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1.
J AAPOS ; 28(3): 103923, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38692561

ABSTRACT

BACKGROUND: Hemodynamically significant patent ductus arteriosus (hsPDA) shunt may predispose infants to retinopathy of prematurity (ROP) because of its higher preductal cardiac output and blood oxygen content, which may augment ocular oxygen delivery. METHODS: A retrospective cohort study of preterm infants, born at <27 weeks' gestation and admitted at <24h postnatal age to a large quaternary referral was conducted. The primary composite outcome was death at <32 weeks or moderate-to-severe ROP (≥stage 2 or requiring treatment) in either eye. Secondary outcomes included ROP requiring treatment, and any ROP. Univariate analysis of patient characteristics and outcomes was performed as well as logistic regression. A receiver operating characteristics curve was generated for the outcome of ROP ≥stage 2 or requiring treatment. RESULTS: A total of 91 patients were screened, of whom 86 (54 hsPDA, 32 controls) were eligible for inclusion. hsPDA patients were younger and lighter at birth and had a higher burden of hyperglycemia and respiratory illness. The rates of the composite outcome (death <32 weeks or moderate-to-severe ROP) and of any ROP were more frequent in the hsPDA group. hsPDA shunt exposure was independently associated with development of any ROP among survivors to assessment (P = 0.006). PDA cumulative exposure score of 78 (clinical equivalent = 7 days high-volume shunt exposure) predicts moderate-to-severe ROP with 80% sensitivity and 78% specificity. CONCLUSIONS: Among infants <27 weeks, hsPDA shunt is associated with increased risks of a composite outcome of death or moderate-to-severe ROP, as well as ROP of any stage. Shunt modulation as a strategy to reduce ROP represents a biologically plausible avenue for investigation.


Subject(s)
Ductus Arteriosus, Patent , Gestational Age , Retinopathy of Prematurity , Humans , Retinopathy of Prematurity/physiopathology , Ductus Arteriosus, Patent/physiopathology , Retrospective Studies , Infant, Newborn , Female , Male , Hemodynamics/physiology , Risk Factors , Infant, Premature , ROC Curve
2.
Implement Sci Commun ; 3(1): 36, 2022 Mar 29.
Article in English | MEDLINE | ID: mdl-35351211

ABSTRACT

BACKGROUND: A significant gap persists between evidence from research and its use in practice. Research funders, important actors in the health research system, can help reduce this gap by initiating dissemination and implementation (D&I) activities. The specific types of D&I activities funders currently lead have not been explored thoroughly. The Ensuring Value in Research (EViR) Funders' Forum-an international collaboration of health-related research funders-was established in 2017 to address research waste issues and increase the value of research. The Forum surveyed funders to learn about their D&I practices and challenges. METHODS: We distributed a five-item exploratory survey to participating funders in August 2018. The results informed the development of a survey instrument, distributed in June 2019. The survey instrument contained 15 items prompting respondents to categorize and describe their level of effort in six practice areas: release of findings, dissemination, knowledge exchange/partnering, implementation, building capacity, and implementation research. In addition, funders were asked to describe examples of their practices in detail. Thirty-one funders completed the survey instrument, a 58% response rate. RESULTS: Most funders regard D&I as a high priority, but funders vary in levels of activity per practice area. Over half of respondents reported that they have at least some activity in all D&I practice areas surveyed, with the exception of implementation research. The vast majority indicated some or significant activity in release of findings (97%) and dissemination (87%). Nearly one-fifth of funders (19%) indicated that implementation is outside their remit, and 26% indicated that implementation research is outside their remit. Survey respondents shared a broad range of examples of activities in each practice area. Lack of evidence for successful approaches and measuring impact were named frequently as challenges and as potential areas for collaboration. CONCLUSIONS: Although models of dissemination and implementation vary across organizations, the majority of funders indicated that D&I of research findings is a priority. Funders indicated a need for evidence on effectiveness of various approaches to D&I. Increased collaboration between funders, including sharing good practices, will increase our collective learning and knowledge development.

