Successful implementation of telehealth visits in the paediatric heart failure and heart transplant population

The Advanced Cardiac Therapies Improving Outcomes Network (ACTION) and Pediatric Heart Transplant Society (PHTS) convened a working group at the beginning of 2020 during the COVID-19 pandemic, with the aim of using telehealth as an alternative medium to provide quality care to a high-acuity paediatric population receiving advanced cardiac therapies. An algorithm was developed to determine appropriateness, educational handouts were developed for both patients and providers, and post-visit surveys were collected. Telehealth was found to be a viable modality for health care delivery in the paediatric heart failure and transplant population and has promising application in the continuity of follow-up, medication titration, and patient education/counselling domains.

Treating Pediatric Myocarditis with High Dose Steroids and Immunoglobulin

There is considerable variability in practice among pediatric centers for treatment of myocarditis. We report outcomes using high dose steroids in conjunction with IVIG. This is a single center retrospective study of children < 21 years of age diagnosed with myocarditis and treated with high dose steroids and IVIG from January 2004-April 2021. Diagnostic criteria for myocarditis included positive endomyocardial biopsy, cardiac magnetic resonance (CMR) imaging meeting Lake Louise criteria, or strictly defined clinical diagnosis. Forty patients met inclusion criteria. Median age at diagnosis was 11.6 years (0.7-14.6). Diagnosis was made clinically in 70% of cases (N = 28), by CMR in 12.5% (N = 5) and by biopsy in 17.5% (N = 7). Median ejection fraction (EF) at diagnosis was 35% (IQR 24-48). Median duration of IV steroids was 7 days (IQR 4-12) followed by an oral taper. Median cumulative dose of IV immunoglobulin (IVIG) was 2 g/kg. There were no serious secondary bacterial infections after steroid initiation. Ten patients (25%) required mechanical circulatory support. Overall transplant free survival was 92.5% with median follow-up of 1 year (IQR 0-6 years). Six patients required re-admission for cardiovascular reasons. By 3 months from diagnosis, 70% of patients regained normal left ventricular function. High dose steroids in conjunction with IVIG to treat acute myocarditis can be safe without significant infections or long-term side effects. Our cohort had excellent recovery of ventricular function and survival without transplant. Prospective comparison of a combination of high dose steroids with IVIG versus other therapies is needed.

Sleep-disordered breathing in pediatric heart transplant recipients

BACKGROUND

Sleep-disordered breathing is commonly found in adults with heart failure both before and after HTx. Untreated sleep-disordered breathing post-transplant has been linked to late graft dysfunction, reduced quality of life, and increased morbidity. Sleep-disordered breathing has not been investigated in pediatric HTx recipients.

METHODS

We conducted retrospective review of patients <21yo who underwent primary HTx at our center from 2009 to 2019 to describe clinical characteristics, cardiac history, and PSG results.

RESULTS

One hundred and fifty patients were included; 60% had congenital heart disease, and 40% had cardiomyopathy. Fifty patients had PSG performed at median age of 6.1 years. Forty-one were referred for symptoms of sleep-disordered breathing. Obstructive sleep apnea was diagnosed in 45 patients and central sleep apnea in 3 patients. Of those with first PSG post-transplant (n = 36), median AHI was 9.1/h, and 19 (53%) were diagnosed with moderate or severe sleep apnea. Patients diagnosed with obstructive sleep apnea on PSG had more post-transplant ventilator days (median 3 vs 2 days, P < .05) and longer post-transplant lengths of stay (median 28 vs 22 days, P < .05).

CONCLUSIONS

In this single-center cohort of pediatric HTx recipients, sleep-disordered breathing was common and associated with longer peri-transplant respiratory support and length of stay. Given the high incidence of moderate and severe OSA detected in this population, clinicians should regularly screen for SDB and consider PSG testing more frequently in children who have undergone HTx. Further study into the long-term impact of sleep-disordered breathing in pediatric HTx recipients is needed.

