Clinical Pharmacology of Vinpocetine: Properties Revisited and Introduction of a Population Pharmacokinetic Model for Its Metabolite, Apovincaminic Acid (AVA)

This paper examines the use of vinpocetine in the context of clinical pharmacology. The main and active metabolite of vinpocetine is apovincaminic acid (AVA). Due to the scarce information in the literature on AVA pharmacokinetics, we propose a population pharmacokinetic (PopPK) model for AVA based on a study in healthy volunteers with three different formulations of vinpocetine. The suggested PopPK model (and simulations) could be helpful in ensuring the more effective and safer use of the vinpocetine in the future given the increasing range of suggested indications for its use.

Blood-brain barrier transport and neuroprotective potential of blackberry-digested polyphenols: an in vitro study

PURPOSE

Epidemiological and intervention studies have attempted to link the health effects of a diet rich in fruits and vegetables with the consumption of polyphenols and their impact in neurodegenerative diseases. Studies have shown that polyphenols can cross the intestinal barrier and reach concentrations in the bloodstream able to exert effects in vivo. However, the effective uptake of polyphenols into the brain is still regarded with some reservations. Here we describe a combination of approaches to examine the putative transport of blackberry-digested polyphenols (BDP) across the blood-brain barrier (BBB) and ultimate evaluation of their neuroprotective effects.

METHODS

BDP was obtained by in vitro digestion of blackberry extract and BDP major aglycones (hBDP) were obtained by enzymatic hydrolysis. Chemical characterization and BBB transport of extracts were evaluated by LC-MSⁿ. BBB transport and cytoprotection of both extracts was assessed in HBMEC monolayers. Neuroprotective potential of BDP was assessed in NT2-derived 3D co-cultures of neurons and astrocytes and in primary mouse cerebellar granule cells. BDP-modulated genes were evaluated by microarray analysis.

RESULTS

Components from BDP and hBDP were shown to be transported across the BBB. Physiologically relevant concentrations of both extracts were cytoprotective at endothelial level and BDP was neuroprotective in primary neurons and in an advanced 3D cell model. The major canonical pathways involved in the neuroprotective effect of BDP were unveiled, including mTOR signaling and the unfolded protein response pathway. Genes such as ASNS and ATF5 emerged as novel BDP-modulated targets.

CONCLUSIONS

BBB transport of BDP and hBDP components reinforces the health benefits of a diet rich in polyphenols in neurodegenerative disorders. Our results suggest some novel pathways and genes that may be involved in the neuroprotective mechanism of the BDP polyphenol components.

Polyphenols journey through blood-brain barrier towards neuronal protection

Age-related complications such as neurodegenerative disorders are increasing and remain cureless. The possibility of altering the progression or the development of these multifactorial diseases through diet is an emerging and attractive approach with increasing experimental support. We examined the potential of known bioavailable phenolic sulfates, arising from colonic metabolism of berries, to influence hallmarks of neurodegenerative processes. In silico predictions and in vitro transport studies across blood-brain barrier (BBB) endothelial cells, at circulating concentrations, provided evidence for differential transport, likely related to chemical structure. Moreover, endothelial metabolism of these phenolic sulfates produced a plethora of novel chemical entities with further potential bioactivies. Pre-conditioning with phenolic sulfates improved cellular responses to oxidative, excitotoxicity and inflammatory injuries and this attenuation of neuroinflammation was achieved via modulation of NF-κB pathway. Our results support the hypothesis that these small molecules, derived from dietary (poly)phenols may cross the BBB, reach brain cells, modulate microglia-mediated inflammation and exert neuroprotective effects, with potential for alleviation of neurodegenerative diseases.

The effects of chronic stress on hippocampal adult neurogenesis and dendritic plasticity are reversed by selective MAO-A inhibition

There is accumulating evidence that adult neurogenesis and dendritic plasticity in the hippocampus are neuroplastic phenomena, highly sensitive to the effects of chronic stress and treatment with most classes of antidepressant drugs, being involved in the onset and recovery from depression. However, the effects of antidepressants that act through the selective inhibition of monoamine oxidase subtype A (MAO-A) in these phenomena are still largely unknown. In the present study, adult neurogenesis and neuronal morphology were examined in the hippocampus of rats exposed to chronic mild stress (CMS) and treated with the selective reversible MAO-A inhibitor (RIMA) drug, pirlindole and the selective serotonin reuptake inhibitor (SSRI), fluoxetine. The results provide the first demonstration that selective MAO-A inhibition with pirlindole is able to revert the behavioural effects of stress exposure while promoting hippocampal adult neurogenesis and rescuing the stress-induced dendritic atrophy of granule neurons.

Bioequivalence studies for two different strengths of montelukast in healthy volunteers: 10 mg film-coated tablets and 5 mg chewable tablets

In order to assess the bioequivalence of 2 different formulations of montelukast, a pivotal trial for the montelukast 10 mg film-coated tablets formulation and a pivotal trial for the montelukast 5 mg chewable tablets formulation were conducted.For the 10 mg study, 34 healthy subjects were enrolled in a single centre, randomised, single-dose, open-label, 2-way crossover study, with a minimum washout period of 7 days, while for the 5 mg study, 42 healthy subjects were included in another study with a similar design. For both studies, plasma samples were collected up to 24 h post-dosing and drug levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection.Pharmacokinetic parameters used for bioequivalence assessment, area under the concentration-time curve from time zero to time of last non-zero concentration (AUC0-t) and from time zero to infinity (AUC0-inf) and maximum observed concentration (Cmax), were determined from the drug concentration data using non-compartmental analysis.In the 10 mg study, the 90% confidence intervals obtained by analysis of variance were 99.62-120.51% for Cmax, 102.25-117.37% for AUC0-t and 101.96-116.67% for AUC0-inf, which were within the predefined acceptable range of 80.00-125.00%.In the 5 mg study, the 90% confidence intervals were 91.14-98.46% for Cmax, 93.02-98.42% for AUC0-t and 93.09-98.63% for AUC0-inf, which were within the predefined acceptable range of 80.00-125.00%.Bioequivalence between formulations was concluded both in terms of rate and extent of absorption for both strengths.

