RESUMO
Intravitreal injections of anti-vascular endothelial growth factor (VEGF) agents are used to treat wet age-related macular degeneration (wAMD); however, they are associated with a considerable treatment burden and poor real-world outcomes. The molecular size and charge of anti-VEGF agents influence drug pharmacokinetics in the vitreous and peak drug efficacy. This article reviews the established and novel strategies to prolong drug action, in the vitreal cavity, and thus reduce dosing frequency. Increased ocular residency can be attained by increasing drug size as with large molecules, such as KSI-301; adding polyethylene glycol to pegcetacoplan (APL-2) or avacincaptad pegol to increase molecular size; or binding to other targets that increase molecular size, such as vitreal albumin in the case of BI-X. Faricimab is a bispecific antibody in which the fragment crystallizable portion is engineered to prolong ocular residency and reduce systemic exposure. Conversely, small VEGF-binding molecules, such as brolucizumab, can be administered at higher clinical doses, with the potential for prolonged clinical activity versus larger molecules. Other important considerations include sustained drug delivery routes, such as the ranibizumab port delivery system or subconjunctival or suprachoroidal injection. More effective and longer-lasting treatments are needed for wAMD to prolong drug action and reduce dosing frequency. Several strategies are under investigation and the prevention of vision loss in patients with AMD or other retinal diseases may be attainable in the near future.
Assuntos
Inibidores da Angiogênese , Degeneração Macular Exsudativa , Humanos , Fator A de Crescimento do Endotélio Vascular/metabolismo , Duração da Terapia , Ranibizumab/uso terapêutico , Degeneração Macular Exsudativa/tratamento farmacológico , Degeneração Macular Exsudativa/metabolismo , Fatores de Crescimento do Endotélio Vascular/uso terapêutico , Injeções IntravítreasRESUMO
The purpose of this study was to elucidate the absolute abundance of transporters, enzymes, receptors, and tight junction and marker proteins at human blood-arachnoid barrier (BAB) and compare with those of dogs and pigs. Protein expression levels in plasma membrane fractions of brain leptomeninges were determined by quantitative targeted absolute proteomics. To realistically compare the absolute abundance of target molecules at the BAB among humans, dogs, and pigs, the unit was converted from fmol/µg-protein to pmol/cm2 -leptomeninges. Of a total of 70 proteins, 52 were detected. OAT1, OAT3, GLUT1, 4F2hc, EAAT1, EAAT2, MCT8, SMVT, CTL2, GFAP, Claudin-5, Na+ /K+ -ATPase, COMT, GSTP1, and CES1 were abundantly expressed at the human BAB (>1 pmol/cm2 ). The protein expression levels were within a 3-fold difference for 16 out of 33 proteins between humans and dogs and for 13 out of 28 proteins between humans and pigs. Both human-dog and human-pig differences in protein expression levels were within 3-fold for OAT1, OAT3, 4F2hc, xCT, OCT2, MDR1, BCRP, PEPT2, SYP, and MCT1. In contrast, OCT3, MCT4, and OATP1A2 were detected in humans but not in dogs or pigs. MRP3 was detected in dogs and pigs but not in humans. The absolute level of GLUT1 in humans was nearly the same as that in dogs but was 6.14-fold greater in pigs. No significant differences in the levels were observed between male and female dogs for nearly all molecules. These results should be helpful in understanding the physiological roles of BAB and cerebrospinal fluid pharmacokinetics in humans and their differences from dogs and pigs.
Assuntos
Barreira Hematoencefálica , Junções Íntimas , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Aracnoide-Máter/metabolismo , Biomarcadores/metabolismo , Barreira Hematoencefálica/metabolismo , Cães , Feminino , Transportador de Glucose Tipo 1/metabolismo , Humanos , Masculino , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Neoplasias/metabolismo , Suínos , Junções Íntimas/metabolismoRESUMO
PURPOSE: The purpose of the present study was to quantitatively determine the expression of transporters, receptors and tight junction molecules at the blood-arachnoid barrier (BAB) and blood-spinal cord barrier (BSCB) in cervical, thoracic and lumbar spines from dogs. METHODS: The expression levels of 31 transporters, 3 receptors, 1 tight junction protein, and 3 marker proteins in leptomeninges and capillaries isolated from spines (3 male and 2 female dogs) were determined by quantitative Targeted Absolute Proteomics (qTAP). The units were converted from fmol/µg protein to pmol/cm (absolute abundance at the BAB and the BSCB in a 1 cm section of spine). RESULTS: The expression of MDR1 and BCRP were greater at the BSCB compared to the BAB (especially in the cervical cord), and the expressions at the lumbar BSCB were lower than that for the cervical BSCB. Among the organic anionic and cationic drug transporters, OAT1, OAT3, MRP1, OCT2 and MATE1/2 were detected only in the BAB, and not at the BSCB). The expression of these transporters was higher in the order: lumbar > thoracic > cervical BAB. The expressions of GLUT1, 4F2hc, EAAT1, 2, PEPT2, CTL1, and MCT1 at the BSCB of the cervical cord were higher than the corresponding values for the cervical BAB, and these values decreased in going down the spinal cord. CONCLUSION: These results provide a better understanding of the molecular mechanisms underlying the concentration gradients of drugs and endogenous substances in the cerebrospinal fluid and parenchyma of the spinal cord.
