Application of the BCS biowaiver approach to assessing bioequivalence of orally disintegrating tablets with immediate release formulations.

The aim of this study was to compare the dissolution profiles of oral disintegrating tablets (ODTs) and immediate release (IR) formulations in order to experimentally validate the regulatory biowaiver scheme (BWS) for biopharmaceutical classification system (BCS) class III drugs. We examined six drugs that show clinical bioequivalence between the ODTs and IR formulations: taltirelin, olopatadine, droxidopa, famotidine, fexofenadine, and hydrochlorothiazide. The dissolution profiles of these drugs were evaluated using the compendium paddle apparatus at pH 1.2 and 6.8. Taltirelin and olopatadine showed very rapid dissolution and met the dissolution criteria in the BWS, whereas droxidopa, famotidine, fexofenadine, and hydrochlorothiazide did not. Furthermore, in the case of famotidine, fexofenadine, and hydrochlorothiazide, the ODTs and IR formulations showed dissimilar dissolution profiles. The dose-to-solubility ratio (D:S) of these drugs was larger than that of the other drugs. The results of this study suggest that extension of the BCS-BWS to ODTs and IR formulations of BCS class III drugs is appropriate. Furthermore, for BCS class III drugs with relatively high D:S, clinical bioequivalence would be achievable even when two formulations showed different dissolution profiles in vitro.

Pharmacokinetic evaluation of olopatadine for the treatment of allergic rhinitis and conjunctivitis.

INTRODUCTION: Olopatadine hydrochloride is an antihistamine and mast cell stabilizer available in three forms, including oral, intranasal and ocular preparations. Most of the practical applications focus on the use of olopatadine for the treatment of allergic rhinitis and conjunctivitis via intranasal and ocular routes. AREAS COVERED: This article was formed from a comprehensive literature search with information taken from meta-analyses, systematic reviews, treatment guidelines and clinical studies on children and adults. Articles that have been selected evaluate the use of intranasal and ocular antihistamines and their role in allergic rhinitis and conjunctivitis. EXPERT OPINION: Olopatadine is significantly more effective than placebos in alleviating the symptoms of allergic rhinitis and conjunctivitis. Olopatadine is a viable alternative and addition to the mainstay therapy of these conditions with intranasal steroids and oral antihistamines. The compliance of the patients would be improved if a once-per-day formulation of olopatadine was developed for intranasal application. The future treatments of allergic rhinitis will probably involve a combination of intranasal antihistamine and steroid because clinical trials have demonstrated an improved efficacy without a significant increase in adverse effects.

Olopatadine nasal spray for the treatment of seasonal allergic rhinitis in patients aged 6 years and older.

IMPORTANCE OF THE FIELD: Allergic rhinitis is an IgE-mediated condition that produces inflammation of the mucosa of the nose, paranasal sinuses and, frequently, of the ocular conjunctiva. Allergic rhinitis causes a significant disease burden in terms of quality of life, lost productivity and medical treatment costs. One of the newest treatments approved by the FDA is Patanase (olopatadine hydrochloride) Nasal Spray, 665 microg/spray (OLO). Olopatadine is an antihistamine with selective H(1)-receptor antagonist activity. AREAS COVERED IN THIS REVIEW: This review details the basic and clinical research on the olopatadine molecule and OLO nasal spray from 1996 to the present day. WHAT THE READER WILL GAIN: The reader will gain a better understanding of the pharmacology of OLO nasal spray, the clinical trial data that have established the efficacy of OLO nasal spray and the overall role of OLO nasal spray in the management of allergic rhinitis. TAKE HOME MESSAGE: Olopatadine nasal spray is one of the newest treatments approved by the FDA for the management of allergic rhinitis. OLO has a rapid onset of action, efficacy comparable to intranasal steroid sprays and is approved for seasonal allergic rhinitis in patients aged > or = 6 years.

Safety and efficacy of olopatadine hydrochloride nasal spray 0.6% in pediatric subjects with allergic rhinitis.

