Manipulation of solid dosage forms for oral administration to paediatric patients for drug-resistant tuberculosis in South Africa: an observation study.

BACKGROUND: Children represent a particularly vulnerable demographic in the context of drug-resistant (DR) tuberculosis (TB) due to their increased likelihood of close contact with adults diagnosed with the disease. Approximately 25 000-30 000 children develop DR-TB annually. While treatment success rates for DR-TB in children surpass those in adults, children and adolescents encounter distinct challenges throughout the diagnosis and treatment of DR-TB (including MDR-TB, Pre-XDR TB, and XDR-TB). AIM: To identify current practices in drug administration to children diagnosed with DR-TB where appropriate dosage forms are not available in South Africa. METHOD: An observational study was carried out at the study site to determine how medication prescribed was manipulated and administered by nursing staff to paediatric patients in the wards. RESULTS: The observational study identified 8 drugs used in DR-TB at the study site, where some manipulation to the formulation was necessary to enable administration to paediatric patients. Linezolid and para-aminosalicylic acid are the only drugs available and registered in the South Africa in a formulation that is suitable for administration to paediatric patients. Activities carried out by nursing staff to enable the administration of DR-TB medication included cutting capsules and tablets and dissolving the tablet or capsule contents in distilled water to obtain the required suitable dose. DISCUSSION: Lack of availability of suitable dosage forms for paediatrics patients results in several challenges, such as additional time required for drug preparation, increased time duration of medication administration, and unpalatability of drugs. These challenges may subsequently affect compliance and therapeutic outcomes of the treatment of paediatric patients, especially as outpatients. CONCLUSION: Research needs to focus on the development of appropriate dosage forms for the paediatric population and focus on identifying cases of DR-TB in children. This will assist in building evidence to advocate for registration of child-friendly dosage forms thereby ensuring a sustainable supply of medication.

Effects of sodium para-aminosalicylic acid on chelation treatment in Pb-exposed mice.

Lead (Pb) is a corrosion-resistant, heavy, non-ferrous metal. Several metal chelators have been used for the treatment of Pb poisoning. However, the efficacy of sodium para-aminosalicylic acid (PAS-Na) in enhancing Pb excretion has yet to be fully characterized. Healthy male mice (90) were divided into six groups, the normal control group was intraperitoneally (i.p.) injected with saline and the remaining group of mice i.p. 120 mg/kg Pb acetate. Four hour later, mice were subcutaneously (back) injected (s.c.) with (80, 160, 240 mg/kg) PAS-Na or 240 mg/kg edetate calcium disodium (CaNa2EDTA) or an equivalent amount of saline, once per day for 6 days. After 24-h urine sample collections, the animals were anesthetized with 5% chloral hydrate and sacrificed in batches on the 2nd, 4th, or 6th day. Levels of Pb [including manganese (Mn) and copper (Cu)] in the urine, whole blood, and brain tissues were analyzed by graphite furnace atomic absorption spectrometry. The results showed that Pb exposure increased its levels in urine and blood, and PAS-Na treatment may afford antagonistic effect on Pb poisoning, suggesting that PAS-Na is a potentially effective treatment to promote excretion of Pb.

Pharmacokinetics and Dose Optimization Strategies of Para-Aminosalicylic Acid in Children with Rifampicin-Resistant Tuberculosis.

