Pharmaceutical applications of cyclodextrins. III. Toxicological issues and safety evaluation

The objective of this review is to summarize recent findings on the safety profiles of three natural cyclodextrins (alpha-, beta- and gamma-CDs) and several chemically modified CDs. To demonstrate the potential of CDs in pharmaceutical formulations, their stability against non-enzymatic and enzymatic degradations in various body fluids and tissue homogenates and their pharmacokinetics via parenteral, oral, transmucosal, and dermal routes of administration are outlined. Furthermore, the bioadaptabilities of CDs, including in vitro cellular interactions and in vivo safety profiles, via a variety of administration routes are addressed. Finally, the therapeutic potentials of CDs are discussed on the basis of their ability to interact with various endogenous and exogenous lipophiles or, especially for sulfated CDs, their effects on cellular processes mediated by heparin binding growth factors.

Efficacy, safety and mechanism of cyclodextrins as absorption enhancers in nasal delivery of peptide and protein drugs

Cyclodextrins are used in nasal drug delivery as absorption enhancing compounds to increase the intranasal bioavailability of peptide and protein drugs. The most effective cyclodextrins in animal experiments are the methylated derivatives, dimethyl-beta-cyclodextrin and randomly methylated beta-cyclodextrin, which are active at low concentrations ranging between 2% and 5%. However, large species differences between rats, rabbits and humans exist for the nasal absorption enhancement by cyclodextrins. Based on toxicological studies of the local effects of cyclodextrins on the nasal mucosa dimethyl-beta-cyclodextrin and randomly methylated beta-cyclodextrin are considered safe nasal absorption enhancers. Their effects were quite similar to controls (physiological saline), but smaller than those of the preservative benzalkonium chloride in histological and ciliary beat frequency studies. In these studies, and in a study of the release of marker compounds after nasal administration, methylated beta-cyclodextrins were less toxic than sodium glycocholate, sodium taurodihydrofusidate, laureth-9 and L-alpha-phosphatidylcholine. Systemic toxicity after nasal cyclodextrin administration is not expected, because very low doses of cyclodextrins are administered and only very small amounts are absorbed. The mechanism of action of cyclodextrins may be explained by their interaction with the nasal epithelial membranes and their ability to transiently open tight junctions.

Effects of structure of polyamidoamine dendrimer on gene transfer efficiency of the dendrimer conjugate with alpha-cyclodextrin

To improve gene transfer activity of a new nonviral vector, a polyamidoamine dendrimer (G2) conjugate with alpha-cyclodextrin (alpha-CDE conjugate (G2)), we prepared alpha-CDE conjugates with dendrimer having different generations (G3 and G4), and their gene transfer activities were compared with those of alpha-CDE conjugate (G2) and TransFast, a novel transfection reagent. alpha-CDE conjugates (G2, G3, and G4) formed the complexes with pDNA, changing the zeta-potential and particle size of pDNA complexes and the protection of pDNA from DNase I in a charge ratio-dependent manner, although their differences at higher charge ratios (vector/pDNA) were small. The gene transfer activity of alpha-CDE conjugates (G2, G3, and G4) was higher than that of the corresponding dendrimer alone in NIH3T3 and RAW264.7 cells. Of these CDE conjugates, alpha-CDE conjugate (G3) had a superior gene transfer activity which was comparable to that of TransFast in NIH3T3 cells. The intracellular distribution of pDNA after application of the pDNA complex with alpha-CDE conjugate (G3) to NIH3T3 cells was different from that with dendrimer alone (G3), although the cellular association of pDNA was almost comparable among all vectors. alpha-CDE conjugate (G3) strongly interacted with a fluorescence probe, 2-(p-toluidinyl)-naphthalene-6-sulfonate (TNS), suggesting that the conjugate possesses the inclusion ability with biomembrane constituents such as phospholipids after transfection. These results suggest that alpha-CDE conjugates, particularly the G3 conjugate, could be novel nonviral gene transfer agents.