Olopatadine (OLO) nasal spray 0.6% is indicated for treatment of seasonal allergic rhinitis (SAR) in subjects > or = 12 years of age. This study was designed to present the results of two studies that evaluated the efficacy, safety, and pharmacokinetics (PK) of OLO in children with allergic rhinitis (AR). These were multicenter, double-blind, randomized, parallel-group studies in subjects 6 to <12 years of age (study 1) and 2 to <6 years of age (study 2) with SAR (study 1) or AR (study 2). In study 1, nasal and ocular symptoms were scored for efficacy, and study 2 included PK analyses. In both studies, subjects were evaluated based on physical/nasal examinations and adverse events (AEs). Overall, 1188 subjects (study 1) and 132 subjects (study 2) were randomized, respectively. OLO (1 or 2 sprays/nostril, b.i.d.) was superior to vehicle in the percent decrease in reflective total nasal symptom scores (p < or = 0.0120). OLO 1 spray/nostril b.i.d. was also superior to vehicle in the percent decreases in reflective total ocular symptom scores (p < or = 0.0084), change from baseline in Pediatric Rhinoconjunctivitis Quality-of-Life Questionnaire scores (p < or = 0.0377), Caregiver Treatment Satisfaction Questionnaire scores (p < or = 0.0450), and proportions of subjects reporting improvements in Subject Global Assessments (p = 0.0035). The most frequently reported treatment-related events in the OLO group were bad/bitter taste and epistaxis. In subjects 6 to <12 years of age, OLO was superior to vehicle in the treatment of SAR. In subjects 2 to <12 years of age, OLO had an overall low rate of AEs and low systemic exposure.

Pharmacokinetics of orally administered single- and multiple-dose olopatadine in healthy Chinese subjects: an open-label study.

BACKGROUND AND OBJECTIVES: Olopatadine is a new selective histamine H(1) receptor antagonist with anti-inflammatory and anti-allergic effects. Its pharmacokinetics and safety have not previously been evaluated in Chinese subjects. The aims of this study were to assess the pharmacokinetics and safety of olopatadine after single- and multiple-dose oral administration in healthy Chinese subjects and to identify any differences in pharmacokinetics between males and females. METHODS: The pharmacokinetic parameters for olopatadine in 12 healthy Chinese subjects (six males and six females) were assessed by determining olopatadine concentrations with a validated liquid chromatography-tandem mass spectrometry method. Safety and tolerability were evaluated by monitoring adverse events, laboratory assay results, vital signs, physical examination findings and 12-lead ECG results. RESULTS: The pharmacokinetic parameters (mean +/- SD) for olopatadine following a single dose were: maximum plasma concentration (C(max)) 69.98 +/-20.87 ng/mL, time to reach C(max) (t(max)) 1.02 +/- 0.34 h, elimination half-life (t1/2) 5.87 +/- 4.24 h, area under the plasma-concentration curve (AUC) from time zero to the time of last quantifiable concentration (AUC(last)) 266.00 +/- 143.95 ng.h/mL, AUC from time zero extrapolated to infinity (AUC(infinity)) 283.46 +/- 152.96 ng.h/mL, apparent oral clearance (CL/F) 23.45 +/- 12.59 L/h and apparent volume of distribution after oral administration (V(d)/F) 133.83 +/- 43.07 L. The pharmacokinetic parameters of olopatadine after multiple doses were similar to those after a single dose. In both studies, significantly higher AUC(last), AUC(infinity) and C(max), longer t1/2 (single-dose only) and lower CL/F were observed in female subjects compared with male subjects after both single and multiple dosing. No serious adverse events occurred. CONCLUSION: Olopatadine was shown to be safe and well tolerated in healthy Chinese subjects. There were no changes in absorption and elimination of olopatadine following multiple doses and no accumulation was found. Possible sex-related differences in absorption and elimination of olopatadine were observed.

P-glycoprotein limits the brain penetration of olopatadine hydrochloride, H1-receptor antagonist.

Olopatadine, a new second-generation antihistamine, is widely used in the treatment of allergic disorders. The low levels of histamine H1 receptor occupancy in human brain by olopatadine, which is related to its minimal sedation, suggest its low penetration into the brain. The present study evaluates the impact of P-glycoprotein (P-gp) on brain penetration and plasma concentration of olopatadine. The uptake amount of olopatadine in human P-gp transfected LLC-PK1 cells (LLC-GA5-COL150) was lower than that in LLC-PK1. The uptake of olopatadine in LLC-GA5-COL150 was increased in the same level as that in LLC-PK1 in the presence of cyclosporine A, a P-gp inhibitor. After intravenous or oral administration of olopatadine to wild type (WT) and mdr1a/1b knockout (KO) mice at a dose of 1 mg/kg, the brain concentration in KO mice was higher than that in WT mice. On the other hand, the plasma concentration of olopatadine after either route of administration was not different between WT and KO mice. These results suggest that olopatadine is a substrate of P-gp, and that P-gp limits the brain penetration but dose not affect the plasma concentration of olopatadine.