Bioequivalence of two formulations of escitalopram

Escitalopram, CAS registry number 128196-01-0 is an orally administrated selective serotonin reuptake inhibitor (SSRI).The objective of this trial was to assess bioequivalence between an escitalopram formulation manufactured by Grupo Tecnimede and that of a European reference formulation, while evaluating both formulations' tolerability as a secondary objective.24 healthy subjects were enrolled in a single centre, randomised, single-dose, open-label, 2-way crossover study. Drug levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection, LC-MS/MS method. Pharmacokinetic parameters used for bioequivalence assessment were determined from the drug concentration data using non-compartmental analysis.Mean±Standard deviation (SD) Cmax values were 18.89±5.06 ng/mL and 18.45±5.05 ng/mL for reference and test, respectively. AUClast was 577.16±196.20 ng · h/mL after the administration of the reference and 577.69±220.88 ng · h/mL for the test. AUCinf was 595.66±203.80 ng · h/mL after the administration of the reference 596.19±235.47 ng · h/mL for the test.The 90% confidence intervals obtained by analysis of variance were 92.38-103.38% for Cmax, 94.10-104.37% for AUClast and 93.80-104.09% for AUCinf, which were within the predefined acceptable range of 80.00-125.00%. Both formulations were well tolerated, with no major side effects and no relevant differences in safety profiles observed between the preparations.The design of the study was adequate to determine the pharmacokinetic parameters of the test and the reference formulations. Bioequivalence between formulations was concluded both in terms of rate and extent of absorption.

Comparative Bioavailability/Bioequivalence of Two Different Sertraline Formulations

An open-label, randomised, crossover single dose study, using 2 periods x 2 sequences, with a minimum washout period of 4 weeks, was conducted in order to assess the comparative bioavailability of two formulations of sertraline hydrochloride (CAS 79617-96-2) 100 mg tablets. Plasma samples were obtained at intake (baseline) and at +1 h, +2 h, +3 h, +4 h, +5 h, +6 h, +7 h, +8 h, +9 h, +12 h, +24 h, +48 h, +72 h and +96 h post administration. Sertraline plasma concentrations were determined by high pressure liquid chromatography with tandem mass detection (HPLC-MS/MS) and the lower limit of quantification was set at 100.15 pg/mL. Pharmacokinetic parameters used for bioequivalence assessment (AUClast, AUCinf and Cmax) were determined by non-compartmental analysis. Classical 90 % confidence intervals (90CI) were calculated for the overall sample, and for males and females separately, and gender effects were investigated using an appropriate model. The results showed that overall classical 90CI were 84.55-100.32 % for Cmax 86.96-98.68 % for AUClast, and 86.79-98.93 for AUCinf, that is, they were all within the predefined ranges for bioequivalence acceptance. Separate gender analysis showed very similar results for males and females when analysed independently, and no gender effects were detected in bioequivalence analysis (p > 0.05). It may be therefore concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.

Quinolones: review of psychiatric and neurological adverse reactions

Quinolones are a class of antibacterial agents for the treatment of several infectious diseases (e.g. urinary and respiratory tract infections). They are used worldwide due to their broad spectrum of activity, high bioavailability and good safety profile. The safety profile varies from quinolone to quinolone. The aim of this article was to review the neurological and psychiatric adverse drug reaction (ADR) profile of quinolones, using a literature search strategy designed to identify case reports and case series. A literature search using PubMed/MEDLINE (from inception to 31 October 2010) was performed to identify case reports and case series related to quinolone-associated neurological and psychiatric ADRs. The search was conducted in two phases: the first phase was the literature search and in the second phase relevant articles were identified through review of the references of the selected articles. Relevant articles were defined as articles referring to adverse events/reactions associated with the use of any quinolone. Abstracts referring to animal studies, clinical trials and observational studies were excluded. Identified case reports were analysed by age group, sex, active substances, dosage, concomitant medication, ambulatory or hospital-based event and seriousness, after Medical Dictionary for Regulatory Activities (MedDRA®) coding. From a total of 828 articles, 83 were identified as referring to nervous system and/or psychiatric disorders induced by quinolones. 145 individual case reports were extracted from the 83 articles. 40.7% of the individual case reports belonged to psychiatric disorders only, whereas 46.9% related to neurological disorders only. Eight (5.5%) individual case reports presented both neurological and psychiatric ADRs. Ciprofloxacin, ofloxacin and pefloxacin were the quinolones with more neurological and psychiatric ADRs reported in the literature. Ciprofloxacin has been extensively used worldwide, which may explain the higher number of reports, while for ofloxacin and pefloxacin, the number of reports may be over-representative. A total of 232 ADRs were identified from the selected articles, with 206 of these related to psychiatric and/or neurological ADRs. The other 26 were related to other body systems but were reported together with the reactions of interest. Mania, insomnia, acute psychosis and delirium were the most frequently reported psychiatric adverse events; grand mal convulsion, confusional state, convulsions and myoclonus were the most frequently reported neurological adverse events. Several aspects should be taken into account in the development of CNS adverse effects, such as the pharmacokinetics of quinolones, chemical structure and quinolone uptake in the brain. These events may affect not only susceptible patients but also 'healthy' patients.

Study on the bioequivalence of two formulations of eplerenone in healthy volunteers under fasting conditions: data from a single-center, randomized, single-dose, open-label, 2-way crossover bioequivalence study

BACKGROUND

Eplerenone (CAS 107724-20-9) prevents the binding of aldosterone, a key hormone in the renin-angiotensin-aldosterone-system (RAAS), which is involved in the regulation of blood pressure and the pathophysiology of cardiovascular disease and is indicated, in addition to standard therapy including beta-blockers, to reduce the risk of cardiovascular mortality and morbidity in stable patients with left ventricular dysfunction (LVEF < or = 40%) and clinical evidence of heart failure after recent myocardial infarction.

OBJECTIVE

The aim of this study was to assess the bioequivalence of a new eplerenone 50 mg formulation (test formulation) vs. the reference product, as required by European regulatory authorities for the marketing of a generic product.

METHODS

This was a single-center, randomized, single-dose, open-label, 2-way crossover study in healthy volunteers under fasting conditions. Plasma samples were collected up to 24 h post-dosing and plasma eplerenone levels were determined by reversed phase high performance liquid chromatography and by tandem mass spectrometry detection (ie, the LC-MS/MS method). Pharmacokinetic parameters were calculated using non-compartmental analysis. Area under the concentration-time curve from time zero to time of last non-zero concentration (AUClast) and maximum observed concentration (Cmax) were the main evaluation criteria. All of the above-mentioned pharmacokinetic parameters were analyzed using 90% geometric confidence interval of the ratio (T/R) of least-squares means from the ANOVA of the 1n-transformed parameter. Tolerability was monitored using physical examination, including vital sign measurements and laboratory analysis.

RESULTS

According to the classical approach, the 90% geometric confidence intervals obtained by analysis of variance for AUClast and Cmax were within the predefined ranges (80.00-125.00%).

CONCLUSION

Bioequivalence between test and reference formulations, both in terms of rate and extension of absorption, under fasting conditions was concluded according to European guidelines. Both formulations were well tolerated.

Truncated areas under the curve in the assessment of pioglitazone bioequivalence. Data from a single-center, single-dose, randomized, open-label, 2-way cross-over bioequivalence study of two formulations of pioglitazone 45 mg tablets under fasting conditions

BACKGROUND

Pioglitazone (CAS 112529-15-4 for the HCl form) is an oral antidiabetic agent that is a member of the group of drugs known as thiazolidinediones. It is indicated for the treatment of type 2 diabetes mellitus.