Treatment options for children with Rifampicin-resistant tuberculosis (RR-TB) remain limited, and para-aminosalicylic acid (PAS) is still a relevant component of treatment regimens. Prevention of resistance to companion drugs by PAS is dose related, and at higher concentrations, PAS may exhibit significant bactericidal activity in addition to its bacteriostatic properties. The optimal dosing of PAS in children is uncertain, specifically for delayed-release granule preparations, which are the most used. A population pharmacokinetic model was developed describing PAS pharmacokinetics in children receiving routine RR-TB treatment. Model-based simulations evaluated current World Health Organization (WHO) weight-band doses against the adult pharmacokinetic target of 50 to 100 mg/liter for peak concentrations. Of 27 children included, the median (range) age and weight were 3.87 (0.58 to 13.7) years and 13.3 (7.15 to 30.5) kg, respectively; 4 (14.8%) were HIV positive. PAS followed one-compartment kinetics with first-order elimination and transit compartment absorption. The typical clearance in a 13-kg child was 9.79 liters/h. Increased PAS clearance was observed in both pharmacokinetic profiles from the only patient receiving efavirenz. No effect of renal function, sex, ethnicity, nutritional status, HIV status, antiretrovirals (lamivudine, abacavir, and lopinavir-ritonavir), or RR-TB drugs was detected. In simulations, target concentrations were achieved only using the higher WHO dose range of 300 mg/kg once daily. A transit compartment adequately describes absorption for the slow-release PAS formulation. Children should be dosed at the higher range of current WHO-recommended PAS doses and in a once-daily dose to optimize treatment.

Para-aminosalicylic acid significantly reduced tenofovir exposure in human subjects: Mismatched findings from in vitro to in vivo translational research.

AIMS: Tenofovir and para-aminosalicylic acid (PAS) may be coprescribed to treat patients with concomitant infections of human immunodeficiency virus and Mycobacterium tuberculosis bacteria. Both drugs are known to have remarkable renal uptake transporter-mediated clearance. Owing to the lack of clinical studies on drug-drug interaction between the 2 drugs, we conducted a translational clinical study to investigate the effect of PAS on tenofovir pharmacokinetics (PK). METHODS: Initially, we studied in vitro renal uptake transporter-mediated drug-drug interactions using stably transfected cells with human organic anion transporters (OAT1 and OAT3). Later, we estimated clinical drug interactions using static and physiologically based PK modelling. Finally, we investigated the effects of PAS-calcium formulation (PAS-Ca) on tenofovir disoproxil fumarate PK in healthy male Korean subjects. RESULTS: PAS inhibited OAT1- and OAT3-mediated tenofovir uptake in vitro. The physiologically based PK drug-drug interaction model suggested a 1.26-fold increase in tenofovir peak plasma concentration when coadministered with PAS. By contrast, an open-label, randomized, crossover clinical trial evaluating the effects of PAS-Ca on tenofovir PK showed significantly altered geometric mean ratio (90% confidence intervals) of maximum plasma concentration (Cmax ) and area under the curve (AUC0-inf ) by 0.33 (0.28-0.38) and 0.29 (0.26-0.33), respectively. CONCLUSION: Our study findings suggest that the PAS-Ca formulation significantly reduced systemic exposure to tenofovir through an unexplained mechanism, which was contrary to the initial prediction. Caution should be exercised while predicting in vivo PK profiles from in vitro data, particularly when there are potential confounders such as pharmaceutical interactions.

Asian Organization for Crohn's and Colitis and Asia Pacific Association of Gastroenterology practice recommendations for medical management and monitoring of inflammatory bowel disease in Asia.

Inflammatory bowel disease (IBD) has increased in incidence and prevalence in Asian countries since the end of the 20th century. Moreover, differences in the cause, phenotypes, and natural history of IBD between the East and West have been recognized. Therefore, the Asian Organization for Crohn's and Colitis and the Asia Pacific Association of Gastroenterology have established recommendations on medical management of IBD in Asia. Initially, the committee members drafted 40 recommendations, which were then assessed according to Grading of Recommendations Assessment, Development and Evaluation. Eight statements were rejected as this indicated that consensus had not been reached. The recommendations encompass pretreatment evaluation; medical management of active IBD; medical management of IBD in remission; management of IBD during the periconception period and pregnancy; surveillance strategies for colitis-associated cancer; monitoring side effects of thiopurines and methotrexate; and infections in IBD.

High-dimensional single-cell proteomics analysis identifies immune checkpoint signatures and therapeutic targets in ulcerative colitis.

