Pharmacokinetics and Metabolism Study of Deep-Sea-Derived Butyrolactone I in Rats by UHPLC-MS/MS and UHPLC-Q-TOF-MS

Butyrolactone I (BTL-I) is a butanolide isolated from the deep-sea-derived fungus, Aspergillus sp. It provides a potential new target for the prevention and treatment of food allergies. This study aimed to investigate the metabolic and pharmacokinetic profile of BTL-I in rats. The metabolic profiles were obtained by UHPLC–Q-TOF-MS. As a result, eleven metabolites were structurally identified, and the proposed metabolic pathways of BTL-I were characterized. The main metabolites were the oxidative and glucuronidative metabolites. In addition, a sensitive UHPLC–MS/MS method was established for the quantitation of BTL-I in rat plasma (LOQ = 2 ng/mL). The method was fully validated and successfully applied to the pharmacokinetic study of BTL-I in rats after oral administration or intravenous administration. The oral bioavailability was calculated as 6.29%, and the maximum plasma concentrations were 9.85 ± 1.54 ng/mL and 17.97 ± 1.36 ng/mL for intravenous and intragastric dosing groups, respectively.

Discovery of Potent Antiallergic Agents Based on an o-Aminopyridinyl Alkynyl Scaffold

Effective therapeutic agents are highly desired for immune-mediated allergic diseases. Herein, we report the design, synthesis, and structure-activity relationship of an o-aminopyridinyl alkyne series as novel orally bioavailable antiallergic agents, which was identified through phenotypic screening. Compound optimization yielded a highly potent compound 36, which effectively suppressed mast cell degranulation in a dose-dependent manner (IC50, 2.54 nM for RBL-2H3 cells; 48.28 nM for peritoneal mast cells (PMCs)) with a good therapeutic index. It also regulated the activation of FcεRI-mediated downstream signaling proteins in IgE/Ag-stimulated RBL-2H3 cells. In addition, 36 exhibited excellent in vivo pharmacokinetic properties and antiallergic efficacy in both passive systemic anaphylaxis (PSA) and house dust mite (HDM)-induced murine models of pulmonary allergic inflammation. Furthermore, preliminary analysis of the kinases profile identified Src-family kinases as potential targets for 36. Compound 36 may serve as a new valuable lead compound for future antiallergic drug discovery.

Bacterial metabolism rescues the inhibition of intestinal drug absorption by food and drug additives

Food and drug products contain diverse and abundant small-molecule additives (excipients) with unclear impacts on human physiology, drug safety, and response. Here, we evaluate their potential impact on intestinal drug absorption. By screening 136 unique compounds for inhibition of the key intestinal transporter OATP2B1 we identified and validated 24 potent OATP2B1 inhibitors, characterized by higher molecular weight and hydrophobicity compared to poor or noninhibitors. OATP2B1 inhibitors were also enriched for dyes, including 8 azo (R-N=N-R') dyes. Pharmacokinetic studies in mice confirmed that FD&C Red No. 40, a common azo dye excipient and a potent inhibitor of OATP2B1, decreased the plasma level of the OATP2B1 substrate fexofenadine, suggesting that FD&C Red No. 40 has the potential to block drug absorption through OATP2B1 inhibition in vivo. However, the gut microbiomes of multiple unrelated healthy individuals as well as diverse human gut bacterial isolates were capable of inactivating the identified azo dye excipients, producing metabolites that no longer inhibit OATP2B1 transport. These results support a beneficial role for the microbiome in limiting the unintended effects of food and drug additives in the intestine and provide a framework for the data-driven selection of excipients. Furthermore, the ubiquity and genetic diversity of gut bacterial azoreductases coupled to experiments in conventionally raised and gnotobiotic mice suggest that variations in gut microbial community structure may be less important to consider relative to the high concentrations of azo dyes in food products, which have the potential to saturate gut bacterial enzymatic activity.

Advances in Chemistry and Bioactivity of Magnoflorine and Magnoflorine-Containing Extracts

The review collects together some recent information on the identity and pharmacological properties of magnoflorine, a quaternary aporphine alkaloid, that is widely distributed within the representatives of several botanical families like Berberidaceae, Magnoliaceae, Papaveraceae, or Menispermaceae. Several findings published in the scientific publications mention its application in the treatment of a wide spectrum of diseases including inflammatory ones, allergies, hypertension, osteoporosis, bacterial, viral and fungal infections, and some civilization diseases like cancer, obesity, diabetes, dementia, or depression. The pharmacokinetics and perspectives on its introduction to therapeutic strategies will also be discussed.

Inhibition of allergen-induced dermal eosinophilia by an oxoeicosanoid receptor antagonist in non-human primates

BACKGROUND AND PURPOSE

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE), acting via the OXE receptor, is unique among 5-lipoxygenase products in its ability to directly induce human eosinophil migration, suggesting its involvement in eosinophilic diseases. To address this hypothesis, we synthesized selective indole-based OXE receptor antagonists. Because rodents lack an OXE receptor orthologue, we sought to determine whether these antagonists could attenuate allergen-induced skin eosinophilia in sensitized monkeys.

EXPERIMENTAL APPROACH

In a pilot study, cynomolgus monkeys with environmentally acquired sensitivity to Ascaris suum were treated orally with the "first-generation" OXE antagonist 230 prior to intradermal injection of 5-oxo-ETE or Ascaris extract. Eosinophils were evaluated in punch biopsy samples taken 6 or 24 hr later. We subsequently treated captive-bred rhesus monkeys sensitized to house dust mite (HDM) allergen with a more recently developed OXE antagonist, S-Y048, and evaluated its effects on dermal eosinophilia induced by either 5-oxo-ETE or HDM.

KEY RESULTS

In a pilot experiment, both 5-oxo-ETE and Ascaris extract induced dermal eosinophilia in cynomolgus monkeys, which appeared to be reduced by 230. Subsequently, we found that the related OXE antagonist S-Y048 is a highly potent inhibitor of 5-oxo-ETE-induced activation of rhesus monkey eosinophils in vitro and has a half-life in plasma of about 6 hr after oral administration. S-Y048 significantly inhibited eosinophil infiltration into the skin in response to both intradermally administered 5-oxo-ETE and HDM.

CONCLUSIONS AND IMPLICATIONS

5-Oxo-ETE may play an important role in allergen-induced eosinophilia. Blocking its effects with S-Y048 may provide a novel therapeutic approach for eosinophilic diseases.

Novel highly potent OXE receptor antagonists with prolonged plasma lifetimes that are converted to active metabolites in vivo in monkeys

BACKGROUND AND PURPOSE

The 5-lipoxygenase product 5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-oxo-ETE), acting through the OXE receptor, is a potent eosinophil chemoattractant that may be an important proinflammatory mediator in eosinophilic diseases such as asthma. We previously identified a series of indole-based OXE receptor antagonists that rapidly appear in the blood following oral administration but have limited lifetimes. The objective of this study was to increase the potency and plasma half-lives of these compounds and thereby identify the optimal candidate for future preclinical studies in monkeys, as rodents do not have an OXE receptor orthologue.

EXPERIMENTAL APPROACH

We synthesized a series of substituted phenylalkyl indoles and compared their antagonist potencies, pharmacokinetics, and metabolism to those of our earlier compounds. The potencies of some of their metabolites were also investigated.

KEY RESULTS

Among the compounds tested, the S-enantiomer of the m-chlorophenyl compound (S-Y048) was the most potent, with an pIC50 of about 10.8 for inhibition of 5-oxo-ETE-induced calcium mobilization in human neutrophils. When administered orally to cynomolgus monkeys, S-Y048 rapidly appeared in the blood and had a half-life in plasma of over 7 hr, considerably longer than any of the other OXE analogues tested. A major hydroxylated metabolite, with a potency close to that of its precursor, was identified in plasma.

CONCLUSION AND IMPLICATIONS

Because of its highly potent antagonist activity and its long lifetime in vivo, S-Y048 may be a useful anti-inflammatory agent for the treatment of eosinophilic diseases such as asthma, allergic rhinitis, and atopic dermatitis.

Population pharmacokinetic modelling of rupatadine solution in 6-11 year olds and optimisation of the experimental design in younger children

AIMS

To optimise a pharmacokinetic (PK) study design of rupatadine for 2-5 year olds by using a population PK model developed with data from a study in 6-11 year olds. The design optimisation was driven by the need to avoid children's discomfort in the study.

METHODS

PK data from 6-11 year olds with allergic rhinitis available from a previous study were used to construct a population PK model which we used in simulations to assess the dose to administer in a study in 2-5 year olds. In addition, an optimal design approach was used to determine the most appropriate number of sampling groups, sampling days, total samples and sampling times.