Assuntos
Barreira Hematoencefálica , Junções Íntimas , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Aracnoide-Máter/metabolismo , Barreira Hematoencefálica/metabolismo , Cães , Feminino , Masculino , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Neoplasias/metabolismo , Medula Espinal/metabolismo , Junções Íntimas/metabolismoRESUMO
Half-life extension strategies to reduce the intravitreal dosing frequency of biomolecules for the treatment of retinal neovascular diseases are attracting increasing interest. This study investigated ocular and systemic pharmacokinetics of the trivalent nanobody BI-X (with affinity to VEGF, Ang-2 and human albumin) in cynomolgus monkeys after intravitreal injection. BI-X concentrations were measured in serial samples of plasma, vitreous humor, aqueous humor and retina. Ocular pharmacokinetics of BI-X exhibited two phases. Initially up to 2-4 weeks after dosing, BI-X concentrations in vitreal, aqueous humor and retina declined with half-lives of around 3 days, which is comparable to macromolecules with a similar molecular weight. Thereafter, only vitreal concentrations were measurable, with a terminal half-life of 13.2 days, which is considerably longer than expected based on the BI-X molecular weight or hydrodynamic radius. It is hypothesized that binding of BI-X to low levels of intraocular albumin resulted in this half-life extension. BI-X was detectable in plasma up to 10 weeks post-dosing. Plasma pharmacokinetics of BI-X exhibited a similar biphasic disposition profile to the vitreous body, with a terminal half-life of 11.8 days, thus reflecting input kinetics from the eye. In conclusion, an important half-life extension principle based on vitreal albumin binding could be confirmed in a primate model, and the data obtained can potentially be translated to humans taking into account the differing vitreal albumin concentrations.
Assuntos
Inibidores da Angiogênese/farmacocinética , Angiopoietina-2/metabolismo , Albumina Sérica Humana/farmacologia , Fator A de Crescimento do Endotélio Vascular/metabolismo , Corpo Vítreo/metabolismo , Animais , Área Sob a Curva , Sinergismo Farmacológico , Feminino , Meia-Vida , Injeções Intravítreas , Macaca fascicularis , MasculinoRESUMO
N-methyl-d-aspartate (NMDA) receptor-dependent long-term potentiation (LTP) is an established cellular model underlying learning and memory, and involves intracellular signaling mediated by the second messenger cyclic guanosine monophosphate (cGMP). As phosphodiesterase (PDE)9A selectively hydrolyses cGMP in areas of the brain related to cognition, PDE9A inhibitors may improve cognitive function by enhancing NMDA receptor-dependent LTP. This study aimed to pharmacologically characterize BI 409306, a novel PDE9A inhibitor, using in vitro assays and in vivo determination of cGMP levels in the brain. Further, the effects of BI 409306 on synaptic plasticity evaluated by LTP in ex vivo hippocampal slices and on cognitive performance in rodents were also investigated. In vitro assays demonstrated that BI 409306 is a potent and selective inhibitor of human and rat PDE9A with mean concentrations at half-maximal inhibition (IC50) of 65 and 168 nM. BI 409306 increased cGMP levels in rat prefrontal cortex and cerebrospinal fluid and attenuated a reduction in mouse striatum cGMP induced by the NMDA-receptor antagonist MK-801. In ex vivo rat brain slices, BI 409306 enhanced LTP induced by both weak and strong tetanic stimulation. Treatment of mice with BI 409306 reversed MK-801-induced working memory deficits in a T-maze spontaneous-alternation task and improved long-term memory in an object recognition task. These findings suggest that BI 409306 is a potent and selective inhibitor of PDE9A. BI 409306 shows target engagement by increasing cGMP levels in brain, facilitates synaptic plasticity as demonstrated by enhancement of hippocampal LTP, and improves episodic and working memory function in rodents. SIGNIFICANCE STATEMENT: This preclinical study demonstrates that BI 409306 is a potent and selective PDE9A inhibitor in rodents. Treatment with BI 409306 increased brain cGMP levels, promoted long-term potentiation, and improved episodic and working memory performance in rodents. These findings support a role for PDE9A in synaptic plasticity and cognition. The potential benefits of BI 409306 are currently being investigated in clinical trials.