3.
Br J Community Nurs ; 23(Sup7): S13-S17, 2018 Jul 01.
Article in English | MEDLINE | ID: mdl-30011234

ABSTRACT

The number of patients receiving Home Enteral Tube Feeding (HETF) has increased over a number of years. Some patients may have a short term nasogastric/nasojejunal tube placed to help them achieve their nutritional requirements in the short term. Other patients may need to be fed via a gastrostomy tube, either fully or in combination with oral diet long-term. It is important that all patients on HETF receive regular and continuous support. In light of this, Trafford NHS Trust has established a multi-professional nutrition support clinic.


Subject(s)
Enteral Nutrition/methods , Home Care Services , Intubation, Gastrointestinal/methods , England , Enteral Nutrition/instrumentation , Female , Gastrostomy , Humans , Intubation, Gastrointestinal/instrumentation , Male
4.
Bioorg Med Chem Lett ; 27(21): 4914-4919, 2017 11 01.
Article in English | MEDLINE | ID: mdl-28958623

ABSTRACT

A series of potent, selective and long-acting quinoline-based sulfonamide human H1 histamine receptor antagonists, designed for once-daily intranasal administration for the treatment of rhinitis were developed. Sulfonamide 33b had a slightly lower affinity for the H1 receptor than azelastine, had low oral bioavailability in the rat and dog, and was turned over to five major metabolites. Furthermore, 33b had longer duration of action than azelastine in guinea pigs, lower rat brain-penetration, and did not cause time dependent inhibition of CYP2D6 or CYP3A4. The clinical dose in humans is expected to be low (approximately 0.5mg per day) based on the clinical dose used for azelastine and a comparison of efficacy data from animal models for 33b and azelastine.


Subject(s)
Histamine H1 Antagonists/chemistry , Quinolines/chemistry , Receptors, Histamine H1/metabolism , Rhinitis, Allergic/drug therapy , Sulfanilamides/chemistry , Sulfonamides/chemistry , Sulfones/chemistry , Administration, Intranasal , Animals , Brain/metabolism , Dogs , Guinea Pigs , Half-Life , Histamine H1 Antagonists/pharmacokinetics , Histamine H1 Antagonists/therapeutic use , Inhibitory Concentration 50 , Quinolines/pharmacokinetics , Quinolines/therapeutic use , Rats , Receptors, Histamine H1/chemistry , Rhinitis, Allergic/metabolism , Rhinitis, Allergic/pathology , Structure-Activity Relationship , Sulfanilamide , Sulfanilamides/pharmacokinetics , Sulfanilamides/therapeutic use , Sulfonamides/pharmacokinetics , Sulfonamides/therapeutic use , Sulfones/pharmacokinetics , Sulfones/therapeutic use
5.
ACS Med Chem Lett ; 8(5): 577-581, 2017 May 11.
Article in English | MEDLINE | ID: mdl-28523114

ABSTRACT

The synthesis of potent amide-containing phthalazinone H1 histamine receptor antagonists is described. Three analogues 3e, 3g, and 9g were equipotent with azelastine and were longer-acting in vitro. Amide 3g had low oral bioavailability, low brain-penetration, high metabolic clearance, and long duration of action in vivo, and it was suitable for once-daily dosing intranasally, with a predicted dose for humans of approximately 0.5 mg per day.

6.
Bioorg Med Chem ; 22(15): 4298-311, 2014 Aug 01.
Article in English | MEDLINE | ID: mdl-24909677

ABSTRACT

A knowledge-based library of 2,3-dichlorophenylsulfonyl derivatives of commercially available aryl amines was synthesised and screened as human CCR4 antagonists, in order to identify a suitable hit for the start of a lead-optimisation programme. Hits were required to be more potent than an existing indazole series, have better physicochemical properties (clogP <3.5, chrom logD7.4 <5.3 and CLND solubility >116 µg/mL), and be stable to acid and light. The benzimidazol-2-one core was identified as a hit suitable for further investigation. Substitution at N1 with small alkyl groups was tolerated; however, these analogues were inactive in the whole blood assay (pA2 <5). Azabenzimidazolone analogues were all found to be active, with compound 38 exhibiting whole blood activity of 6.1, low molecular weight (389) and chrom logD7.4 (2.4), high LE (0.43), and solubility (152 µg/mL). In addition, 38 had human serum albumin binding of around 93% and met all the criteria for progression to lead optimisation.


