ITPA Activity in Adults and Children Treated With or Without Azathioprine: Relationship Between TPMT Activity, Thiopurine Metabolites, and Co-medications.

BACKGROUND: The implication of inosine triphosphate pyrophosphatase (ITPA) on thiopurine drug response variability has been investigated but little data are available on its role on thiopurine metabolites. The ability of ITPA to modify the thiopurine metabolite levels is currently used to optimize azathioprine (AZA) therapy in relation to thiopurine S-methyltransferase (TPMT) activity, the aim of this study is to investigate ITPA phenotype in a large population and to evaluate the relation between ITPA and TPMT activities and thiopurine metabolites. METHODS: ITPA activity was determined in 183 adults and 138 children with or without AZA therapy. 6-thioguanine nucleotides (6-TGN), 6-methylmercaptopurine nucleotides (6-MeMPN) levels, and ITPA as well as TPMT activities were measured in red blood cells. Using the Gaussian mixture model, distribution of ITPA activity was evaluated. Intraindividual variability and influence of age, sex, AZA treatment and associated co-medications on ITPA activity were also assessed. RESULTS: This retrospective study shows a quadrimodal distribution in ITPA activity. No influence of age, sex, AZA therapy, and co-medications was found. In adults, ITPA activity was not significantly associated with 6-TGN or 6-MeMPN concentrations, whereas a weak negative correlation was observed with 6-MeMPN levels in pediatric populations (rs = -0.261; P = 0.024). A weak positive correlation was observed between ITPA and TPMT activities in children (rs = 0.289; P = 0.001). CONCLUSIONS: ITPA activity was poorly influenced by nongenetic parameters and has no influence on 6-TGN and 6-MeMPN concentrations in adults and only a weak correlation with 6-MeMPN and TPMT activity in children. These results demonstrate that ITPA is not a rate-limiting enzyme in the formation of 6-TGN but suggest that a decrease in ITPA activity in children may be a risk factor for accumulation of 6-MeMPN in cells.

Relationship between azathioprine dosage and thiopurine metabolites in pediatric IBD patients: identification of covariables using multilevel analysis.

BACKGROUND: Previous studies have reported no or only a very poor correlation between 6-methylmercaptopurine/6-thioguanine nucleotide (6-MeMPN/6-TGN) and azathioprine (AZA) dose in the treatment of inflammatory bowel disease (IBD). However, metabolite levels are often repeatedly measured yielding a hierarchical data structure that requires more appropriate data analysis. METHODS: This study explored the relationship between the weight-based dosage of AZA and metabolites levels in 86 pediatric IBD patients using multilevel analysis. Other covariates related to patient characteristics and treatment were evaluated. RESULTS: This is the first study to demonstrate positive correlations between AZA dose and 6-TGN and 6-MeMPN levels and 6-MeMPN/6-TGN ratio (P < 0.001) in IBD children. Other novel predictors of metabolites were reported. Younger children exhibited lower 6-TGN and 6-MeMPN levels, probably suggesting age-related differences in metabolism and/or absorption of thiopurines. Coadministration of infliximab resulted in a significant increase in 6-TGN levels (P = 0.023). Moreover, alanine aminotransferase values positively correlated with 6-MeMPN levels (P = 0.032). The duration of AZA therapy, gender, and thiopurine methyltransferase activity were associated with metabolite levels. The wide interindividual variability in metabolite levels that accounted for 67.7%, 48.6%, and 49.4% of variance in the 6-TGN and 6-MeMPN levels and the ratio, respectively, were confirmed. CONCLUSIONS: The reliable AZA dose-metabolites relationship is useful for clinicians to guide the dosing regimen to maximize clinical response and minimize side effects or to consider alternative therapies when patients have preferential production of the toxic 6-MeMPN. These results may be of potential interest for optimizing thiopurine therapy to achieve safe and efficacious AZA use in pediatric IBD patients.

[Cooperation between general practitioners and pharmacists: a systematic review]. / Coopération entre médecins généralistes et pharmaciens : une revue systématique de la littérature.