Immune checkpoints are regulators of immune cells and play key roles in the modulation of immune responses. The role of checkpoints in autoimmune disease is poorly understood but likely to be central since checkpoint inhibition during cancer treatment can cause autoimmunity. We generated a high-dimensional single-cell proteomics data set from PBMCs of healthy individuals and patients with ulcerative colitis (UC) by mass cytometry, enabling systems-wide analyses of immune cell frequencies and cell type-specific expression patterns of 12 immune checkpoints. Subtle but significant changes in immune cell frequencies and checkpoint expression were observed between UC patients on different treatment regimens and between patients and healthy controls. Most strikingly, UC patients showed a reduced number of peripheral NK-cells and those cells showed an altered phenotype including increased TIGIT expression. Based on these results, we modulated NK-cell function ex vivo through targeting of TIGIT pathway members. In summary, we describe a pattern of changes in immune cell abundance and checkpoint expression as a basis for UC patient stratification and we show modulation of a corresponding immune cell subset through checkpoint targeting. Our approach can be used for the identification of pathogenic immune cell subsets and guide target selection in autoimmunity and chronic inflammation.

Histological Remission in Ulcerative Colitis: Under the Microscope Is the Cure.

In recent years, the therapeutic goals in ulcerative colitis (UC) have become increasingly stringent. Histological features seem to be a reliable predictor of disease outcomes after therapy, and histological remission (HR) is the new frontier in the treatment of UC. Here, we first provide a historical perspective before reviewing indexes in the era of biologics; histology as a treatment goal in UC trials; the poor correlation between symptoms, endoscopy, and histology; and the impact of histology on disease outcomes. HR seems to be a promising end point for the treatment of UC because it is typically associated with better outcomes. Two new validated indexes are available to assess histology more accurately in trials, and they may also be applicable to clinical practice. Additional interventional trials are now necessary to establish definitions of HR and its potential for disease modification.

The pharmacokinetics of para-aminosalicylic acid and its relationship to efficacy and intolerance.

Following its introduction as an antituberculosis agent close to 75 years ago, the use of para-aminosalicylic acid (PAS) has been limited by gastrointestinal intolerance and multiple formulations were produced in attempts to reduce its occurrence. More recently, an enteric-coated, granular, slow-release PAS formulation (PASER) was introduced and is now in wide-spread use for the treatment of drug-resistant tuberculosis. The current PASER dosing regimen is based on recommendations derived from older studies using a variety of different PAS formulations and relegate PAS to a role as an exclusively bacteriostatic agent. However, there is ample evidence that if sufficiently high serum concentrations are reached, PAS can be bactericidal and that intolerance following once daily dosing, that aids the achievement of such concentrations, is no worse than that following intermittent daily dosing. In particular, prevention of resistance to companion drugs appears to be dependent on the size of the single dose, and hence the peak concentrations, and not on maintaining serum levels consistently above minimum inhibitory concentration. We present a narrative review of the development of PAS formulations, dosing practices, and published data regarding pharmacokinetics and pharmacodynamics and the relationship of PAS dosage to intolerance and efficacy. Our conclusions suggests that we are at present not using PAS to its maximum ability to contribute to regimen efficacy and protect companion drugs.

Nuclear Receptors in the Pathogenesis and Management of Inflammatory Bowel Disease.

Nuclear receptors (NRs) are ligand-dependent transcription factors that regulate the transcription of target genes. Previous epidemiological and genetic studies have documented the association of NRs with the risk of inflammatory bowel disease (IBD). Although the mechanisms of action of NRs in IBD have not been fully established, accumulating evidence has demonstrated that NRs play complicated roles in regulating intestinal immunity, mucosal barriers, and intestinal flora. As one of the first-line medications for the treatment of IBD, 5-aminosalicylic acid (5-ASA) activates peroxisome proliferator-activated receptor gamma (PPARγ) to attenuate colitis. The protective roles of rifaximin and rifampicin partly depend on promoting pregnane X receptor (PXR) expression. The aims of this review are to discuss the roles of several important NRs, such as PPARγ, PXR, vitamin D receptor (VDR), farnesoid X receptor (FXR), and RAR-related orphan receptor gammat (RORγt), in the pathogenesis of IBD and management strategies based on targeting these receptors.