Colon-specific delivery of prednisolone-appended alpha-cyclodextrin conjugate: alleviation of systemic side effect after oral administration

Prednisolone (PD), a typical glucocorticoid, has been widely used for the treatment of inflammatory bowel disease (IBD). However, when PD is administered orally, a large amount of the drug is absorbed from the upper gastrointestinal (GI) tract and causes systemic side effects. In this study, the anti-inflammatory effect and systemic side effect of the PD succinate/alpha-cyclodextrin (PDsuc/alpha-CyD) ester conjugate after oral administration were studied using IBD model rats. The anti-inflammatory effect of the PDsuc/alpha-CyD conjugate was comparable to those of PD alone. On the other hand, the systemic side effect of the PDsuc/alpha-CyD conjugate was much lower than that of PD alone when administered orally. The lower side effect of the conjugate was attributable to passage of the conjugate through the stomach and small intestine without significant degradation or absorption, followed by the degradation of the conjugate site-specifically in the large intestine. The oral administration of PD alone gave higher plasma concentrations of PD, giving the significant systemic side effect. The results suggested that the PDsuc/alpha-CyD conjugate is useful as a delayed-release type prodrug of PD for colon-specific delivery, owing to alleviation of the systemic side effect, while maintaining the therapeutic effect.

Safety, pharmacokinetics, and pharmacodynamics of cyclodextrin itraconazole in pediatric patients with oropharyngeal candidiasis

The safety, pharmacokinetics, and pharmacodynamics of cyclodextrin itraconazole (CD-ITRA) oral suspension were investigated in an open sequential dose escalation study with 26 human immunodeficiency virus (HIV)-infected children and adolescents (5 to 18 years old; mean CD4(+)-cell count, 128/microl) with oropharyngeal candidiasis (OPC). Patients received CD-ITRA at either 2.5 mg/kg of body weight once a day (QD) or 2.5 mg/kg twice a day (BID) for a total of 15 days. Pharmacokinetic sampling was performed after the first dose and for up to 120 h after the last dose, and antifungal efficacy was evaluated by standardized scoring of the oropharynx. Apart from mild to moderate gastrointestinal disturbances in three patients (11.5%), CD-ITRA was well tolerated. Two patients (7.6%) discontinued treatment prematurely due to study drug-related adverse events. After 15 days of treatment, the peak concentration of drug in plasma (C(max)), the area under the plasma concentration-time curve (AUC) from 0 to 24 h (AUC(0-24)), the concentration in plasma at the end of the dosing interval (predose) (C(min)), and the terminal half-life of itraconazole (ITRA) were (means and standard deviations) 0.604 +/- 0.53 microg/ml, 6.80 +/- 7.4 microg. h/ml, 0.192 +/- 0.06 microg/ml, and 56.48 +/- 44 h, respectively, for the QD regimen and 1.340 +/- 0.75 microg/ml, 23.04 +/- 14.5 microg. h/ml, 0.782 +/- 0.19 microg/ml, and 104.22 +/- 94 h, respectively, for the BID regimen. The mean AUC-based accumulation factors for ITRA on day 15 were 4.14 +/- 0.9 and 3.53 +/- 0.6, respectively. A comparison of the dose-normalized median AUC of the two dosage regimens revealed a trend toward nonlinear drug disposition (P = 0.05). The mean metabolic ratios (AUC of hydroxyitraconazole/AUC of ITRA) at day 15 were 1.96 +/- 0.1 for the QD regimen and 1.29 +/- 0.2 for the BID regimen, respectively (P < 0.05). The OPC score (range, 0 to 13) for all 26 patients decreased from a mean of 7.46 +/- 0.8 at baseline to 2.8 +/- 0.7 at the end of therapy (P < 0.001), demonstrating antifungal efficacy in this setting. The relationships among C(max), C(min), AUC(0-12), C(max)/MIC, C(min)/MIC, AUC(0-12)/MIC, time during the dosing interval when the plasma drug concentrations were above the MIC for the infecting isolate, and the residual OPC score at day 15 for the entire study population fit inhibitory effect pharmacodynamic models (r, 0.595 to 0.421; P, <0.01 to <0.05). All patients with fluconazole-resistant isolates responded to treatment with CD-ITRA; however, there was no clear correlation between the MIC of ITRA and response to therapy. In conclusion, CD-ITRA was well tolerated and efficacious for the treatment of OPC in HIV-infected pediatric patients. Pharmacodynamic modeling revealed significant correlations between plasma drug concentrations and antifungal efficacy. Based on this documented safety and efficacy, a dosage of 2.5 mg/kg BID can be recommended for the treatment of OPC in pediatric patients > or =5 years old.