INTRODUCTION: Despite the emphasis on interprofessional cooperation between general practitioners and pharmacists, the effectiveness of interventions in this area is poorly understood. The purpose of this study was to assess the effectiveness of interventions based on cooperation between general practitioners and pharmacists. METHODS: A systematic literature review was conducted using MEDLINE, the Cochrane Database and the PASCAL database. Keywords and/or search terms ("family physician(s)" or "general practitioner(s)" and "pharmacist(s)") were cross-referenced. We included the results of all randomized clinical trials published in English or French and assessed the effectiveness of pharmacist interventions designed to complement the work of general practitioners. RESULTS: In total, 22 articles were included. Sixteen trials showed that pharmacist interventions in the management of chronic health conditions and drug therapy management benefit patients. The evidence suggests that pharmacist interventions have a positive impact on the management of arterial hypertension and hypercholesterolemia and the management of drug-related problems. The criteria used for the trials were generally procedural or surrogate criteria and never included cost-effectiveness analyses. DISCUSSION: Cooperation between pharmacists and general practitioners can contribute to improving the quality of primary care, especially in the areas of cardiometabolic and prescription problems.

Determination of inosine triphosphate pyrophosphatase phenotype in human red blood cells using HPLC.

BACKGROUND: Thiopurine drugs, widely used in cancer chemotherapy, inflammatory bowel disease, and autoimmune hepatitis, are responsible for common adverse events. Only some of these may be explained by genetic polymorphism of thiopurine S-methyltransferase. Recent articles have reported that inosine triphosphate pyrophosphatase (ITPase) deficiency was associated with adverse drug reactions toward thiopurine drug therapy. Here, we report a weak anion exchange high-performance liquid chromatography method to determine ITPase activity in red blood cells and to investigate the relationship with the occurrence of adverse events during azathioprine therapy. METHODS: ITPase activity was assessed by the enzymatic conversion of inosine triphosphate (ITP) to inosine monophosphate (IMP). The reaction was stopped by heating for 3 minutes at 120°C. IMP, inosine diphosphate, and ITP were analyzed on a Hypersil APS-2 column, a weak anion exchange phase that exhibits both ionic and hydrophobic properties. RESULTS: The chromatographic method reported allows the analysis of IMP, inosine diphosphate, and ITP in a single run in <12.5 minutes. The method was linear in the range 5-1500 µmole/L of IMP. Intraassay and interassay precisions were <5% for red blood cell lysates supplemented with 50, 500, and 1000 µmole/L IMP. Km and Vmax evaluated by Lineweaver-Burk plot were 677.4 µmole/L and 19.6 µmole·L·min, respectively. The frequency distribution of ITPase from 73 patients was investigated. CONCLUSIONS: The method described is useful to determine the ITPase phenotype from patients on thiopurine therapy and to investigate the potential relation between ITPase deficiency and the occurrence of adverse events.

Monitoring of azathioprine metabolites in pediatric patients with autoimmune hepatitis.

Azathioprine is commonly used in the treatment of autoimmune hepatitis (AIH). Few data are available on drug monitoring of azathioprine metabolites in patients with AIH, especially in pediatric patients. The purpose of this study was to investigate intracellular thiopurine metabolites in children with AIH and to assess the relevance of drug monitoring compared with the efficacy and toxicity. Data from 28 patients with AIH treated by azathioprine for at least 3 months were recorded. 6-Thioguanine nucleotides (6-TGN) and 6-methyl mercaptopurine nucleotides (6-MeMPN) concentrations and TPMT activity were determined by high-performance liquid chromatography. Blood cell counts and liver function tests were also collected and the clinical outcome was documented. A wide interindividual variability in 6-TGN and 6-MeMPN concentrations was observed with values ranging from 51 to 1966 pmol/8 x 10(8) red blood cells (RBCs) for 6-TGN and from 42 to 8189 pmol/8 x 10(8) RBCs for 6-MeMPN. A total of 61.4% of the patients achieved remission and only 32.6% of these children had 6-TGN values within the target range proposed for inflammatory bowel disease (250-450 pmol/8 x 10(8) red blood cells). No difference in metabolite concentrations was observed between children in remission and those with active disease. Azathioprine dosage was significantly related to 6-TGN and 6-MeMPN levels (r = 0.308, P < 0.001 and r = 0.405, P < 0.001, respectively). A significant negative correlation was observed between 6-TGN concentrations and erythrocyte and lymphocyte counts, whereas 6-MeMPN was not related to blood cell counts. Although leukocyte counts were not related to 6-TGN concentrations, patients with leucopenia exhibited higher 6-TGN values than those without leucopenia (median values 438 pmol/8 x 10(8) RBCs versus 405 pmol/8 x 10(8) RBCs, respectively). Thiopurine metabolite monitoring appears useful in identifying the myelotoxicity and the hepatotoxicity as a result of azathioprine with disease recurrence and to assess adherence to therapy. A further larger study will be required to confirm the optimal recommended target for thiopurine metabolites to achieve remission in patients with AIH.

