Precipitation in the small intestine may play a more important role in the in vivo performance of poorly soluble weak bases in the fasted state: Case example nelfinavir

The aim of this study was to evaluate the utility of biorelevant dissolution tests coupled with in silico simulation technology to forecast in vivo bioperformance of poorly water-soluble bases, using nelfinavir mesylate as a model compound.An in silico physiologically based pharmacokinetic (PBPK) model for poorly water-soluble, weakly basic drugs was used to generate plasma profiles of nelfinavir by coupling dissolution results and estimates of precipitation with standard gastrointestinal (GI) parameters and the disposition pharmacokinetics of nelfinavir. In vitro dissolution of nelfinavir mesylate film-coated tablets was measured in biorelevant and compendial media. Drug precipitation in the small intestine was estimated from crystal growth theory. GI parameters (gastric emptying rate and fluid volume) appropriate to the dosing conditions (fasting and fed states) were used in the PBPK model. The disposition parameters of nelfinavir were estimated by fitting compartmental models to the in vivo oral PK data. The in vivo performance in each prandial state was simulated with the PBPK model, and predicted values for AUC and C_max were compared to observed values.Dissolution results in FaSSIF-V2 and FeSSIF-V2, simulating the fasting and fed small intestinal conditions, respectively, correctly predicted that there would be a positive food effect for nelfinavir mesylate, but overestimated the food effect observed in healthy human volunteers. In order to better predict the food effect, an in silico PBPK simulation model using STELLA® software was evolved. Results with the model indicated that invoking drug precipitation in the small intestine is necessary to describe the in vivo performance of nelfinavir mesylate in the fasted state, whereas a good prediction under fed state conditions is obtained without assuming any precipitation. In vitro–in silico–in vivo relationships (IVISIV-R) may thus be a helpful tool in understanding the critical parameters that affect the oral absorption of poorly soluble weak bases.     

Whole‐body physiologically based pharmacokinetic population modelling of oral drug administration: inter‐individual variability of cimetidine absorption

Objectives Inter‐individual variability of gastrointestinal physiology and transit properties can greatly influence the pharmacokinetics of an orally administered drug in vivo. To predict the expected range of pharmacokinetic plasma concentrations after oral drug administration, a physiologically based pharmacokinetic population model for gastrointestinal transit and absorption was developed and evaluated. Methods Mean values and variability measures of model parameters affecting the rate and extent of cimetidine absorption, such as gastric emptying, intestinal transit times and effective surface area of the small intestine, were obtained from the literature. Various scenarios incorporating different extents of inter‐individual physiological variability were simulated and the simulation results were compared with experimental human study data obtained after oral cimetidine administration of four different tablets with varying release kinetics. Key findings The inter‐individual variability in effective surface area was the largest contributor to absorption variability. Based on in‐vitro dissolution profiles, the mean plasma cimetidine concentration–time profiles as well as the inter‐individual variability could be well described for three cimetidine formulations. In the case of the formulation with the slowest dissolution kinetic, model predictions on the basis of the in‐vitro dissolution profile underestimated the plasma exposure. Conclusions The model facilitates predictions of the inter‐individual pharmacokinetic variability after oral drug administration for immediate and extended‐release formulations of cimetidine, given reasonable in‐vitro dissolution kinetics.     

Calreticulin mutation analysis in non-mutated Janus kinase 2 essential thrombocythemia patients in Chiang Mai University: analysis of three methods and clinical correlations

ABSTRACT

Objectives: The primary objective was to determine the prevalence of calreticulin (CALR) mutation in patients with non-JAK2V617F mutated essential thrombocythemia (ET). The secondary objectives were to evaluate the accuracy of CALR mutation analysis by high-resolution melting (HRM) analysis and real-time polymerase chain reaction (PCR) compared with DNA sequencing and to compare clinical characteristics of CALR mutated and JAK2V617F mutated ET.