RESULTS

A two-compartmental model with first-order absorption and elimination, with clearance dependent on weight adequately described the PK of rupatadine for 6-11 year olds. The dose selected for a trial in 2-5 year olds was 2.5 mg, as it provided a Cmax below the 3 ng/ml threshold. The optimal study design consisted of four groups of children (10 children each), a maximum sampling window of 2 hours in two clinic visits for drawing three samples on day 14 and one on day 28 coinciding with the final examination of the study.

CONCLUSIONS

A PK study design was optimised in order to prioritise avoidance of discomfort for enrolled 2-5 year olds by taking only four blood samples from each child and minimising the length of hospital stays.

Caco-2 Permeability Studies and In Vitro hERG Liability Assessment of Tryptanthrin and Indolinone

Tryptanthrin and (E,Z)-3-(4-hydroxy-3,5-dimethoxybenzylidene)indolinone (indolinone) were recently isolated from Isatis tinctoria as potent anti-inflammatory and antiallergic alkaloids, and shown to inhibit COX-2, 5-LOX catalyzed leukotriene synthesis, and mast cell degranulation at low µM to nM concentrations. To assess their suitability for oral administration, we screened the compounds in an in vitro intestinal permeability assay using human colonic adenocarcinoma cells. For exact quantification of the compounds, validated UPLC-MS/MS methods were used. Tryptanthrin displayed high permeability (apparent permeability coefficient > 32.0 × 10(-6) cm/s) across the cell monolayer. The efflux ratio below 2 (< 1.12) and unchanged apparent permeability coefficient values in the presence of the P-glycoprotein inhibitor verapamil (50 µM) indicated that tryptanthrin was not involved in P-glycoprotein interactions. For indolinone, a low recovery was found in the human colon adenocarcinoma cell assay. High-resolution mass spectrometry pointed to extensive phase II metabolism of indolinone (sulfation and glucuronidation). Possible cardiotoxic liability of the compounds was assessed in vitro by measurement of an inhibitory effect on human ether-a-go-go-related gene tail currents in stably transfected HEK 293 cells using the patch clamp technique. Low human ether-a-go-go-related gene inhibition was found for tryptanthrin (IC50 > 10 µM) and indolinone (IC50 of 24.96 µM). The analysis of compounds using various in silico methods confirmed favorable pharmacokinetic properties, as well as a slight inhibition of the human ether-a-go-go-related gene potassium channel at micromolar concentrations.

Absorption and Clearance of Pharmaceutical Aerosols in the Human Nose: Effects of Nasal Spray Suspension Particle Size and Properties

PURPOSE

The objective of this study was to use a recently developed nasal dissolution, absorption, and clearance (DAC) model to evaluate the extent to which suspended drug particle size influences nasal epithelial drug absorption for a spray product.

METHODS

Computational fluid dynamics (CFD) simulations of mucociliary clearance and drug dissolution were used to calculate total and microscale epithelial absorption of drug delivered with a nasal spray pump. Ranges of suspended particle sizes, drug solubilities, and partition coefficients were evaluated.

RESULTS

Considering mometasone furoate as an example, suspended drug particle sizes in the range of 1-5 μm did not affect the total nasal epithelial uptake. However, the microscale absorption of suspended drug particles with low solubilities was affected by particle size and this controlled the extent to which the drug penetrated into the distal nasal regions.

CONCLUSIONS

The nasal-DAC model was demonstrated to be a useful tool in determining the nasal exposure of spray formulations with different drug particle sizes and solubilities. Furthermore, the model illustrated a new strategy for topical nasal drug delivery in which drug particle size is selected to increase the region of epithelial surface exposure using mucociliary clearance while minimizing the drug dose exiting the nasopharynx.

Pharmacokinetics/Pharmacodynamics of Desloratadine and Fluoxetine in Healthy Volunteers

The authors assessed the potential for a pharmacokinetic/pharmacodynamic interaction between desloratadine and fluoxetine. This randomized, placebo-controlled, open-label study was conducted in 54 healthy volunteers. Subjects received 1 of 3 treatments: desloratadine 5 mg plus fluoxetine 20 mg, desloratadine 5 mg plus placebo, or fluoxetine 20 mg plus placebo. Serial electrocardiograms (ECGs) were performed at baseline and day 35. Treatment effects on C(max) and AUC were assessed. During coadministration of desloratadine with fluoxetine, the ratio of the mean log-transformed C(max) and AUC values for desloratadine following concomitant fluoxetine therapy revealed a small increase in C(max) values of 15% (90% confidence interval [CI], 95%-139%) but no increase for AUC values (90% CI, 82%-123%). Corresponding values for 3-OH desloratadine demonstrated small increases in mean log-transformed C(max) and AUC ratios: 17% (90% CI, 100%-136%) and 13% (90% CI, 96%-132%), respectively. Statistical evaluation of the ratio of the mean C(max) and AUC values for fluoxetine following concomitant desloratadine therapy revealed small decreases of 9% (90% CI, 72%-115%) and 11% (90% CI, 69%-113%), respectively. Corresponding values for norfluoxetine demonstrated modest increases in mean log-transformed C(max) and AUC ratios: 22% (90% CI, 100%-139%) and 18% (90% CI, 101%-136%), respectively. Coadministration of desloratadine with a potent inhibitor of CYP2D6 did not result in clinically relevant changes in its pharmacokinetic parameters. Desloratadine administration was not associated with clinically important changes in the pharmacokinetics of fluoxetine, a drug metabolized by CYP2D6. The most common adverse event in all groups was headache (65%). Desloratadine plus fluoxetine caused no significant changes in ECGs or ventricular rate.

Non-clinical pharmacology, pharmacokinetics, and safety findings for the antihistamine bepotastine besilate

SCOPE

The purpose of this review is to examine published non-clinical literature on the antihistamine bepotastine besilate, including pharmacokinetic and pharmacologic properties.

METHODS

Standard literature searches using diverse databases were used to find articles on bepotastine besilate published between 1997 and 2009. Articles primarily described non-clinical data utilized for the development of an oral formulation of bepotastine besilate and were published in Japanese. No publications of non-clinical data for an ophthalmic formulation were found in the database searches.

FINDINGS

Bepotastine besilate is a second-generation antihistamine drug possessing selective histamine H(1) receptor antagonist activity. Bepotastine has negligible affinity for receptors associated with undesirable adverse effects, including histamine H(3), α(1)-, α(2)-, and β-adrenergic, serotonin (5-HT(2)), muscarinic, and benzodiazepine receptors. Bepotastine possesses additional anti-allergic activity including stabilization of mast cell function, inhibition of eosinophilic infiltration, inhibition of IL-5 production, and inhibition of LTB(4) and LTD(4) activity. Bepotastine in vivo dose-dependently inhibited the acceleration of histamine-induced vascular permeability and inhibited homologous passive cutaneous anaphylaxis in guinea pig studies. In mouse models of itching, oral bepotastine inhibited the frequency and duration of scratching behavior. Multiple in vivo animal toxicology studies have demonstrated bepotastine to be safe with no significant effects on respiratory, circulatory, central nervous, digestive, or urinary systems. The concentration of bepotastine after intravenous administration of bepotastine besilate (3 mg/kg) in rats was lower in the brain than in plasma, predicting reduced sedation effects compared to older antihistamines.

CONCLUSION

Non-clinical in vitro and in vivo studies have demonstrated bepotastine is a histamine H(1) receptor antagonist with favorable pharmacokinetic, pharmacologic, safety, and antihistamine properties as well as operating on other pathways leading to allergic inflammation beyond those directly involving the histamine H(1) receptor.

Grapefruit juice--drug interactions: importance for pharmacotherapy

In spite of known health benefits of grapefruit juice, its consumption in combination with drugs requires caution. The drugs most susceptible to pharmacokinetic interactions with clinical significance are those with narrow therapeutic index and low bioavailability due to important first-pass metabolism. Most vulnerable populations are elderly, cirrhotics, subjects with genetic polymorphisms and individuals taking other CYP3A4 inhibitors. The major drug classes that have been reported to present interactions with grapefruit juice are antiallergics, antibiotics, antimalaria drugs, anxiolytics, calcium channel blockers, HIV protease inhibitors, HMG-CoA reductase inhibitors; the degree of pharmacokinetic interaction varies among the compounds of the same class.

Use of mometasone furoate administered via a dry powder inhaler in the treatment of asthma

BACKGROUND

Inhaled corticosteroids (ICSs) are effective controller medications that treat the chronic inflammation of asthma. The goal of asthma treatment is to improve lung function, symptoms, and the ability to perform daily activities, while decreasing the risk of exacerbations. Mometasone furoate delivered via a dry powder inhaler (MF-DPI) is indicated for once-daily maintenance treatment of asthma in patients as young as 4 years old.

