anti-wrinkle effect of the DCPmod-SLN formulation was Rpal dose-dependent. However, the anti-wrinkle effects of the DCPmod-SLN formulations were significantly different from that of the negative control and effectively prevented the reduction of elastin and superoxide dismutase by UV irradiation. In conclusion, the DCPmod-SLN system presented is a good candidate for topical Rpal delivery.

Molecular modeling-based inclusion mechanism and stability studies of doxycycline and hydroxypropyl-β-cyclodextrin complex for ophthalmic delivery

The aim of the present study was to prepare a stable complex of doxycycline (Doxy) and hydroxypropyl-β-cyclodextrin (HPβCD) for ophthalmic delivery and investigate the inclusion mechanism and the inclusion effects on the stability of Doxy. The Doxy/HPβCD complex was prepared by solution stirring and then characterized by scanning electron microscopy and ultraviolet spectroscopy. Based on results of nuclear magnetic resonance, molecular model of Doxy/HPβCD complex was established using computational simulation of PM3 method implemented in Gaussian 03. Stabilities of Doxy/HPβCD complex in both aqueous solution and solid state at 25°C were evaluated by HPLC. Finally, in vitro antibacterial activity of the Doxy/HPβCD complex was evaluated by disk diffusion test. It was found that the stabilities of Doxy/HPβCD complex in both aqueous solution and solid state were improved obviously as compared with Doxy alone. This stability enhancement is consistent with the inclusion mechanism between HPβCD and Doxy, which showed that the unstable site of Doxy molecule at 6-CH3 was protected in the hydrophobic cavity of HPβCD, additionally, the chelation of Mg2+ provided a synergetic protection of the other unstable site of Doxy at 4-N(CH3)2. The antibacterial activity results indicated that Doxy/HPβCD complex might have potential for clinical applications.

Solid State Characterization of Domperidone: Hydroxypropyl-β-Cyclodextrin Inclusion Complex

The purpose of the present study was to prepare inclusion complex of domperidone with hydroxylpropyl-β-cyclodextrin in order improved the solubility and hence to increase dissolution of domperidone. An effect of concentration of hydroxylpropyl-β-cyclodextrin on the aqueous solubility of domperidone was determined by phase-solubility method. The aqueous solubility of domperidone increased as a function of hydroxylpropyl-β-cyclodextrin concentration, showing AL type diagram. Solid domperidone/hydroxylpropyl-β-cyclodextrin complex was prepared in ratio 1:1 by ultrasonication and kneading method. Solid state inclusion complex was characterized by FTIR, powder X-ray diffraction and differential-scanning calorimetry techniques. FTIR studies showed intactness of drug in complex whereas powder diffraction studies showed that hydroxylpropyl-β-cyclodextrin complex was amorphous. Solubility studies showed that complexation increased domperidone solubility as compared to pure drug in 0.1M hydrochloric acid and distilled water. Drug content confirms that ultrasonication is one of the efficient methods to prepare inclusion complex. Dissolution data of inclusion complexes also indicated that there is 1.4 folds increase in dissolution as compared to pure drug and was observed in case of inclusion complexes prepared by ultrasonication.

Complexation and full characterization of the tretinoin and dimethyl-β-cyclodextrin complex

The aim of this work is to prepare tretinoin/dimethyl-beta-cyclodextrin complexes and fully characterize them through various analytical techniques. According to the phase solubility studies performed, the equilibrium for maximum complexation is reached in about 8 days presenting an A(L)-type diagram (soluble complexes) corresponding mainly to 1:1 stoichiometry (K(s) = 13,600 M(-1)), although the possibility of the presence of 1:2 complexes was mathematically proven. Differential scanning calorimetry, X-ray diffraction and all the other analytical techniques have proven the presence of true complex formation in all the preparation methods tested. H-NMR and FTIR spectra allowed the selection of the best complexation method. The comparison between Raman spectra revealed that the more relevant feature is the band at 1,573 cm(-1), which corresponds to the entire delocalization of the superconjugated system, and after inclusion is observed as a positive frequency shift. Based on these results and the data obtained by molecular modelling calculations, it is proposed that the structure of the drug included into the cyclodextrin corresponds to the side chain including the functional group COOH. The complex was also analysed by atomic force microscopy to determine its size distribution which was heterogeneous and polymodal. However, it could be observed that they all have the same phase constitution.