No Benefit of Concomitant 5-Aminosalicylates in Patients With Ulcerative Colitis Escalated to Biologic Therapy: Pooled Analysis of Individual Participant Data From Clinical Trials.

OBJECTIVES: 5-aminosalicylates (5-ASA) are frequently continued in patients with moderate-severe ulcerative colitis (UC), even after escalation to biologic agents, without evaluation of the benefit of this approach. We conducted an individual participant data (IPD) pooled analysis of trials of infliximab and golimumab in UC, to evaluate whether concomitant use of 5-ASA modifies clinical outcomes among anti-tumor necrosis factor (TNF)-α-treated patients. METHODS: We included IPD from five trials of infliximab and golimumab in patients with moderate-severe UC (ACT-1 and -2, PURSUIT-SC, PURSUIT-M, NCT00336492). Patients treated with infliximab or golimumab were categorized as receiving concomitant 5-ASA or not at time of trial entry. Primary outcome was clinical remission (Mayo Clinic Score < 3) at last follow-up for each trial; secondary outcomes were clinical response and mucosal healing. Using multivariable logistic regression analysis, we evaluated association between concomitant 5-ASA and clinical remission, after adjusting for sex, smoking, baseline disease activity, disease extent, biochemical variables (C-reactive protein, albumin, hemoglobin), and concomitant prednisone and immunomodulators. RESULTS: We included 2183 infliximab-treated or golimumab-treated patients (1715 [78.6%] on 5-ASA). Concomitant use of 5-ASA was not associated with odds of achieving clinical remission (adjusted OR, 0.67 [95% CI, 0.45-1.01], p = 0.06), clinical response (aOR, 0.89 [0.60-1.33], p = 0.58) or mucosal healing (aOR, 1.12 [0.82-1.51], p = 0.48). These results were consistent in trials of induction and maintenance therapy, and in trials of infliximab and golimumab. CONCLUSIONS: Based on IPD pooled analysis, in patients with moderate-severe UC who are escalated to anti-TNF therapy, continuing 5-ASA does not improve clinical outcomes.

Promises and Dangers of Combination Therapy.

The efficiency of the existing methods of treating inflammatory bowel disease (IBD) is limited. There are 2 ways to address this problem - either create new treatment modalities or optimize current therapies. Optimisation may be accomplished by using combinations of established therapeutic strategies. With regard to topically acting compounds such as 5-aminosalicylic acid, combining oral and rectal preparations is a commonly used method. Another commonly used combination is anti-tumor necrosis factor (TNF)-α antibody modalities together with immunosuppressants (thiopurines, methotrexate). Several aspects favour those combinations such as increased effectivity, prevention of immunogenicity and perhaps less adverse events. Currently, discussion on directly additive therapeutic effects is in progress, which have been demonstrated in some clinical trials. As on date, the combination of infliximab with azathioprine is most likely the most effective treatment of Crohn's disease. On the other hand, a combination therapy with both compounds affecting the immune system has, of course, risks. For sure, the frequency with which serious infectious complications are arising is increasing. Furthermore, the number of patients experiencing malignancies such as hepato-splenic lymphoma or melanoma is strongly suspected to be on the rise. In summary, combinations of current treatments for IBD are widely established. Various strategies have been studied and significant improvements of therapeutic effects have been demonstrated. Unfortunately, some of those proven combinations increase therapeutic risks, for example, increase the frequency of serious infections and also of some malignancies. Therefore, great caution has to be exercised when applying combination therapies.

De novo inflammatory bowel disease after pediatric kidney or liver transplant.

