Interferon-γ increases expression of the di/tri-peptide transporter,h-PEPT1, and dipeptide transport in cultured human intestinal monolayers

The di/tri-peptide transporter h-PEPT1 plays an important role in the oral absorption of di/tri-peptides and numerous drugs. Inflammatory conditions may influence intestinal xenobiotic transporter function; however, the effects of inflammation on h-PEPT1 have not been well described. This study was conducted to determine the effects of the inflammatory cytokine interferon-γ (IFN-γ) on h-PEPT1 mediated dipeptide absorption. Caco-2 monolayers were grown on permeable supports. The effective apical-to-basolateral permeability (P_eff) of glycylsarcosine (Gly-Sar) was measured following incubation with IFN-γ or control media. Additional experiments were conducted at 4 °C, and with escalating concentrations of Gly-Sar. h-PEPT1 expression was determined using semiquantitative RT-PCR. IFN-γ 50 ng/ml increased Gly-Sar P_eff 28.6% compared to controls (p = 0.03). In experiments conducted at 4 °C, Gly-Sar P_eff decreased 39.6% in IFN-γ treated cells (p = 0.003) and 28.4% in controls (p = 0.006). In controls and IFN-γ treated cells, concentration dependent transport was seen with escalating concentrations of Gly-Sar. Compared to controls, IFN-γ 50 and 100 ng/ml increased h-PEPT1 mRNA expression by 14.2% and 11.5%, respectively (p = 0.019). In summary, IFN-γ increases h-PEPT1 expression and permeation of the dipeptide Gly-Sar in Caco-2 monolayers. These findings imply that intestinal absorption of peptides and peptidomimetic drugs may be increased in certain inflammatory conditions.     

Prediction of phospholipidosis-inducing potential of drugs by in vitro biochemical and physicochemical assays followed by multivariate analysis

An in vitro method to predict phospholipidosis-inducing potential of cationic amphiphilic drugs (CADs) was developed using biochemical and physicochemical assays. The following parameters were applied to principal component analysis, as well as physicochemical parameters: pK_a and clog P; dissociation constant of CADs from phospholipid, inhibition of enzymatic phospholipid degradation, and metabolic stability of CADs. In the score plot, phospholipidosis-inducing drugs (amiodarone, propranolol, imipramine, chloroquine) were plotted locally forming the subspace for positive CADs; while non-inducing drugs (chlorpromazine, chloramphenicol, disopyramide, lidocaine) were placed scattering out of the subspace, allowing a clear discrimination between both classes of CADs. CADs that often produce false results by conventional physicochemical or cell-based assay methods were accurately determined by our method. Basic and lipophilic disopyramide could be accurately predicted as a nonphospholipidogenic drug. Moreover, chlorpromazine, which is often falsely predicted as a phospholipidosis-inducing drug by in vitro methods, could be accurately determined. Because this method uses the pharmacokinetic parameters pK_a, clog P, and metabolic stability, which are usually obtained in the early stages of drug development, the method newly requires only the two parameters, binding to phospholipid, and inhibition of lipid degradation enzyme. Therefore, this method provides a cost-effective approach to predict phospholipidosis-inducing potential of a drug.     

Predicting the oral uptake efficiency of chemicals in mammals: Combining the hydrophilic and lipophilic range

Environmental risk assessment requires models for estimating the bioaccumulation of untested compounds. So far, bioaccumulation models have focused on lipophilic compounds, and only a few have included hydrophilic compounds. Our aim was to extend an existing bioaccumulation model to estimate the oral uptake efficiency of pollutants in mammals for compounds over a wide K_ow range with an emphasis on hydrophilic compounds, i.e. compounds in the lower K_ow range. Usually, most models use octanol as a single surrogate for the membrane and thus neglect the bilayer structure of the membrane. However, compounds with polar groups can have different affinities for the different membrane regions. Therefore, an existing bioaccumulation model was extended by dividing the diffusion resistance through the membrane into an outer and inner membrane resistance, where the solvents octanol and heptane were used as surrogates for these membrane regions, respectively. The model was calibrated with uptake efficiencies of environmental pollutants measured in different mammals during feeding studies combined with human oral uptake efficiencies of pharmaceuticals. The new model estimated the uptake efficiency of neutral (RMSE = 14.6) and dissociating (RMSE = 19.5) compounds with logK_ow ranging from ? 10 to + 8. The inclusion of the K_hw improved uptake estimation for 33% of the hydrophilic compounds (logK_ow < 0) (r² = 0.51, RMSE = 22.8) compared with the model based on K_ow only (r² = 0.05, RMSE = 34.9), while hydrophobic compounds (logK_ow > 0) were estimated equally by both model versions with RMSE = 15.2 (K_ow&K_hw) and RMSE = 15.7 (K_ow only). The model can be used to estimate the oral uptake efficiency for both hydrophilic and hydrophobic compounds.     