OBJECTIVE

The aim of this study was to assess the bioequivalence of a new pioglitazone 45 mg formulation (test formulation) vs. the reference product, as required by European regulatory authorities for the marketing of a generic product. Additionally, the applicability of the truncated area under the plasma concentration curve (AUC) approach to this drug and under these test conditions was determined.

METHODS

This was a single-center, randomized, single-dose, open-label, 2-way crossover study in healthy volunteers under fasting conditions. Plasma samples were collected up to 120 h post-dosing. Pioglitazone and hydroxypioglitazone plasma levels were determined by reverse liquid chromatography and by tandem mass spectrometry detection (LC-MS/MS). Pharmacokinetic parameters were calculated using non-compartmental analysis. Area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(last)) and maximum observed concentration (C(max)) were the main evaluation criteria, while the area under the concentration-time curve from time zero to infinity (AUC(inf)) was also analyzed for additional information. For the assessment of the applicability of the truncated AUC approach, AUCs truncated at 24, 48, 72, 96, and 120 h were calculated. All of the abovementioned pharmacokinetic parameters were analyzed using 90% geometric confidence interval of the ratio (T/R) of least-squares means from the ANOVA of the In-transformed parameter. Tolerability was monitored using physical examination, including vital sign measurements and laboratory analysis.

RESULTS

According to the classical approach, the 90% geometric confidence intervals obtained by ANOVA for AUC(last), C(max) and AUC(inf) were within the predefined ranges (80-125%) for both analytes. Truncated AUCs were also in all cases within the predefined ranges for acceptance of bioequivalence (e.g. 90% confidence interval).

CONCLUSION

Bioequivalence between test and reference formulations, both in terms of rate and extension of absorption, under fasting conditions was concluded according to European guidelines. Both formulations were well tolerated. The conclusion of bioequivalence was also supported using the truncated AUCs approach.

Mycophenolate mofetil 500-mg tablet under fasting conditions: single-dose, randomized-sequence, open-label, four-way replicate crossover, bioequivalence study in healthy subjects

BACKGROUND

Mycophenolate mofetil (MMF), a prodrug of mycophenolic acid (MPA), is an immunosuppressive agent indicated for the prophylaxis of organ rejection in allogeneic kidney, heart, or liver transplant recipients. The European regulatory authorities require bioequivalence studies for the marketing of generic products.

OBJECTIVE

The aim of this study was to assess the bioequivalence of a generic (test) and branded (reference) formulation of MMF 500 mg and MPA.

METHODS

This single-center, single-dose, randomized, open-label, 4-way crossover study was conducted at Anapharm's Clinical Research Facility, Québec, Québec, Canada. Healthy volunteers aged 18 to 55 years were eligible. Subjects were assigned to receive, in randomized order, a single dose of the test and reference formulations of MMF 500 mg under fasting conditions. Because the study design was 4-way replicate, there were 2 test periods and 2 reference periods. The 4 study periods were each separated by a 14-day washout period. Blood samples were collected over a period of 12 hours after administration for the determination of MMF pharmacokinetic properties, and over 48 (+/-0.5) hours, for MPA properties. Concentrations of the analytes were determined by reverse LC and detected using LC-MS/MS. Pharmacokinetic parameters were calculated from MMF and MPA concentration data using noncompartmental analysis. C(max) and AUC(0-t) were the primary evaluation criteria, while AUC(0-infinity) was a secondary parameter. The drugs were to be considered bioequivalent if the 90% CIs for the test/reference ratios of natural logarithm-transformed values of these parameters (obtained using ANOVA) were between 80% and 125%, per European regulations for bioequivalence. Tolerability was monitored using physical examination, including vital sign measurements, laboratory analysis, and adverse-events (AE) monitoring (including patient interview).

RESULTS

A total of 103 subjects were enrolled (64 men, 39 women; 101 white, 2 black; mean [SD] age, 38 [10] years; weight, 68.2 [9.1] kg). The 90% CIs were as follows: MMF, C(max), 85.94% to 106.63%; AUC(0-t), 91.94% to 102.20%; and AUC(0-infinity), 93.15% to 105.48%; MPA, C(max), 92.03% to 105.82%; AUC(0-t), 97.42% to 100.59%; and AUC(0-infinity), 96.96% to 100.90%. These values met with the regulatory definition of bioequivalence. A total of 148 AEs were reported (68 in subjects who received the test treatment and 80 in subjects who received the reference treatment). The most commonly reported AEs were procedural pain (13/102 [12.7%] and 10/101 [9.9%] with the test and reference formulations, respectively), procedural site reaction (12 [11.8%] and 4 [4.0%]), and somnolence (7 [6.9%] and 14 [13.9%]).

CONCLUSIONS

The generic and branded formulations of MMF 500 mg met the European regulatory criteria for assuming bioequivalence, based on the rate and extent of absorption of a single dose under fasting conditions. Both formulations were well tolerated in these healthy volunteers.

Bioequivalence study of two different tablet formulations of donepezil using truncated areas under the curve. A single-center, single-dose, randomized, open-label, 2-way crossover study under fasting conditions

BACKGROUND

Donepezil hydrochloride (CAS 120014-06-4) is a piperidine-based, reversible inhibitor of the enzyme acetylcholinesterase (AChE). It is postulated to exert its therapeutic effect by enhancing cholinergic function. This is accomplished by increasing the concentration of acetylcholine (ACh) through reversible inhibition of its hydrolysis by AChE.

OBJECTIVE

The aim of this study was to assess the bioequivalence of a new donepezil 10 mg formulation (test formulation) vs. the reference product, as required by European regulatory authorities for the marketing of a generic product. Additionally, the applicability of the truncated area under the plasma concentration curve (AUC) approach to this drug and under these test conditions was determined.

METHODS

This was a single center, randomized, single-dose, open-label, 2-way crossover study in healthy volunteers under fasting conditions. Plasma samples were collected up to 288 h post-dosing and (+)-donepezil and (-)-donepezil plasma levels were determined by reverse liquid chromatography and by tandem mass spectrometry detection (ie, the LCMS/MS method). Pharmacokinetic parameters were calculated using non-compartmental analysis. Area under the concentration-time curve from time zero to the time of the last non-zero concentration (AUC(last)) and maximum observed concentration (C(max)) were the main evaluation criteria, while area under the concentration-time curve from time zero to infinity (AUC(inf)) was also analyzed for additional information. For the assessment of the applicability of the truncated AUC approach, AUCs truncated at 24, 48, 72, 96, 144, 192, 240, and 288 h were calculated. All of the abovementioned pharmacokinetic parameters were analyzed using 90% geometric confidence interval of the ratio (T/R) of least-squares means from the ANOVA of the In-transformed parameter. Tolerability was monitored using physical examination, including vital sign measurements and laboratory analysis.