A subset of children who receive a liver and/or kidney transplant develop de novo inflammatory bowel disease-like chronic intestinal inflammation, not explained by infection or medications, following transplant. We have conducted a single-center, retrospective case series describing the unique clinical and histologic features of this IBD-like chronic intestinal inflammation following solid organ transplant. At our center, nine of 327 kidney or liver recipients developed de novo IBD following transplant (six liver, two kidney, one liver-kidney). Most children presented with prolonged hematochezia and diarrhea and were treated with aminosalicylates. At time of diagnosis, five were not currently using mycophenolate mofetil for transplant immunosuppression. Histologic and endoscopic findings at IBD diagnosis included inflammation, ulcerations, granulomas, and chronic colitis. Since diagnosis, no patients have required surgical intervention, or escalation to biologic therapy, nor developed stricturing or perianal disease. In this case series, de novo post-transplant IBD developed in 4% of pediatric liver and/or kidney recipients; however, it often does not fit the classic patterns of Crohn's disease or ulcerative colitis.

Synthesis and Evaluation of a Sodium Alginate-4-Aminosalicylic Acid Based Microporous Hydrogel for Potential Viscosupplementation for Joint Injuries and Arthritis-Induced Conditions.

A microporous hydrogel was developed using sodium alginate (alg) and 4-aminosalicylic acid (4-ASA). The synthesized hydrogel was characterized using various analytical techniques such as Fourier transform infrared spectroscopy (FTIR), Carbon-13 nuclear magnetic resonance (13C-NMR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Additonal carboxyl and hydroxyl functional groups of 4-ASA provided significant lubrication and stress-triggered sol-gel transition to the conjugated hydrogel. In addition, cytotoxicity analysis was undertaken on the conjugated hydrogel using human dermal fibroblast-adult (HDFa) cells, displaying non-toxic characteristics. Drug release profiles displaying 49.6% in the first 8 h and 97.5% within 72 h, similar to the native polymer (42.8% in first 8 h and 90.1% within 72 h). Under applied external stimuli, the modified hydrogel displayed significant gelling properties and structure deformation/recovery behaviour, confirmed using rheological evaluation (viscosity and thixotropic area of 8095.3 mPas and 26.23%, respectively). The modified hydrogel, thus, offers great possibility for designing smart synovial fluids as a biomimetic aqueous lubricant for joint-related injuries and arthritis-induced conditions. In addtion, the combination of thixotropy, non-toxicity, and drug release capabilities enables potential viscosupplementation for clinical application.

The changing face of Crohn's disease: a population-based study of the natural history of Crohn's disease in Örebro, Sweden 1963-2005.

OBJECTIVE: Changes in medical therapy and surgery might have influenced the natural history of Crohn's disease (CD). Our aim was to explore the short-term outcome of CD and to specifically assess trends in disease phenotype, medications and surgery in the first five years from diagnosis. MATERIAL AND METHODS: A population-based cohort comprising 472 CD patients diagnosed within the primary catchment area of Örebro University Hospital 1963-2005 were identified retrospectively and described. Data on medication, surgery, progression in disease location and behavior, were extracted from the medical records. Patients were divided into three cohorts based on year of diagnosis. RESULTS: The proportion of patients with complicated disease behavior five years after diagnosis decreased from 54.4% (95%CI, 43.9-65.6) to 33.3% (27.4-40.0) in patients diagnosed 1963-1975 and 1991-2005, respectively (p = 0.002), whereas the proportion of patients progressing to complicated disease behavior was stable among those with non-stricturing, non-penetrating disease at diagnosis (p = 0.435). The proportion of patients undergoing surgery decreased from 65.8% (55.4-76.0) to 34.6% (28.6-41.5) in patients diagnosed 1963-1975 and 1991-2005, respectively (p < 0.001). The reduction in surgery preceded an increased use of immunomodulators and was explained by a decrease in surgery within three months from diagnosis (p = 0.001). CONCLUSIONS: We observed a striking decrease in complicated disease behavior and surgery five years after CD diagnosis, the latter largely due to a decrease in early surgery. Our findings suggest that the introduction of new treatments alone does not explain the reduction in surgery rates, the increasing proportion of patients with inflammatory disease at diagnosis also play an important role.

Antibiotic resistance mechanisms in M. tuberculosis: an update.