Relationship Between the Urinary Excretion Mechanisms of Drugs and Their Physicochemical Properties

The purpose of this study was to clarify the relationship between the physicochemical properties of drugs and their urinary excretion mechanisms. Three hundred twenty-five drugs were classified into the reabsorption, intermediate, and secretion types based on their ratio of renal clearance to protein-unbound fraction glomerular filtration rate. Fifty percent of ionized and neutral drugs were the secretion and reabsorption types, respectively. The mean molecular weight of the neutral drugs was slightly smaller than those of the ionized drugs (296 vs. 330–368 g/mol). The reabsorption-type anionic drugs were characterized by their low molecular weights (mean value 269 g/mol) and the logarithmic measure of the acid dissociation constants (pK_a s) greater than 4.5, whereas the secretion-type anionic drugs all had pK_as below 4.5. Cationic drugs with pK_as lower than 8.0 tended to be the reabsorption type. Some cationic drugs were classified as the secretion type, despite their high molecular weights (734–811 g/mol) and high log P values (3.1–5.3). The organic anion transporter (OAT)1 and OAT3 substrates were all secretion-type drugs. The same trend was observed for the substrates of organic cation transporter 2, multidrug and toxin extrusion, multidrug resistance-associated protein 4, and multidrug resistance 1/breast cancer resistance protein, but substantial fractions of the substrates were categorized as the intermediate or reabsorption types (9%–38%). This work provides a clue to the renal elimination mechanism of new chemical entities during drug development.     

Towards Prediction of In Vivo Intestinal Absorption Using a 96-Well Caco-2 Assay

We systematically validated a robust 96-well Caco-2 assay via an extended set of 93 marketed drugs with diverse transport mechanisms and quantified by LC/MS/MS, to investigate its predictive utility while dealing with challenging discovery compounds. Utilizing nonlinear fit, the validation led to a good correlation (R² = 0.76) between absorptive permeability, log-P_app(A–B), from in vitro Caco-2 assay and reported human fraction of dose absorbed. We observed that paracellular compounds could be flagged by log P_app(A–B) (<?5.5 cm/s) and physicochemical property space (c log P < 1). Of 8000 Novartis discovery compounds examined 13% were subject to low recovery (< 30%). Compound loss was investigated by comparing cell monolayer and artificial membrane, while 0.5% bovine serum albumin (in both donor and acceptor compartments) was utilized to improve recovery. The second focus of this study was to investigate the advantages and limitations of the current Caco-2 assay for predicting in vivo intestinal absorption. Caco-2 measurements for compounds with high aqueous solubility and low in vitro metabolic clearance were compared to 88 in vivo rat bioavailability studies. Despite the challenges posed by discovery compounds with suboptimal physicochemical properties, Caco-2 data successfully projected low intestinal absorption. This platform sets the stage for mechanistically evaluating compounds towards improving in vitro–in vivo correlations.     

The contribution of physicochemical properties to multiple in vitro cytotoxicity endpoints

Attrition due to safety reasons remains a serious problem for the pharmaceutical industry. This has prompted efforts to develop early predictive in vitro screens that can assist in selecting compounds with a more desirable safety profile early on in the drug discovery process. Here we examined the relationship between physicochemical properties, such as partition coefficient (clogP), topological polar surface area (TPSA), acid dissociation constant (pK_a), and in vitro mechanistic endpoints generated using a high content imaging approach. We demonstrate in our initial analysis that compounds with clogP > 2 and pK_a > 5.5 flagged more endpoints than compounds with clogP ? 2 and pK_a ? 5.5. In contrast, TPSA did not stand on its own in predicting cytotoxicity. When this knowledge was applied to eight different mechanistic cytotoxicity endpoints (cell loss, apoptosis, ER stress, DNA fragmentation, mitochondrial potential, nuclear size, neutral lipids/steatosis and lysosomal mass), we found that compounds with such properties preferentially flagged in the lysosomal endpoint. We also saw a slight enrichment of such compounds in the endpoints cell loss, DNA fragmentation and nuclear size. We demonstrate that lysosomal compound accumulation is a potential contributor to cell death and possibly organ toxicity.     