Cyclodextrins, Natural Compounds, and Plant Bioactives-A Nutritional Perspective

Cyclodextrins (CDs) are a group of cyclic oligosaccharides produced from starch or starch derivatives. They contain six (αCD), seven (βCD), eight (γCD), or more glucopyranose monomers linked via α-1,4-glycosidic bonds. CDs have a truncated cone shape with a hydrophilic outer wall and a less hydrophilic inner wall, the latter forming a more apolar internal cavity. Because of this special architecture, CDs are soluble in water and can simultaneously host lipophilic guest molecules. The major advantage of inclusion into CDs is increased aqueous solubility of such lipophilic substances. Accordingly, we present studies where the complexation of natural compounds such as propolis and dietary plant bioactives (e.g., tocotrienol, pentacyclic triterpenoids, curcumin) with γCD resulted in improved stability, bioavailability, and bioactivity in various laboratory model organisms and in humans. We also address safety aspects that may arise from increased bioavailability of plant extracts or natural compounds owing to CD complexation. When orally administered, α- and βCD—which are inert to intestinal digestion—are fermented by the human intestinal flora, while γCD is almost completely degraded to glucose units by α-amylase. Hence, recent reports indicate that empty γCD supplementation exhibits metabolic activity on its own, which may provide opportunities for new applications.

Long-Term Treatment of Niemann-Pick Type C1 Disease With Intrathecal 2-Hydroxypropyl-β-Cyclodextrin

BACKGROUND

Intrathecal 2-hydoxypropyl-β-cyclodextrin has been found to mobilize cholesterol, extend life, reduce cerebellar pathology, and delay onset of ataxia in the mouse and cat models of Niemann-Pick disease, type C1, a clinically variable progressive and ultimately fatal neurodegenerative storage disorder characterized by endolysosomal accumulation of unesterified cholesterol.

OBJECTIVE

In this study, the long-term effects of intrathecal 2-hydoxypropyl-β-cyclodextrin treatment for 2.5 to three years in humans with Niemann-Pick disease, type C, were evaluated.

METHODS

Three patients with Niemann-Pick disease, type C, in different stages of progression and displaying varying disease manifestations were treated with intrathecal 2-hydoxypropyl-β-cyclodextrin (VTS-270) delivered by lumbar puncture infusion through an intermediate-size patient population investigational new drug application for expanded access. Disease progression was monitored with the Niemann-Pick disease, type C, Neurological Severity Scale and numerous objective measures of function in five neurological domains typically impacted by the disease: cognitive/language, gait/balance, fine motor, swallowing, and eye movement.

RESULTS

No worsening in any domain except eye movements (vertical pursuit gain) was seen for any of the three patients, and in the other domains, improved scores on measures were seen over time for one or more patients. The Niemann-Pick disease type C (NPC) Neurological Severity Scale (NSS) showed stable to slightly improved ratings.

CONCLUSIONS

These trajectories are not consistent with the typical trajectory of the disease and suggest that intrathecal 2-hydoxypropyl-β-cyclodextrin has stabilized the disease over an extended period of time, supporting the current phase 2/3 controlled registration trial with VTS-270.

Vaginal transmission of cell-associated HIV-1 in the mouse is blocked by a topical, membrane-modifying agent

Because both HIV-1 virions and HIV-infected cells are present in the semen and cervical mucus of infected individuals, HIV-1 prevention strategies must consider both cell-free and cell-associated virus. Antibodies that target HIV-1 virions have been shown to prevent vaginal transmission of cell-free virus in macaques, but since cell-associated transmission has not been reliably demonstrated in this model system, no strategies to prevent such transmission have been tested. We have employed a mouse model in which SCID mice carry human peripheral blood leukocytes (HuPBLs). In these mice, vaginal transmission of cell-associated, but not cell-free, HIV-1 transmission occurs, mediated by transepithelial migration of HIV-infected cells. Topical application of beta-cyclodextrin (beta-CD), a cholesterol-sequestering agent that interferes with cell migration and budding of virus from lipid rafts, blocks transmission of cell-associated HIV-1. The HuPBL-SCID model of vaginal HIV-1 transmission should prove useful for investigating cell-associated HIV-1 transmucosal HIV-1 transmission, as well as for screening reagents for their potential efficacy in preventing sexual HIV-1 transmission.