RESULTS

According to the classical approach, the 90% geometric confidence intervals obtained by analysis of variance for AUC(last), C(max) and AUC(inf) were within the predefined ranges (80.00-125.00%) for both analytes. Truncated AUCs were also in all cases within the predefined ranges for acceptance of bioequivalence.

CONCLUSION

Bioequivalence between test and reference formulations, both in terms of rate and extension of absorption, under fasting conditions, was concluded according to European guidelines. Both formulations were well tolerated. The conclusion of bioequivalence was also supported using the truncated AUCs approach.

Results of a single-center, single-dose, randomized-sequence, open-label, two-way crossover bioequivalence study of two formulations of valsartan 160-mg tablets in healthy volunteers under fasting conditions

BACKGROUND

Valsartan is a nonpeptide, orally active angiotensin II type 1 receptor blocker used to treat hypertension alone or in combination with other antihypertensive agents.

OBJECTIVE

The aim of this study was to compare the relative bioavailability of a new valsartan 160-mg formulation (ie, test drug) and that of a reference formulation so that bioequivalence could be assessed, as required by European regulatory authorities for the marketing of a generic product.

METHODS

This was a single-center, single-dose, randomized-sequence, open-label, 2-way crossover study with a minimum washout period of 7 days; drug was administered to healthy volunteers under fasting conditions. Blood samples were collected up to 36 hours postadministration, and valsartan levels were gauged from plasma by reverse liquid chromatography and tandem mass spectrometry detection (ie, the LC-MS/MS method). Pharmacokinetic parameters were calculated from valsartan concentration data using noncompartmental analysis. AUC(last), AUC(infinity), and C(max) were analyzed. The 90% CIs of the ratios of the test-versus-reference pharmacokinetic parameters (AUC(last), AUC(infinity), and C(max)) were obtained by ANOVA on ln-transformed data. The 90% CIs were required to be within 80.00% to 125.00% of the 90% CI to meet the criteria for bioequivalence. Tolerability was monitored using physical examination (including vital-sign measurements) and ECG performed at screening, as well as laboratory analysis, including biochemistry tests, hematology tests, and urinalysis, which were performed at screening and during the study period.

RESULTS

Thirty-eight white (90.5%), 2 black (4.8%), and 2 Hispanic subjects (4.8%) enrolled in the study; the sample included a total of 27 men and 15 women. The mean (SD) age was 37 (11) years and mean weight was 65.4 (7.6) kg. The 90% CI values for pharmacokinetic measurements were as follows: AUC(last), 94.45% to 118.59%; AUC(infinity), 93.58% to 116.51%; and C(max), 93.61% to 122.02%. Thus, they were all within the predefined 80.00% to 125.00% range. Thirty-six postadministration adverse events were reported; the most common was blood pressure decrease. A decrease of blood pressure was experienced by 6 subjects (14.6%) after the administration of the test formulation, and by 5 subjects (12.5%) after the administration of the reference formulation. Thirty-three of these adverse events were graded as mild and 3 as moderate; 11 were judged as probably related, 12 as possibly related, 3 as remotely related, and 10 as unrelated to the study medication.

CONCLUSIONS

In this open-label study of healthy volunteers, the test and reference formulations of valsartan 160 mg met the European regulatory definition of bioequivalence, based on the rate and extent of absorption of a single dose under fasting conditions. Both formulations were well tolerated.

Bioequivalence studies of two different film-coated tablet formulations of valacyclovir of two different strengths in healthy volunteers

These studies were conducted in order to assess the bioequivalence of two film-coated formulations containing 250 mg and 1000 mg of valacyclovir (INN: valaciclovir; CAS 124832-26-4), which is the L-valyl ester and a pro-drug of the antiviral drug acyclovir (INN: aciclovir). In the study with valacyclovir 250 mg, 36 healthy subjects were enrolled in a randomized, single-dose, open-label, 2-way crossover study, with a washout period of 10 days. In the study with valacyclovir 1000 mg, 46 healthy subjects were enrolled in a randomized, single-dose, open-label, 2-way crossover study, with a washout period of 7 days. Plasma samples were collected up to 36 h postdose for both studies. Valacyclovir levels were determined by liquid chromatography with tandem mass detection (ie, the LC/MS/MS method) (lower limit of quantification: 0.50 ng/ mL for valacyclovir and 9.93 ng/mL for acyclovir for the 250 mg study and 1.00 ng/mL for valacyclovir and 20.00 ng/ mL for acyclovir for the 1000 mg study). Pharmacokinetic parameters used for bioequivalence assessment were the area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(0-t)) and from time zero to infinity (AUC(0-inf) and maximum observed concentration (C(max)). These parameters were determined from the valacyclovir concentration data using non-compartmental analysis. In the tained by analysis of variance (ANOVA) for valacyclovir were 107.54-124.26% for C(max), 95.45-103.46% for AUC(0-Inf) and 95.53-103.63% for AUC(0-t) whereas for acyclovir the 90% confidence intervals obtained were 103.19-117.02% for C(max), 99.61-106.92% for AUC(0-Inf) and 99.58-106.94% for AUC(0-t). In the study with valacyclovir 1000 mg formulations, the 90% confidence intervals obtained for valacyclovir were 93.20-107.35% for C(max), 90.87-96.27% for AUC(0-inf) and 90.87-96.27% for AUC(0-t) whereas for acyclovir the 90% CIs obtained were 95.98-104.94% for C(max), 97.13-103.94% for AUC(0-inf) and 97.14-104.09% for AUC(0-t). All the 90% confidence intervals obtained for all the parameters assessed were within the predefined range (80-125%). Based on these results, it can be concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.

Bioequivalence study of two different film-coated tablet formulations of losartan-hydrochlorothiazide in healthy volunteers

The study was conducted in order to assess the bioequivalence of two film-coated formulations containing 100 mg of losartan (CAS 124750-99-8) and 12.5 mg of hydrochlorothiazide (CAS 58-93-5). Seventy-three healthy subjects were enrolled in a randomised, single-dose, open-label, two-way crossover study, with a minimum washout period of 7 days. A total of 21 blood samples were collected up to 36 h post-dosing. Losartan, losartan carboxy acid and hydrochlorothiazide levels were determined by liquid chromatography with tandem mass detection (lower limit of quantification: 1.01 ng/mL for hydrochlorothiazide, 2.02 ng/mL for losartan and 2.51 ng/mL for losartan carboxy acid). Pharmacokinetic parameters used for bioequivalence assessment (AUC(0-t) and Cmax as primary and AUC(0-inf) as secondary pharmacokinetic parameters) were determined from the losartan and hydrochlorothiazide concentration data using non-compartmental analysis. Data from losartan carboxy acid was reported and presented as supportive data. The 90% confidence intervals (obtained by ANOVA) for losartan were 97.05-118.48% for Cmax 100.76-106.10% for AUC(0-t) and 100.80-106.10% for AUC(0-inf) whereas for hydrochlorothiazide the 90% confidence intervals obtained were 103.94-115.33% for Cmax, 101.97-109.61% for AUC(0-t) and 101.77-109.02% for AUC(0-inf), and for losartan carboxy acid the intervals obtained were 98.31-107.82% for Cmax, 97.89-104.30% for AUC(0-t) and 98.06-104.30% for AUC(0-inf). All the 90% confidence intervals obtained for all the parameters assessed were within the predefined ranges (80-125%). Based on these results, it can be concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.