Biorelevant media for transport experiments in the Caco-2 model to evaluate drug absorption in the fasted and the fed state and their usefulness

In this work we developed and characterized transport media that simulate the composition of micellar phase of intestinal fluids in the fasted and, especially, in the fed state and are appropriate for evaluating intestinal drug permeability characteristics using the Caco-2 model (FaSSIF-TM_Caco and FeSSIF-TM_Caco, respectively). Media composition was based on FaSSIF-V2 and FeSSIF-V2 and recently reported data on total lipid concentrations in the micellar phase of contents of the upper small intestine in the fasted and the fed state and was adapted for cell culture compatibility. Permeation data were evaluated by compartmental kinetic modeling. Permeability coefficients, P, of hydrophilic drugs were not affected by media composition. In contrast, P values of a series of lipophilic compounds measured with FaSSIF-TM_Caco and FeSSIF-TM_Caco, and reflecting transport by diffusion were smaller than those obtained with a purely aqueous reference transport medium, aq-TM_Caco, following the rank order aq-TM_Caco > FaSSIF-TM_Caco > FeSSIF-TM_Caco. The decline of permeability values was stronger as lipophilicity of the compounds increased. Compared with values estimated using aq-TM_Caco, permeability was reduced, depending on the compound, by more than 20- to 100-fold when measured with FeSSIF-TM_Caco whereas compound ranking in regard to the permeability characteristics was also affected. The impact of reduced P value on flux through the mucosa, hence on drug absorption, in combination with the drug amount loaded on colloidal particles needs to be taken into consideration in PBPK modeling especially when the food effect is evaluated.     

The Solubility–Permeability Interplay in Using Cyclodextrins as Pharmaceutical Solubilizers: Mechanistic Modeling and Application to Progesterone

A quasi-equilibrium mass transport analysis has been developed to quantitatively explain the solubility-permeability interplay that exists when using cyclodextrins as pharmaceutical solubilizers. The model considers the effects of cyclodextrins on the membrane permeability (P_m) as well as the unstirred water layer (UWL) permeability (P_aq), to predict the overall effective permeability (P_eff) dependence on cyclodextrin concentration (C_CD). The analysis reveals that: (1) UWL permeability markedly increases with increasing C_CD since the effective UWL thickness quickly decreases with increasing C_CD; (2) membrane permeability decreases with increasing C_CD, as a result of the decrease in the free fraction of drug; and (3) since P_aq increases and P_m decreases with increasing C_CD, the UWL is effectively eliminated and the overall P_eff tends toward membrane control, that is, P_eff ≈ P_m above a critical C_CD. Application of this transport model enabled excellent quantitative prediction of progesterone P_eff as a function of HPβCD concentrations in PAMPA assay, Caco-2 transepithelial studies, and in situ rat jejunal-perfusion model. This work demonstrates that when using cyclodextrins as pharmaceutical solubilizers, a trade-off exists between solubility increase and permeability decrease that must not be overlooked; the transport model presented here can aid in striking the appropriate solubility-permeability balance in order to achieve optimal overall absorption.     

Determination of lamivudine and zidovudine permeability using a different ex vivo method in Franz cells