Subject(s)
Benzimidazoles/chemistry , Receptors, CCR4/antagonists & inhibitors , Sulfonamides/chemistry , Aza Compounds/chemistry , Humans , Indazoles/chemistry , Protein Binding , Receptors, CCR4/metabolism , Serum Albumin/chemistry , Serum Albumin/metabolism , Structure-Activity Relationship , Sulfonamides/chemical synthesis , Sulfonamides/metabolism
7.
Eur J Pharmacol ; 729: 75-85, 2014 Apr 15.
Article in English | MEDLINE | ID: mdl-24534492

ABSTRACT

The chemokine receptor CCR4 has at least two natural agonist ligands, MDC (CCL22) and TARC (CCL17) which bind to the same orthosteric site with a similar affinity. Both ligands are known to evoke chemotaxis of CCR4-bearing T cells and also elicit CCR4 receptor internalization. A series of small molecule allosteric antagonists have been described which displace the agonist ligand, and inhibit chemotaxis. The aim of this study was to determine which cellular coupling pathways are involved in internalization, and if antagonists binding to the CCR4 receptor could themselves evoke receptor internalization. CCL22 binding coupled CCR4 efficiently to ß-arrestin and stimulated GTPγS binding however CCL17 did not couple to ß-arrestin and only partially stimulated GTPγS binding. CCL22 potently induced internalization of almost all cell surface CCR4, while CCL17 showed only weak effects. We describe four small molecule antagonists that were demonstrated to bind to two distinct allosteric sites on the CCR4 receptor, and while both classes inhibited agonist ligand binding and chemotaxis, one of the allosteric sites also evoked receptor internalization. Furthermore, we also characterize an N-terminally truncated version of CCL22 which acts as a competitive antagonist at the orthosteric site, and surprisingly also evokes receptor internalization without demonstrating any agonist activity. Collectively this study demonstrates that orthosteric and allosteric antagonists of the CCR4 receptor are capable of evoking receptor internalization, providing a novel strategy for drug discovery against this class of target.


Subject(s)
Chemotaxis/physiology , Endocytosis/physiology , Receptors, CCR4/antagonists & inhibitors , Receptors, CCR4/metabolism , Allosteric Regulation/drug effects , Allosteric Regulation/physiology , Animals , Basophils/drug effects , Basophils/metabolism , CHO Cells , Cells, Cultured , Chemokine CCL17/pharmacology , Chemokine CCL22/pharmacology , Chemotaxis/drug effects , Cricetinae , Cricetulus , Dose-Response Relationship, Drug , Endocytosis/drug effects , Humans
8.
J Med Chem ; 57(1): 159-70, 2014 Jan 09.
Article in English | MEDLINE | ID: mdl-24359185

ABSTRACT

A series of novel, potent, and selective human ß2 adrenoceptor agonists incorporating a sulfone moiety on the terminal right-hand-side phenyl ring of (R)-salmeterol is presented. Sulfone 10b had salmeterol-like potency and selectivity profile, long duration of action on guinea pig trachea, and longer than salmeterol duration of action in vivo, suitable for once-daily dosing. It had lower than salmeterol oral absorption in rat, lower bioavailability in rat and dog, and a high turnover in human hepatocytes. It was metabolized in human hepatocytes by hydroxylation, oxidation, cleavage, and conjugation; most of the metabolites would be expected to have reduced or no ß2 activity. The 4-biphenylsulfonic acid was identified as a crystalline, non-hygroscopic salt of 10b, suitable for inhaled delivery. Furthermore, it was free of any genetic toxicity issues and was considered as a backup to vilanterol.