OBJECTIVE

To review the quality of evidence for the clinical efficacy and safety of MF-DPI in both adults and children in the context of grading systems for guideline recommendations. Publications were identified by searching PubMed (MEDLINE) for 'mometasone furoate AND dry powder inhaler AND asthma' in any field with search limits for publications from 1 January 1995 to 1 August 2008.

FINDINGS

MF-DPI has been evaluated in 21 randomized, double-blind, active- or placebo-controlled trials in adults with asthma. Clinical trials investigating the efficacy in patients previously treated with only short-acting beta(2)-agonists, other ICSs, or oral corticosteroids revealed that MF-DPI is efficacious in these populations. The results of a pooled analysis of ten trials and individual results of three long-term safety trials indicate that MF-DPI is well-tolerated with minimal adverse events. Six clinical trials of MF-DPI have been completed in children. Studies of pediatric patients treated with approved doses of MF-DPI indicate that children previously maintained on twice-daily treatment of other ICSs showed improvements in lung function, health-related quality of life, and rescue medication use. In addition, there is no effect on growth velocity or the hypothalamic-pituitary-adrenal axis. In both adults and children, once-daily dosing of MF-DPI has been demonstrated to be as efficacious as twice-daily dosing.

CONCLUSION

The findings of this single-database review are that once-daily MF-DPI is efficacious and safe in both adults and children with asthma.

Validation and application of a liquid chromatography-tandem mass spectrometric method for quantification of the drug transport probe fexofenadine in human plasma using 96-well filter plates

A rapid method to determine fexofenadine concentrations in human plasma using protein precipitation in 96-well plates and liquid chromatography-tandem mass spectrometry was validated. Plasma proteins were precipitated with acetonitrile containing the internal standard fexofenadine-d6, mixed briefly, and then filtered into a collection plate. The resulting filtrate was diluted and injected onto a Phenomenex Gemini C18 (50 mm x 2.0 mm, 5 microm) analytical column. The mobile phase consisted of 0.1% formic acid, 5 mM ammonium acetate in deionized water and methanol (35:65, v/v). The flow rate was 0.2 ml/min and the total run time was 2 min. Detection of the analytes was achieved using positive ion electrospray ionization and high resolution multiple reaction monitoring mode (H-SRM). The linear standard curve ranged from 1 to 500 ng/ml and the precision and accuracy (intra- and inter-run) were within 4.3% and 8.0%, respectively. The method has been applied successfully to determine fexofenadine concentrations in human plasma samples obtained from subjects administered a single oral dose of fexofenadine. The method is rapid, sensitive, selective and directly applicable to human pharmacokinetic studies involving fexofenadine.

Molecular and clinical pharmacology of intranasal corticosteroids: clinical and therapeutic implications

Intranasal corticosteroids (INSs) are effective treatments for allergic rhinitis, rhinosinusitis, and nasal polyposis. In recent years, increased understanding of corticosteroid and glucocorticoid receptor pharmacology has enabled the development of molecules designed specifically to achieve potent, localized activity with minimal risk of systemic exposure. Pharmacologic potency studies using affinity and other assessments have produced similar rank orders of potency, with the most potent being mometasone furoate, fluticasone propionate, and its modification, fluticasone furoate. The furoate and propionate ester side chains render these agents highly lipophilic, which may facilitate their absorption through nasal mucosa and uptake across phospholipid cell membranes. These compounds demonstrate negligible systemic absorption. Systemic absorption rates are higher among the older corticosteroids (flunisolide, beclomethasone dipropionate, triamcinolone acetonide, and budesonide), which have bioavailabilities in the range of 34-49%. Studies, including 1-year studies with mometasone furoate, fluticasone propionate, and budesonide that evaluated potential systemic effects of INSs in children have generally found no adverse effects on hypothalamic-pituitary-adrenal axis function or growth. Clinical data suggest no significant differences in efficacy between the INSs. Theoretically, newer agents with lower systemic availability may be preferable, and may come closer to the pharmacokinetic/pharmacologic criteria for the ideal therapeutic choice.

Disposition of loratadine in healthy volunteers

The absorption, metabolism and excretion of carbon-14-labeled loratadine (LOR, SCH 29851, Claritin) administered orally to healthy male volunteers were evaluated. Following a single oral 10-mg dose of [(14)C]LOR ( approximately 102 microCi), concentrations of LOR and desloratadine (DL; a pharmacologically active descarboethoxy metabolite of LOR) were determined in plasma. Metabolites in plasma, urine and feces were characterized using a liquid chromatography-mass spectrometry system (LC-MS) connected in line with a flow scintillation analyzer (FSA). Maximum plasma LOR and DL concentrations were achieved at 1.5 h and 1.6 h, respectively; thus, LOR was rapidly absorbed but also rapidly metabolized as indicated by these similar t(max) values. Metabolite profiles of plasma showed that LOR was extensively metabolized via descarboethoxylation, oxidation and glucuronidation. Major circulating metabolites included 3-hydroxy-desloratadine glucuonide (3-OH-DL-Glu), dihydroxy-DL-glucuronides, and several metabolites resulting from descarboethoxylation and oxidation of the piperidine ring. LOR was completely metabolized by 6 h post-dose. LOR-derived radiocarbon was excreted almost equally in the urine (41%) and feces (43%). About 13% of the dose was eliminated in the urine as 3-OH-DL-Glu. DL accounted for less than 2% of the dose recovered in the urine and only trace amounts of LOR were detected. 3-OH-DL was the major fecal metabolite ( approximately 17% of the dose). The combined amount of 5- and 6-hydroxy-DL contributed to an additional 10.7% of the dose in feces. Approximately 5.4% and 2.7% of the dose were excreted in the feces as unchanged drug and DL, respectively.

[HPLC-MS/MS method for determination of sodium cromoglycate concentration in human plasma and its pharmacokinetics]

The study established an HPLC-MS/MS method for determining the concentrations of sodium cromoglycate in human plasma and evaluated the pharmacokinetics of nasal drops and nasal spray. A C18 column was used to separate sodium cromoglycate in plasma with a mobile phase of a mixture of ammonium-methanol (involves 50% acetonitrile) (15:85) at a flow rate of 0.4 mL x min(-1). Electronic spray ionization (ESI) and multiple-reaction monitoring (MRM) were used for the determination of sodium cromoglycate in human plasma. The linear range of the standard curve of sodium cromoglycate was from 0.3 to 20 ng x mL(-1), and the minimum concentration of detection was 0.3 ng x mL(-1). The extraction recovery was more than 94.1%, intra-day and inter-day RSD were less than 14.3%. After a single dose of sodium cromoglycate, the main pharmacokinetic parameters of nasal spray and nasal drops were as follows, T(1/2)(1.82 +/- 0.54) h, (1.59 +/- 0.52) h; Tmax (0.47 +/- 0.12) h, (0.44 +/- 0.15) h; Cmax, (9.79 +/- 4.66) ng x mL(-1), (10.88 +/- 4.05) ng x mL(-1); AUC(0-5 h)(11.52 +/- 3.46) ng x mL(-1) x h x h, (12.63 +/- 4.23) ng x mL(-1) x h, Fr(93.6 +/- 13.8)%. The method is sensitive, rapid and accurate. It is suitable for therapeutic drug monitoring and human pharmacokinetic study of sodium cromoglycate.

Cetirizine in horses: Pharmacokinetics and pharmacodynamics following repeated oral administration

The pharmacokinetics of the histamine H(1)-antagonist cetirizine and its effect on histamine-induced cutaneous wheal formation were studied in six healthy horses following repeated oral administration. After three consecutive administrations of cetirizine (0.2 mg/kg body weight, bw) every 12h, the trough plasma concentration of cetirizine was 16+/-4 ng/mL (mean+/-SD) and the wheal formation was inhibited by 45+/-23%. After four additional administrations of cetirizine (0.4 mg/kg bw) every 12 h, the trough plasma concentration was 48+/-15 ng/mL and the wheal formation was inhibited by 68+/-11%. The terminal half-life was about 5.8 h. A pharmacokinetic/pharmacodynamic link model showed that the maximal inhibition of wheal formation was about 95% and the EC(50) about 18 ng/mL. It is concluded that cetirizine in doses of 0.2-0.4 mg/kg bw administered at 12 h intervals exhibits favourable pharmacokinetic and pharmacodynamic properties without causing visible side effects, and the drug may therefore be a useful antihistamine in equine medicine.