Treatment of tuberculosis (TB) has been a therapeutic challenge because of not only the naturally high resistance level of Mycobacterium tuberculosis to antibiotics but also the newly acquired mutations that confer further resistance. Currently standardized regimens require patients to daily ingest up to four drugs under direct observation of a healthcare worker for a period of 6-9 months. Although they are quite effective in treating drug susceptible TB, these lengthy treatments often lead to patient non-adherence, which catalyzes for the emergence of M. tuberculosis strains that are increasingly resistant to the few available anti-TB drugs. The rapid evolution of M. tuberculosis, from mono-drug-resistant to multiple drug-resistant, extensively drug-resistant and most recently totally drug-resistant strains, is threatening to make TB once again an untreatable disease if new therapeutic options do not soon become available. Here, I discuss the molecular mechanisms by which M. tuberculosis confers its profound resistance to antibiotics. This knowledge may help in developing novel strategies for weakening drug resistance, thus enhancing the potency of available antibiotics against both drug susceptible and resistant M. tuberculosis strains.

[The evolution of knowledge about the inflammatory bowel diseases]. / Vývoj znalostí o idiopatických strevních zánetech.

Crohns disease and ulcerative colitis has affected people for many centuries however its incidence most likely used to be very low. The knowledge of the idiopathic intestinal inflammation at that time was also very limited - an interest about the disease has emerged since the second half of 19th century. Despite all the progress in medicine its etiology still remains unclear.Diagnosis had for a long been based only on clinical investigation and later radiography, endoscopy came in to use in the 1970s. First significant advances in therapy came during the 1940s and 1950s with the invention of aminosalicylates, antibiotics and corticoids. The most advanced conservative therapy today is biological treatment although the importance of gastrointestinal surgery should not be overlooked.The aim of this article is to briefly review the development of knowledge of the idiopathic intestinal inflammation with an emphasis on the 20th century.

N-acetyltransferase genotypes and the pharmacokinetics and tolerability of para-aminosalicylic acid in patients with drug-resistant pulmonary tuberculosis.

The aim of this study was to examine the relationships between N-acetyltransferase genotypes, pharmacokinetics, and tolerability of granular slow-release para-aminosalicylic acid (GSR-PAS) in tuberculosis patients. The study was a randomized, two-period, open-label, crossover design wherein each patient received 4 g GSR-PAS twice daily or 8 g once daily alternately. The PAS concentration-time profiles were modeled by a one-compartment disposition model with three transit compartments in series to describe its absorption. Patients' NAT1 and NAT2 genotypes were determined by sequencing and restriction enzyme analysis, respectively. The number of daily vomits was modeled by a Poisson probability mass function. Comparisons of other tolerability measures by regimens, gender, and genotypes were evaluated by a linear mixed-effects model. The covariate effects associated with efavirenz, gender, and NAT1*3, NAT1*14, and NAT2*5 alleles corresponded to 25, 37, -17, -48, and -27% changes, respectively, in oral clearance of PAS. The NAT1*10 allele did not influence drug clearance. The time above the MIC of 1 mg/liter was significantly different between the two regimens but not influenced by the NAT1 or NAT2 genotypes. The occurrence and intensity of intolerance differed little between regimens. Four grams of GSR-PAS twice daily but not 8 g once daily ensured concentrations exceeding the MIC (1 mg/liter) throughout the dosing interval; PAS intolerance was not related to maximum PAS concentrations over the doses studied and was not more frequent after once-daily dosing. We confirm that the slow phenotype conferred by the NAT1*14 and NAT1*3 alleles resulted in higher PAS exposure but found no evidence of increased activity of the NAT1*10 allele.

Update on the Medical Management of Crohn's Disease.

The medical management of Crohn's disease is a rapidly evolving field with expanding therapeutic drug options and treatment strategies. In addition to corticosteroids, immunomodulators, and anti-tumor necrosis (anti-TNF) agents, a new anti-adhesion medication (vedolizumab) has been approved. Individualized patient-based dosing of immunomodulators and biologic agents is now possible with therapeutic drug monitoring (TDM). There is a changing paradigm in treatment goals to achieve deeper remission identified by composite clinical and endoscopic endpoints. More aggressive treatment strategies in the postoperative setting have been proposed due to emerging data on medication efficacy in this setting. Management algorithms that stratify CD patients into risk groups to balance treatment benefit against adverse events and costs are being developed to translate research into clinical practice. This review provides an update on these new developments for practicing gastroenterologists.