Methods: This was a prospective cohort study involving ET patients registered at Chiang Mai University in the period September 2015–September 2017 who were aged more than 2 years, and did not harbor JAK2V617F mutation. The presence of CALR mutation was established by DNA sequencing, HRM, and real-time PCR for type 1 and type 2 mutation. Clinical data were compared with that from ET patients with mutated JAK2V617F.

Results: Twenty-eight patients were enrolled onto the study. CALR mutations were found in 10 patients (35.7%). Three patients had type 1 mutation, 5 patients had type 2 mutation, 1 patient had type 18 mutation, and 1 patients had novel mutations (c.1093 C–G, c.1098_1131 del, c.1135 G–A). HRM could differentiate between the types of mutation in complete agreement with DNA sequencing. Patients with a CALR mutation showed a significantly greater male predominance and had a higher platelet count when compared with 42 JAK2V617F patients.

Discussion and Conclusions: The prevalence of CALR mutation in JAK2V617F-negative ET in this study is 35.7%. HRM is an effective method of detecting CALR mutation and is a more advantageous method of screening for CALR mutation.     

Biowaiver monographs for immediate release solid oral dosage forms: Doxycycline hyclate

Literature data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing doxycycline hyclate are reviewed. According to the Biopharmaceutics Classification System (BCS), doxycycline hyclate can be assigned to BCS Class I. No problems with BE of IR doxycycline formulations containing different excipients and produced by different manufacturing methods have been reported and hence the risk of bioinequivalence caused by these factors appears to be low. Doxycycline has a wide therapeutic index. Further, BCS-based dissolution methods have been shown to be capable of identifying formulations which may dissolve too slowly to generate therapeutic levels. It is concluded that a biowaiver is appropriate for IR solid oral dosage forms containing doxycycline hyclate as the single Active Pharmaceutical Ingredient (API) provided that (a) the test product contains only excipients present in doxycycline hyclate IR solid oral drug products approved in the International Conference on Harmonization (ICH) or associated countries; and (b) the comparator and the test products comply with the BCS criteria for “very rapidly dissolving” or, alternatively, when similarity of the dissolution profiles can be demonstrated and the two products are “rapidly dissolving.”. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1639–1653, 2010     

Dissolution Media Simulating Conditions in the Proximal Human Gastrointestinal Tract: An Update

PURPOSE: The aim of this study was to update the compositions of biorelevant media to represent the composition and physical chemical characteristics of the gastrointestinal fluids as closely as possible while providing physical stability during dissolution runs and short-term storage. METHODS: Media were designed to reflect postprandial conditions in the stomach and proximal small intestine in the "early", "middle", and "late" phases of digestion. From these "snapshot" media, general media for simulating postprandial conditions were devised. Additionally, media reflecting preprandial conditions in the stomach and small intestine were revisited. RESULTS: A set of four media is presented. A recently published medium to represent the fasted stomach, FaSSGF, needed no further revision. To simulate the postprandial stomach, a new medium, FeSSGF, is presented. Media representing the upper small intestine in the fed and fasted states were fine-tuned according to physicochemical and biochemical characteristics in vivo. All four media proved to be stable under ambient storage conditions for at least 72 h as well as under usual dissolution test conditions. CONCLUSIONS: The updated dissolution media can be used to predict formulation performance and food effects in vivo. These media are more physiologically relevant and show better physical stability than their corresponding predecessors.     

The biowaiver procedure: its application to antituberculosis products in the WHO prequalification programme

In 2005, the World Health Organization (WHO) proposed that provided an active pharmaceutical ingredient could meet certain criteria, bioequivalence could be evaluated with a set of laboratory tests, obviating the need for expensive and time-consuming pharmacokinetic studies in humans. The aim of this work was to determine whether this so-called "biowaiver" procedure can be applied to antituberculosis products. Antituberculosis products from the WHO Prequalification Programme, including three ethambutol, two isoniazid and one pyrazinamide product, were investigated. In vitro dissolution data for these products were generated according to the biowaiver method stipulated in the WHO Guidance, and the bioequivalence decision based on these data was compared with that based on the corresponding in vivo pharmacokinetic data. In no case was a "false positive" bioequivalence decision reached using the biowaiver procedure, that is, all products deemed bioequivalent according to the biowaiver methods also proved to be bioequivalent in the corresponding pharmacokinetic study. These findings open the way to a simplified method of ensuring bioequivalence of antituberculosis drug products, thereby improving access to high quality antituberculosis medicines for a greater number of patients.     