Onset of action of ciclesonide once daily in the treatment of seasonal allergic rhinitis

Ciclesonide is an intranasal corticosteroid approved for the treatment of allergic rhinitis. We conducted a randomized, double-blind, parallel-group, placebo-controlled study to evaluate the time to onset of action of ciclesonide 200 microg once daily in 502 adults with seasonal allergic rhinitis of at least 2 years' duration. To trigger immunologic priming, patients underwent between one and five priming sessions with exposure to 3,500 grains/m(3) (+/-500) of ragweed pollen in an environmental exposure chamber. The criteria for a successful priming session were a patient-assessed instantaneous total nasal symptom score of at least 6 (of a possible 12) and a nasal congestion or rhinorrhea score of at least 2 (of a possible 3) 90 minutes after allergen exposure during at least two consecutive priming sessions. Patients were then randomly assigned to receive either a single dose of ciclesonide 200 microg (n = 251) or placebo (n = 251) administered intranasally. The difference in the change from baseline total nasal symptom scores in the two groups was assessed hourly for 12 hours after administration. Onset of action was determined to have taken place the first time that the effects of ciclesonide, as reflected in the total nasal symptom score, were significantly greater than those of placebo at a particular hourly assessment, provided that the subsequent hourly assessment also showed a statistically significant difference. The onset of action of ciclesonide occurred within 1 hour of administration (p = 0.01 vs. placebo), and the significant difference in total nasal symptom scores between ciclesonide and placebo was maintained through post-treatment hour 12 (p = 0.018).

Rupatadine in allergic rhinitis and chronic urticaria

Histamine is the primary mediator involved the pathophysiology of allergic rhinitis and chronic urticaria, and this explains the prominent role that histamine H(1)-receptor antagonists have in the treatment of these disorders. However, histamine is clearly not the only mediator involved in the inflammatory cascade. There is an emerging view that drugs which can inhibit a broader range of inflammatory processes may prove to be more effective in providing symptomatic relief in both allergic rhinitis and chronic urticaria. This is an important consideration of the Allergic Rhinitis and its Impact on Asthma (ARIA) initiative which provides a scientific basis for defining what are the desirable properties of an 'ideal' antihistamine. In this review of rupatadine, a newer dual inhibitor of histamine H(1)- and PAF-receptors, we evaluate the evidence for a mechanism of action which includes anti-inflammatory effects in addition to a powerful inhibition of H(1)- and PAF-receptors. We assess this in relation to the clinical efficacy (particularly the speed of onset of action) and safety of rupatadine, and importantly its longer term utility in everyday life. In clinical trials, rupatadine has been shown to be an effective and well-tolerated treatment for allergic rhinitis and chronic idiopathic urticaria (CIU). It has a fast onset of action, producing rapid symptomatic relief, and it also has an extended duration of clinical activity which allows once-daily administration. In comparative clinical trials rupatadine was shown to be at least as effective as drugs such as loratadine, cetirizine, desloratadine and ebastine in reducing allergic symptoms in adult/adolescent patients with seasonal, perennial or persistent allergic rhinitis. Importantly, rupatadine demonstrated no adverse cardiovascular effects in preclinical or extensive clinical testing, nor negative significant effects on cognition or psychomotor performance (including a practical driving study). It improved the overall well-being of patients with allergic rhinitis or CIU based on findings from quality of life questionnaires and patient global rating scores in clinical trials. Thus, rupatadine is a recently introduced dual inhibitor of histamine H(1)- and PAF-receptors, which has been shown to be an effective and generally well-tolerated treatment for allergic rhinitis and chronic urticaria. It possesses a broader profile of anti-inflammatory properties inhibiting both inflammatory cells and a range of mediators involved in the early- and late-phase inflammatory response, but the clinical relevance of these effects remain to be clarified.

[Role of ciclesonide in asthma therapy]

Ciclesonide is a modern inhaled corticosteroid registered for asthma treatment. It is delivered as an inactive prodrug and undergoes conversion to an active metabolite in the lungs. Ciclesonide has been formulated as an aerosol solution in a metered dose inhaler with hydrofluoralkane which characterizes a high deposition rate over 50%. Lots of clinical trials show that ciclesonide is effective in asthma control in a wide range of doses from 40 do 1280 mug/day in a dose-dependent manner. It reduces the need for systemic corticosteroids. Due to the unique pharmacokinetics, ciclesonide has a favorable safety profile both in the low and in the high doses. It is recommended by GINA in every case when the glucocorticosteroids are indicated, as a drug with reduced local and systemic side effects. This article is a review of clinical trials on efficacy and safety of ciclesonide as the resume of authors' clinical experience.

Some pharmacokinetic aspects of the lipophilic terfenadine and zwitterionic fexofenadine in humans

Fexofenadine, an active metabolite of the second-generation histamine H1 receptor antagonist (antihistamine) terfenadine, does not have the disadvantage of QT prolongation. In addition, unlike first-generation antihistamines, it is associated with few CNS adverse effects. Chemically, fexofenadine has a zwitterionic structure that makes it an interesting molecule for use as an oral drug. Fexo-fenadine has negligible hepatic metabolism in humans, and is recovered mainly in the faeces in an unchanged form after oral administration. The absolute oral bioavailability of fexofenadine in humans is not known because of a lack of studies of intravenous administration of this agent. Its apparent elimination half-life (t1/2) ranges from 3 to 17 hours and is highly dependent on study design, i.e. the length of blood sampling. This large discrepancy might be associated with a 'flip-flop' phenomenon caused by slow absorption of the zwitterionic molecule. This review summarises the available literature related to the absorption, elimination and excretion of fexofenadine and terfenadine. Based on these data, the volume of distribution, t1/2 and oral bioavailability of fexofenadine in humans are estimated. Understanding these pharmacokinetic aspects of this drug might be very useful for medicinal chemists utilising fexofenadine/terfenadine as an example for designing zwitterionic compounds to combat cardiotoxicity and other issues related to basic and lipophilic molecules.

RP-HPLC study of resveratrol derivative (BTM-0512) in rat plasma and tissue distribution

This paper described a rapid and sensitive HPLC method to analyze (E)-3,5,4'-trimethoxystilbene (BTM-0512) in rat plasma and tissues. The analysis used a BDS Hypersil C18 analytical column (250 mm x 4.6 mm ID, 5 microm) and acetonitrile/water as the mobile phase. The UV detection wavelength was 319 nm. Proteins were precipitated with acetonitrile and diethylstilbestrol as internal standard. The method was validated according to State Food and Drug Administration of China and ICH of Technical Requirements for Registration of Pharmaceuticals for Human Use Guidelines. The limit of detection (S/N: 3/1) for BTM-0512 was 0.005 microg x mL(-1) for plasma. The method performances were shown to be selective for BTM-0512 and the linearity of the assay method was up to 10.0 microg x mL(-1) and 40.0 microg x g(-1) for plasma and tissues, respectively. At 0.1, 1 and 5 microg x mL(-1) (n=5), intraday and interday precision values (% RSD) were in the range of 2.6% - 5.1% and 2.4% - 4.8%, respectively. Mean accuracy and absolute recoveries of BTM-0512 ranged from 95.3% - 100.1% and 95.9% - 100.9% for plasma and tissues, respectively. This method can be quite useful for BTM-0512 pharmacokinetic and tissue distribution studies, for purpose which multiple plasma and tissue samples can be analyzed quickly with high reproducibility.

Microdose clinical trial: Quantitative determination of fexofenadine in human plasma using liquid chromatography/electrospray ionization tandem mass spectrometry

A sample treatment procedure and high-sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for quantitative determination of fexofenadine in human plasma was developed for a microdose clinical trial with a cold drug, i.e., a non-radioisotope-labeled drug. Fexofenadine and terfenadine, as internal standard, were extracted from plasma samples using a 96-well solid-phase extraction plate (Oasis HLB). Quantitation was performed on an ACQUITY UPLC system and an API 5000 mass spectrometer by multiple reaction monitoring. Chromatographic separation was achieved on an XBridge C18 column (100 mm x 2.1 mm i.d., particle size 3.5 microm) using acetonitrile/2 mM ammonium acetate (91:9, v/v) as the mobile phase at a flow rate of 0.6 ml/min. The analytical method was validated in accordance with the FDA guideline for validation of bioanalytical methods. The calibration curve was linear in the range of 10-1000 pg/ml using 200 microl of plasma. Analytical method validation for the clinical dose, for which the calibration curve was linear in the range of 1-500 ng/ml using 20 microl of plasma, was also conducted. Each method was successfully applied for making determinations in plasma using LC/ESI-MS/MS after administration of a microdose (100 microg solution) and a clinical dose (60 mg dose) in eight healthy volunteers.

Azelastine hydrochloride: a review of pharmacology, pharmacokinetics, clinical efficacy and tolerability

INTRODUCTION

Azelastine hydrochloride (Astelin) nasal spray 0.1% solution is a second-generation intranasal antihistamine available in the US for treatment of both seasonal allergic rhinitis (SAR) and nonallergic vasomotor rhinitis (VMR).