In vitro corneal permeability of diclofenac sodium in formulations containing cyclodextrins compared to the commercial product voltaren ophtha

The influence of different cyclodextrin derivatives on the in vitro permeability of diclofenac sodium through pig cornea was investigated and compared to the commercial product Voltaren ophtha. (Hydroxypropyl)-beta-cyclodextrin (HP beta CD) and two amorphous methylated cyclodextrins with different degrees of substitution were used. In hemolysis studies on human erythrocytes, the hemolytic activity of the different cyclodextrins and the drug was assessed. It was shown that HP beta CD reveals the most favorable toxicological properties. A decrease in the hemolytic activity of diclofenac was yielded by adding HP beta CD. In the permeability experiments the dependency of the permeability coefficients and lag times on the type of cyclodextrin and pH of the solutions were examined. A solution containing HP beta CD buffered in the pH range 6.5 to 7 is proposed as a useful eye drop formulation. All cyclodextrin formulations showed advantages as compared to Voltaren ophtha.

Preclinical results of camptothecin-polymer conjugate (IT-101) in multiple human lymphoma xenograft models

PURPOSE

Camptothecin (CPT) has potent broad-spectrum antitumor activity by inhibiting type I DNA topoisomerase (DNA topo I). It has not been used clinically because it is water-insoluble and highly toxic. As a result, irinotecan (CPT-11), a water-soluble analogue of CPT, has been developed and used as salvage chemotherapy in patients with relapsed/refractory lymphoma, but with only modest activity. Recently, we have developed a cyclodextrin-based polymer conjugate of 20-(S)-CPT (IT-101). In this study, we evaluated the preclinical antilymphoma efficacy of IT-101 as compared with CPT-11.

EXPERIMENTAL DESIGN

We determined an in vitro cytotoxicity of IT-101, CPT-11, and their metabolites against multiple human lymphoma cell lines. In human lymphoma xenografts, the pharmacokinetics, inhibitions of tumor DNA topo I catalytic activity, and antilymphoma activities of these compounds were evaluated.

RESULTS

IT-101 and CPT had very high in vitro cytotoxicity against all lymphoma cell lines tested. As compared with CPT-11 and SN-38, IT-101 and CPT had longer release kinetics and significantly inhibit higher tumor DNA topo I catalytic activities. Furthermore, IT-101 showed significantly prolonged the survival of animals bearing s.c. and disseminated human xenografts when compared with CPT-11 at its maximum tolerated dose in mice.

CONCLUSIONS

The promising present results provide the basis for a phase I clinical trial in patients with relapsed/refractory lymphoma.

Apolipoprotein A-I, cyclodextrins and liposomes as potential drugs for the reversal of atherosclerosis. A review

Several studies have revealed that high-density lipoprotein (HDL) is the most reliable predictor for susceptibility to cardiovascular disease. Since apolipoprotein A-I (apoA-I) is the major protein of HDL, it is worthwhile evaluating the potential of this protein to reduce the lipid burden of lesions observed in the clinic. Indeed, apoA-I is used extensively in cell culture to induce cholesterol efflux. However, while there is a large body of data emanating from in-vitro and cell-culture studies with apoA-I, little animal data and scant clinical trials examining the potential of this apolipoprotein to induce cholesterol (and other lipid) efflux exists. Importantly, the effects of oxysterols, such as 7-ketocholesterol (7KC), on cholesterol and other lipid efflux by apoA-I needs to be investigated in any attempt to utilise apoA-I as an agent to stimulate efflux of lipids. Lessons may be learnt from studies with other lipid acceptors such as cyclodextrins and phospholipid vesicles (PLVs, liposomes), by combination with other effluxing agents, by remodelling the protein structure of the apolipoprotein, or by altering the composition of the lipoprotein intended for administration in-vivo. Akin to any other drug, the usage of this apolipoprotein in a therapeutic context has to follow the traditional sequence of events, namely an evaluation of the biodistribution, safety and dose-response of the protein in animal trials in advance of clinical trials. Mass production of the apolipoprotein is now a simple process due to the advent of recombinant DNA technology. This review also considers the potential of cyclodextrins and PLVs for use in inducing reverse cholesterol transport in-vivo. Finally, the potential of cyclodextrins as delivery agents for nucleic acid-based constructs such as oligonucleotides and plasmids is discussed.