CD146 expression in oral lichen planus and oral cancer

Clinical Oral Investigations - To examine the CD146/METCAM expression on keratinocytes in normal oral mucosa (NOM), oral lichen planus (OLP), oral epithelial dysplasia (OED), and oral squamous cell...     

Useful clinical features and hematological parameters for the diagnosis of dengue infection in patients with acute febrile illness: a retrospective study

Background

Dengue infection patients are presented with acute febrile illness. Clinical presentations may mimic other infections. The serology for definite diagnosis is costly and inaccessible in many hospitals. We sought to identify the clinical features and hematologic parameters from a complete blood count (CBC) which distinguish dengue infection from other causes.

Methods

This was a retrospective single center study from Chiang Mai University Hospital. All patients who presented with acute fever between September 2013 and July 2015 were included. The diagnosis of dengue infection must be confirmed by serology. The control groups were patients who presented with acute febrile illness without localizing signs. Clinical data and CBC results were reviewed and compared. The Chi-square test was used to compare categorical variables. The CBC parameters were analyzed using the linear mixed model.

Results

One hundred and fifty-four dengue and 146 control patients were included. Headache, nausea, loss of appetite and bleeding diathesis were significantly symptoms in dengue patients (p?<?0.05). There was some diversity in the the CBC in the dengue patients compared to the control group. Moreover, this study also identified the day of fever which these parameters were statistically significant. The dengue group had higher hemoglobin and hematocrit from day 3 to day 10 (p?<?0.001), lower white blood cell count from day 1 to day 10 (p?<?0.001), lower platelet count from day 3 to day 10 (p?<?0.001), higher monocyte on day 1–4 (p?<?0.001), higher atypical lymphocyte percentage on day 5–9 (p?<?0.001) and higher eosinophil percentage on day 9–10 (p?=?0.001). Furthermore, the neutrophil to lymphocyte percentage ratio of dengue group was >?1 on the first 5 days then reversed on day 6 to Day 9 but in non-dengue group, the ratio was always >?1.

Conclusion

We identified important clinical features and CBC parameters to differentiate dengue patients from other patients who had acute febrile illness from other causes. This identification could be done in local hospitals to give an accurate diagnosis, enabling further investigation to be tailored and treatment commenced earlier.

     

Clinical characteristics and long-term outcomes of warm-type autoimmune hemolytic anemia

Objectives: To study the clinical manifestations, outcomes, and survival of warm-type autoimmune hemolytic anemia (AIHA) patients.

Methods: This study was a retrospective single-center study from 2002 to 2013. Clinical data of AIHA patients were reviewed and analyzed.

Results: One hundred and one patients were included, of whom 77% were female with a median age of 43 years. Primary AIHA was found in 61% of the patients. The secondary causes were systemic lupus erythematosus (SLE) (64%), solid malignancies (13%), lymphomas (10%), drugs (8%), and infections (5%). Most patients (96%) responded to steroids, which were not different between primary and secondary AIHA. Second-line treatments were required in 33 patients (33%). The indications were steroid dependence (58%), relapse (30%), and others (12%). The most common second-line treatment was cyclophosphamide (52%). The response rate for second-line treatments was 93%. Relapse occurred in 50 patients (50%) in which 58% occurred more than 3 years after diagnosis. The SLE patients relapsed and received second-line therapy more than the non-SLE group (P?<?0.001). At the median 53-month follow-up, the overall survival (OS) was 84%. The independent risk factors for OS were age more than 50 years and malignancy. Sepsis was the most common cause of death.

Discussion and conclusion: AIHA has a good prognosis and long-term survival especially in young patients without malignancy. Most patients have responded initially to steroids and have a high response rate to second-line therapy. Carefully adjusted and rapid taper of immunosuppressant is necessary to avoid sepsis complications.