Assuntos
Química Encefálica/efeitos dos fármacos , GMP Cíclico/análise , Memória/efeitos dos fármacos , Plasticidade Neuronal/efeitos dos fármacos , Inibidores de Fosfodiesterase/farmacologia , Pirazóis/farmacocinética , Pirimidinas/farmacocinética , 3',5'-AMP Cíclico Fosfodiesterases/antagonistas & inibidores , Animais , GMP Cíclico/líquido cefalorraquidiano , Potenciação de Longa Duração/efeitos dos fármacos , Potenciação de Longa Duração/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pirazóis/farmacologia , Pirimidinas/farmacologia , Ratos , Ratos WistarRESUMO
Transporters at the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) play a pivotal role as gatekeepers for efflux or uptake of endogenous and exogenous molecules. The protein expression of a number of them has already been determined in the brains of rodents, nonhuman primates, and humans using quantitative targeted absolute proteomics (QTAP). The dog is an important animal model for drug discovery and development, especially for safety evaluations. The purpose of the present study was to clarify the relevance of the transporter protein expression for drug distribution in the dog brain and CSF. We used QTAP to examine the protein expression of 17 selected transporters and receptors at the dog BBB and BCSFB. For the first time, we directly linked the expression of two efflux transporters, P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), to regional brain and CSF distribution using specific substrates. Two cocktails, each containing one P-gp substrate (quinidine or apafant) and one BCRP substrate (dantrolene or daidzein) were infused intravenously prior to collection of the brain. Transporter expression varied only slightly between the capillaries of different brain regions and did not result in region-specific distribution of the investigated substrates. There were, however, distinct differences between brain capillaries and choroid plexus. Largest differences were observed for BCRP and P-gp: both were highly expressed in brain capillaries, but no BCRP and only low amounts of P-gp were detected in the choroid plexus. Kp,uu,brain and Kp,uu,CSF of both P-gp substrates were indicative of drug efflux. Also, Kp,uu,brain for the BCRP substrates was low. In contrast, Kp,uu,CSF for both BCRP substrates was close to unity, resulting in Kp,uu,CSF/Kp,uu,brain ratios of 7 and 8, respectively. We conclude that the drug transporter expression profiles differ between the BBB and BCSFB in dogs, that there are species differences in the expression profiles, and that CSF is not a suitable surrogate for unbound brain concentrations of BCRP substrates in dogs.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Encéfalo/irrigação sanguínea , Capilares/metabolismo , Plexo Corióideo/metabolismo , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/sangue , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/líquido cefalorraquidiano , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/sangue , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/líquido cefalorraquidiano , Animais , Azepinas/farmacocinética , Transporte Biológico , Barreira Hematoencefálica , Encéfalo/metabolismo , Dantroleno/farmacocinética , Cães , Feminino , Perfilação da Expressão Gênica , Isoflavonas/farmacocinética , Masculino , Proteômica/métodos , Quinidina/farmacocinética , Distribuição Tecidual , Triazóis/farmacocinéticaRESUMO
Transporter gene knockout rat models are attracting increasing interest for mechanistic studies of new drugs as transporter substrates or inhibitors in vivo. However, limited data are available on the functional validity of such models at the blood-brain barrier. Therefore, the present study evaluated Mdr1a [P-glycoprotein (P-gp)], Bcrp, and combined Mdr1a/Bcrp knockout rat strains for the influence of P-gp and breast cancer resistance protein (BCRP) transport proteins on brain penetration of the selective test substrates [(14)C]WEB 2086 (3-[4-(2-chlorophenyl)-9-methyl-6H-thieno[3,2-f][1,2,4]triazolo-[4,3-a][1,4]-diazepin-2-yl]-1-(4-morpholinyl)-1-propanon) for P-gp and dantrolene for BCRP. Brain-to-plasma concentration ratios (BPR) were measured after intravenous coinfusions of 5.5 µmol/kg per hour [(14)C]WEB 2086 and 2 µmol/kg per hour dantrolene for 2 hours in groups of knockout or wild-type rats. Compared with wild-type controls, mean BPR of [(14)C]WEB 2086 increased 8-fold in Mdr1a knockouts, 9.5-fold in double Mdr1a/Bcrp knockouts, and 7.3-fold in zosuquidar-treated wild-type rats, but was unchanged in Bcrp knockout rats. Mean BPR of dantrolene increased 3.3-fold in Bcrp knockouts and 3.9-fold in double Mdr1a/Bcrp knockouts compared with wild type, but was unchanged in the Mdr1a knockouts. The human intestinal CaCo-2 cell bidirectional transport system in vitro confirmed the in vivo finding that [(14)C]WEB 2086 is a substrate of P-gp but not of BCRP. Therefore, Mdr1a, Bcrp, and combined Mdr1a/Bcrp knockout rats provide functional absence of these efflux transporters at the blood-brain barrier and are a suitable model for mechanistic studies on the brain penetration of drug candidates.