Subject(s)
Adrenergic beta-2 Receptor Agonists/chemical synthesis , Sulfones/chemical synthesis , Adrenergic beta-2 Receptor Agonists/metabolism , Adrenergic beta-2 Receptor Agonists/pharmacology , Animals , CHO Cells , Cricetinae , Cricetulus , Dogs , Drug Administration Schedule , Drug Discovery , Guinea Pigs , Hepatocytes/metabolism , Humans , Rats , Sulfones/metabolism , Sulfones/pharmacology , Trachea/drug effects
9.
J Med Chem ; 56(5): 1946-60, 2013 Mar 14.
Article in English | MEDLINE | ID: mdl-23409871

ABSTRACT

A series of indazole arylsulfonamides were synthesized and examined as human CCR4 antagonists. Methoxy- or hydroxyl-containing groups were the more potent indazole C4 substituents. Only small groups were tolerated at C5, C6, or C7, with the C6 analogues being preferred. The most potent N3-substituent was 5-chlorothiophene-2-sulfonamide. N1 meta-substituted benzyl groups possessing an α-amino-3-[(methylamino)acyl]-group were the most potent N1-substituents. Strongly basic amino groups had low oral absorption in vivo. Less basic analogues, such as morpholines, had good oral absorption; however, they also had high clearance. The most potent compound with high absorption in two species was analogue 6 (GSK2239633A), which was selected for further development. Aryl sulfonamide antagonists bind to CCR4 at an intracellular allosteric site denoted site II. X-ray diffraction studies on two indazole sulfonamide fragments suggested the presence of an important intramolecular interaction in the active conformation.


Subject(s)
Indazoles/pharmacology , Receptors, CCR4/antagonists & inhibitors , Sulfonamides/chemical synthesis , Sulfonamides/pharmacology , Animals , Dogs , Humans , Indazoles/chemical synthesis , Indazoles/pharmacokinetics , Male , Rats , Structure-Activity Relationship , Sulfonamides/pharmacokinetics
10.
Cleft Palate Craniofac J ; 50(5): 548-54, 2013 Sep.
Article in English | MEDLINE | ID: mdl-22906392

ABSTRACT

Objective : To compare nasoalveolar molding (NAM) effect employing a nasal elevator plus DynaCleft® and NAM-Grayson system in patients with complete unilateral cleft lip and palate. Method : Prospective study in two groups. Group A included 20 consecutive patients treated with DynaCleft® and a nasal elevator before lip surgery. Group B included 20 patients treated with NAM-Grayson system. Maxillary casts and standard view photographs were done before and after treatment. Columella deviation angle, soft tissue distance of the cleft, intercommisural distance, and nostril height and width were traced and measured on the printed photos; a ratio was obtained and compared before and after treatment. Cleft width, anterior width, and anteroposterior distances were measured on the maxillary cast. Results : Group A began treatment at an average age of 14.3 days and group B at an average age of 16.9 days; no complications were observed. For group A, the initial average alveolar cleft within the cast was 10.7 mm, and after treatment it was 6.6 mm. For group B, pretreatment width was 11.2 mm, and after treatment it was 5.9 mm. No differences were found on the anterior and posterior width, and A-P distance of both groups. The initial mean columellar angle in group A was 38.1°, and after treatment it was 61.5°; for group B the initial mean columellar angle was 33.6°, and after treatment it was 59.5°. Results of Mann-Whitney U and Student's t tests showed no differences (P > .05). Width and height dimensions of the nostril showed minor differences. Conclusions : Both methods significantly reduced the cleft width and improved the nasal asymmetry. Our findings show that both methods produced similar results.