[Therapeutic drug monitoring of 6-thioguanine nucleotides in inflammatory bowel disease: interest and limits]. / Suivi thérapeutique pharmacologique des 6-thioguanine nucléotides dans les maladies inflammatoires cryptogéniques de l'intestin: intérêt et limites.

Azathioprine, 6-mercaptopurine, and 6-thioguanine are immunosuppressive drugs indicated in the prevention of graft rejection, and treatment of auto-immune disease or inflammatory bowel disease. Their anti-nucleotidic properties are also used for the treatment of acute leukaemia. Their metabolism involves thiopurine methyl transferase, which activity varies according to genetic polymorphisms. In inflammatory bowel disease patients, there is no recommended therapeutic range of intra-erythrocyte 6-thioguanine nucleotide concentration, the active metabolite. Therapeutic drug monitoring of 6-thioguanine nucleotide concentrations is however proposed in the following clinical situations: to check the observance, to try to explain therapeutic failure, to manage patients with limited thiopurine methyl transferase activity or patients treated with associated drugs that can modify thiopurine methyl transferase activity. The literature review shows that high concentrations of 6-thioguanine nucleotides and methylated metabolites are associated with an increased risk of bone marrow toxicity. In addition, high concentrations of methylated metabolite might increase the risk of hepatic toxicity. These major side-effects can be prevented by the use of pre-treatment screening for thiopurine methyl transferase activity or genotype in inflammatory bowel disease patients in order to propose an adapted dosing.

[Not Available]. / Suivi thérapeutique pharmacologique des 6-thioguanine nucléotides dans les maladies inflammatoires cryptogéniques de l'intestin : intérêt et limites.

Azathioprine, 6-mercaptopurine, and 6-thioguanine are immunosuppressive drugs indicated in the prevention of graft rejection, and treatment of auto-immune disease or inflammatory bowel disease. Their anti-nucleotidic properties are also used for the treatment of acute leukaemia. Their metabolism involves thiopurine methyl transferase, which activity varies according to genetic polymorphisms. In inflammatory bowel disease patients, there is no recommended therapeutic range of intra-erythrocyte 6-thioguanine nucleotide concentration, the active metabolite. Therapeutic drug monitoring of 6-thioguanine nucleotide concentrations is however proposed in the following clinical situations: to check the observance, to try to explain therapeutic failure, to manage patients with limited thiopurine methyl transferase activity or patients treated with associated drugs that can modify thiopurine methyl transferase activity. The literature review shows that high concentrations of 6-thioguanine nucleotides and methylated metabolites are associated with an increased risk of bone marrow toxicity. In addition, high concentrations of methylated metabolite might increase the risk of hepatic toxicity. These major side-effects can be prevented by the use of pre-treatment screening for thiopurine methyl transferase activity or genotype in inflammatory bowel disease patients in order to propose an adapted dosing.

Advanced Characterization of Imiquimod-Induced Psoriasis-Like Mouse Model.

Many autoimmune disorders such as psoriasis lead to the alteration of skin components which generally manifests as unwanted topical symptoms. One of the most widely approved psoriasis-like animal models is the imiquimod (IMQ)-induced mouse model. This representation mimics various aspects of the complex cutaneous pathology and could be appropriate for testing topical treatment options. We perform a thorough characterization of this model by assessing some parameters that are not fully described in the literature, namely a precise description of skin disruption. It was evaluated by transepidermal water loss measurements and analyses of epidermis swelling as a consequence of keratinocyte hyperproliferation. The extent of neo-angiogenesis and hypervascularity in dermis were highlighted by immunostaining. Moreover, we investigated systemic inflammation through cytokines levels, spleen swelling and germinal centers appearance in draining lymph nodes. The severity of all parameters was correlated to IMQ concentration in skin samples. This study outlines new parameters of interest useful to assess this model. We highlight the skin barrier disruption and report a systemic inflammatory reaction occurring at distance both in spleen and lymph nodes. These newly identified biological endpoints could be exploited to investigate the efficacy of therapeutic candidates for psoriasis and more extensively for several other skin inflammatory diseases.