Iron Laboratory Studies in Pediatric Patients With Heart Failure from Dilated Cardiomyopathy

Iron deficiency (FeD), with or without anemia, in adults with heart failure (HF) is associated with poor outcomes, which can be improved with replacement therapy. A similar therapeutic opportunity may exist for children; however, iron laboratory measurements and FeD have not been described in pediatric patients with HF. A single-center, retrospective study was conducted on 28 patients <21 years old with a diagnosis of dilated cardiomyopathy and HF who had iron laboratories (serum iron, iron saturation, and ferritin) performed. The mean (standard deviation) age at time of laboratory collection was 10.3 (5.5) years. Twenty-seven patients (96.4%) met the criteria for FeD. Serum iron and iron saturation were significantly associated with inpatient hospitalization, being on inotropic medications, or having stage D HF. Low-serum iron was associated with a higher left ventricular end-diastolic dimension and left ventricular end-systolic dimension z-score by echocardiography ((β -2.58, 95% confidence interval [CI] -4.76, -0.40, p = 0.02) and (β -2.43, 95% CI -4.70, -0.17, p = 0.04)), respectively. Low ferritin was associated with higher mortality (relative risk 0.29, 95% CI 0.12, 0.70, p = 0.006). In conclusion, FeD was common in this pediatric cohort with more advanced HF. Iron profile abnormalities were associated with worse HF severity and outcomes including mortality.

In vitro bioaccessibility of proteins and lipids of pH-shift processed Nannochloropsis oculata microalga

The pH-shift process fractionates biomass into soluble proteins and insoluble fractions, followed by precipitation and recovery of the solubilized proteins. Nannochloropsis oculata in seawater was subjected to the pH-shift process, followed by digestion of various intermediates and product fractions of the process, using the Infogest in vitro digestion model (Minekus et al., 2014) with added gastric lipase. As measures for protein and lipid accessibility, degrees of protein hydrolysis and fatty acid liberation were assessed post-digestion and compared to the amounts of peptide bonds and total fatty acids present in the raw materials. Results showed that neither proteins nor lipids of intact Nannochloropsis cells were accessible to the mammalian digestive enzymes used in the digestion model. Cell disruption, and to a lesser extent, further pH-shift processing with protein solubilisation at pH 7 or pH 10, increased the accessibility of lipids. For proteins, differences amongst the pH-shift processed materials were non-significant, though pre-freezing the product prior to digestion increased the accessibility from 32% to 47%. For fatty acids, pH-shift process-products gave rise to 43% to 52% lipolysis, with higher lipolysis for products solubilised at pH 10 as opposed to pH 7. Our results indicate the importance of processing to produce an algal product that has beneficial nutritional properties when applied as food or feed.

Posterior reversible encephalopathy syndrome after pediatric heart transplantation: Increased risk for children with preexisting Glenn/Fontan physiology

Identification of risk factors for PRES after organ transplant can improve early detection and avoid permanent neurological injury. High calcineurin-inhibitor levels and hypertension are recognized risk factors for PRES in adult transplant recipients. Limited data exist regarding PRES after pediatric HTx, with studies limited to case reports. We performed a retrospective review of 128 pediatric HTx recipients to identify risk factors for PRES. Seven of 128 (5.5%) recipients developed PRES at a median of 10 days (5-57) after HTx. The median age of recipients with PRES was 10.0 yr (5.7-19.0), compared to 1.4 yr (0.0-19.8) for recipients without PRES (p = 0.010). Fewer than half of recipients with PRES had elevated post-transplant calcineurin-inhibitor levels (n = 3) and/or preceding severe hypertension (n = 3). Four of seven who developed PRES (57%) had pretransplant Glenn or Fontan physiology (G/F). G/F was a significant risk factor for PRES (RR 4.99, 95% CI: 1.19-21.0, p = 0.036). Two recipients (29%), both with severe PRES, had residual neurological symptoms. In summary, PRES occurred in 5.5% of pediatric HTx recipients and presented early after HTx. All recipients with PRES were > 5 yr. Patients with pretransplant G/F were at increased risk, a risks factor not previously described.

Impact of donor-recipient sex match on long-term survival after heart transplantation in children: An analysis of 5797 pediatric heart transplants

The effect of donor-recipient sex matching on long-term survival in pediatric heart transplantation is not well known. Adult data have shown worse survival when male recipients receive a sex-mismatched heart, with conflicting results in female recipients. We analyzed 5795 heart transplant recipients ≤ 18 yr in the Scientific Registry of Transplant Recipients (1990-2012). Recipients were stratified based on donor and recipient sex, creating four groups: MM (N = 1888), FM (N = 1384), FF (N = 1082), and MF (N = 1441). Males receiving sex-matched donor hearts had increased unadjusted allograft survival at five yr (73.2 vs. 71%, p = 0.01). However, this survival advantage disappeared with longer follow-up and when adjusted for additional risk factors by multivariable Cox regression analysis. In contrast, for females, receiving a sex-mismatched heart was associated with an 18% higher risk of allograft loss over time compared to receiving a sex-matched heart (HR 1.18, 95% CI: 1.00-1.38) and a 26% higher risk compared to sex-matched male recipients (HR 1.26, 95% CI: 1.10-1.45). Females who receive a heart from a male donor appear to have a distinct long-term survival disadvantage compared to all other groups.