Subject(s)
Cleft Lip , Cleft Palate , Cleft Lip/surgery , Cleft Palate/surgery , Humans , Infant , Nose/surgery , Prospective Studies , Treatment Outcome
11.
J Pharmacol Exp Ther ; 344(1): 218-30, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23131596

ABSTRACT

Vilanterol trifenatate (vilanterol) is a novel, long-acting ß(2)-adrenoceptor (ß(2)-AR) agonist with 24 h activity. In this study, we describe the preclinical pharmacological profile of vilanterol using radioligand binding and cAMP studies in recombinant assays as well as human and guinea pig tissue systems to characterize ß(2)-AR binding and functional properties. Vilanterol displayed a subnanomolar affinity for the ß(2)-AR that was comparable with that of salmeterol but higher than olodaterol, formoterol, and indacaterol. In cAMP functional activity studies, vilanterol demonstrated similar selectivity as salmeterol for ß(2)- over ß(1)-AR and ß(3)-AR, but a significantly improved selectivity profile than formoterol and indacaterol. Vilanterol also showed a level of intrinsic efficacy that was comparable to indacaterol but significantly greater than that of salmeterol. In cellular cAMP production and tissue-based studies measuring persistence and reassertion, vilanterol had a persistence of action comparable with indacaterol and longer than formoterol. In addition, vilanterol demonstrated reassertion activity in both cell and tissue systems that was comparable with salmeterol and indacaterol but longer than formoterol. In human airways, vilanterol was shown to have a faster onset and longer duration of action than salmeterol, exhibiting a significant level of bronchodilation 22 h after treatment. From these investigations, the data for vilanterol are consistent, showing that it is a novel, potent, and selective ß(2)-AR receptor agonist with a long duration of action. This pharmacological profile combined with clinical data is consistent with once a day dosing of vilanterol in the treatment of both asthma and chronic obstructive pulmonary disease (COPD).


Subject(s)
Adrenergic beta-2 Receptor Agonists/pharmacology , Benzyl Alcohols/pharmacology , Chlorobenzenes/pharmacology , Adrenergic beta-2 Receptor Agonists/metabolism , Adrenergic beta-2 Receptor Agonists/pharmacokinetics , Adrenergic beta-3 Receptor Antagonists/pharmacology , Albuterol/analogs & derivatives , Albuterol/pharmacology , Animals , Binding, Competitive/drug effects , CHO Cells , Cell Membrane/metabolism , Cells, Cultured , Cricetinae , Cricetulus , Cyclic AMP/biosynthesis , Cyclic AMP/metabolism , Data Interpretation, Statistical , Fluorescence Polarization , Guinea Pigs , Humans , Kinetics , Propanolamines/metabolism , Propanolamines/pharmacokinetics , Propanolamines/pharmacology , Pulmonary Disease, Chronic Obstructive/drug therapy , Radioligand Assay , Receptors, Adrenergic, beta-2/drug effects , Receptors, Adrenergic, beta-2/metabolism , Salmeterol Xinafoate
13.
Bioorg Med Chem ; 19(20): 6026-32, 2011 Oct 15.
Article in English | MEDLINE | ID: mdl-21925889

ABSTRACT

A series of novel, potent and selective human ß(2) adrenoceptor agonists incorporating a urea moiety on the terminal right-hand side phenyl ring of (R)-salmeterol is presented. Urea 9j had long duration of action in vitro on guinea pig trachea, and also in vivo similar to that of salmeterol. It had lower oral absorption and bioavailability than salmeterol in both rat and dog. It had a turnover ratio similar to salmeterol, with no evidence for formation of any aniline metabolites in human liver microsomes and hepatocytes. However no crystalline salts suitable for inhaled delivery were identified.


Subject(s)
Adrenergic beta-2 Receptor Agonists/chemical synthesis , Asthenia/drug therapy , Bronchodilator Agents/pharmacology , Urea/analogs & derivatives , Urea/pharmacology , Adrenergic beta-2 Receptor Agonists/chemistry , Adrenergic beta-2 Receptor Agonists/pharmacokinetics , Adrenergic beta-2 Receptor Agonists/pharmacology , Albuterol/analogs & derivatives , Albuterol/chemistry , Albuterol/pharmacokinetics , Albuterol/pharmacology , Animals , CHO Cells , Cricetinae , Cricetulus , Dogs , Dose-Response Relationship, Drug , Female , Guinea Pigs , Humans , Male , Rats , Salmeterol Xinafoate , Stereoisomerism
14.
Bioorg Med Chem ; 19(14): 4192-201, 2011 Jul 15.
Article in English | MEDLINE | ID: mdl-21696967