IntroductionThe major processes that control the absorption of orally administered drugs are dissolution and gastrointestinal permeation. These processes depend on two main properties: solubility and permeability. Based on these characteristics, the Biopharmaceutical Classification System (BCS) was proposed as a tool to assist in biowaiver and bioavailability prediction of drugs.MethodsThe purpose of the present study was to evaluate the permeability of lamivudine (3TC) and zidovudine (AZT) using a different ex vivo method in Franz cells. A segment of jejunum was inserted in a Franz cells apparatus, in order to assess drug permeability in the apical–basolateral (A–B) and basolateral–apical (B–A) directions. Each drug was added to the donor chamber, collected from the acceptor chamber and analyzed by HPLC. Fluorescein (FLU) and metoprolol (METO) were used as low and high permeability markers, respectively.ResultsThe apparent permeability (P_app) results for the A–B direction were: P_{app FLU A–B} = 0.54 × 10^? 4 cm·s^? 1, P_{app METO A–B} = 7.99 × 10^? 4 cm·s^? 1, P_{app 3TC A–B} = 4.58 × 10^? 4 cm·s^? 1 and P_{app AZT A–B} = 5.34 × 10^? 4 cm·s^? 1. For the B–A direction, the P_app results were: P_{app FLU B–A} = 0.56 × 10^? 4 cm·s^? 1, P_{app METO B–A} = 0.25 × 10^? 4 cm·s^? 1, P_{app 3TC B–A} = 0.24 × 10^? 4 cm·s^? 1 and P_{app AZT B–A} = 0.19 × 10^? 4 cm·s^? 1.DiscussionFor the A–B direction, the P_app results of fluorescein and metoprolol show low and high permeability, respectively, indicating that the membranes were appropriate for permeability studies. For the A–B direction, the P_app results of 3TC and AZT suggest that these antiretroviral drugs have permeability values close to metoprolol. Nevertheless, for the B–A direction the P_app results do not suggest efflux mechanism for any of the drugs. Thereby, the different ex vivo methods using Franz cells can be successfully applied in drug permeability studies, in particular for drug biopharmaceutical classification.     

Evaluation of the in vitro activities of ceftobiprole and comparators in staphylococcal colony or microtitre plate biofilm assays

The aim of this study was to evaluate the in vitro efficacy of ceftobiprole and comparator antibiotics, either alone or in combination, in staphylococcal MBEC™ (minimum biofilm eradication concentration) and colony biofilm assays at dilutions of the maximum free-drug plasma concentration attained during clinical use (fC_max). Staphylococci tested included meticillin-susceptible and meticillin-resistant Staphylococcus aureus (n = 6) and Staphylococcus epidermidis (n = 2). Relative to no-drug controls, after 7 days of exposure ceftobiprole concentrations from 1/4 fC_max to fC_max generally decreased CFUs in MBEC or colony biofilms of S. aureus isolates by ca. 1.5 log₁₀ to ≥2.5 log₁₀. Gentamicin reduced colony biofilm CFUs by ≥1.4 log₁₀ at these concentrations with gentamicin-susceptible isolates. Following 7 days of exposure, vancomycin and rifampicin were ineffective as single agents or in combination in the colony model, but yielded CFU decreases from 0 to 5 log₁₀ in the MBEC model. Treatment of biofilms with rifampicin for 7 days yielded rifampicin-resistant mutants, and the selection of rifampicin resistance was inhibited by co-treatment with ceftobiprole. Thus, ceftobiprole alone or in combination demonstrated promising activity against biofilms of meticillin-susceptible and -resistant staphylococci at clinically relevant concentrations. In contrast, vancomycin and rifampicin, two agents used clinically for the treatment of biofilm infections, tested separately or together gave inconsistent results and generally had little impact on cell viability.     

Lisinopril Dihydrate: Single-Crystal X-Ray Structure and Physicochemical Characterization of Derived Solid Forms

Screening for new solid forms of the antihypertensive lisinopril was performed by recrystallization of the commercial form, lisinopril dihydrate, from various solvents and by exposing the product of its dehydration to a series of vapors under controlled conditions. Modifications other than the dihydrate encountered in the study included new anhydrous and amorphous forms, with intrinsic dissolution rates significantly greater than that of the dihydrate. Further physicochemical characterization included constant and programmed temperature powder X-ray diffraction, differential scanning calorimetry, thermogravimetry, and Fourier transform infrared spectroscopy. In the course of this study, the single-crystal X-ray structure of lisinopril dihydrate, [a = 14.550(2), b = 5.8917(8), c = 14.238(2) Å, β = 112.832(3)° at T = 173(2) K , space group P2₁, Z = 2], was determined for the first time, revealing its double zwitterionic character in the solid state.     