Long-term therapeutic effectiveness of maintenance enteral nutrition for Crohn's disease.

BACKGROUND: Long-term effectiveness of enteral nutrition for maintaining remission in pediatric Crohn's disease (CD) is poorly documented. The aim of this study was therefore to examine the long-term effectiveness of enteral nutrition with aminosalicylates as maintenance therapy for those in whom remission was primarily induced by total parenteral nutrition or exclusive enteral nutrition with aminosalicylates. METHODS: We retrospectively analyzed data for 58 pediatric patients with newly diagnosed CD during a median follow-up period of 50 months (range, 12-216 months). Data for remission-induced patients in whom enteral nutrition with aminosalicylates was used as maintenance therapy were analyzed with particular reference to time to first relapse and time to first intestinal surgery. RESULTS: Twenty-five (43.1%) of the patients relapsed with a median duration of remission of 32.4 months (range, 6-73.2 months). The cumulative rates of continuous remission were 0.88 (95%CI: 0.79-0.96) at 1 year, 0.73 (95%CI: 0.61-0.85) at 2 years, and 0.52 (95%CI: 0.35-0.68) at 5 years. None of the patients received corticosteroids, immunomodulators or anti-tumor necrosis factor agents until relapse. Disease location had no impact on timing of relapse, but with regard to disease behavior there was a trend towards earlier relapse in patients with penetrating type. Only six of the 58 patients (10.3%) needed intestinal surgery. There was a trend towards need for surgery in patients with ileal disease and with stricturing type. CONCLUSIONS: Enteral nutrition therapy with aminosalicylates is effective for maintaining remission and decreasing the rate of intestinal surgery in pediatric CD.

Pharmacokinetics of para-aminosalicylic acid in HIV-uninfected and HIV-coinfected tuberculosis patients receiving antiretroviral therapy, managed for multidrug-resistant and extensively drug-resistant tuberculosis.

The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis prompted the reintroduction of para-aminosalicylic acid (PAS) to protect companion anti-tuberculosis drugs from additional acquired resistance. In sub-Saharan Africa, MDR/XDR tuberculosis with HIV coinfection is common, and concurrent treatment of HIV infection and MDR/XDR tuberculosis is required. Out of necessity, patients receive multiple drugs, and PAS therapy is frequent; however, neither potential drug interactions nor the effects of HIV infection are known. Potential drug-drug interaction with PAS and the effect of HIV infection was examined in 73 pulmonary tuberculosis patients; 22 (30.1%) were HIV coinfected. Forty-one pulmonary MDR or XDR tuberculosis patients received 4 g PAS twice daily, and in a second crossover study, another 32 patients were randomized, receiving 4 g PAS twice daily or 8 g PAS once daily. A PAS population pharmacokinetic model in two dosing regimens was developed; potential covariates affecting its pharmacokinetics were examined, and Monte Carlo simulations were conducted evaluating the pharmacokinetic-pharmacodynamic index. The probability of target attainment (PTA) to maintain PAS levels above MIC during the dosing interval was estimated by simulation of once-, twice-, and thrice-daily dosing regimens not exceeding 12 g daily. Concurrent efavirenz (EFV) medication resulted in a 52% increase in PAS clearance and a corresponding >30% reduction in mean PAS area under the concentration curve in 19 of 22 HIV-M. tuberculosis-coinfected patients. Current practice recommends maintenance of PAS concentrations at ≥1 µg/ml (the MIC of M. tuberculosis), but the model predicts that at only a minimum dose of 4 g twice daily can this PTA be achieved in at least 90% of the population, whether or not EFV is concomitantly administered. Once-daily dosing of 12 g PAS will not provide PAS concentrations exceeding the MIC over the entire dosing interval if coadministered with EFV, while 4 g twice daily ensures concentrations exceeding MIC over the entire dosing interval, even in HIV-infected patients who received EFV.