ABSTRACT

A series of novel, potent and selective human ß(2) adrenoceptor agonists incorporating a hydantoin or a uracil ring on the right-hand side phenyl ring of (R)-salmeterol is presented. Hydantoin 12a had long duration of action in vitro on guinea pig trachea, and 12h in guinea pigs in vivo at its EC(90) 25 µM. It had lower oral absorption than salmeterol in rats, and lower bioavailability than salmeterol in vivo in both rats and dogs (2% and 5%, respectively). An improved method for measuring the absorbed fraction of analogues dosed to rats, which considers the glucuronidated fraction is presented. Compound 12a was metabolised in human liver microsomes and hepatocytes to the active hydantoic acid 12m.


Subject(s)
Adrenergic beta-2 Receptor Agonists/chemical synthesis , Drug Discovery , Hydantoins/chemistry , Uracil/chemistry , Adrenergic beta-2 Receptor Agonists/metabolism , Adrenergic beta-2 Receptor Agonists/pharmacology , Animals , CHO Cells , Cricetinae , Cricetulus , Dogs , Dose-Response Relationship, Drug , Female , Guinea Pigs , Hepatocytes/chemistry , Hepatocytes/metabolism , Humans , Male , Microsomes, Liver/chemistry , Microsomes, Liver/metabolism , Molecular Structure , Rats , Rats, Wistar , Receptors, Adrenergic, beta-2/metabolism , Stereoisomerism , Trachea/drug effects
15.
J Med Chem ; 53(11): 4522-30, 2010 Jun 10.
Article in English | MEDLINE | ID: mdl-20462258

ABSTRACT

A series of saligenin beta(2) adrenoceptor agonist antedrugs having high clearance were prepared by reacting a protected saligenin oxazolidinone with protected hydroxyethoxyalkoxyalkyl bromides, followed by removal of the hydroxy-protecting group, alkylation, and final deprotection. The compounds were screened for beta(2), beta(1), and beta(3) agonist activity in CHO cells. The onset and duration of action in vitro of selected compounds were assessed on isolated superfused guinea pig trachea. Compound 13f had high potency, selectivity, fast onset, and long duration of action in vitro and was found to have long duration in vivo, low oral bioavailability in the rat, and to be rapidly metabolized. Crystalline salts of 13f (vilanterol) were identified that had suitable properties for inhaled administration. A proposed binding mode for 13f to the beta(2)-receptor is presented.


Subject(s)
Adrenergic beta-2 Receptor Agonists , Adrenergic beta-Agonists/chemistry , Adrenergic beta-Agonists/pharmacology , Adrenergic beta-Agonists/chemical synthesis , Adrenergic beta-Agonists/metabolism , Animals , Benzyl Alcohol/chemistry , Benzyl Alcohols/chemical synthesis , Benzyl Alcohols/chemistry , Benzyl Alcohols/metabolism , Benzyl Alcohols/pharmacology , CHO Cells , Chlorobenzenes/chemical synthesis , Chlorobenzenes/chemistry , Chlorobenzenes/metabolism , Chlorobenzenes/pharmacology , Cricetinae , Cricetulus , Humans , Models, Molecular , Protein Conformation , Rats , Receptors, Adrenergic, beta-2/chemistry , Structure-Activity Relationship
16.
J Med Chem ; 52(8): 2280-8, 2009 Apr 23.
Article in English | MEDLINE | ID: mdl-19317397

ABSTRACT

A series of saligenin alkoxyalkylphenylsulfonamide beta(2) adrenoceptor agonists were prepared by reacting a protected saligenin oxazolidinone with alkynyloxyalkyl bromides, followed by Sonogashira reaction, hydrogenation, and deprotection. The meta-substituted primary sulfonamide was more potent than the para- and the ortho-analogues. Primary sulfonamides were more potent than the secondary and tertiary analogues. The onset and duration of action in vitro of selected compounds was assessed on isolated superfused guinea pig trachea. Sulfonamide 29b had the best profile of potency, selectivity, onset, and duration of action on both guinea pig trachea and human bronchus. Furthermore, 29b was found to have low oral bioavailability in rat and dog and also to have long duration of action in an in vivo model of bronchodilation. Crystalline salts of 29b were identified that had suitable properties for inhaled administration. A proposed binding mode for 29b to the beta(2)-receptor is presented.