HD-03/ES: A promising herbal drug for HBV antiviral therapy

IntroductionThe present study was designed to study the genotypes associated with different groups of chronic liver disease and to see their response to HD-03/ES (an antiviral herbal molecule) on chronic HBV patients.MethodsA total of 51 patients of chronic liver disease were recruited in the study and were given HD-03/ES, two capsules twice daily for 6 months. Liver function tests were done every month after initiating treatment. Serum was analyzed for HBsAg, HBeAg and HBV DNA and quantitative estimation of HBV at baseline, 4 and 6 months after therapy. The genotype of all the cases was also determined by PCR-RFLP method.ResultsAfter 6 months of therapy with HD-03/ES, a significant reduction of ALT values from 71.2 ± 16.3 to 36.4 ± 6.8 and a significant HBeAg loss (27.4%) and HBV DNA loss (27.4%) was observed. Adverse effects were mild. Genotype D was found in 39 (76.5%) while genotype A was found in 12 (33.5%) cases, respectively. The mean reduction in viral load was observed from log₁₀ 7.1 ± 1.8 copies/ml to log₁₀ 4.4 ± 1.1 copies/ml. However, a sharp decline in viral load was observed in patients infected with genotype A (log₁₀ 6.8 ± 2.5 to log₁₀ 4.9 ± 1.8; P < 0.01) compared to genotype D (log₁₀ 7.0 ± 2.6 to log₁₀ 5.9 ± 3.5; P = 0.074).ConclusionThe study had shown that majority of the patients of chronic HBV related liver disease had genotype D. In additional, the molecule HD03/ES had a better therapeutic capability of lowering the HBV viral load in patients with genotype A, which needs to be validated in larger studies.     

The effects of sulfur mustard exposure and freezing on transdermal penetration of tritiated water through ex vivo pig skin

The percutaneous absorption of tritiated water (³H₂O) through sulfur mustard (SM) exposed abdominal pig skin was measured using in vitro Franz-type static diffusion cells. The barrier function to water permeation following exposure to liquid SM for 8 min and excision 3 h later did not change significantly. A small, but statistically significant difference (P < 0.05) in steady state penetration (Jss), permeability coefficient (Kp) and lag time (t_L) of ³H₂O was observed between fresh skin and skin stored frozen (?20 °C) for up to two weeks. Steady-state penetration and Kp values were significantly higher (P < 0.05) in skin stored frozen compared with fresh skin. Fresh naïve skin had an average Kp of 1.65 × 10^?3 cm h^?1, whereas frozen naïve skin was 2.04 × 10^?3 cm h^?1. Fresh SM exposed skin had a mean Kp of 1.72 × 10^?3 cm h^?1, whereas frozen SM exposed skin was 2.31 × 10^?3 cm h^?1. Lag times were also shorter (P < 0.05) in skin that had been stored frozen. Frozen, SM-exposed porcine abdominal skin may be used for in vitro penetration studies, but effects of treatment and storage on the barrier layer should be taken into account.     

Sodium caprate-induced increases in intestinal permeability and epithelial damage are prevented by misoprostol

Epithelial damage caused by intestinal permeation enhancers is a source of debate concerning safety. The medium chain fatty acid, sodium caprate (C₁₀), causes reversible membrane perturbation at high dose levels required for efficacy in vivo, so the aim was to model it in vitro. Exposure of Caco-2 monolayers to 8.5 mM C₁₀ for 60 min followed by incubation in fresh buffer led to (i) recovery in epithelial permeability (i.e. transepithelial electrical resistance (TEER) and apparent permeability coefficient (P_app) of [¹⁴C]-mannitol), (ii) recovery of cell viability parameters (monolayer morphology, plasma membrane potential, mitochondrial membrane potential, and intracellular calcium) and (iii) reduction in mRNA expression associated with inflammation (IL-8). Pre-incubation of monolayers with a mucosal prostaglandin cytoprotectant was attempted in order to further decipher the mechanism of C₁₀. Misoprostol (100 nM), inhibited C₁₀-induced changes in monolayer parameters, an effect that was partially attenuated by the EP₁ receptor antagonist, SC51322. In rat isolated intestinal tissue mucosae and in situ loop instillations, C₁₀-induced respective increases in the [¹⁴C]-mannitol P_app and the AUC of FITC-dextran 4000 (FD-4) were similarly inhibited by misoprostol, with accompanying morphological damage spared. These data support a temporary membrane perturbation effect of C₁₀, which is linked to its capacity to mainly increase paracellular flux, but which can be prevented by pre-exposure to misoprostol.     