Interrelationships between Helicobacter pylori infection, nonsteroidal antiinflammatory drugs and gastroduodenal disease. A prospective study in healthy volunteers

Helicobacter pylori and nonsteroidal antiinflammatory drugs independently cause gastroduodenal mucosal injury but the relationship between them remains unclear. We have performed a double-blind, parallel-group, placebo-controlled prospective study in 77 healthy volunteers aged 19-35 years who were randomly allocated to indomethacin (N = 15), one of three oxicams (piroxicam, chlortenoxicam, or CHF 1194; N = 36), or placebo (N = 26). Esophagogastroduodenoscopy was performed before and after four weeks of treatment and the mucosal appearances graded. Colonization with H. pylori was established at each endoscopy and gastrointestinal symptoms were assessed by daily diary card. Seven subjects (9%) were positive for H. pylori before treatment (one placebo, one indomethacin, and five an oxicam); their H. pylori status remained unchanged. Two of 70 H. pylori-negative subjects became H. pylori-positive (2.9%), both of whom had received placebo. The endoscopic score deteriorated in 1/6 drug-treated H. pylori-positive subjects and in 0/1 taking placebo. Of the H. pylori-negative subjects whose endoscopic score deteriorated, three (13%) were taking placebo, four (28.6%) indomethacin, and eight (25.8%) an oxicam. Upper gastrointestinal symptoms were reported in eight (30.8%) of the subjects taking placebo (one subject negative for H. pylori became positive), eight (53.3%) indomethacin (one H. pylori-positive), and 10 (27.8%) an oxicam (one H. pylori-positive). There were no statistically significant differences between the H. pylori-negative and H. pylori-positive groups whether on drug or placebo.(ABSTRACT TRUNCATED AT 250 WORDS)

Safety of parenteral hydroxypropyl beta-cyclodextrin

Post-treatment data were collected on a patient who received intravenous hydroxypropyl beta-cyclodextrin in a dose of 1.5 g/kg in 1985. Although no untoward effects were observed in this patient, rarely occurring agitation and pulmonary edema have been noted after injections into rabbits and dogs, respectively. These complications are analyzed here on the basis of symptoms and on the effects of hydroxypropyl beta-cyclodextrin on the biochemistry of a representative lipid, cholesterol, which were studied in rats. It is hypothesized that these untoward effects of parenteral hydroxypropyl beta-cyclodextrin are due to complex formation, with lipid mediators of pathological responses, of which prostaglandins are one example. These mediators normally have brief and localized functions; if hydroxypropyl beta-cyclodextrin happens to be injected when these mediator systems are activated, their influence and the responses of the organism may be increased.

Piroxicam-beta-cyclodextrin. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in rheumatic diseases and pain states

Piroxicam-beta-cyclodextrin is a complex of the established nonsteroidal antiinflammatory drug (NSAID) piroxicam and an inert cyclic macromolecule, beta-cyclodextrin. In clinical trials in patients with rheumatic diseases or pain arising from other conditions, it was as effective an analgesic as standard piroxicam, and showed a faster onset of action on the first day of treatment. In short term pharmacodynamic studies in healthy volunteers, piroxicam-beta-cyclodextrin was equivalent to or tended to show less gastrointestinal mucosal toxicity than standard piroxicam, as assessed by endoscopy and faecal blood loss. However, no data are available on its comparative gastrointestinal mucosal effects from long term clinical trials using similar measures. Preliminary findings from a clinical study suggest piroxicam-beta-cyclodextrin caused fewer gastroduodenal lesions than tenoxicam. As with other NSAIDs, the majority of adverse events associated with piroxicam-beta-cyclodextrin in clinical trials were gastrointestinal in origin, with epigastric pain, heartburn and nausea the most common. Thus, piroxicam-beta-cyclodextrin is an effective agent in patients with rheumatic diseases or other pain states. When rapid analgesia is required in the initial treatment of acute pain, the faster onset of action of piroxicam-beta-cyclodextrin may be an advantage over the parent compound; however, this is unlikely to be important during long term therapy. The results of further long term trials are awaited before firm conclusions can be reached regarding the gastrointestinal tolerability of piroxicam-beta-cyclodextrin compared with that of standard piroxicam and other NSAIDs.