Bioequivalence study of two enteric-coated formulations of pantoprazole in healthy volunteers under fed conditions

This study was conducted in order to assess the bioequivalence of two enteric-coated formulations of 40 mg pantoprazole (CAS 102625-70-7), under fed conditions. Seventy-four healthy subjects, age ranging from 24 to 55 years, were enrolled in a two-centre, randomised, single-dose, open-label, 2-way crossover study, with a minimum washout period of 7 days. Plasma samples were collected up to 30.0 h post-dosing. Pantoprazole levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection (LC-MS/ MS). Pharmacokinetic parameters used for bioequivalence assessment were the AUClast (area under the concentration-time curve from time zero to time of last observed non-zero concentration), AUCinf (area under the concentration-time curve from time zero to infinity) and Cmax, (maximum observed concentration). These parameters were determined from the pantoprazole concentration data using non-compartmental analysis. Gender-related differences were found in the variability of all relevant pharmacokinetic parameters. The 90% CI (90% confidence intervals), obtained by analysis of variance (ANOVA) were within the predefined ranges. Bioequivalence between the test and reference formulation, under fed conditions, was concluded both in terms of rate and extent of absorption.

Bioequivalence study of two tablet formulations of sildenafil

This study was conducted in order to assess the bioequivalence of two tablet formulations containing 100 mg sildenafil (1-[4-ethoxy-3-(6,7-dihydro-1-,ethyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)phenylsulphonyl] -4-methyl piperazine, CAS 139755-83-2). Twenty-eight healthy subjects were enrolled in a single-centre, randomised, single-dose, open-label, 2-way crossover study, with a minimum washout period of 7 days. Plasma samples were collected up to 18.0 h postdosing. Sildenafil levels were determined by reverse liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS). Pharmacokinetic parameters used for bioequivalence assessment [area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(last)) and maximum observed concentration (C(max)) were main evaluation criteria; however, the area under the concentration-time curve from time zero to infinity (AUC(inf)) was also analysed] were determined from the sildenafil concentration data using non-compartmental analysis. The 90% confidence intervals (obtained by analysis of variance, ANOVA) were 86.70-108.19 for C(max), 86.67-99.26 for AUC(last) and 87.19-99.82 for AUC(inf) within the predefined ranges. Bioequivalence between the two formulations was concluded both in terms of rate and extent of absorption.

Bioequivalence study of two letrozole tablet formulations. Single dose, randomized, open-label, two-way crossover bioequivalence study of letrozole 2.5 mg tablets in healthy volunteers under fasting conditions

The study was conducted in order to compare the bioavailability of two tablet formulations containing letrozole 2.5 mg (CAS 112809-51-5). Twenty healthy subjects were enrolled in a single-centre, bioequivalence, randomised, single-dose, open-label, two-way crossover study, performed under fasting conditions with a minimum washout period of 21 days. Plasma samples were collected up to 240 h post-dosing. Letrozole levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection, LC/MS/MS method. Pharmacokinetic parameters used for bioequivalence assessment, area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(0-t)) and from time zero to infinitive (AUC(0-inf)) and maximum observed concentration (Cmax), were determined from the letrozole concentration data using non-compartmental analysis. The 90% confidence intervals obtained by analysis of variance were 90% geometric confidence Intervals of the ratio (A/B) of least-squares means from the analysis of variance (ANOVA) of the In-transformed AUC(0-t), and Cmax was within 80% to 125%. Bloequivalence between formulations was concluded both in terms of rate and extent of absorption.

Truncated AUCs in the assessment of the bioequivalence of topiramate, a long half-life drug

This study was conducted in order to assess the bioequivalence of two tablet formulations containing topiramate (CAS 97240-79-4), 25 mg. Twenty-four healthy volunteers were enrolled in an open-label, randomised, crossover, 2 periods x 2 sequences, with a minimum washout period of 21 days, single dose study. Blood samples were collected prior to study drug administration and 0.167, 0.333, 0.500, 0.667, 1.00, 1.33, 1.67, 2.00, 2.50, 3.00, 4.00, 6.00, 8.00, 12.0, 24.0, 48.0, 96.0, 144, 192, and 264 h post-dose in each period. Plasma levels of topiramate from the 23 subjects who completed the study, were determined by high-pressure liquid chromatography with tandem mass detection, HPLC/MS/MS (lower limit of quantification 9.98 ng/mL). Pharmacokinetic parameters used for bioequivalence assessment (AUC(last), AUC(inf) and C(max)) were determined from the plasma concentration data using non-compartmental analysis. Mean +/- standard deviation elimination half-life for the reference formulation was 84.18 +/- 14.61h whereas for the test formulation it was 80.82 +/- 11.50h. The 90% Confidence Intervals (90 CI) were 98.00-111.35% for C(max), 98.44-103.76% for AUC(last) and 96.61-103.00% for AUC(inf), that is, within the ranges defined in the protocol for acceptance of bioequivalence. The 90 CIs obtained for the truncated AUCs were as follows: 100.27-105.32% for AUC0-48, 99.28-104.62% for AUC0-48, 99.13-104.56% for AUC0-96, 95.67-104.82% for AUC0-144, and 100.04-103.76% for AUC0-192. Both analysed formulations are bioequivalent irrespective of whether the conventional or truncated AUC approach is used. This study demonstrated that topiramate can be viewed as a long half-life drug and that the truncated AUC ap proach could be considered for bioequivalence assessment.

In vitro disintegration and dissolution and in vivo bioequivalence of two alendronate once-weekly formulations

Bioequivalence of two tablet formulations of 70 mg alendronate (CAS 121268-17-5) was assessed in a single-dose, open-label, randomised, fasted state crossover trial, with a washout period of 21 days, in 80 healthy subjects. Urine samples were collected up to +36 h post dosing and the concentrations of alendronic acid were assessed using a high-performance liquid chromatographic method with pre-derivatization and fluorescence detection (HPLC/FL) method. The 90 % confidence intervals (90 % CI) obtained for Ae0-36 (cumulative urinary excretion) and Rmax (maximum rate of urinary excretion) were 98.67-118.99 % and 102.22-122.46 %, respectively. The intra-subject coefficient of variation was between 32-35 % for both parameters. No relevant tolerability problems were detected. Both formulations can be considered bioequivalent. In vitro testing was performed to confirm the adequacy of the quality control conditions and no significant differences were detected neither in the disintegration test nor in the dissolution tests conducted in HCl 0.1 N and H2O and thus in these conditions the lack of statistically significant differences in vitro was accompanied by in vivo bioequivalence.