Modulation of trichloroethylene in vitro metabolism by different drugs in rats

Trichloroethylene (TCE) is a widely used chemical to which humans are frequently exposed. Toxicological interactions with drugs are among factors having the potential to modulate the toxicity of TCE. The aim of this study was to identify metabolic interactions between TCE and 14 widely used drugs in rat suspended hepatocytes and characterize the strongest using microsomal assays (oxidation and/or glucuronidation). The concentrations of TCE and its metabolites, trichloroethanol (TCOH) and trichloroacetate (TCA), were measured by gas chromatography with injection headspace coupled to mass spectrometry (GC–MS). Results in hepatocyte incubations show that selected drugs can be segregated into four groups: group 1: drugs causing no significant interactions (five drugs: amoxicillin, carbamazepine, ibuprofen, mefenamic acid and ranitidine); group 2: increasing both TCE metabolites (two drugs: naproxen and salicylic acid); group 3: decreasing both TCE metabolites (five drugs: acetaminophen, gliclazide, valproic acid, cimetidine and diclofenac) and group 4: affecting only one (two drugs: erythromycin and sulphasalazine). Naproxen and salicylic acid (group 2) and acetaminophen, gliclazide and valproic acid (from group 3) presented the strongest interactions (i.e. drugs changing metabolite levels by 50% or more). For group 2 drugs, characterization in rat microsomes confirmed interaction with naproxen only, which was found to partially competitively inhibit TCOH glucuronidation (K_i = 211.6 μM). For group 3 selected drugs, confirmation was positive only for gliclazide (K_i = 58 μM for TCOH formation) and valproic acid (K_i = 1215.8 μM for TCA formation and K_i = 932.8 μM for TCOH formation). The inhibition was found to be partial non competitive for both drugs. Our results confirm the existence of interactions between TCE and a variety of widely used drugs. Further efforts are undertaken to determine if these interactions are plausible in humans and if they can impact the risk of toxicity of TCE in medicated population.     

Calculation of Molecular Lipophilicity: State-of-the-Art and Comparison of Log P Methods on more than 96,000 Compounds

We first review the state-of-the-art in development of log P prediction approaches falling in two major categories: substructure-based and property-based methods. Then, we compare the predictive power of representative methods for one public (N = 266) and two in house datasets from Nycomed (N = 882) and Pfizer (N = 95809). A total of 30 and 18 methods were tested for public and industrial datasets, respectively. Accuracy of models declined with the number of nonhydrogen atoms. The Arithmetic Average Model (AAM), which predicts the same value (the arithmetic mean) for all compounds, was used as a baseline model for comparison. Methods with Root Mean Squared Error (RMSE) greater than RMSE produced by the AAM were considered as unacceptable. The majority of analyzed methods produced reasonable results for the public dataset but only seven methods were successful on the both in house datasets. We proposed a simple equation based on the number of carbon atoms, NC, and the number of hetero atoms, NHET: log P = 1.46(±0.02) + 0.11(±0.001) NC?0.11(±0.001) NHET. This equation outperformed a large number of programs benchmarked in this study. Factors influencing the accuracy of log P predictions were elucidated and discussed.     

Darunavir/ritonavir and raltegravir coadministered in routine clinical practice: Potential role for an unexpected drug interaction