Age-related variability of mycophenolate mofetil exposure in stable pediatric liver transplant recipients and influences of donor characteristics.

Despite the increasing use of mycophenolate mofetil (MMF) in pediatric liver transplantation recipients, data on MMF pharmacokinetics in this population are relatively scattered. This pilot study was performed to explore whether recipient age-related factors, in conjunction with donor factors, can explain variability in mycophenolic acid (MPA) exposure. Thirty-four MPA pharmacokinetic profiles were performed in 20 stable pediatric liver transplantation recipients (median age, 12 years; range, 1-18 years; median delay after liver transplant, 88 months; range, 3-179 months). Ten children were converted to MMF; the others received MMF as a primary immunosuppressive regimen. MMF was used in combination with tacrolimus. Plasma MPA concentrations were analyzed samples collected at 0, 1, 3, and 6 hours after MMF administration using the enzyme multiplied immunotechnique immunoassay. The median MMF dose was 431 mg/m2 per day (range, 189-833 mg/m2 per day) leading to a median estimated MPA-AUC0-12h of 27 mg/h/L (range, 17-79 mg/h/L). Dose-normalized MPA-AUCs were characterized by high interpatient variability. Young children receiving a liver from a pediatric donor had lower MPA exposure compared with those receiving liver from an adult donor. No correlation was seen between MPA-C0 and MPA-AUC 0-6h in infants, whereas this correlation was significant but moderate in older children. The interpatient variability of MPA exposure observed with this pilot study is an argument for developing therapeutic drug monitoring-based dose adaptation strategies in pediatric liver transplantation recipients. A marked MPA underexposure was observed among young children receiving livers from pediatric donors, indicating that higher doses (mg/m2 of body surface area) might be required to reach the same MPA exposure as in adolescents.

A comparative evaluation of the publications of French public teaching hospitals from 2004 to 2014.

Care, teaching, and research are all priorities of the French public teaching hospitals. In 2004, the remuneration method evolved from a global endowment to a fee-for-services system, based on the use of bibliometric tools. These were used in the present study to describe the research patterns of public teaching hospitals in regards to care and teaching activities. The present study was based on data from the 32 French public teaching hospitals, between 2004 and 2014. Records concerning the publications number, hospital stays, full-time equivalent (FTE) practitioners, and residents per FTE physician were accessed. Statistical analyses were performed using means, Pearson correlation coefficients, and regression lines. The mean number of publications per FTE physician was 0.73, the mean number of hospital stays per FTE physician was 235.8 and the mean number of residents per FTE physician was 0.63. There was a moderate positive correlation between the number of publications per FTE physician and the number of residents per FTE physician (R=0.53) and a negligible correlation between the number of residents per FTE physician and the number of hospital stays per FTE physician (R=0.12). There was a low negative correlation between publication numbers per FTE physician and the number of stays per FTE physician (R=-0.41). All public teaching hospitals presented different patterns in terms of care, teaching, and research activities. None of the 32 hospitals performed well in all three activities. Only nine performed well in at least two out of the three missions.

Bibliometrics and French healthcare institutions from 2004 to 2014.

INTRODUCTION: Research activity evaluation in French hospitals is based on the number of publications, author position (first, second, third, second-to-last, last, investigator list, and "Other") and journal category (A being the highest category followed by B, C, D, E, and NC). METHODS: The profile of publications over the 2004-2014 period in terms of these indicators was evaluated. Hospitals were classified into six groups according to administrative status. Time trends were analysed by three models. One-way ANOVA followed by Tukey's test was performed. RESULTS: A total of 192886 publications were analysed. The increase in the number of publications ranged from 628% for for-profit private hospitals to 141% for public teaching hospitals. The most frequent category was B for cancer centres (25%), whereas this was E in public teaching (22%) and non-teaching hospitals (28%), in not-for-profit private hospitals (25%), in the military hospital (30%), and in for-profit private hospitals (24%). The first position was the most frequent for public teaching hospitals (38%) and the military hospital (44%), whereas the "Other" position was the most frequent in cancer centres (26%), in public non-teaching hospitals (28%), in not-for-profit private hospitals (27%), and in for-profit private hospitals (29%). DISCUSSION: Different patterns were identified. The author position indicated that all types of hospital are involved in research projects. This study also found that public non-teaching hospitals, not-for-profit private hospitals, for-profit private hospitals, and cancer centres collaborated with other institutions which were often distinguished by publishing in high-category journals.