Comparative study on the bioequivalence of two formulations of pravastatin. Data from a crossover, randomised, open-label bioequivalence study in healthy volunteers

An open-label, randomised, crossover single-dose study, using two periods, two sequences, with a minimum washout period of 7 days, was conducted in order to assess the comparative bioavailability of a pravastatin (CAS 81131-70-6) 40 mg formulation and that of a reference formulation. Blood samples were collected up to +14 h post dosing, the plasma was separated and pravastatin concentrations were determined by high-performance liquid chromatographic method with tandem mass spectrometry detection (HPLC-MS/MS), with a lower limit of quantification of 0.40 ng/mL. Bioequivalence analyses were conducted using two models. The main analysis was done according to a general linear model (model I) using formulation, period and sequence as fixed model effects, and subject(sequence) and residual as random effects; gender-related differences were investigated using ANOVA (model II), including formulation, period, sequence, gender, sequence-by-gender interaction and gender-by-formulation interaction as fixed model effects and subject within sequence-by-gender interaction and residual as random effect. Mean values of the individual Cmax were 126.73 +/- 61.99 ng/mL and 123.52 +/- 52.78 ng/mL for the test and reference, spectively. Mean +/- SD total area under the curve up to the last measurable concentration (AUClast) was 224.26 +/- 104.74 ng x h/mL for the test formulation and 216.55 +/- 80.30 ng x h/mL for the reference formulation. Mean +/- SD total area under the curve (AUCinf) was 226.72 +/- 104.69 ng x h/mL for the test formulation and 218.81 +/- 79.95 ng x h/mL for the reference. Terminal elimination half-life was 2.15 +/- 0.85 h for test and 1.97 +/- 0.54 h for the reference. Ninety percent confidence intervals were comprised within the bioequivalence acceptance criteria (80-125 %) for all of the parameters analysed, both using model I and model II. Model II returned a statistically significant gender effect (p < 0.05) for Cmax, AUClast and AUCinf but the effect became non-significant (p > 0.05) when the dose was adjusted per body weight for all three parameters. The comparison between male and female mean body weight showed a significant difference: p = 0.03, 95 % confidence intervals 68.27-76.93 kg (men), 56.84-60.61 kg (women). These results suggest that the effect of gender in the bioequivalence analysis in model I could be due to a difference in body weight between males and females. Both formulations were shown to be bioequivalent in terms of rate and extent of absorption, irrespectively of the model used.

Comparative study on the bioequivalence of two different gabapentin formulations. A randomised, two-period, two-sequence, crossover clinical trial in healthy volunteers

The bioequivalence of two capsule formulations containing 400 mg gabapentin (CAS 60142-96-3) was assessed in 24 healthy volunteers in an open, randomised, crossover, 2 periods x 2 sequences, with a minimum washout period of 7 days, single-dose study. Plasma samples were obtained at fixed time points, over 48 h (baseline (pre-dose), +0.5 h, +1 h, +1.5, +2, +2.5, +3, +3.5, +4, +8, +5, +6, +8, +10, +12, +24, +36 and +48 h after administration) and gabapentin concentrations were determined by means of an HPLC-MS method (LLOQ 50.2 ng/mL). Pharmacokinetic parameters used for bioequivalence assessment (AUCtlast, AUCinf and Cmax) were determined from the gabapentin concentration data using non-compartmental analysis. The results showed that all 90 % confidence intervals (obtained by ANOVA) were all within the predefined ranges: 93.87-111.87 % for Cmax 94.04-108.21 % for AUCtlast and 94.23-108.29 % for AUCinf. Consequently, this bioequivalence study was well designed in order to conclude that the test formulation and reference formulation were bioequivalent in terms of rate and extent of absorption.

Comparative bioavailability of two formulations of levofloxacin and effect of sex on bioequivalence analysis. Data from a randomised, 2 x 2 crossover trial in healthy volunteers

Bioequivalence of levofloxacin (CAS 100986-85-4) 500 mg tablets was assessed in a single dose, open, randomised, crossover trial, with a minimum washout period of 7 days. Serum samples were obtained over 36 h (at baseline, 0.250, 0.500, 0.750, 1.00, 1.25, 1.50, 1.75, 2.00, 2.33, 2.67, 3.00, 4.00, 6.00, 8.00, 12.0, 16.0, 24.0, and 36.0 h post-dose). Levofloxacin serum concentration levels were determined by high-pressure liquid chromatography with fluorescence detection (LOQ 98.31 ng/mL). The 90% confidence intervals (90% Cls; obtained by ANOVA using In-transformed data) for overall bioequivalence analysis were 99.09-115.26% for Cmax, 99.41-105.60% for AUClast and 98.68-104.93% for AUCinf, that is, all within the predefined ranges. Within-gender analysis also produced 90% CIs within the predefined ranges. The use of gender-related model effects showed that sex was a significant factor for AUClast and AUCinf, however, when parameters were normalised by body weight adjusted dose, none of the tested model effects were significant. Comparison between male and female body weight showed significant differences. It may be therefore concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption and that possible differences between male and female pharmacokinetic parameters may be related to differences in body weight.

Bioequivalence study of two different tablet formulations of carvedilol in healthy volunteers

OBJECTIVE

The aim of this study was to compare the extent and rate of absorption of two different carvedilol (CAS 72956-09-3) tablet formulations: 25 mg tablets, as the test formulation and the reference innovator product (25 mg tablets).

METHODS

This study was designed as a single-dose, open-label, randomised, with a two-period and two-sequence crossover design, with blind determination of drug plasma concentration and a minimum 7-day washout period. Twenty-four healthy volunteers of both sexes were randomly assigned to treatment sequences. Carvedilol concentrations were determined in plasma samples obtained over a 24-h interval: baseline (pre-administration) and at 14 different times within the 24 h after administration. The analytical method, which used HPLC coupled with a MS/MS detector, was duly validated and the analytical assay was performed in compliance with Good Laboratory Practice (GLP). The limit of quantification (LOQ) was 0.50 ng/mL. Pharmacokinetic parameters representing the extent and/or rate of absorption (AUCinf, AUClast, and Cmax) were obtained. As secondary objective the tolerability of both formulations was also evaluated.

RESULTS

The geometric mean of the test/reference formulations individual percent ratio was 98.14 % for AUCinf, 98.44 % for AUClast and 98.39 % for Cmax. The 90 % CI for the geometric mean of the individual ratio test/references formulations was 95.13 to 101.24 % for AUCinf, 95.23 to 101.76 % for AUClast, and 88.26 to 109.67 % for Cmax.