SCOPE

Searches of journal articles including the title word 'azelastine' from 1979 through the present were conducted by the product manufacturer primarily through Medline and EMBASE but also included, at various times, Dialog, Biosis, Toxline, and Diogenes (an adverse-event database). One limitation of the present review is that it could not exclude the possibility of publication bias, whereby findings from smaller studies and/or trials with negative findings may not have been published.

FINDINGS

Azelastine is a phthalazinone derivative with H(1)-receptor binding approximately tenfold greater than chlorpheniramine on a milligram-per-milligram basis. Azelastine has demonstrated a wide range of pharmacologic effects on chemical mediators of inflammation including leukotrienes, kinins, and platelet activating factor in vitro and in vivo. The molecule also has been shown to downregulate intercellular adhesion molecule-1 expression and to reduce inflammatory cell migration in patients with rhinitis. Well-controlled studies in SAR and VMR demonstrated that azelastine nasal spray improves nasal symptoms of rhinitis, including congestion and postnasal drip, and has a rapid onset of action that appears likely due to topical activity. Azelastine nasal spray has demonstrated greater efficacy when used in combination with fluticasone propionate nasal spray when compared to either agent alone, and this combination may provide benefit for patients with moderate-to-severe rhinitis. Bitter taste is the most common side effect associated with azelastine nasal spray and this problem can be mitigated by the dosing technique recommended by the manufacturer in the product labeling. The incidence of somnolence also may be reduced with the recommended administration technique.

CONCLUSIONS

Azelastine is an effective, rapid-acting, and well-tolerated second-generation antihistamine that improves nasal symptoms associated with SAR and VMR. Clinical studies demonstrated that azelastine nasal spray can improve symptoms of SAR in patients who remained symptomatic after treatment with oral antihistamines and that azelastine nasal spray in combination with fluticasone nasal spray provided significantly (p < 0.05) greater relief than either agent alone in patients with SAR.

Long-term safety of fluticasone furoate nasal spray in adults and adolescents with perennial allergic rhinitis

BACKGROUND

Fluticasone furoate is a novel-enhanced affinity glucocorticoid and its long-term safety must be assessed. This study was designed to assess the safety and tolerability of 12-month intranasal administration of fluticasone furoate in adult and adolescent patients with perennial allergic rhinitis (PAR).

METHODS

In this randomized, double-blind, placebo-controlled, parallel-group study, 806 patients with PAR were randomized to once daily (od) fluticasone furoate nasal spray 110 microg (n = 605) or vehicle placebo nasal spray (n = 201) for 12 months, following a 7- to 14-day screening period. Safety was assessed by monitoring adverse events (AEs), 24-h urinary cortisol excretion, nasal and ophthalmic examinations, electrocardiograms and clinical laboratory tests. Plasma concentrations of fluticasone furoate were determined from blood samples.

RESULTS

Fluticasone furoate was well tolerated. The incidence of most AEs was similar to that observed with placebo, with the exception of epistaxis, which was more frequently reported on active treatment. There were no clinically meaningful differences between fluticasone furoate and placebo in terms of safety assessments, including mean changes in ophthalmic parameters and 24-h urine cortisol excretion. Plasma concentrations of fluticasone furoate were not quantifiable in the majority of patients following intranasal administration.

CONCLUSIONS

Long-term (12-month) administration of fluticasone furoate 110 microg od revealed an AE profile typical of the intranasal corticosteroid class in both adult and adolescent patients with PAR, with no evidence of clinically relevant systemic corticosteroid exposure.

Skin permeation of ketotifen applied from stick-type formulation

A stick-typed long lasting device for both transdermal and topical drug delivery has been developed. Ketotifen fumarate (KT) was used as a model drug. The effect of a variety of permeation enhancers was investigated using hairless mouse skin in vitro. Polyoxyethylene oleyl ether (POE), among the enhancers used, most enhanced the skin permeation of KT. The permeation enhancement was mainly due to the increase in the drug solubility in the stratum corneum and the resulting increase in the partition coefficient. The rate of skin permeation of KT was approximately proportional to the loading dose of the drug.

Duration of Action of Topical Antiallergy Drugs in a Guinea Pig Model of Histamine-Induced Conjunctival Vascular Permeability

The topical application of 0.1% olopatadine has been shown to provide significant attenuation of histamine-induced conjunctival vascular permeability (CVP) within 5 min and for as long as 24 h following a topical administration. The duration of the action of olopatadine was compared to that of epinastine, azelastine, and ketotifen. Male Hartley outbred guinea pigs (weighing 250-300 g) were administered a drug or vehicle as single O.D. topical drops, at times ranging from 4 to 24 h prior to histamine challenge. One (1) h prior to histamine challenge, the animals were administered 1 mL of Evans blue dye (1 mg/mL) through the marginal ear vein. Histamine (300 ng) was administered by a subconjunctival injection, and the guinea pigs were sacrificed 30 min later. CVP was assessed as the area and color intensity stained with Evans blue dye. The potencies of each drug were determined by calculating a 50% effective dose (ED(50)) for the inhibition of vascular leakage, compared to vehicle treatment, at each time point. Olopatadine was the only compound tested that was significantly effective 16 h following a single topical application. The ED(50) for olopatadine at 16 h was 0.031%. Epinastine, azelastine, and ketotifen were only significantly effective for up to 4 h. Olopatadine exhibited the longest duration of action for inhibition of histamine-induced vascular permeability in guinea pigs of any topical antiallergic drug tested. Concentrations of olopatadine, which provided a greater than 50% inhibition of the histamine-induced vascular response, were consistently less than 0.1% over a 16-h pretreatment interval.

Improvement of atopic dermatitis in NC/Nga mice by topical application of CpG phosphodiester-ODN

Atopic dermatitis (AD) is a chronic inflammatory skin disease with pruritic and eczematous lesions characterized by increased total IgE level, inflammatory cell infiltration, and the elevated expression of Th2 cytokines. Synthetic oligodeoxynucleotides containing unmethylated CpG dinucleotides are known to have immunostimulatory activities in mice and to convert from Th2 to Th1 immune responses in AD. Previous work has shown clinical effectiveness of CpG phosphorothioate-ODN in AD mice model. However, due to longer in vivo half-life and the possibility of causing unwanted side effects, therapeutic use of CpG phosphorothioate-ODN can be limited. Thus, we investigated the efficacy of CpG phosphodiester-ODN with a novel sequence in NC/Nga mice. Topical application of phosphodiester-ODN penetrated rapidly from epidermis to the lymph nodes, accompanied by reduced infiltration of inflammatory cells and decreased number of cells expressing cytokines such as IL-4, IL-10 and IFN-gamma. Furthermore, the expression of IFN-gamma was reduced in the CpG ODNs-treated NC/Nga mice while the expression of IL-12p40 was increased, suggesting stimulation of Th1 immune response. The expression of IL-10 was strongly reduced, which meant the suppression of Th2 immune response in NC/Nga mice, accompanied by reduced level of IgE and IgG1, but increased level of IgG2a in sera. Since phosphodiester-ODN has been shown to cause minimum side effect comparing its phosphorothioate counterpart, it is proposed to become a new therapeutic modality for AD.

Absolute Bioavailability of Intranasal Fluticasone Furoate in Healthy Subjects

BACKGROUND

Fluticasone furoate (drug code GW685698) is an enhanced-affinity glucocorticoid that has been developed for the treatment of allergic rhinitis.

OBJECTIVES

The objectives of this study were to estimate the absolute bioavailability of fluticasone furoate nasal spray and to describe the intranasal (IN) and IV pharmacokinetics of fluticasone furoate in healthy subjects.

METHODS

This was a single-center, randomized, open label, 2-period crossover study. Healthy male and female subjects were randomized to receive supra-therapeutic doses of fluticasone furoate 880 microg IN qSh for 10 doses in 1 treatment period, and a single IV dose of 250 pg fluticasone furoate given as an infusion over 20 minutes in the other treatment period. Each treatment period was separated by a 4- to 5-day washout period. Blood sampling was carried out over 8 hours following the final IN dose and 24 hours following the IV dose to determine plasma fluticasone furoate concentrations. Plasma samples were analyzed for fluticasone furoate using online solid-phase extraction with high-performance liquid chromatography with tandem mass-spectrometric detection. The lower limit of quantification was 10 pg/mL. The sample size was based primarily on logistical considerations. Sample-size sensitivity was assessed by estimating the 90% CI for the absolute bioavailability of IN fluticasone furoate, based on different estimated bioavailabilities and within-subject SDs. The following pharmacokinetic parameters were derived: IN administration: AUC from time 0 to the end of the dosing interval (AUC(0-tau)), AUC(0-t), C(max), and T(max); IV administration: AUC(0-infinity), AUC(0-t), t(1/2), C(max), T(max), total systemic clearance, and volume of distribution at steady state.