Red Blood cell IMPDH activity in adults and children with or without azathioprine: Relationship between thiopurine metabolites, ITPA and TPMT activities.

Inosine monophosphate dehydrogenase (IMPDH) is considered as the limiting enzyme of thiopurine metabolism for the formation of 6-thioguanine nucleotides (6-TGN). No data are available on the influence of RBC IMPDH activity on the metabolism of thiopurine drugs in individuals with IBD. The aims of this study were as follows: (a) to carry out a phenotypic study of RBC IMPDH activity in adults and children treated or not with azathioprine (AZA) for autoimmune diseases, and (b) to investigate the relationship between the activities of IMPDH, thiopurine metabolites, inosine triphosphatase (ITPA) and thiopurine methyltransferase (TPMT). IMPDH activity was determined in 97 adults and 67 children treated or not with AZA. 6-Thioguanine nucleotides (6-TGN), 6-methylmercaptopurine nucleotide (6-MeMPN) levels, and ITPA as well as TPMT activities were measured in RBCs by HPLC. Using the Gaussian mixture model, distribution of IMPDH activity was evaluated. Influence of age, sex and AZA treatment on IMPDH activity was also assessed. A bimodal distribution in IMPDH activity was found with 87% of patients exhibiting normal activity and 13% of patients with high activity. No influence of age, sex and AZA therapy was found. There is no relationship between TPMT, ITPA and IMPDH activities. A negative correlation between IMPDH activity and 6-MeMPN was shown in adults and children (rs = -0.335 P = 0.014 and rs = -0.383 P = 0.012, respectively). Our results suggest that AZA-treated patients exhibiting lower IMPDH activity could have higher Me-6MPN levels with higher risk of hepatotoxicity. We demonstrated that RBC matrix could be an interesting alternative to lymphocyte matrix to monitor thiopurine metabolites and enzyme activity.

ITPA Activity in Children Treated by Azathioprine: Relationship to the Occurrence of Adverse Drug Reactions and Inflammatory Response.

Azathioprine (AZA), a thiopurine drug, is widely used in the treatment of children with immunological diseases such as inflammatory bowel disease (IBD) and autoimmune hepatitis (AIH); however, interindividual variability in the occurrence of adverse drug reactions (ADRs) and drug response is observed. This study investigated (i) the relationships between inosine triphosphate pyrophosphatase (ITPA) activity, an enzyme involved in thiopurine metabolism, and the occurrence of ADRs in children with immunological disease on AZA therapy, and (ii) the relationship between ITPA activity and the inflammatory activity observed in children with IBD. ITPA and TPMT activities were determined in 106 children with immunological disease on AZA therapy. Markers of hepatotoxicity, myelotoxicity, pancreatitis and inflammation as well as clinical information were retrospectively collected during regular medical visits. No significant association was found between ITPA activity and hepatotoxicity or clinical ADRs such as cutaneous reactions, arthralgia, flulike symptoms and gastrointestinal disorders. Concerning myelotoxicity, a significant relation was observed between ITPA activity and RBC mean corpuscular volume (MCV; p=0.003). This observation may be related to the significant relationship found between high ITPA activity and the increase in γ-globulin level reflecting inflammation (p=0.005). In our study, ITPA activity was not associated with occurrence of ADRs, but a relationship between high ITPA activity and γ-globulin, a marker of inflammation, was found in children with IBD. Therefore, measurement of ITPA activity may help to identify children with IBD predisposed to residual inflammation on AZA therapy. Further prospective studies are needed to confirm this result.

Relationship between MPA free fraction and free MPAG concentrations in heart transplant recipients based on simultaneous HPLC quantification of the target compounds in human plasma.