CONCLUSIONS

The 90 % CI values obtained for AUCinf, AUClast, and Cmax are within the interval proposed by the EMEA/CPMP and the FDA as bioequivalence acceptance criteria, and consequently it can be conclude that the test formulation is bioequivalent with the reference formulation both in terms of rate and extent of absorption after single dose administration. The results from a previous pilot study allowed an optimal design for this trial.

Bioequivalence study of two different coated tablet formulations of finasteride in healthy volunteers

This study was conducted in order to assess the bioequivalence of two different coated tablet formulations containing 5 mg finasteride (CAS 98319-26-7). Twenty-six healthy volunteers were enrolled in an open, randomised, crossover single dose study with 2 periods x 2 sequences and a minimum washout period of 7 days. Plasma samples were obtained over 24 h (at baseline, +0.5 h, +1 h, +1.5 h, +2 h, +2.5 h, +3 h, 3.5 h, +4 h, +4.5 h, +5 h, +6 h, +8 h, +10 h, +12 h, +16 h and +24 h after administration). Finasteride levels were determined by high-pressure liquid chromatography with tandem mass detection, HPLC-MS/ MS, (LOQ 0.50 ng/mL). Pharmacokinetic parameters used for bioequivalence assessment (AUClast and Cmax were main evaluation criteria, however, AUCinf was also analysed) were determined from the finasteride concentration data using non-compartmental analysis. The 90 % confidence intervals (obtained by ANOVA) were 86.31-98.69 for Cmax, 95.40-104.88 for AUClast and 96.20-105.81 for AUCinf that is, they were all within the predefined ranges. It may be therefore concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.

Truncated AUC in the evaluation of fluconazole bioequivalence. A cross-over, randomised, open-label study in healthy volunteers

The bioequivalence of two capsule formulations (test and reference) containing 200 mg fluconazole (CAS 86386-73-4) was assessed in 24 healthy volunteers in an open, randomised, crossover, 2 periods x 2 sequences single dose study with a minimum washout period of 14 days. Plasma samples were obtained over 168 h (at baseline, 1 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 5 h, 6 h, 8 h, 12 h, 24 h, 48 h, 72 h, 120 h and 168 h after administration) and fluconazole concentrations were determined by means of an HPLC-WV method (limit of quantification: 0.2 microg/mL). Pharmacokinetic parameters used for bioequivalence assessment (AUClast, AUCinf and Cmax) were determined from the fluconazole concentration data using non-compartmental analysis. The results showed that all 90% confidence intervals (obtained by ANOVA) were 100.89-110.24 for Cmax, 99.07-107.35 for AUClast and 95.42-105.17 for AUCinf, that is, all within the predefined ranges. Furthermore AUCs truncated at 24, 48, 72 and 120 h were also within the 80-125% range. It may be therefore concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.

Comparative bioavailability of two formulations of terbinafine. Data from a cross-over, randomised, open-label bioequivalence study in healthy volunteers

An open-label, randomised, cross-over single dose study, using 2 periods x 2 sequences, with a minimum washout period of 21 days, was conducted in order to assess the comparative bioavailability of two formulations of terbinafine (CAS 78628-80-5) 250 mg tablets. Plasma samples were obtained at baseline, +0.333; 0.667; 1.00; 1.33; 1.67; 2.00; 2.33; 2.67; 3.00; 3.50; 4.00; 6.00; 8.00; 12.0; 24.0; 36.0; 48.0 and 72.0 h post-administration. Terbinafine levels were determined by high pressure liquid chromatography with tandem mass detection (HPLC-MS/MS) and the lower limit of quantification was set at 9.99 ng/mL. The pharmacokinetic parameters used for the bioequivalence assessment (AUClast, AUCinf and Cmax) were determined from the terbinafine concentration data using non-compartmental analysis. Classical 90% confidence intervals (90CI) were calculated for the overall sample, and for males and females separately, and gender effects were investigated using an appropriate model. The results showed that overall classical 90CI were 96.08-105.40% for AUCinf, 95.68-105.33 for AUClast and 88.24-112.83 for Cmax, that is, all within the predefined ranges for bioequivalence acceptance. Separate gender analysis showed very similar results for males and females when analysed independently, and no gender effects were detected (p>0.05 for all of the tested model effects). It may be therefore concluded that the evaluated formulations are bioequivalent in terms of rate and extent of absorption.

Cationic liposomes for gene delivery: from biophysics to biological applications

The use of an efficient carrier for nucleic acid-based medicines is considered to be a determinant factor for the successful application of gene therapy. The drawbacks associated with the use of viral vectors, namely those related with safety problems, have prompted investigators to develop alternative methods for gene delivery, cationic lipid-based systems being the most representative. Despite extensive research in the last decade on the use of cationic liposomes as gene transfer vectors and the development of elegant strategies to enhance their biological activity, these systems are still far from being viable alternatives to the use of viral vectors in gene therapy. In this review considerations are made regarding the structure-activity relationships of cationic liposome/DNA complexes and the key formulation parameters influencing the features of lipoplexes are presented and discussed in terms of their effect on biological activity. Particular emphasis is given to the interaction of the lipoplexes with serum components as well as to novel strategies developed to circumvent difficulties that may emerge upon iv administration of the complexes. Finally, since the ability of the lipoplexes to be stored while preserving their transfection activity is a crucial issue for the repeated use of such carriers, approaches reported on the improvement of their physical stability are also reviewed.

Transcriptional regulation in megakaryocytes: the thrombopoietin receptor gene as a model

The MPL gene codes for the thrombopoietin receptor, whose ligand specifically controls megakaryocytic differentiation. In order to understand the molecular basis for the megakaryocyte-specific expression of MPL, we analyzed the regulatory elements of this gene. Two regions are hypersensitive to DNase I in nuclei of cells that express MPL: the promoter and a portion of intron 6. The latter behaves as a chromatin-dependent enhancer. A 200 bp fragment of the promoter is sufficient for high-level specific expression. This fragment can bind several transacting factors in vitro, including GATA-1 and members of the Ets family. GATA-1 binds with low affinity to a unique GATA motif at -70 in the MPL promoter, and destruction of this site yields only a modest decrease in expression level in human erythroleukemia (HEL) cells. Ets proteins also bind with low affinity to two sites. One is located at position -15 and its destruction reduces expression to 50%; the other is located immediately downstream of the GATA motif and plays a crucial role in expression of the promoter in HEL cells, as its inactivation reduces expression to 15%. This study indicates a molecular basis for the coregulation of markers of megakaryocyte differentiation. Finally, we describe other nuclear factor binding sites that may be involved in the cell-type-specific expression of MPL.