RESULTS

A total of 16 subjects were included in the study. Their mean age was 27.8 years (range, 19-45 years), and their mean body weight was 72.84 kg (range, 55.3-97.2 kg). The geometric mean AUC(0-tau) for 880 microg IN was 74.9 pg x mL/h and geometric mean AUC(0-infinity) for 250 microg IV was 4259 pg x mL/h. The geometric mean of the absolute bioavailability of fluticasone furoate nasal spray in these healthy subjects was 0.50% (90% CI, 0.34%-0.74%). The administration of large doses by the IN route did not elicit clinical concern. Three (19%) of 16 subjects reported adverse events (AEs) during the IN administration period, with 2 subjects experiencing dizziness and 1, toothache. Five (31%) subjects reported AEs during the IV administration period, with 3 subjects experiencing infusion-site or IV catheter-related events; 1 subject, dizziness; and 1 subject, headache.

CONCLUSIONS

The geometric mean of the absolute bioavailability of fluticasone furoate 880 microg IN qSh for 10 doses in these healthy subjects was low--0.50%.

Peripheral and central H1 histamine receptor occupancy by levocetirizine, a non-sedating antihistamine; a time course study in the guinea pig

BACKGROUND AND PURPOSE

The H(1) receptor occupancy (H1RO) in brain is an indicator of central side effects of antihistamines. Here, we determined the kinetics of central and peripheral H1RO by levocetirizine in relation to its brain and plasma concentration, and investigated the role of the blood-brain barrier in any delay in brain H1RO.

EXPERIMENTAL APPROACH

Concentration-time profiles in plasma and brain were obtained after 0.1 and 1 mg kg(-1) oral doses of levocetirizine in guinea pigs. H1RO in brain was measured ex vivo using [3H]-mepyramine and, in the periphery, by measuring the degree of inhibition of histamine-induced contractions of isolated guinea pig ileum.

KEY RESULTS

The concentration-time profile of levocetirizine indicated lower levels (partition coefficient, K(p)=0.06-0.08), higher t(max) (2-4 h vs 1-1.5 h) and longer terminal half-life (4-5.6 h vs 2.1-2.8 h) in brain than plasma. The H1RO at 0.1 and 1 mg kg(-1) were 75% and 97%, respectively, at 1 hr in the periphery and, in the brain, were <20% and 28-67% respectively, at all time points studied. Brain H1RO vs plasma concentrations profile showed a delay, but not when compared to brain concentrations.

CONCLUSIONS AND IMPLICATIONS

This study demonstrates an effective peripheral antihistamine effect of levocetirizine without central adverse effects at the dose close to human therapeutic dose. The slow increase in H1RO in the brain with time was caused by slow blood-brain barrier transport of levocetirizine. This demonstrates the importance of measuring time course of brain H1RO in relation to brain concentrations of drugs.

BIOEQUIVALENCE OF TWO FEXOFENADINE FORMULATIONS IN HEALTHY HUMAN VOLUNTEERS AFTER SINGLE ORAL ADMINISTRATION

AIM

A randomized, two-way, crossover, bioequivalence study was conducted in 25 fasting, healthy, male volunteers to compare two brands of fexofenadine 180 mg tablets, FEXOFENADINE 180 mg Film Tablet (Drogsan A.S., Ankara, Turkey) as test and Telfast 180 mg Tablet (Aventis Pharma, Frankfurt am Main, Germany) as a reference product.

METHOD

One tablet of either formulation was administered after 10 h of overnight fasting. After dosing, serial blood samples were collected during a period of 48 hours. Plasma samples were analysed for fexofenadine by a validated HPLC method. The pharmacokinetic parameters AUC(0-48), AUC(0-alpha), C(max), T(max), K(el), T(1/2), and CL were determined from plasma concentration-time profiles for both formulations and were compared statistically.

RESULTS AND CONCLUSIONS

The analysis of variance (ANOVA) did not show any significant difference between the two formulations and 90% confidence intervals (CI) fell within the acceptable range, satisfying the bioequivalence criteria of the FDA. Based on these statistical inferences it was concluded that the two brands exhibited comparable pharmacokinetics profiles and that Drogsan's Fexofenadine is equivalent to Telfast of Aventis Pharma, Frankfurt am Main, Germany.

Evaluation of Human Pharmacokinetics, Therapeutic Dose and Exposure Predictions Using Marketed Oral Drugs

In this article approaches to predict human pharmacokinetics (PK) are discussed and the capability of the exemplified methodologies to estimate individual PK parameters and therapeutic dose for a set of marketed oral drugs has been assessed. For a set of 63 drugs where the minimum efficacious concentration (MEC) and human PK were known, the clinical dose was shown to be well predicted or in some cases over-estimated using a simple one-compartment oral PK model. For a subset of these drugs, in vitro potency against the primary human targets was gathered, and compared to the observed MEC. When corrected for plasma protein binding, the MEC of the majority of compounds was < or=3 fold over the respective in vitro target potency value. A series of in vitro and in vivo experiments were conducted to predict the human PK parameters. Metabolic clearance was generally predicted well from human hepatocytes. Interestingly, for this compound set, allometry or glomerular filtration rate (GFR) ratio methods appeared to be applicable for renal CL even where CL(renal) > GFR. For approximately 90% of compounds studied, the predicted CL using in vitro-in vivo (IVIV) extrapolation together with a CL(renal) estimate, where appropriate, was within 2-fold of that observed clinically. Encouragingly volume of distribution at steady state (V(ss)) estimated in preclinical species (rat and dog) when corrected for plasma protein binding, predicted human V(ss) successfully on the majority of occasions--73% of compounds within 2-fold. In this laboratory, absorption estimated from oral rat PK studies was lower than the observed human absorption for most drugs, even when solubility and permeability appeared not to be limiting. Preliminary data indicate absorption in the dog may be more representative of human for compounds absorbed via the transcellular pathway. Using predicted PK and MEC values estimated from in vitro potency assays there was a good correlation between predicted and observed dose. This analysis suggests that for oral therapies, human PK parameters and clinical dose can be estimated from a consideration of data obtained from in vitro screens using human derived material and in vivo animal studies. The benefits and limitations of this holistic approach to PK and dose prediction within the drug discovery process are exemplified and discussed.

Clinical efficacy and pharmacokinetic profiles of intranasal and oral cetirizine in a repeated allergen challenge model of allergic rhinitis

BACKGROUND

Intranasal and oral antihistamines are effective in treating allergic rhinitis. Studies comparing these routes of administration of an antihistamine regarding efficacy and pharmacokinetic profile are lacking.

OBJECTIVE

To compare topical and oral routes of administration of cetirizine regarding efficacy, plasma exudation, and systemic drug levels in a repeated allergen challenge model of allergic rhinitis.

METHODS

Oral cetirizine dihydrochloride, 10 mg once daily, and topical cetirizine dinitrate in a dose corresponding to 4.4 mg of the dihydrochloride salt twice daily were given to grass pollen-sensitive individuals for 12 days in a double-blind, placebo-controlled, crossover design. Timothy grass pollen allergen challenges were given once daily for 7 days using a nasal spray device. Nasal symptoms and peak inspiratory flow were recorded in the morning, 10 minutes after allergen challenge, and in the evening. The pharmacokinetics of the treatments was monitored in 8 patients. The remaining 28 patients were challenged topically with histamine 12 and 24 hours after the final topical and oral cetirizine doses, respectively. Nasal lavage levels of alpha2-macroglobulin were determined to evaluate histamine-induced mucosal plasma exudation.

RESULTS

During the last 3 days of the repeated allergen challenge model, chronic symptoms were established. Both treatments reduced symptoms 10 minutes after allergen challenge (P < .001 vs placebo). Neither treatment reduced morning and evening symptoms or nasal peak inspiratory flow. Topical, but not oral, cetirizine reduced histamine-induced plasma exudation (P < .01 vs placebo) when systemic drug levels were similar in the 2 treatment regimens.

CONCLUSIONS

Topical and oral cetirizine reduced acute nasal symptoms produced by allergen challenges in patients with established chronic symptoms. There were also antihistaminic effects of topical cetirizine not related to systemic drug levels.

Pharmacokinetic and pharmacodynamic properties of inhaled ciclesonide

Inhaled corticosteroids are recommended first-line therapy for persistent asthma of all severities; however, oropharyngeal and systemic adverse events can be a concern. Inhaled corticosteroids exert their therapeutic and adverse effects by interacting with glucocorticoid receptors within and outside the lungs, respectively. Ciclesonide is a novel inhaled corticosteroid that possesses a unique pharmacokinetic and pharmacodynamic profile. Ciclesonide is inactive itself and converted to its pharmacologically active metabolite, desisobutyryl-ciclesonide, in the target organ, the lungs. Pulmonary activation combined with low oral deposition may minimize oropharyngeal adverse events, and low oral bioavailability, rapid clearance, and high protein binding may reduce systemic exposure. In addition, high pulmonary deposition due to the highly respirable particles, combined with the potential for prolonged lung retention via lipid conjugation, provides for effective therapeutic action.