Human rights and access to hepatitis C treatment for people who inject drugs

BACKGROUND

People who inject drugs (PWID) achieve adherence to and outcomes from hepatitis C virus (HCV) treatment comparable to other patients. Nonetheless, this population has been excluded from treatment by regulation or practice. Approval of safer and more effective oral HCV medicines should offer greater treatment options for PWID, although high medicine prices have led to continued treatment rationing and exclusion in developed countries. In middle-income countries (MICS), treatment is largely unavailable and unaffordable for most PWID.

METHODS

Human rights analysis, with its emphasis on the universal and interconnected nature of the economic, social and political spheres, offers a useful framework for HCV treatment reform. Using peer-reviewed and grey literature, as well as community case reports, we discuss barriers to treatment, correlate these barriers to rights violations, and highlight examples of community advocacy to increase treatment for PWID.

RESULTS

Structural drivers of lack of treatment access for PWID include stigma in health settings; drug use status as a criterion for treatment exclusion; requirements for fees or registration by name as a drug user prior to treatment initiation; and incarceration/detention in prisons and rehabilitation centers where treatment is unavailable. High medicine prices force further exclusion of PWID, with cost containment masked as concern about treatment adherence. These barriers correlate to multiple rights violations, including of the rights to privacy; non-discrimination; health; freedom of information; fair trial; and freedom from cruel, inhuman and degrading treatment.

CONCLUSIONS

Needed reforms include decriminalization of drug use, possession of drugs and drug injecting equipment; removal of exclusionary or discriminatory treatment protocols; approaches to strengthen links between health providers and increase participation of PWID in treatment design and implementation; and measures to increase transparency in government/pharmaceutical company negotiations and reduce treatment price.

Eosinophil count, allergies, and rejection in pediatric heart transplant recipients

BACKGROUND

Allograft rejection and long-term immunosuppression remain significant challenges in pediatric heart transplantation. Pediatric recipients are known to have fewer rejection episodes and to develop more allergic conditions than adults. A T-helper 2 cell dominant phenotype, manifested clinically by allergies and an elevated eosinophil count, may be associated with immunologic quiescence in transplant recipients. This study assessed whether the longitudinal eosinophil count and an allergic phenotype were associated with freedom from rejection.

METHODS

This single-center, longitudinal, observational study included 86 heart transplant patients monitored from 1994 to 2011. Post-transplant biannual complete blood counts, allergic conditions, and clinical characteristics related to rejection risk were examined.

RESULTS

At least 1 episode of acute cellular rejection (ACR) occurred in 38 patients (44%), antibody-mediated rejection (AMR) occurred in 11 (13%), and 49 patients (57%) were diagnosed with an allergic condition. Patients with ACR or AMR had a lower eosinophil count compared with non-rejectors (p = 0.011 and p = 0.022, respectively). In the multivariable regression analysis, the presence of panel reactive antibodies to human leukocyte antigen I (p = 0.014) and the median eosinophil count (p = 0.011) were the only independent covariates associated with AMR. Eosinophil count (p = 0.010) and female sex (p = 0.009) were independent risk factors for ACR. Allergic conditions or young age at transplant were not protective from rejection.

CONCLUSIONS

This study demonstrates a novel association between a high eosinophil count and freedom from rejection. Identifying a biomarker for low rejection risk may allow a reduction in immunosuppression. Further investigation into the role of the T-helper 2 cell phenotype and eosinophils in rejection quiescence is warranted.