Macrothrombocytopenia with abnormal demarcation membranes in megakaryocytes and neutropenia with a complete lack of sialyl-Lewis-X antigen in leukocytes--a new syndrome?

A new megathrombocytopenic syndrome with giant platelets in peripheral blood and severe thrombocytopenia was diagnosed in a 4-month-old boy. His clinical course included repeated hemorrhagic incidents leading to death at age 37 months. Bone marrow ultrastructural analysis revealed numerous dystrophic megakaryocytes with giant membrane complexes. Although these features were similar to those described for megakaryocytes in mice lacking the gene for transcription factor p45-NF-E2, no abnormalities in the p45-NF-E2 gene could be documented. Platelet membrane analysis showed a reduction in glycoprotein (GP) Ib, but normal content of GPIIb and GPIIIa. Analysis of genes encoding for GPIb alpha and beta, GPV, and GPIX ruled out the possibility that the observed platelet abnormality is a variant of Bernard-Soulier syndrome. A moderate neutropenia was associated with a complete lack of expression of sialyl-Lewis-X on the surface of polymorphonuclear neutrophils. A common defect in posttranslational modification of glycoproteins could account for the diverse cellular abnormalities.

Regulation of embryonic/fetal globin genes by nuclear hormone receptors: a novel perspective on hemoglobin switching

The CCAAT box is one of the conserved motifs found in globin promoters. It binds the CP1 protein. We noticed that the CCAAT-box region of embryonic/fetal, but not adult, globin promoters also contains one or two direct repeats of a short motif analogous to DR-1 binding sites for non-steroid nuclear hormone receptors. We show that a complex previously named NF-E3 binds to these repeats. In transgenic mice, destruction of the CCAAT motif within the human epsilon-globin promoter leads to substantial reduction in epsilon expression in embryonic erythroid cells, indicating that CP1 activates epsilon expression; in contrast, destruction of the DR-1 elements yields striking epsilon expression in definitive erythropoiesis, indicating that the NF-E3 complex acts as a developmental repressor of the epsilon gene. We also show that NF-E3 is immunologically related to COUP-TF orphan nuclear receptors. One of these, COUP-TF II, is expressed in embryonic/fetal erythroid cell lines, murine yolk sac, intra-embryonic splanchnopleura and fetal liver. In addition, the structure and abundance of NF-E3/COUP-TF complexes vary during fetal liver development. These results elucidate the structure as well as the role of NF-E3 in globin gene expression and provide evidence that nuclear hormone receptors are involved in the control of globin gene switching.

[Murine typhus in Portugal]

Murine typhus or endemic typhus is a wide spread infectious disease, with a low prevalence in developed countries, but surely underdiagnosed. Its relative benignity, the similarity to other infectious diseases and the discretion of its epidemiologic chain, as well as the usual unexpectedness of its existence, makes its diagnosis more difficult. The clinical presentation and evolution of this case illustrate the necessity of being aware of this nosological entity.

p45 NF-E2 regulates expression of thromboxane synthase in megakaryocytes

Transcription factor p45 NF-E2 is highly expressed in the erythroid and megakaryocytic lineages. Although p45 recognizes regulatory regions of several erythroid genes, mice deficient for this protein display only mild dyserythropoiesis but have abnormal megakaryocytes and lack circulating platelets. A number of megakaryocytic marker genes have been extensively studied, but none of them is regulated by NF-E2. To find target genes for p45 NF-E2 in megakaryopoiesis, we used an in vivo immunoselection assay: genomic fragments bound to p45 NF-E2 in the chromatin of a megakaryocytic cell line were immunoprecipitated with an anti-p45 antiserum and cloned. One of these fragments belongs to the second intron of the thromboxane synthase gene (TXS). We demonstrate that the TXS gene, which is mainly expressed in megakaryocytes, is indeed directly regulated by p45 NF-E2. First, its promoter contains a functional NF-E2 binding site; second, the intronic NF-E2 binding site is located within a chromatin-dependent enhancer element; third, p45-null murine megakaryocytes do not express detectable TXS mRNA, although TXS expression can be detected in other cells. These data, and the structure of the TXS promoter and enhancer, suggest that TXS belongs to a distinct subgroup of genes involved in platelet formation and function.

Analysis of the thrombopoietin receptor (MPL) promoter implicates GATA and Ets proteins in the coregulation of megakaryocyte-specific genes

The MPL gene codes for the thrombopoietin receptor, whose ligand specifically controls megakaryocytic differentiation. To understand the molecular basis for the megakaryocyte-specific expression of MPL, we analyzed the promoter of this gene. A 200 bp fragment is sufficient for high-level specific expression. This fragment can bind several trans-acting factors in vitro, including GATA-1 and members of the Ets family. GATA-1 binds with low affinity to a unique GATA motif at -70 in the MPL promoter, and destruction of this site yields only a modest decrease in expression level in HEL cells. Ets proteins also bind with low affinity to two sites. One is located at position -15 and its destruction reduces expression to 50%; the other is located immediately downstream of the GATA motif and plays a crucial role in expression of the promoter in HEL cells, as its inactivation reduces expression to 15%. Furthermore, GATA-1 and two Ets proteins, Ets-1 and Fli-1, can trans-activate the MPL promoter in heterologous cells. The effects of GATA-1 and these two Ets proteins are additive. Together with our previous results on the glycoprotein IIb (GpIIb) promoter, this study indicates a molecular basis for the coregulation of early markers of megakaryocyte differentiation.

[Seroprevalence of Coxiella burnetii and Rickettsia conorii infection in the province of Soria]

BACKGROUND

Determine the antibodies prevalence against Coxiella burnetii and Rickettsia conorii in Soria (Spain).

METHODS

By an indirect immunofluorescence test we examined sera samples for antibodies (IgG, IgM and IgA) against C. burnetii (phase II, formolized antigen) and R. conorii (moroccan strain). The test has been applied to 298 sera (150 men and 148 women) from Soria (Spain). The age of the study population ranged between 2 and 91 years. The results were considered positive when the titres were greater than or equal to 1/80 for C. burnetii and 1/40 for R. conorii.

RESULTS

Antibodies against C. burnetii were present in 20.8% of the examined sera, 8.8% for women (13/148) and 32.7% for men (49/150). We demonstrated titers of antibodies upper to 1/40 in all age groups, and a greater number of positive results in the persons older than 40 years old (p = 0.0001). In all areas we detected positive results and in many of these areas, the positivity was high (38%). We demonstrated positive results against R. conorii in 5% of the people (4.7% for women and 5.3% for men). More than 90% of the positive cases was present in the eastern part of Soria, and in an small area, the positivity was 20%.

CONCLUSIONS

These results confirm a high prevalence of antibodies against C. burnetii in the Soria people, and the existence of R. conorii infection in this area of Spain with a particular distribution. We believe that it is very important to establish an epidemiological surveillance for the detection of clinic cases.