Review of azelastine nasal spray in the treatment of allergic and non-allergic rhinitis

Azelastine is a potent H(1)-antihistamine, which is available as a topical nasal spray and indicated for both seasonal allergic and non-allergic vasomotor rhinitis. In addition to its antihistaminic effects, it has also been shown to have a number of other potentially important attributes, including effects on cytokines, adhesion molecules and inflammatory cells. Azelastine nasal spray has been shown to benefit patients who have not responded adequately to loratadine and fexofenadine, and is significantly more efficacious than cetirizine and levocabastine in patients with seasonal allergic rhinitis. Given its unique pharmacologic properties and clinical profile, azelastine maintains an important role in the treatment of chronic rhinitis.

[Omalizumab (Xolair). Product description]

Xolair, Omalizumab is a monoclonal antibody targeting the high-affinity receptor binding site on human immunoglobulin E (IgE). Currently, omalizumab has been approved for the treatment of persistent allergic asthma in patients who are poorly controlled with inhaled corticosteroids. However, other allergic disorders may be amenable to treatment with omalizumab because of its ability to inhibit effector functions of IgE. Treatment with omalizumab should be administered by specialists with training in diagnosis and treatment of allergic asthma. The treatment should be withheld if no positive treatment effects are observed after 4 months.

Optimal dose selection of fluticasone furoate nasal spray for the treatment of seasonal allergic rhinitis in adults and adolescents

Efficacy and safety of fluticasone furoate nasal spray, administered using a unique side-actuated device, were evaluated in patients > or =12 years of age with seasonal allergic rhinitis to determine the optimal dose. A randomized, double-blind, parallel-group, placebo-controlled, dose-ranging study was performed on 641 patients who received placebo (n=128) or fluticasone furoate, 55 microg (n=127), 110 microg (n=127), 220 microg (n=129), or 440 microg (n=130), once daily for 2 weeks. Fluticasone furoate was significantly more effective than placebo for mean changes from baseline over the 2-week treatment period in daily reflective total nasal symptom score (primary end point; p < 0.001 each dose vs. placebo), morning predose instantaneous total nasal symptom score (p < 0.001 each dose versus placebo), daily reflective total ocular symptom score (p < or = 0.013 each dose versus placebo), and morning predose instantaneous total ocular symptom score (p < or = 0.019 for three highest doses versus placebo). The onset of action for fluticasone furoate nasal spray versus placebo was observed 8 hours after the first. dose of study medication in the 110 and 440 microg treatment groups (p < or = 0.032). The incidence of adverse events, results of clinical laboratory tests, and changes in 24-hour urinary cortisol values were similar between active treatment groups and placebo. The preliminary profile of fluticasone furoate is that of a rapidly effective therapy that confers 24-hour efficacy for both nasal and ocular symptoms with once-daily dosing. The 110-microg dose was chosen for phase III development because it achieved statistically significant and clinically meaningful results for all efficacy end points and provided the optimal risk-benefit ratio.

How much is too much? Oligosymptomatic presentation after 11.5 g of diphenhydramine

We report the case of a 47-year-old male obese Caucasian patient presenting 2 hours after ingestion of 11.5 g of diphenhydramine. Despite this excessive overdose, he showed only a few hours of impaired consciousness and no further symptoms. A diphenhydramine plasma concentration of 15 352 nmol/L was measured 8 hours after the overdose ingestion. A heterogeneous CYP2D6 extensive metabolizer genotype excludes a pharmacokinetic explanation for this unusually oligosymptomatic presentation. However, the patient suffered from longstanding, refractory depression despite numerous treatment attempts with various drugs, pointing to the possibility of decreased pharmacodynamic responsiveness for therapeutic and toxic effects. Human & Experimental Toxicology (2007) 26, 131-133

Rupatadine

Rupatadine (Rupafin, Rinialer, Rupax, Alergoliber) is a selective oral histamine H(1)-receptor antagonist that has also been shown to have platelet-activating factor (PAF) antagonist activity in vitro. It is indicated for use in seasonal allergic rhinitis (SAR), perennial allergic rhinitis (PAR) and chronic idiopathic urticaria (CIU) in patients aged >/=12 years. Clinical trials show that rupatadine is an effective and generally well tolerated treatment for allergic rhinitis and CIU. It has a rapid onset of action and a prolonged duration of activity. Importantly, it has no significant effect on cognition, psychomotor function or the cardiovascular system. Once-daily rupatadine significantly improves allergic rhinitis symptoms in patients with SAR, PAR or persistent allergic rhinitis (PER) compared with placebo, and provides similar symptom control to that of loratadine, desloratadine, cetirizine or ebastine. In patients with CIU, longer-term use of rupatadine improves CIU symptoms to a greater extent than placebo. It is as well tolerated as other commonly used second-generation H(1)-receptor antagonists. Thus, the introduction of rupatadine extends the range of oral agents available for the treatment of allergic disorders, including allergic rhinitis and CIU.

Inhibition of eosinophilia in vivo by a small molecule inhibitor of very late antigen (VLA)-4

The alpha4beta1 integrin (very late antigen-4, VLA-4) plays an important role in the migration of lymphocytes, monocytes, and eosinophils, but not neutrophils, to sites of inflammation. Pharmacological antagonism of VLA-4 is an attractive prospect for the treatment of predominantly eosinophil mediated diseases such as asthma and allergic rhinitis. We report here on a potent and selective, small molecule VLA-4 inhibitor, (2S)-3-(2', 5'-dichlorobiphenyl-4-yl)-2-({[1-(2-methoxybenzoyl)piperidin-3-yl]carbonyl}amino) propanoic acid, compound 1, and characterize the antagonist activities of this molecule in various cell-based assays and in an animal model of eosinophil migration. Compound 1 inhibited VLA-4/ vascular cell adhesion molecule-1(VCAM-1) interactions with in vitro potencies (IC50 value of 210 nM) in VLA-4-expressing Ramos cells, although the compound did not inhibit cell adhesion to fibronectin via alpha5beta1 integrin (very late antigen-5, VLA-5). Blockade of phorbol-12-myristate-13-acetate (PMA)- or Mn2+-stimulated VLA-4 interactions with compound 1 was observed in human T lymphocytes (IC50 value of 230 nM), human eosinophils (IC50 value of 4.0 microM) and mouse eosinophils (IC50 value of 1.6 microM). Furthermore, compound 1 administered by intraperitoneal injection inhibited eosinophil infiltration in a dose-dependent manner by up to 80% in an air pouch model. These data support the use of small molecule VLA-4 antagonists in the treatment of relevant diseases, such as asthma, atopic dermatitis, or allergic rhinitis.

The Interaction and Compatibility Between a Soft Contact Lens and an Ophthalmic Drug

PURPOSE

To investigate the interaction and compatibility between a soft contact lens (SCL) and an ophthalmic drug.

METHODS

Samples were prepared with the nonionic SCL (groups I and II), the anionic SCL (group IV), and the zwitter ionic SCL (group IV). Chlorpheniramine maleate and sodium cromoglycate were used to measure the drug uptake into the SCL.

RESULTS

The results showed the largest drug uptake into the anionic SCL accompanied with dimensional changes and lower drug uptakes into the nonionic and the zwitter ionic SCL with dimensional stability. The cell permeability of the substances when instilled in the eye over the SCL was also measured. The zwitter ionic SCL allowed cell permeability comparable to that by oral administration.

CONCLUSIONS

These results indicated the possibility for the zwitter ionic SCL as a lens to be worn concomitantly with ophthalmic drug instillation.

Magnetic resonance spectroscopy for measuring the biodistribution and in situ in vivo pharmacokinetics of fluorinated compounds: validation using an investigation of liver and heart disposition of tecastemizole

BACKGROUND AND OBJECTIVE

The study of biodistribution and in situ pharmacokinetics is a challenging, but sometimes very important, aspect of premarketing characterization of drugs. We aimed to develop a non-invasive fluorine magnetic resonance (MR) spectroscopic method for the absolute quantitation of a mono-fluorinated compound and of its metabolites in the heart and liver of healthy subjects for this purpose.

METHOD

We used fluorine MR spectroscopy (MRS) at 4 T (Tesla) and external standardization in an open label multiple-dose study. Twenty-three healthy adult subjects were enrolled in the study. The surface coil localized fluorine MR spectrum was monitored in the heart and liver at baseline and after oral administration of multiple doses of tecastemizole. Steady-state measurements were made at set time points that depended upon dose, and washout measurements were made only on subjects in which in vivo fluorine signal was observed.