Perioperative plasma F(2)-Isoprostane levels correlate with markers of impaired ventilation in infants with single-ventricle physiology undergoing stage 2 surgical palliation on the cardiopulmonary bypass

Cardiopulmonary bypass (CPB) produces inflammation and oxidative stress, which contribute to postoperative complications after cardiac surgery. F(2)-Isoprostanes (F(2)-IsoPs) are products of lipid oxidative injury and represent the most accurate markers of oxidative stress. In adults undergoing cardiac surgery, CPB is associated with elevated IsoPs. The relationship between F(2)-IsoPs and perioperative end-organ function in infants with single-ventricle physiology, however, has not been well studied. This study prospectively enrolled 20 infants (ages 3-12 months) with univentricular physiology undergoing elective stage 2 palliation (bidirectional cavopulmonary anastomosis). Blood samples were collected before the surgical incision (T0), 30 min after initiation of CPB (T1), immediately after separation from CPB (T2), and 24 h postoperatively (T3). Plasma F(2)-IsoP levels were measured at each time point and correlated with indices of pulmonary function and other relevant clinical variables. Plasma F(2)-IsoPs increased significantly during surgery, with highest levels seen immediately after separation from CPB (p < 0.001). After separation from CPB, increased F(2)-IsoP was associated with lower arterial pH (ρ = -0.564; p = 0.012), higher partial pressure of carbon dioxide (PaCO(2); ρ = 0.633; p = 0.004), and decreased lung compliance (ρ = -0.783; p ≤ 0.001). After CPB, F(2)-IsoPs did not correlate with duration of CPB, arterial lactate, or immediate postoperative outcomes. In infants with single-ventricle physiology, CPB produces oxidative stress, as quantified by elevated F(2)-IsoP levels. Increased F(2)-IsoP levels correlated with impaired ventilation in the postoperative period. The extent to which F(2)-IsoPs and other bioactive products of lipid oxidative injury might predict or contribute to organ-specific stress warrants further investigation.

Evaluation of 2 hematology analyzers in body fluid mode versus flow cytometry immunophenotyping of mainly neurosurgical cerebrospinal fluid samples

BACKGROUND

For CSF analysis, exact knowledge of the type and amount of cells is essential, especially for detection of infection or bleeding. The chamber count has been the current reference method to date, yet it is problematic due to its subjectivity depending on the examiner's skill and experience. Therefore, as a reference method, we used an impulse cytophotometric measurement with Epics XL owing to its improved objectify ability and compared this method to the measurement of CSF samples performed with the ADVIA 2120 and XE-5000.

MATERIAL AND METHODS

101 CSF samples were measured with the ADVIA 2120, XE-5000, and Epics XL. For impulse cytophotometric measurement, CD235a was used for identification of erythrocytes; CD45 for the entire leukocyte population; CD56, CD16 and CD14 for monocytes; CD3, CD4 and CD19 for lymphocytes;and CD13, CD15 and CD33 for neutrophile granulocytes.

RESULTS

Regarding leukocyte measurements, a strong correlation was obtained between Epics XL and XE-5000 (r = 0.990), with the correlation between Epics XL and ADVIA 2120 not as strong (r = 0.538). This finding is due to the fact that with blood-stained CSF samples (erythrocytes >1,500/µl), no valid results were produced by the ADVIA 2120. In measurements of blood-free CSF samples, correlations between Epics XL, XE-5000, and ADVIA 2120 were almost identical (r = 0.985 and r = 0.964). The same applies to the correlation between polymorphonuclear and mononuclear cells (range 0.920-0.972). In erythrocyte measurements, the correlation between XE-5000 and ADVIA 2120 was excellent (r = 0.945). Impulse cytophotometric measurement of erythrocytes with CD 238 antibodies did not appear to be functional.

CONCLUSION

In the measurement of leukocytes in CSF with the ADVIA 2120, no valid results could be obtained in blood-stained CSF samples (erythrocytes >1,500/µl). In blood-free CSF samples (erythrocytes <1,500/µl), measurements of leukocytes, and polymorphonuclear and mononuclear cells performed with the ADVIA 2120 and XE-5000 produced almost identical good results. Determination of CSF cells with the XE-5000 is presently the best automated method for counting leukocytes of blood-stained CSF.

Flux balance analysis for ethylene formation in genetically engineered Saccharomyces cerevisiae