A simple and sensitive HPLC method for the simultaneous analysis of free MPA and free MPAG was developed. Separation was achieved on a X-Terra RP18 column with acetonitrile-40 mM orthophosphoric acid as eluents using a gradient elution mode over 35 min at a flow rate of 1.5 ml/min. The assay was linear in the range 0.005 mg/L (LOQ) to 5mg/L for free MPA and 0.05 mg/L (LOQ) to 200 mg/L for free MPAG. Isolation of free MPA and free MPAG was done by ultrafiltration and the ultrafiltrate was directly injected. A positive correlation between MPA free fractions and free MPAG concentrations was found. Likewise, free MPAG was related to total MPAG concentrations in the seven heart transplant patients.

A rapid and simple HPLC method for the analysis of propofol in biological fluids.

A selective and sensitive high-performance liquid chromatographic method for the analysis of propofol in biological samples was developed. Propofol and thymol (internal standard) were analysed on a Purospher RP-18 endcapped (75 mmx4 mm, 3 microm) stationary phase using acetonitrile and water (65:35, v/v) as eluents at a flow rate of 0.6 mL/min. The excitation and emission wavelengths were 276 and 310 nm, respectively. Sample treatment consisted of deproteinization by acetonitrile containing the internal standard and direct injection of the supernatant. Mean analytical recovery were 105% (CV 2.0%) at concentrations ranging from 0.05 to 10 mg/L. The quantification limit was 3 ng/mL for a 500 microL sample plasma volume and 5 ng/mL for a 500 microL blood sample. The intra-day and inter-day precisions were lower than 5.5% for three concentrations assessed (0.05, 1.0 and 10.0 mg/L). Considering the column size and the flow rate, the separation was achieved with an analysis time less than 6 min with a reduced consumption of solvent. This rapid HPLC method using a simple treatment procedure is sensitive enough for monitoring propofol in human biological samples.

Determination of inosine 5'-monophosphate dehydrogenase activity in red blood cells of thiopurine-treated patients using HPLC.

Thiopurine drugs are commonly used in immune diseases and to a lesser extent, in transplant rejection prophylaxis: however interindividual variability in drug response and in the occurrence of adverse events is observed. Genetic variation in thiopurine S-methyltransferase (TPMT) doesn't completely explain the occurrence of all adverse events and drug response variability. The potential implication of other enzymes involved in thiopurine metabolism, such as ITPA, has been investigated over the last decade but little data is available on inosine 5'-monophosphate dehydrogenase (IMPDH) in patients treated with thiopurine drugs. The authors reported a HPLC method to determine IMPDH activity in the red blood cells (RBCs) of thiopurine-treated patients. IMPDH activity was evaluated by enzymatic conversion of inosine 5'-monophosphate (IMP) to xanthosine 5'-monophosphate (XMP). The XMP formed was analyzed on a Luna® NH2 stationary phase, a weak anion exchange phase that exhibits both ionic and hydrophobic properties. XMP was eluted below 15min. Intra-assay and inter-assay precisions were below 9% for RBCs supplemented with 2, 40 and 80µmol/L of XMP. IMPDH activity was measured in adults without thiopurine treatment as well as in adult and paediatric patients treated with thiopurines. A wide interindividual variability in IMPDH activity in RBCs was observed. No difference in IMPDH activity was found between untreated subjects and adult and paediatric patients on thiopurine therapy (median value 11.8, 7.9 and 7.7nmol XPM/g Hb/h respectively). The method described is useful in the determination of IMPDH phenotype from patients on thiopurine therapy and in the investigation of the potential relationship between IMPDH activity in RBCs and the occurrence of adverse events and drug response variability.

Cyclosporine monitoring in renal transplant recipients with induction therapy: C2 levels in patients monitored on C0.

