Bile acid structure-activity relationship: evaluation of bile acid lipophilicity using 1-octanol/water partition coefficient and reverse phase HPLC.

Two independent methods have been developed and compared to determine the lipophilicity of a representative series of naturally occurring bile acids (BA) in relation to their struc- ture. The BA included cholic acid (CA), chenodeoxycholic acid (CDCA), ursodeoxycholic acid (UDCA), deoxycholic acid (DCA), hyodeoxycholic acid (HDCA), ursocholic acid (UCA), hyocholic acid (HCA), as well as their glycine and taurine ami- dates. Lipophilicity was determined using a 1-octanol/water shake-flask procedure and the experiments were performed at different pH and ionic strengths and at initial BA concentrations below their critical micellar concentrations (CMC) and the water solubility of the protonated form. The experimental data show that both the protonated (HA) and ionized (A-) forms of BA can distribute in 1-octanol, and consequently a partition co- efficient for HA (logP' HA) and for A- (logP' A-) must be defined. An equation to predict a weighted apparent distribution coefficient (D) value as a function of pH and pKa has been de- veloped and fits well with the experimental data. Differences be- tween logP for protonated and ionized species for unconjugated BA were in the order of 1 log unit, which increased to 2 for glycine-amidated BA. The partition coefficient of the A- form in- creased with Na+ concentration and total ionic strength, suggest- ing an ion-pair mechanism for its partition into 1-octanol. Lipophilicity was also assessed using reverse phase chromatogra- phy (C-18-HPLC), and a capacity factor (K') for ionized species was determined. Despite a broad correlation with the logP data, some BA behaved differently. The logP values showed that the order of lipophilicity was DCA >CDCA >UDCA > HDCA > HCA>CA >UCA for both the protonated and ionized uncon- jugated and glycine-amidated BA, while the K' data showed an inversion for some BA, i.e., DCA>CDCA >CA> HCA> UDCA > HDCA >UCA. The logP data fitted well with other in- direct measurements of BA monomeric lipophilicity such as al- bumin binding or accessible total hydrophobic surface area data calculated by energy minimization and molecular computer graphics. Differences between unconjugated and amidated BA are consistent with the presence of an amide bond and a lower pKa when pH dependence was studied. Capacity factors, on the other hand, were related to properties of BA micelles such as cholesterol-solubilizing capacity and membrane disruption, reflecting the BA detergency. The extrapolation of these data to biological phenomena must carefully consider the experimental conditions in which the interaction occurs, Le., total BA concen- tration, ionic strength, Na+ concentration, and pH, which in turn determine the BA species existing in solution that coul

Physicochemical and biological properties of natural and synthetic C-22 and C-23 hydroxylated bile acids.

In order to define the effect of a side chain hydroxy group on bile acid (BA) physicochemical and biological properties, 23-hydroxylated bile acids were synthesized following a new efficient route involving the alpha-oxygenation of silylalkenes. 22-Hydroxylated bile acids were also studied. The synthesized bile acids included R and S epimers of 3 alpha,7 alpha,23-trihydroxy-5 beta-cholan-24-oic acid (23R epimer: phocaecholic acid), 3 alpha,12 alpha,23-trihydroxy-5 beta-cholan-24-oic (23R epimer: bitocholic acid), and 3 alpha,7 beta,23-trihydroxy-5 beta-cholan-24-oic acid. A 3 alpha,7 alpha,22-trihydroxy-5 beta-cholan-24-oic acid (haemulcholic acid) was also studied. The presence of a hydroxy group on the side chain slightly modified the physicochemical behavior in aqueous solution with respect to common BA: the critical micellar concentration (CMC) and the hydrophilicity were similar to naturally occurring trihydroxy BA such as cholic acid. The pKa value was lowered by 1.5 units with respect to common BA, being 3.8 for all the C-23 hydroxy BA. C-22 had a higher pKa (4.2) as a result of the increased distance of the hydroxy group from the carboxy group. When the C-23 hydroxylated BA were intravenously administered to bile fistula rats, they were efficiently recovered in bile (more than 80% unmodified) while the corresponding analogs, lacking the 23- hydroxy group, were almost completely glycine- or taurine-conjugated. On the other hand, the C-22 hydroxylated BA were extensively conjugated with taurine and less than 40% of the administered dose was secreted without being conjugated. In the presence of intestinal bacteria, they were mostly metabolized to the corresponding 7-dehydroxylated compound similar to common BA with the exception of bitocholic acid which was relatively stable. The presence of a hydroxy group at the C-23 position increased the acidity of the BA and this accounted for poor absorption within the biliary tree and efficient biliary secretion without the need for conjugation. 3 alpha,7 beta-23 R/S trihydroxy-5 beta-cholan-24-oic acids could improve the efficiency of ursodeoxycholic acid (UDCA) for gallstone dissolution or cholestatic syndrome therapy, as it is relatively hydrophilic and efficiently secreted into bile without altering the glycine and taurine hepatic pool