Biosynthesis of ethylene (ethene) is mainly performed by plants and some bacteria and fungi, via two distinct metabolic routes. Plants use two steps, starting with S-adenosylmethionine, while the ethylene-forming microbes perform an oxygen dependent reaction using 2-oxoglutarate and arginine. Introduction of these systems into Saccharomyces cerevisiae was studied in silico. The reactions were added to a metabolic network of yeast and flux over the two networks was optimised for maximal ethylene formation. The maximal ethylene yields obtained for the two systems were similar in the range of 7-8 mol ethylene/10 mol glucose. The microbial metabolic network was used for testing different strategies to increase the ethylene formation. It was suggested that supplementation of exogenous proline, using a solely NAD-coupled glutamate dehydrogenase, and using glutamate as the nitrogen source, could increase the ethylene formation. Comparison of these in silico results with published experimental data for yeast expressing the microbial system confirmed an increased ethylene formation when changing nitrogen source from ammonium to glutamate. The theoretical analysis methods indicated a much higher maximal yield per glucose for ethylene than was experimentally observed. However, such high ethylene yields could only be obtained with a concomitant very high respiration (per glucose). Accordingly, when ethylene production was optimised under the additional constraint of restricted respiratory capacity (i.e. limited to experimentally measured values) the theoretical maximal ethylene yield was much lower at 0.2/10 mol glucose, and closer to the experimentally observed values.

Determination of eflornithine enantiomers in plasma by precolumn derivatization with o-phthalaldehyde-N-acetyl-L-cysteine and liquid chromatography with UV detection

A bioanalytical method for indirect determination of eflornithine enantiomers in 75 microL human plasma has been developed and validated. L- and D-eflornithine were derivatized with o-phthalaldehyde and N-acetyl-L-cysteine to generate diastereomers which were separated on two serially connected Chromolith Performance columns (RP-18e 100 x 4.6 mm i.d.) by a isocratic flow followed by a gradient flow for elution of endogenous compounds. The diastereomers were detected with UV (340 nm). The between-day precisions for L- and D-eflornithine in plasma were 8.4 and 2.3% at 3 microm, 4.0 and 5.1% at 400 microm, and 2.0 and 3.7% at 1000 microm. The lower limit of quantification was determined to be 1.5 microm, at which precision was 14.9 and 9.9% for L- and D-eflornithine, respectively.

Ethylene production by metabolic engineering of the yeast Saccharomyces cerevisiae

The non-ethylene producing yeast, Saccharomyces cerevisiae, was transformed into an ethylene producer by introducing the ethylene forming enzyme from the plant pathogenic bacterium Pseudomonas syringae. Cultivation of the metabolically engineered strain was performed in well-controlled bioreactors as aerobic batch cultures with an on-line monitoring of ethylene production. The highest productivity was obtained during the respiro-fermentative growth on glucose but there was also a significant rate of formation during the subsequent phase of ethanol respiration. Furthermore, investigations were performed whether substitution of the original nitrogen source, NH(4)(+), for glutamate could improve productivity and yield of ethylene even more. The rationale being that one of the substrates for the enzyme is 2-oxoglutarate and this compound can be formed from glutamate in a single reaction. Indeed, there was a substantial improvement in the rate of production and the final yield of ethylene was almost three times higher when NH(4)(+) was replaced by glutamate.

Placental pathology casebook. Complete hydatidiform mole with coexistent term twin pregnancy

A case of twin pregnancy consisting of a complete hydatidiform mole with a coexistent, viable fetus is presented. The case is distinctive for its presentation on ultrasound, its unusually low levels of serum hCG, its remarkable histology, and its term delivery.

Cyclodextrin derivatives in pharmaceutics

The current cyclodextrin (CD) literature is reviewed concerning synthesis, characterization, and pharmaceutical relevant applications of CD derivatives. Although natural CDs have been used extensively to improve pharmaceutical properties, the effects of chemically modified CDs on the solubility, dissolution rate, and stability of drugs are overproportional. Concerning the parenteral application, the major interest is focussed on highly water-soluble, randomly substituted hydroxyalkyl derivatives of beta- and gamma-CD such as 2-hydroxypropyl-beta-cyclodextrin (2-HP-beta-CD). Although the heptakis-(2,6-di-O-methyl)-beta-cyclodextrin is applied in the pharmaceutical field, 2-HP-beta-CD is predestined as a parenteral drug carrier owing to its weak hemolytic activity and intrinsically amorphous character. A minimal average degree of substitution is especially preferred when 2-HP-beta-CD is used as solubilizer of pharmaceuticals for the use in parenteral applications. The influence of the type, degree, and pattern of substitution of the CDs, as well as substituent effects of the guest molecule is elucidated.