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.

Preclinical and clinical antiallergic effect of olopatadine 0.2% solution 24 hours after topical ocular administration.

Pharmacologic studies examined the potential of a solution containing olopatadine to maintain and extend antiallergic efficacy after single topical ocular drop administration over 24 hours. Results of these preclinical experiments conducted in guinea pigs indicated that olopatadine 0.2% (wt/vol) solution was significantly effective 24 hours after dosing. This concentration of olopatadine provided significantly more efficacy than Patanol (olopatadine 0.1%) 24 hours after administration while being as effective as Patanol (olopatadine 0.1%) 5 minutes after administration. Results from a human conjunctival allergen challenge trial in sensitive subjects confirmed clinical efficacy of olopatadine 0.2% solution over 24 hours. When individuals were challenged with antigen at onset, 16 and 24 hours after drug administration onto the eye, significant reductions were observed in the scores for active drug as compared with placebo for pruritus (77, 77, and 61%), conjunctival redness (35, 28, and 20%), and chemosis (53, 41, and 31%), respectively. These data suggest that topically applied olopatadine 0.2% solution will be an effective once-a-day therapy for allergic conjunctivitis.

Properties of olopatadine hydrochloride, a new antiallergic/antihistaminic drug.

Olopatadine hydrochloride (CAS 140462-76-6, KW-4679, AL-4943A; hereinafter referred to as olopatadine) is a novel antiallergic drug that is a selective histamine H1 receptor antagonist possessing inhibitory effects on the release of inflammatory lipid mediators such as leukotriene and thromboxane from human polymorphonuclear leukocytes and eosinophils. Olopatadine also inhibits the tachykininergic contractions in guinea pig bronchi by prejunctional inhibition of peripheral sensory nerves. Oral administration of olopatadine at doses of 0.03 mg/kg or higher reduces the symptoms of experimental allergic cutaneous responses and rhinoconjunctivitis in sensitized animals. Preclinical and clinical evaluations have demonstrated that olopatadine is a safe drug. After oral administration to healthy volunteers, olopatadine was rapidly and extensively absorbed. Unlike most other antiallergic drugs which are eliminated via hepatic metabolism, olopatadine is mainly excreted into urine. Olopatadine did not affect cytochrome P450 activities in human liver microsomes and consequently drug-drug metabolic interactions are unlikely. In double-masked clinical trials, olopatadine was shown to be effective at alleviating symptoms of allergic diseases. The drug (Allelock) was approved in Japan for the treatment of allergic rhinitis, chronic urticaria, eczema dermatitis, prurigo, cutaneous pruritus, psoriasis vulgaris and erythema exsudativum multiforme in December, 2000. An ophthalmic solution of olopatadine is also useful for the treatment of allergic conjunctivitis: this formulation (Patanol) was approved in the USA and the European Union for the treatment of seasonal and perennial allergic conjunctivitis in 1996 and 2002, respectively.

Randomized, double-masked comparison of olopatadine ophthalmic solution, mometasone furoate monohydrate nasal spray, and fexofenadine hydrochloride tablets using the conjunctival and nasal allergen challenge models.