Complexation of zolpidem with 2-hydroxypropyl-beta-, methyl-beta-, and 2-hydroxypropyl-gamma-cyclodextrin: effect on aqueous solubility, dissolution rate, and ataxic activity in rat

The effect of some chemically modified cyclodextrins [namely, 2-hydroxypropyl-beta-, methyl-beta-, and 2-hydroxypropyl-gamma-cyclodextrin (HP-beta-CD, Me-beta-CD, and HP-gamma-CD, respectively)] on the aqueous solubility and dissolution rate of the hypnotic agent Zolpidem (ZP) was investigated. Solid complexes were prepared by freeze drying and characterized by infrared spectroscopy, X-ray powder diffraction, and differential scanning calorimetry. The solubility and dissolution rate of the drug were significantly improved by complexation with HP-beta-CD or Me-beta-CD. The structure of the inclusion complex ZP-HP-beta-CD in CH(3)COOD/D(2)O was investigated by (1)H and (13)C NMR spectroscopy, including NOE measurements. These measurements revealing a weak interaction between the tolyl moiety of the guest molecule and the HP-beta-CD cavity. The ataxic activity in rat was also investigated and it was found that ZP-HP-beta-CD and ZP-Me-beta-CD complexes showed almost 2-fold longer ataxic induction times than controls.

Prednisolone-appended alpha-cyclodextrin: alleviation of systemic adverse effect of prednisolone after intracolonic administration in 2,4,6-trinitrobenzenesulfonic acid-induced colitis rats

The titled compound is a cyclodextrin derivative in which prednisolone 21-succinate (PDsuc) is covalently bound to one of the secondary hydroxyl groups of alpha-cyclodextrin (alpha-CyD) via an ester linkage. In this study, the PDsuc-appended alpha-CyD ester conjugate (PDsuc/alpha-CyD conjugate) was intracolonically administered to rats with 2,4,6-trinitrobenzensulfonic acid-induced colitis, and its antiinflammatory and systemic adverse effects were compared with those of prednisolone (PD) alone and the PD/2-hydroxypropyl-beta-CyD complex (PD/HP-beta-CyD complex), which is a noncovalent inclusion complex. Colonic damage score, ratio of distal colon wet weight to body weight, and myeloperoxidase activity were evaluated as measures of the therapeutic effect of PD, whereas the ratio of thymus wet weight to body weight was evaluated as a measure of the side effect of PD. The local antiinflammatory activity increased in the order of PD alone approximately PDsuc/alpha-CyD conjugate < PD/HP-beta-CyD complex. As to systemic adverse effect, the PD/HP-beta-CyD complex and PD alone caused thymolysis at doses of 5-10 mg/kg. In contrast, the PDsuc/alpha-CyD conjugate showed no clear systemic adverse effect at the same doses. The low adverse effect of the conjugate may be ascribed to the slow release of PD in the colon, which keeps the local concentration in the colon at a low but constant level. The results suggest that the PDsuc/alpha-CyD conjugate can alleviate the systemic adverse effect of PD while maintaining the therapeutic activity of PD. This kind of knowledge will be useful in the rational design of steroid prodrugs for the colon-specific drug delivery system.

Gastrointestinal tolerance of gamma-cyclodextrin in humans

The gastrointestinal tolerance of gamma-cyclodextrin (gamma-CD) was examined in 24 healthy human volunteers. In a double-blind, placebo-controlled, randomized cross-over study, single acute doses of 8 g maltodextrin (placebo) or 8 g gamma-CD (test) were consumed as a mid-morning snack after addition to 100 g yogurt. Gastrointestinal symptoms as well as frequency and consistency of stools were recorded before and after lunch at between 3-4 and 7-8 h after intake respectively. The perception of the symptoms was rated on a subjective scale ranging from 1 ('more than normal') to 3 ('exceptionally more than normal'). Following consumption of maltodextrin, five subjects reported a total of 12 symptoms of which seven, two and three were rated as having grade 1, 2 and 3, respectively. Following consumption of gamma-CD, five subjects reported six symptoms all of which were graded as 1. Two subjects reported flatulence, which is a frequent consequence of the consumption of malabsorbed carbohydrates, after placebo and test treatment. The incidence of individual and combined side-effects as well as the number and consistency of faeces passed was not significantly different between placebo and test treatment. It is concluded that single doses of 8 g gamma-CD and maltodextrin are tolerated equally well. This is in keeping with a good digestibility of gamma-CD by salivary and pancreatic amylase.