The aim of this retrospective study was to compare the cyclosporine C(2) blood levels in renal transplant recipients with induction therapy, monitored on C(0) levels during the early and long-term post-transplantation periods in different French transplantation centres, to the target values recommended by the International Consensus on Neoral and used in the Mo2art study. A retrospective study was conducted by the therapeutic drug monitoring (TDM) committee of the French Pharmacological Society. Cyclosporine C(0) and C(2) concentrations from 168 renal transplant recipients were collected at different post-transplantation periods by six TDM laboratories of transplantation centres from April 2001 to April 2002. Cyclosporine blood levels were determined by fluorescence polarization immunoassay (mFPIA, AxSYM, Abbott) or enzyme immunoassay (EMIT, Dade Behring). Most patients had C(0) values in the recommended target ranges, with C(2) levels below the targets used in the Mo2art study or proposed by the International Consensus Conference, both during the early and long-term post-transplantation periods. Sixty-eight per cent of patients had C(2) below 1,500 microg/L +/- 20% in the first 2 months post-transplantation and 55% had C(2) below 800 microg/L +/- 20% in the late post-transplantation period (>1 year). Cyclosporine dose should be increased by 40% on average during the first week post-transplantation period and by 50% during the maintenance period to achieve the C(2) targets. In France, most renal transplant recipients receiving induction agents monitored on C(0) had C(2) levels below the targets recommended by the International Consensus Conference. In clinical practice, the optimal therapeutic windows for CsA monitoring based on C(2) needs to be more precisely defined, both during the early and long-term post-transplantation periods in renal transplant recipients receiving induction agents.

Ex-Vivo percutaneous absorption of enrofloxacin: Comparison of LMOG organogel vs. pentravan cream.

The objective of this study was to investigate the percutaneous absorption of enrofloxacin from two base formulations, Pentravan cream and LMOG organogel. Ex-vivo experiments were carried out on pig ear skin. The percutaneous permeation through pig skin of two formulations containing 5 wt% of enrofloxacin was measured and compared using Franz diffusion cells. At appropriate intervals up to 120 h, diffusion samples were taken and analyzed using HPLC assays. Permeation profiles were established and the parameters Tlag and flux values were calculated. In this ex-vivo study, the flux values were 0.35 µgcm(-2)h(-1) for Pentravan and 1.22 µgcm(-2)h(-1) for LMOG organogel, corresponding respectively to 7.9 % and 29.3 % of enrofloxacin absorbed after 120 h by these formulations. The lag time (T lag) of Pentravan and organogel were 6.32 and 0.015 h respectively. The absorption time to reach the antibiotic concentration of enrofloxacin (2 µgmL(-1)) in the receptor was 60 h with Pentravan and 30 h with the organogel, suggesting more effective treatment by the latter. Enrofloxacin contained in organogel could be absorbed through pig ear skin 3.7 times greater than that in Pentravan (commercial formulation). This study demonstrates the perspective of organogel formulations as potential drug delivery systems.

HPLC determination of mycophenolic acid and mycophenolic acid glucuronide in human plasma with hybrid material.

Mycophenolic acid (MPA), the active metabolite of the prodrug mycophenolate mofetil is an immunosuppressive agent which inhibits inosine monophosphate dehydrogenase. MPA is metabolised to phenolic glucuronide (MPAG) that may be hydrolysed in vivo to form free MPA. Drug monitoring is required in patients with multi-organ failure. Here, we report a HPLC method with organic/inorganic hybrid material for the simultaneous analysis of MPA and MPAG in human plasma. MPA and MPAG and carboxy butoxy ether mycophenolic acid (MPAC) used as internal standard were analysed on a bonded X-Terra column with a linear gradient elution mode using orthophosphoric acid and acetonitrile as eluents. Sample treatment procedure consists of deproteinisation with acetonitrile. Analytical recoveries were higher than 98 and 89% at concentrations ranging from 1 to 25 and 20 to 200mg/L for MPA and MPAG, respectively. Calibration curves fitted by plotting the peak area ratio (compound of interest/internal standard) versus concentration were linear in the range 0.2-50mg/L for MPA and in the range 1-500mg/L for MPAG. The quantification limit was 0.2mg/L for MPA and 1mg/L for MPAG with a coefficient of variation less than 20% for a 500microL sample volume. Intra- and inter-assay coefficient of variation was lower than 7% for all compounds. Detection was performed at 215nm. Peak identity was confirmed through library matching by comparison with reference spectra. The X-Terra column provides good peak shape and may be used at low pH with a long life-time column. This HPLC method using a simple sample treatment procedure appears suitable for therapeutic drug monitoring in organ-transplant patients. The method is sensitive enough for monitoring MPA and MPAG during pharmacokinetic studies.