BACKGROUND: It is presumed that exposure to allergens in the environment occurs through both the eyes and the nose. Allergic rhinoconjunctivitis is typically treated with a nasal spray or systemic antihistamine, neither of which may provide adequate relief of the ocular component of the disease. OBJECTIVE: This study was designed to gain a better understanding of the physiologic interaction between the conjunctival and nasal mucosa and thus help establish a profile for the most effective ocular treatment in patients whose allergies have both an ocular and a nasal component. METHODS: This was a single-center, randomized, double-masked clinical study using the conjunctival allergen challenge (CAC) and nasal allergen challenge (NAC) models. It compared the clinical signs and symptoms induced by CAC and NAC, the effects of drugs administered by 3 different routes, and the movement of fluorescein after instillation into the eye and nose (Jones test), and assessed levels of of inflammatory mediators in tears and nasal secretions. At visit l, subjects previously identified as CAC responders underwent NAC to determine the dose of allergen necessary to elicit a sufficient positive reaction. At visit 2, which took place 1 week later, subjects with a positive reaction at visit 1 were randomized to group A (CAC) or group B (NAC), and underwent challenge to confirm the allergen dose necessary to produce a positive reaction. Subjects who qualified were randomized to receive 1 of 3 treatments: olopatadine 0.1% ophthalmic solution, placebo nasal spray, and placebo tablets; mometasone furoate monohydrate 50-microg nasal spray, placebo topical solution, and placebo tablets; or fexofenadine hydrochloride 180-mg tablets, placebo topical solution, and placebo nasal spray. All study medications were administered according to their approved labeling: drops were administered twice daily in the eyes, and the nasal sprays and tablets were administered once daily. At visit 3, which took place 1 week after visit 2, subjects received study medication and 15 minutes later underwent CAC or NAC as before. The primary efficacy variables were ocular itching, ocular redness, and overall nasal symptoms (sneezing, rhino rrhea/postnasal drip, nasal pruritus, palatal pruritus, and nasal congestion) rated on standard scales. Peak nasal inspiratory flow (PNIF) was measured at each visit, and the Jones test was performed at visits 1 and 3. At baseline and after challenge at visits 2 and 3, tear and nasal lavage samples were collected from a subset of randomly selected subjects for analysis of eosinophil cationic protein and tryptase. RESULTS: Seventy-three subjects (42 women, 31 men; mean age, 45.26 years [range, 21-73 years]) were screened, and all were randomized to treatment. Two subjects did not complete the study. CAC induced clinically significant (>1 unit difference) ocular and nasal signs and symptoms, whereas NAC induced clinically significant nasal signs and symptoms only. In group A, there was a greater reduction in ocular itching with olopatadine compared with mometasone and fexofenadine at 3 minutes (P = 0.003 and P = 0.008, respectively) and 5 minutes (P = 0.007 and P = 0.013) after challenge. Although the difference was not statistically significant, overall relief of conjunctival redness (average of 3 vessel beds) was greatest in the olopatadine group, followed by fexofenadine. In group B, prevention of total nasal symptoms was significantly greater with mometasone compared with fexofenadine at 20 minutes (P = 0.006) and 30 minutes (P = 0.014) after challenge. There were no statistically significant differences between treatment groups in nasal symptom scores at any time point after CAC. There were also no significant differences in PNIF between treatment groups. Fluorescein was present in nasal secretions within 5 minutes of being instilled into the eye; no fluorescein was detected in the eye after instillation into the nose. CONCLUSIONS: In this study, exposure of the nasal mucosa to allergen resulted in allergic rhinitis, and exposure of the ocular the ocular surface to allergen resulted in conjunctivitis with a secondary effect in the nose. These results suggest movement of allergens, their mediators, and antiallergy drugs from the ocular surfaces into the nasal cavity, with no meaningful movement from the nasal cavity to the ocular surface. In this controlled model, both the systemic agent and the nasal spray failed to control ocular symptoms. The topical ophthalmic solution provided the most effective management of allergic ocular signs and symptoms, and the nasal spray was most effective for nasal symptoms. Combined use of a nasal spray and topical ophthalmic solution may provide maximal relief in patients whose allergies have both ocular and nasal components.

Pharmacological, pharmacokinetic and clinical properties of olopatadine hydrochloride, a new antiallergic drug.