Sulfolipo-cyclodextrin in squalane-in-water as a novel and safe vaccine adjuvant

Previously, we described synergistic adjuvanticity of combinations of synthetic sulfolipo(SL)-derivatives of polysaccharide (SL-polysaccharides) and squalane-in-water emulsions (squalane/W). In this paper, effects of type of polysaccharide and nature of oil on adjuvanticity, reactogenicity and stability are described. SL-derivatives of the following polysaccharides were synthesised: synthetic polysucroses with weight-average molecular weight (MW) of 400,000 (Ficoll400), 70,000 (Ficoll70) and 39,000 Da (Ficoll39), polyfructose of 5,000 Da (inulin), linear polyglucose of 1,200 Da (maltodextrin) and cyclic polyglucose of 1,135 Da (beta-cyclodextrin). The number of sulphate groups per monosaccharide of the different SL-polysaccharides varied between 0.15 and 0.23 and the number of lipid groups per monosaccharide between 1.15 and 1.29. Adjuvant formulations were prepared by incorporating these SL-polysaccharides into oil-in-water emulsions of either squalane, hexadecane, soya oil or mineral oil. Adjuvanticity of the formulations obtained for humoral responses to inactivated pseudorabies virus (PRV) and inactivated influenza virus strains A/Swine (A/Swine) and MRC-11 (MRC-11) in pigs and MRC-11 and ovalbumin (OVA) in mice depended on the type of oil (squalane = mineral oil > hexadecane = soya oil) but not on the type of polysaccharide backbone of the SL-derivative. Reactogenicity assessed by local swelling in mice decreased with decreasing MW (SL-Ficoll400 = Ficoll70 = Ficoll39 > SL-inulin = SL-maltodextrin > SL-cyclodextrin) when combined with squalane and decreased with the type of oil in the following order: squalane > mineral oil > hexadecane > soya oil when combined with SL-Ficoll400. Stability of the SL-polysaccharide/squalane/W emulsions at elevated temperature increased with decreasing MW of the SL-polysaccharide (SL-Ficoll400 < SL-Ficoll70 = SL-Ficoll39 < SL-inulin = SL-maltodextrin = SL-cyclodextrin). SL-cyclodextrin/squalane/W remained stable for > 2.5 years at 4 degrees C, > 18 weeks at 37 degrees C and > 10 days at 60 degrees C. We concluded that reactogenicity and stability but not adjuvanticity of SL-polysaccharide/squalane/W formulations depended on the MW of SL-polysaccharide and that SL-cyclodextrin/squalane/W is a promising non-mineral oil adjuvant as it combines strong adjuvanticity (i.e. better than the mineral oil-based adjuvant presently applied) with low reactogenicity and good stability.

Comparison of faecal blood loss, upper gastrointestinal mucosal integrity and symptoms after piroxicam beta-cyclodextrin, piroxicam and placebo administration

In order to evaluate the gastric tolerance of the new piroxicam formulation CHF 1194 (piroxicam complexed with beta-cyclodextrin), a double-blind randomized trial was carried out in 21 young healthy volunteers comparing CHF 1194 with piroxicam and placebo. Faecal blood loss measurement by the Cr-51 labelled red blood cell technique, upper gastrointestinal endoscopic evaluation, titration of gastric pH and gastric biopsies before, during and after treatment were used to assess drug tolerability. Four out of 7 volunteers in the piroxicam-treated group withdrew because of severe gastrointestinal symptoms and oesophageal and/or gastroduodenal lesions, while all subjects treated with CHF 1194 or placebo completed the treatment. There was a significant difference between the endoscopic scores of the piroxicam and placebo groups, whereas no differences were found between CHF 1194 and placebo, nor between piroxicam and CHF 1194. Daily mean gastrointestinal blood loss was greater in the piroxicam group than in either the CHF 1194 or placebo groups, but the difference was not significant, due to the small number of piroxicam-treated subjects who completed the study. When administered for a short period to healthy young subjects, CHF 1194 caused less gastric damage and was better tolerated than piroxicam.