Subject(s)
2-Hydroxyphenethylamine/analogs & derivatives , Adrenergic beta-2 Receptor Agonists , Sulfonamides/chemical synthesis , 2-Hydroxyphenethylamine/chemical synthesis , 2-Hydroxyphenethylamine/chemistry , 2-Hydroxyphenethylamine/pharmacology , Administration, Oral , Albuterol/analogs & derivatives , Albuterol/chemistry , Albuterol/pharmacology , Animals , Biological Availability , Bronchi/drug effects , Bronchi/physiology , CHO Cells , Cricetinae , Cricetulus , Cyclic AMP/biosynthesis , Dogs , Guinea Pigs , Humans , In Vitro Techniques , Microsomes/metabolism , Models, Molecular , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Muscle, Smooth/physiology , Rats , Salmeterol Xinafoate , Stereoisomerism , Structure-Activity Relationship , Sulfonamides/chemistry , Sulfonamides/pharmacology , Trachea/drug effects , Trachea/physiology
17.
Eur J Pharmacol ; 519(3): 237-45, 2005 Sep 20.
Article in English | MEDLINE | ID: mdl-16129425

ABSTRACT

Recent clinical evidence indicates that the broad spectrum anticonvulsant drug lamotrigine is effective against the depressive phase of bipolar illness and the difficult to treat rapid cycling form of the disorder. However, the molecular mechanism underlying this therapeutic action remains uncertain. Given that inhibition of the A-type of monoamine oxidase (MAO) is a proven antidepressant mechanism, we investigated the effects of lamotrigine on MAO activities in vitro and on monoamine disposition in vivo. In vitro, lamotrigine inhibited rat brain MAO activities with Ki values (MAO-A, 15 microM; MAO-B, 18 microM) potentially within the therapeutic range for this drug. The effects of lamotrigine on the MAO-A activities of rat brain and human liver preparations were almost identical suggesting minimal species or tissue variation. In contrast, there was no (MAO-A) or minimal (MAO-B) reduction in brain MAO activities when assayed ex vivo following the administration of lamotrigine to rats. In vivo brain microdialysis failed to detect meaningful alterations in extracellular hippocampal or frontal cortex monoamine concentrations. Furthermore, lamotrigine did not modulate oral tyramine-induced hypertension in rats or 5-hydroxytryptophan-induced head shaking in mice, providing strong evidence that the drug does not perturb monoamine metabolism in vivo. The absence of observable effects of lamotrigine on monoamine disposition in vivo may be explained by the competitive and highly reversible nature of the interaction of lamotrigine with MAO isoforms. Thus, altered monoamine metabolism in vivo is unlikely to account for the antidepressant action of the drug in bipolar depression.


Subject(s)
Anticonvulsants/pharmacology , Biogenic Monoamines/metabolism , Monoamine Oxidase/metabolism , Triazines/pharmacology , 5-Hydroxytryptophan/pharmacology , Administration, Oral , Animals , Behavior, Animal/drug effects , Blood Pressure/drug effects , Brain/drug effects , Brain/enzymology , Cerebellum/drug effects , Cerebellum/enzymology , Dopamine/metabolism , Dose-Response Relationship, Drug , Extracellular Space/drug effects , Extracellular Space/metabolism , Humans , Lamotrigine , Liver/drug effects , Liver/enzymology , Male , Microdialysis , Norepinephrine/metabolism , Rats , Rats, Wistar , Serotonin/metabolism , Time Factors , Tyramine/pharmacology
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