RESULTS AND DISCUSSION

At 4 T, under the given experimental conditions, the method had a lower limit of quantitation (LLOQ) of about 2.6 microm and a limit of detection (LOD) of about 0.3 microm for solution state samples (linewidth approximately 15 Hz). The measurement reproducibility was 6.4% using a 50 microm phantom. The effect of MR operator and spectral analyst on the calculated calibration curve slope was small, with inter-rater correlation coefficients of 0.999 and 0.998 respectively. MR signal from fluorine-containing tecastemizole-related moieties was observed in situ only at day 8 in the liver of three of five subjects dosed at 270 mg/day. The average in situ concentration was estimated to be 58+/-22 microm, with an average test-retest reproducibility of 216%. Extrapolating the in vitro results to human measurements, with an approximate linewidth of 250 Hz, predicts in situ LOD and LLOQ values of approximately 6 and 44 microm respectively. However, the human study had a fluorine MRS LOD of approximately 20 microm. The decrease in sensitivity and the increase in variability of the in vivo, in situ measurements compared with the validation study most likely arose from coil placement and incomplete rephasing of the MR signal by the respiratory phase compensation method.

CONCLUSION

The measured concentrations were the lowest ever recorded for a multi-dose exogenous mono-fluorinated compound in the human liver using a validated fluorine MR quantitation method. The proposed non-invasive MR method for studying the biodistribution and in situ pharmacokinetics of mono-fluorinated compounds in the liver and heart should have broader application to the development of non-invasive biomarkers.

Effect of erythromycin on the absorption of fexofenadine in the jejunum, ileum and colon determined using local intubation in healthy volunteers

OBJECTIVE

To investigate the in vivo intestinal absorption mechanism(s) and systemic availability of fexofenadine in the jejunum, ileum and colon in humans.

METHOD

A single dose of fexofenadine hydrochloride (60 mg as solution) was applied under fasting conditions, either alone or directly after a solution of erythromycin lactobionate (corresponding to a dose of 250 mg erythromycin), to the jejunum, ileum and colon in 6 healthy volunteers (3 male and 3 female) using a regional intubation dosing technology (Bioperm AB, Lund, Sweden). A total of 36 fexofenadine administrations were performed. The administration of fexofenadine to the specified location either alone or in combination with erythromycin was conducted in a randomized manner on 2 consecutive days with a 5-day washout period between doses.

RESULTS

The plasma AUC for fexofenadine (mean +/- SEM) was higher (2.7-to 2.3-fold, p < 0.001) after application to the jejunum (1090 +/- 134 h x ng/ml) than to the ileum (404 +/- 102 h x ng/ml) or colon (476 +/- 212 h x ng/ml). No significant differences were found between application to the ileum and colon. The administration of erythromycin affected the absorption rate after jejunal application with a prolonged tmax from a median of 40 min (range 10-90 min) to a median of 3 hours (range 10-180 min) (p = 0.009). A change in tmax was not observed with application to the ileum and colon. The concomitant administration of erythromycin in the jejunum tended to increase the plasma AUC of fexofenadine from 1090 +/- 134 to 1750 +/- 305 h x ng/ml (p = 0.069).

CONCLUSIONS

The systemic availability of fexofenadine was significantly higher after jejunal administration in accordance with a low permeability compound. The effects of erythromycin suggest that absorption of fexofenadine involves an uptake transport in addition to passive diffusion in the jejunum and predominantly passive diffusion in the ileum and colon.

EFFECT OF P-GLYCOPROTEIN ON INTESTINAL ABSORPTION AND BRAIN PENETRATION OF ANTIALLERGIC AGENT BEPOTASTINE BESILATE

The antiallergic agent bepotastine besilate is a nonsedating, second-generation H1-antagonist with high oral absorption and negligible distribution into brain. To clarify the role of P-glycoprotein (P-gp) in the pharmacokinetics of bepotastine, intestinal absorption and brain penetration studies were performed. [(14)C]Bepotastine transport in P-gp-overexpressed LLC-PK1 cells indicated that bepotastine was a substrate of P-gp. The affinity of bepotastine to P-gp estimated by ATPase activity assay was low, with a K(m) value of 1.25 mM. After i.v. administration, the brain/plasma free concentration ratio in mdr1-knockout mice was 3 times higher than that in wild-type mice. The in situ intestinal absorption studies of [(14)C]bepotastine in rats showed a clear regional difference, showing highest permeability at the upper part of small intestine with a decreasing permeability in the descending part of small intestine. The apparent absorption rate constant (ka) of [(14)C]bepotastine in the small intestine was greatly increased by cyclosporin A and verapamil, especially in the distal portion, and the site-specific absorption of [(14)C]bepotastine disappeared. The concentration dependence of ka of [(14)C]bepotastine was observed with a higher ka at higher concentration (20 mM) compared with that at lower concentration (1 microM). In conclusion, bepotastine is a substrate for P-gp, and P-gp clearly limited the brain distribution of bepotastine, whereas the effect of P-gp on intestinal absorption of bepotastine was minimal, presumably because of high membrane permeability at the upper region of small intestine where P-gp is less expressed. Such intestinal absorption property of bepotastine is distinctly different from the low membrane-permeable P-gp substrate fexofenadine.

Transporter-mediated Intestinal Absorption of Fexofenadine in Rats

Both influx and efflux transporters are thought to be involved in the intestinal absorption of fexofenadine. The present study examined the influx transporter-mediated intestinal absorption of fexofenadine in rats, focusing on the role of rat oatp3 (Oatp1a5). The intestinal permeability of fexofenadine was evaluated by means of the Ussing chamber method in the presence of a P-glycoprotein inhibitor to block efflux transport. The permeability of fexofenadine from the mucosal to the serosal side was higher than that from the serosal side to the mucosal side. Transport of fexofenadine was saturable, and was significantly decreased by an organic anion transporting polypeptide (oatp) inhibitor. Furthermore, uptake of fexofenadine by Xenopus oocytes expressing rat oatp3 was significantly greater than that by water-injected oocytes, and the affinity of oatp3 for fexofenadine (Km) was about 60 microM, which is comparable with the value obtained by the Ussing chamber method using rat intestinal tissues. These results indicate that oatp3 plays a role as an influx transporter in the intestinal absorption of fexofenadine in rats.

Liquid chromatographic/tandem mass spectrometric method for the quantitation of tranilast in human plasma

An analytical method for the determination of tranilast in human plasma using tramadol as the internal standard has been developed based on liquid chromatography/tandem mass spectrometry. Sample preparation involved protein precipitation with methanol. Separation by reversed-phase high-performance liquid chromatography using methanol/10 mM ammonium acetate (70: 30, v/v) as mobile phase was complete in a run time of 2.4 min. Detection on a Q TRAP system used multiple reaction monitoring. The method was linear in the range 0.06-20 microg/mL with intra- and inter-day precisions (as relative standard deviation) of 2.2-2.6% and 2.3-2.9%, respectively. Accuracy (as relative error) was <-2.5%. The method was applied in a pharmacokinetic study in healthy volunteers treated with a single 80 mg oral dose of tranilast.

Stereoselective pharmacokinetics of cetirizine in the guinea pig: role of protein binding

PURPOSE

To characterize the pharmacokinetics of cetirizine enantiomers in the guinea pig including protein binding in both the guinea pig and human plasma.

METHODS

Plasma concentrations of cetirizine enantiomers in the guinea pig were determined using a LC-MS/MS method after a short i.v. infusion (1, 2 and 4 mg/kg) of racemic cetirizine. Protein binding was determined using an in vitro equilibrium dialysis technique. A pharmacokinetic model was developed using NONMEM and the differences in pharmacokinetic parameters of levocetirizine and dextrocetirizine were estimated.

RESULTS

The plasma concentration time data of both the enantiomers were best described by a three-compartment pharmacokinetics model. The clearance (CL) of levocetirizine and dextrocetirizine was 1.2 and 2.7 ml/min, respectively, and the volume of distribution at steady state (Vss) was 457 ml and 996 ml, respectively. The fraction unbound (fu) in guinea pig plasma for levocetirizine and dextrocetirizine was 7-10% and 16-21% while in human plasma, it was 8% and 12%, respectively. The factor describing the difference in the pharmacokinetic parameters of the cetirizine enantiomers was estimated to be 2.26.

CONCLUSIONS

Cetirizine pharmacokinetics is stereoselective in the guinea pig. For levocetirizine, fu, CL and Vss were half those of dextrocetirizine, indicating that protein binding is an important factor affecting the pharmacokinetics of cetirizine. The effect of protein binding on the pharmacokinetics of the cetirizine enantiomers could be extrapolated to humans.