Pharmacokinetics of dipyridamole-beta-cyclodextrin complex in healthy volunteers after single and multiple doses

Dipyridamole is a well known anti-aggregating agent characterized by poor water solubility as well as scant and variable bioavailability. Recently, the compound was complexed with beta-cyclodextrin forming a molecular encapsulation resulting in better oral absorption and stronger biological activities in animals. In the present study, a randomized double blind cross-over comparison between dipyridamole-beta-cyclodextrin complex (dip-beta-CD) and dipyridamole was performed in 12 healthy subjects after single (75mg) and multiple oral treatments (75mg TID). Dip-beta-CD showed better bioavailability and less interindividual variability than dipyridamole either after single or multiple doses. In particular, dip-beta-CD had a greater AUC and Cmax, and a smaller Tmax even at the steady state. In addition, 100% of the subjects receiving a single dose of dip-beta-CD, as compared to 66.7% of those treated with dipyridamole, had plasma levels superior to 1 microgram/ml (which is the supposed anti-aggregating threshold level). In contrast, 0 and 33.03% of the subjects showed plasma levels superior to 2.5 micrograms/ml (which might cause the appearance of side-effects) on the 7th day of the multiple treatment with dip-beta-CD and dipyridamole, respectively. In fact, the subjects presenting higher levels after uncomplexed dipyridamole also complained of headache and/or dizziness on occasion. No adverse side effects were reported for dip-beta-CD.

Surface modification of polymeric biomaterials: Utilization of cyclodextrins for blood compatibility improvement

A novel modified polymeric biomaterial surface using cyclodextrins (CDs) for improved blood compatibility was studied. Plasticized poly(vinyl chloride) (PVC-P) was selected for modification and polyethylene was used as a reference material. The modification was achieved by polymer blending. Fibrinogen and albumin adsorption were utilized as indices for the assessment of the blood compatibility. Surface characterization confirmed that CDs were able to accumulate at the PVC surface and alter the surface properties. The combination of other hydrophilic polymers such as poly(ethylene oxide) (PEO) and PEO/poly(propylene oxide) (PPO) copolymers, such as Pluronic F68 (F68), with CDs were also investigated. These modified materials have a remarkable protein-resistant surface. The combination of B-cyclodextrin (B-CD)/PEO and B-CD/F68 in certain feeding ratio are synergistic in producing enhanced blood compatibility.

Placebo-controlled comparison of piroxicam-beta-cyclodextrin, piroxicam, and indomethacin on gastric potential difference and mucosal injury in humans

The acute gastroduodenal mucosa injury and gastric potential difference (GPD) drops provoked by 14-day administration of 20 mg/day of a new piroxicam formulation (piroxicam-beta-cyclodextrin), 20 mg/day standard piroxicam and 100 mg/day indomethacin were evaluated and compared in a randomized, double-blind, placebo-controlled study carried out on 64 volunteers. Endoscopic examinations, performed after 14-day treatment, demonstrated that piroxicam-beta-cyclodextrin was less gastrolesive (mean endoscopic score +/- SE = 0.56 +/- 0.2) than either piroxicam (2.06 +/- 0.5) or indomethacin (2.25 +/- 0.5) (p < 0.01). The drop in GPD after a single dose of the assigned drug was considerably greater for piroxicam and indomethacin than for piroxicam-beta-cyclodextrin (p < 0.01), which registered similar values to placebo. Since GPD is an expression of the anatomo-functional integrity of the gastric barrier, the results indicate that piroxicam-beta-cyclodextrin exerts less direct acute damage on the gastric mucosa. Therefore, when administered short-term, piroxicam-beta-cyclodextrin appears to be less gastrolesive than either indomethacin or the standard piroxicam formulation.

Cyclodextrins and oligonucleotide delivery to solid tumours

Cyclodextrins (CyDs) have traditionally been used for dissolving hydrophobic chemicals into aqueous media, and more recently, for inducing cholesterol efflux from lipid-laden cells as a proposed mechanism for reversal of cardiovascular disease. This review discusses the potential of delivering therapeutic oligonucleotides to solid tumours using CyD molecules. The physicochemical properties of these oligosaccharide molecules, and the barriers posed by the solid tumour itself, factors that affect may affect the uptake of oligonucleotides by CyDs, are the major foci of this review.