The present study aimed to investigate potential drug interactions between darunavir and raltegravir in patients treated for HIV infection. We enrolled HIV-infected subjects on darunavir-containing regimens that underwent measurement of plasma darunavir trough concentration (12 ± 3 h after dosing). Two groups of patients were compared: those taking darunavir plus a nucleoside/nucleotide backbone (group 1) or a backbone + raltegravir (group 2). Interindividual pharmacokinetic variability was evaluated through the coefficient of variation (CV_inter).We obtained 156 plasma samples from 63 patients, of which 44 in group 1 and 19 in group 2. Overall, darunavir geometric mean concentration was 2.90 mg/L (95% CI 2.34–3.60) while ritonavir geometric mean concentration was 0.21 mg/L (95% CI 0.17–0.27). We observed a high inter-individual variability in darunavir (CV_inter 59%) and ritonavir (CV_inter 103%) plasma levels. Darunavir concentration correlated with concomitant ritonavir levels (r = 0.476, p < 0.001). Patients in group 1 had a higher darunavir geometric mean concentration than those in group 2 [3.44 mg/L (95% CI 2.79–4.23) versus 1.95 mg/L (95% CI 1.19–3.20), p = 0.017]. However, the proportion of subjects with concomitant HIV-RNA <50 copies/mL was higher in group 2 (78.9% versus 47.7%, p = 0.028). In a multivariable model, raltegravir co-administration was independently related to a lower darunavir concentration (mean difference ?0.25 log₁₀ mg/L, 95% CI ?0.46/?0.04, p = 0.020) after adjusting for time from last drug intake and concomitant drugs used.In conclusion, a potential drug interaction between darunavir and raltegravir was observed, although this did not seem virologically significant. For the distinct metabolic pathways of these drugs, its mechanism remains to be determined.     

Pig and guinea pig skin as surrogates for human in vitro penetration studies: A quantitative review

Both human and animal skin in vitro models are used to predict percutaneous penetration in humans. The objective of this review is a quantitative comparison of permeability and lag time measurements between human and animal skin, including an evaluation of the intra and inter species variability. We limit our focus to domestic pig and rodent guinea pig skin as surrogates for human skin, and consider only studies in which both animal and human penetration of a given chemical were measured jointly in the same lab. When the in vitro permeability of pig and human skin were compared, the Pearson product moment correlation coefficient (r) was 0.88 (P < 0.0001), with an intra species average coefficient of variation of skin permeability of 21% for pig and 35% for human, and an inter species average coefficient of variation of 37% for the set of studied compounds (n = 41). The lag times of pig skin and human skin did not correlate (r = 0.35, P = 0.26). When the in vitro permeability of guinea pig and human skin were compared, r = 0.96 (P < 0.0001), with an average intra species coefficient of variation of 19% for guinea pig and 24% for human, and an inter species coefficient of variation of permeability of 41% for the set of studied compounds (n = 15). Lag times of guinea pig and human skin correlated (r = 0.90, P < 0.0001, n = 12). When permeability data was not reported a factor of difference (FOD) of animal to human skin was calculated for pig skin (n = 50) and guinea pig skin (n = 25). For pig skin, 80% of measurements fell within the range 0.3 < FOD < 3. For guinea pig skin, 65% fell within that range. Both pig and guinea pig are good models for human skin permeability and have less variability than the human skin model. The skin model of choice will depend on the final purpose of the study and the compound under investigation.     

Physiological,haematological and histopathological responses in common carp (Cyprinus carpio L.) fingerlings fed with differently detoxified Jatropha curcas kernel meal

Protein rich Jatropha curcas kernel meal is toxic. It was detoxified using heat treatment and solvent extraction. Two duration of detoxification process were investigated: shorter (30 min) and longer (60 min) and the detoxified meals so obtained were designated as J_a and J_b respectively. Common carp fingerlings (252 fish; 3.2 ± 0.07 g) were fed with the following diets: Control containing fishmeal (FM); S_50, J_a50 and J_b50: 50% of FM protein replaced by soybean meal (SBM), detoxified Jatropha kernel meal (DJ_aKM and DJ_bKM); S₇₅, J_a75 and J_b75: 75% of FM protein replaced by SBM, DJ_aKM and DJ_bKM. White blood cells count, mean cell volume and mean cell haemoglobin concentration, calcium and sodium ions and total bilirubin in blood did not differ significantly among the groups. Higher (P > 0.05) RBC count was observed in plant protein fed groups compared to control group. Highest alkaline phosphatase and alanine transaminase activities in blood were observed in J_a75, which were not different (P > 0.05) from those in J_a50 group, but were higher than in the other groups. No adverse histopathological changes in liver and muscle of any group were observed, but intestinal mucosa of J_a75 groups showed severe pathological lesions. The results demonstrate that Jb was completely detoxified. Since the performance of J_b50 group was similar to control group and better than the other groups, optimum inclusion level of J_b is 50% replacement of FM protein.