Olopatadine hydrochloride (olopatadine, 11-[(Z)-3-(dimethylamino)propylidene]-6,11-dihydrodibenz[b,e]oxepin-2-acetic acid monohydrochloride) is a novel antiallergic/histamine H1-receptor antagonistic drug that was synthesized and evaluated in our laboratories. Oral administration of olopatadine at doses of 0.03 mg/kg or higher inhibited the symptoms of experimental allergic skin responses, rhinoconjunctivitis and bronchial asthma in sensitized guinea pigs and rats. Olopatadine is a selective histamine H1-receptor antagonist possessing inhibitory effects on the release of inflammatory lipid mediators such as leukotriene and thromboxane from human polymorphonuclear leukocytes and eosinophils. Olopatadine also inhibited the tachykininergic contraction in the guinea pig bronchi by prejunctional inhibition of peripheral sensory nerves. Olopatadine exerted no significant effects on action potential duration in isolated guinea pig ventricular myocytes, myocardium and human ether-a-go-go-related gene channel. Olopatadine was highly and rapidly absorbed in healthy human volunteers. The urinary excretion of olopatadine accounted for not less than 58% and the contribution of metabolism was considerably low in the clearance of olopatadine in humans. Olopatadine is one of the few renal clearance drugs in antiallergic drugs. Olopatadine was shown to be useful for the treatment of allergic rhinitis and chronic urticaria in double-blind clinical trials. Olopatadine was approved in Japan for the treatment of allergic rhinitis, chronic urticaria, eczema dermatitis, prurigo, pruritus cutaneous, psoriasis vulgaris and erythema exsudativum multiforme in December, 2000. Ophthalmic solution of olopatadine was also approved in the United States for the treatment of seasonal allergic conjunctivitis in December, 1996 (Appendix: also in the European Union, it was approved in February 2002).

[Pharmacological, pharmacokinetic and clinical properties of olopatadine hydrochloride' (olopatadine), an antiallergic drug].

Olopatadine is a selective histamine H1-receptor antagonist possessing inhibitory effects on the release of inflammatory lipid mediators such as leukotriene and thromboxane from human polymorphonuclear leukocytes and eosinophils. Olopatadine also inhibited the tachykininergic contraction in the guinea pig bronchi by prejunctional inhibition of peripheral sensory nerves. Oral administration of olopatadine inhibited passive cutaneous anaphylaxis in rats, experimental allergic rhinitis and bronchial asthmatic responses in actively sensitized guinea pigs. Olopatadine exerted no significant effects on action potential duration in isolated guinea pig myocardium and ventricular myocytes. Olopatadine was highly and rapidly absorbed in healthy volunteers. The urinary excretion of olopatadine accounted for not less than 58% and the contribution of metabolism was low in the elimination of olopatadine. Olopatadine was shown to be useful for the treatment of allergic rhinitis and chronic urticaria in double-blind clinical trials. Olopatadine was approved in Japan for the treatment of allergic rhinitis, chronic urticaria, eczema dermatitis, prurigo, pruritus cutaneous, psoriasis vulgaris and erythema exsudativum multiforme in December, 2000.

Determination of olopatadine, a new antiallergic agent, and its metabolites in human plasma by high-performance liquid chromatography with electrospray ionization tandem mass spectrometry.

A rapid, sensitive and specific assay method has been developed to determine plasma concentrations of olopatadine hydrochloride (A) and its metabolites, M1 (B), M2 (C) and M3 (D), using high-performance liquid chromatography with electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS). Olopatadine, its metabolites, and internal standard, KF11796 (E), were separated from plasma using solid-phase extraction (Bond Elut C18 cartridge). The eluate was dried, reconstituted and injected into the LC-ESI-MS-MS system. The calibration curves showed good linearity over the ranges 1-200 ng/ml for olopatadine and M3, and 2-100 ng/ml for M1 and M2, and the method was thoroughly validated and applied to the determination of olopatadine and its metabolites in plasma collected during Phase I clinical trials. Furthermore, the assay values were compared with those determined by the radioimmunoassay method, which has been routinely used to determine olopatadine in plasma.

Pharmacokinetics of KW-4679 in the elderly: single-dose and multiple-dose trials.

We evaluated the pharmacokinetics of KW-4679, a new antiallergic agent, in the elderly in trials of both single and multiple dosing. In the single-dose trial, the pharmacokinetics of a single dose of 10 mg KW-4679 in elderly male subjects was compared with those in young male subjects. In the multiple-dose trial lasting 6 consecutive days with elderly male subjects, the pharmacokinetics of the last dose of 10 mg KW-4679 were compared with those of the first dose to evaluate the accumulation of KW-4679 and/or its metabolites. In the single-dose trial, the maximum concentration and the area under the concentration time curve of KW-4679 in the elderly subjects were significantly greater than those in the young subjects, while the apparent total body clearance was significantly lower in the elderly subjects. There was no significant difference in the fraction of KW-4679 excreted in the urine between the elderly and the young subjects. The renal clearance of KW-4679 in the elderly subjects was significantly lower than that in the young subjects. Although the renal clearance was correlated with the creatinine clearance, the renal clearance was significantly greater than the creatinine clearance, suggesting that this agent undergoes renal tubular secretion. In the multiple-dose trial, all pharmacokinetic parameters examined, except the maximum concentration, showed no difference between the first and the last administration. No accumulation of KW-4679 or its metabolites could be detected in the elderly subjects examined in the 6-day multiple-dose trial, though the present results suggest the dose should be reduced in the elderly subjects who have lower creatinine clearance.