Influence of the nitrogen source on Saccharomyces cerevisiae anaerobic growth and product formation

To prevent the loss of raw material in ethanol production by anaerobic yeast cultures, glycerol formation has to be reduced. In theory, this may be done by providing the yeast with amino acids, since the de novo cell synthesis of amino acids from glucose and ammonia gives rise to a surplus of NADH, which has to be reoxidized by the formation of glycerol. An industrial strain of Saccharomyces cerevisiae was cultivated in batch cultures with different nitrogen sources, i.e., ammonium salt, glutamic acid, and a mixture of amino acids, with 20 g of glucose per liter as the carbon and energy source. The effects of the nitrogen source on metabolite formation, growth, and cell composition were measured. The glycerol yields obtained with glutamic acid (0.17 mol/mol of glucose) or with the mixture of amino acids (0.10 mol/mol) as a nitrogen source were clearly lower than those for ammonium-grown cultures (0.21 mol/mol). In addition, the ethanol yield increased for growth on both glutamic acid (by 9%) and the mixture of amino acids (by 14%). Glutamic acid has a large influence on the formation of products; the production of, for example, alpha-ketoglutaric acid, succinic acid, and acetic acid, increased compared with their production with the other nitrogen sources. Cultures grown on amino acids have a higher specific growth rate (0.52 h-1) than cultures of both ammonium-grown (0.45 h-1) and glutamic acid-grown (0.33 h-1) cells. Although the product yields differed, similar compositions of the cells were attained. The NADH produced in the amino acid, RNA, and extracellular metabolite syntheses was calculated together with the corresponding glycerol formation. The lower-range values of the theoretically calculated yields of glycerol were in good agreement with the experimental yields, which may indicate that the regulation of metabolism succeeds in the most efficient balancing of the redox potential.

Complexation of steroid hormones with cyclodextrin derivatives: substituent effects of the guest molecule on solubility and stability in aqueous solution

The inclusion complexation of homologous derivatives of steroid hormones with cyclodextrins and 2-hydroxypropyl-beta-cyclodextrin (2-HP-beta-CD) was investigated with regard to underlying structure-interaction relationship. The interaction was studied by phase solubility analysis and stabilization effects of complex formation with 2-HP-beta-CD. The solubilizing and stabilizing abilities of 2-HP-beta-CD were generally more effective for testosterone derivatives than for estradiol esters. Within a homologous series of steroid hormones, the steepest linear solubility isotherms were found for 17-methyl and 3-methyl derivatives. The solubilization of steroid esters by 2-HP-beta-CD depended on the structure and length of the ester side chain. The interaction of 2-HP-beta-CD with the steroids was hindered by long-chain fatty acid ester groups. With increasing length of the side chain, a decline of the isotherms occurred and the phase solubility behavior changed from linear to exponential. Contrary to expectations, benzoylation of steroids considerably decreased the guest-host interaction. The observed rates of degradation of the steroid esters were significantly reduced by 2-HP-beta-CD, depending on the chain length, and correlated well with the order found in phase solubility analysis. The degradation showed no deviations from pseudo-first-order kinetics, and the degradation mechanism was not changed because of complexation. The results suggest that interaction of 2-HP-beta-CD with steroid esters involves the ester functions of the prodrugs and is more suitable for unsubstituted guest molecules.

Effect of hydrotropic substances on the complexation of sparingly soluble drugs with cyclodextrin derivatives and the influence of cyclodextrin complexation on the pharmacokinetics of the drugs

The influence of hydrotropic compounds on complex formation by 2-hydroxypropyl-beta-cyclodextrin (2-HP-beta-CD) was investigated with methyltestosterone (MeT). Various representatives of the lyotropic series were used for this purpose. Additive hydrotropic effects were observed for nicotinamide and urea, which disrupt the water structure, while structure formers such as sorbitol exerted negative effects. The effects of hydrotropic substances on the phase solubility relationship of MeT showed that inclusion complex formation with 2-HP-beta-CD depends on the degree of ordering of the solvent and is apparently subject to entropy effects. Combined systems comprising 2-HP-beta-CD and auxiliary substances with various underlying solubilizing principles were also investigated. Combination of 2-HP-beta-CD with conventional solubilizers, such as 1,2-propylene glycol or sodium deoxycholate, reduced the solubilization capacity of 2-HP-beta-CD. Competitive displacement of the inclusion molecule from its 2-HP-beta-CD complex by sodium deoxycholate suggested that cholesterol participates in the release mechanism of the inclusion molecule under in vivo conditions. The spontaneous release of complexed drug molecules could indirectly be shown on the basis of the spontaneous action of a complexed dihydropyridine derivative after iv administration in rats. The bioavailability of an investigational drug in cynomolgus monkeys could be enhanced sevenfold by inclusion complexation with 2-HP-beta-CD.