Nonsystem Reasons for Delay in Door-to-Balloon Time and Associated In-Hospital Mortality A Report From the National Cardiovascular Data Registry

ObjectivesThe goal of this study was to characterize nonsystem reasons for delay in door-to-balloon time (D2BT) and the impact on in-hospital mortality.BackgroundStudies have evaluated predictors of delay in D2BT, highlighting system-related issues and patient demographic characteristics. Limited data exist, however, for nonsystem reasons for delay in D2BT.MethodsWe analyzed nonsystem reasons for delay in D2BT among 82,678 ST-segment elevation myocardial infarction patients who underwent primary percutaneous coronary intervention within 24 h of symptom onset in the CathPCI Registry from January 1, 2009, to June 30, 2011.ResultsNonsystem delays occurred in 14.7% of patients (n = 12,146). Patients with nonsystem delays were more likely to be older, female, African American, and have greater comorbidities. The in-hospital mortality for patients treated without delay was 2.5% versus 15.1% for those with delay (p < 0.01). Nonsystem delay reasons included delays in providing consent (4.4%), difficult vascular access (8.4%), difficulty crossing the lesion (18.8%), “other” (31%), and cardiac arrest/intubation (37.4%). Cardiac arrest/intubation delays had the highest in-hospital mortality (29.9%) despite the shortest time delay (median D2BT: 84 min; 25th to 75th percentile: 64 to 108 min); delays in providing consent had a relatively lower in-hospital mortality rate (9.4%) despite the longest time delay (median D2BT: 100 min; 25th to 75th percentile: 80 to 131 min). Mortality for delays due to difficult vascular access, difficulty crossing a lesion, and other was also higher (8.0%, 5.6%, and 5.9%, respectively) compared with nondelayed patients (p < 0.0001). After adjustment for baseline characteristics, in-hospital mortality remained higher for patients with nonsystem delays.ConclusionsNonsystem reasons for delay in D2BT in ST-segment elevation myocardial infarction patients presenting for primary percutaneous coronary intervention are common and associated with high in-hospital mortality

MF59®-Adjuvanted H5N1 Vaccine Induces Immunologic Memory and Heterotypic Antibody Responses in Non-Elderly and Elderly Adults

Pathogenic avian influenza virus (H5N1) has the potential to cause a major global pandemic in humans. Safe and effective vaccines that induce immunologic memory and broad heterotypic response are needed.Healthy adults aged 18-60 and > 60 years (n = 313 and n = 173, respectively) were randomized (1:1) to receive two primary and one booster injection of 7.5 microg or 15 microg doses of a subunit MF59-adjuvanted H5N1 (A/Vietnam/1194/2004) (clade 1) vaccine. Safety was monitored until 6 months after booster. Immunogenicity was assessed by hemagglutination inhibition (HI), single radial hemolysis (SRH) and microneutralization assays (MN). Mild injection-site pain was the most common adverse reaction. No serious adverse events relating to the vaccine were reported. The humoral immune responses to 7.5 microg and 15 microg doses were comparable. The rates for seroprotection (HI>40; SRH>25 mm(2); MN > or = 40) after the primary vaccination ranged 72-87%. Six months after primary vaccination with the 7.5 microg dose, 18% and 21% of non-elderly and elderly adults were seroprotected; rates increased to 90% and 84%, respectively, after the booster vaccination. In the 15 microg group, seroprotection rates among non-elderly and elderly adults increased from 25% and 62% after primary vaccination to 92% and 88% after booster vaccination, respectively. A heterologous immune response to the H5N1/turkey/Turkey/05 strain was elicited after second and booster vaccinations.Both formulations of MF59-adjuvanted influenza H5N1 vaccine were well tolerated. The European Union requirement for licensure for pre-pandemic vaccines was met by the lower dose tested. The presence of cross-reactive antibodies to a clade 2 heterologous strain demonstrates that this vaccine may be appropriate for pre-pandemic programs.(ClinicalTrials.gov) NCT00311480

Nasal powders of progesterone: manufacturing and bioavailability

EUR. J. PHARM. BIPHARM