Central 5-HT2A and D2 dopamine receptor occupancy after sublingual administration of ORG 5222 in healthy men.

It has been suggested that a combined blockade of 5-HT2A and D2-dopamine receptors improves efficacy and reduces the risk for extrapyramidal symptoms when treating schizophrenic patients with antipsychotic drugs. ORG 5222 is a new potential antipsychotic drug which has high affinity for 5-HT2A, D2-dopamine and alpha 1 adrenergic receptors in vitro. The objective of this study was to examine if ORG 5222 occupies 5-HT2A and D2-dopamine receptors in human subjects in vivo. Central receptor occupancy was measured by positron emission tomography (PET) in three healthy subjects after sublingual administration of 100 micrograms ORG 5222. [11C]N-methylspiperone ([11C] NMSP) was the radioligand used to measure 5-HT2A receptor binding in the neocortex and [11C]raclopride to measure D2-dopamine receptor binding in the striatum. The 5-HT2A occupancy was 15-30% and the D2-dopamine receptor occupancy was 12-23%. The study confirms that ORG 5222 binds to 5-HT2A and D2-dopamine receptors in human brain. Since receptor occupancy of ORG 5222 is rather low, doses higher than 100 micrograms are suggested in future clinical trials to evaluate the antipsychotic drug effect of ORG 5222.

Determination of AJ-3941, a possible agent for the treatment of cerebrovascular disorders, in plasma and brain by means of high-performance liquid chromatography with fluorescence detection.

A sensitive and selective high-performance liquid chromatographic method with fluorescence detection is described for the determination of AJ-3941 (I), a possible agent for the treatment of cerebrovascular disorders, in plasma and brain tissue. A simple hexane extraction was used for plasma, and for brain homogenate the hexane extract was further purified by solid-phase extraction. The determination limit was ca. 3 ng/ml for both plasma (0.5 ml) and 10% (w/v) brain homogenate (1 ml). The method was applied to the determination of I in plasma and brain samples of experimental animals.

Biotransformation of the partial beta-agonist doxaminol in dog.

The biotransformation of the positive inotropic compound doxaminol (N-methyl-N-(2-hydroxy-3-phenoxy-propyl)-11-(2-amino-ethyl)-6,11- dihydrodibenz[b,e]oxepine, neutral fumarate; BM 10.188) was examined in bastard shepherd dogs. Metabolic products, formed by oxidative cleavage of various side chain carbon atoms of the molecule, as well as conjugated complexes with glucuronic and sulfuric acid, were isolated from urine and plasma. As main metabolites 2-hydroxy-3-phenoxy-propionic acid and phenoxyacetic acid were formed. By means of 1HNMR and 13C-NMR spectroscopy and various mass spectroscopic methods, the chemical structures of the metabolites were elucidated.

Pharmacokinetics of the partial beta-agonist doxaminol in dog.

The pharmacokinetic behaviour of doxaminol (N-methyl-N-(2-hydroxy-3-phenoxy-propyl)-11-(2-amino-ethyl)-6, 11-dihydrodibenz[b,e]oxepine, neutral fumarate; BM 10.188) was examined in dogs using peroral and intravenous application of the 14C-labelled drug. The maximum plasma concentration was reached 1 h after application, indicating a relatively quick absorption of doxaminol. Decrease of total radioactivity after intravenous and peroral application is characterized by two phases, the elimination half-lives being 1.33 and 1.55 h, respectively, and 24.05 and 21.05 h, respectively. The biological availability of doxaminol was ca. 60%. The plasma levels of the unchanged drug showed that doxaminol was very rapidly eliminated and metabolized. Within the examined period of 96 h, the elimination of doxaminol and its metabolites via urine and faeces amounted to 76.5% after intravenous application, and 44.1% of the applied dose after peroral application. The major amount of radioactivity is eliminated via faeces (61.5% and 31.2% of dose, respectively) while the elimination through urine is found to be 15.0 and 12.9% of the dose, respectively.