Assuntos
Subfamília B de Transportador de Cassetes de Ligação de ATP/deficiência , Transportadores de Cassetes de Ligação de ATP/deficiência , Azepinas/farmacocinética , Encéfalo/metabolismo , Dantroleno/farmacocinética , Triazóis/farmacocinética , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Azepinas/sangue , Células CACO-2 , Dantroleno/sangue , Dibenzocicloeptenos/farmacologia , Técnicas de Inativação de Genes , Humanos , Masculino , Quinolinas/farmacologia , Ratos , Triazóis/sangueRESUMO
BI-X, a therapeutic protein under development for the treatment of human ocular disease via intravitreal administration, binds to its therapeutic targets and endogenous albumin in the vitreous humor. A monkey ocular pharmacokinetic (PK) study following BI-X administration was conducted to measure drug and albumin levels in plasma, the vitreous humor, the aqueous humor, and retina tissue at various timepoints post-dose. A comprehensive bioanalytical approach was implemented in support of this study. Five immunocapture-LC-MS/MS assays were developed and qualified for quantitating BI-X in different matrices, while ELISA was used for albumin measurement. Immunocapture at the protein or peptide level was evaluated to achieve adequate assay sensitivity. Drug and albumin assays were applied for the analysis of the monkey study samples.
RESUMO
For autologous-disc-derived chondrocyte transplantation (ADCT) a transglutaminase crosslinked gelatine gel and an albumin hyaluronic acid gel, crosslinked with bis-thio-polyethylene glycol, were injected through a syringe into a degenerated intervertebral disc, where they solidified in situ. This biomechanical in vitro study with lumbar bovine motion segments evaluated disc height changes, motion characteristics in a quasi-static spine loading simulators, and the potential extrusion risk of these biomaterials in a complex dynamic multi-axial loading set-up with 100,000 loading cycles. After the injection and formation of the gel in the center of the nucleus, the disc height increase was about 0.3 mm. During cyclic testing, a gradual decrease in height could be detected due to viscoelastic effects and fluid loss. No gel extrusion could be observed for all specimens during the entire test procedure. A macroscopic inspection after dissections showed an accumulation of the solidified gel in the center of the nucleus. The results demonstrate that the injection of in situ solidifying gels through the intact annulus allows for the stable maintenance of the injected gel at the target location, with high potential for use as a suitable scaffold to anchor therapeutically applied cells for disc regeneration within the treated nucleus pulposus.
RESUMO
Purpose: Inflammation is implicated in the etiology of diverse retinopathies including uveitis, age-related macular degeneration or diabetic retinopathy. Tumor necrosis factor alpha (TNF-α) is a well-known proinflammatory cytokine that is described as a biomarker for inflammation in diverse retinopathies and therefore emerged as an interesting target to treat inflammation in the eye by neutralizing anti-TNF-α antibodies. Methods: Recently, we have demonstrated that Adeno-associated virus (AAV)-mediated expression of human TNF-α in the murine eye induces retinal inflammation including vasculitis and fibrosis, thereby mimicking human disease-relevant pathologies. In a proof-of-mechanism study, we now tested whether AAV-TNF-α induced pathologies can be reversed by neutralizing TNF-α antibody treatment. Results: Strikingly, a single intravitreal injection of the TNF-α antibody golimumab reduced AAV-TNF-α-induced retinal inflammation and retinal thickening. Furthermore, AAV-TNF-α-mediated impaired retinal function was partially rescued by golimumab as revealed by electroretinography recordings. Finally, to study TNF-α-induced vasculitis in human in vitro cell culture assays, we established a monocyte-to-endothelium adhesion co-culture system. Indeed, also in vitro TNF-α induced monocyte adhesion to human retinal endothelial cells, which was prevented by golimumab. Conclusions: Overall, our study describes valuable in vitro and in vivo approaches to study the function of TNF-α in retinal inflammation and demonstrated a preclinical proof-of-mechanism treatment with golimumab. Translational Relevance: The AAV-based model expressing human TNF-α allows us to investigate TNF-α-driven pathologies supporting research in mechanisms of retinal inflammation.
Assuntos
Doenças Retinianas , Fator de Necrose Tumoral alfa , Vasculite , Animais , Dependovirus/genética , Células Endoteliais/patologia , Humanos , Inflamação , Camundongos , Camundongos Endogâmicos C57BL , Doenças Retinianas/etiologia , Doenças Retinianas/metabolismo , Doenças Retinianas/patologia , Inibidores do Fator de Necrose Tumoral/farmacologia , Fator de Necrose Tumoral alfa/biossíntese , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/imunologia , Vasculite/etiologia , Vasculite/patologiaRESUMO
Retinopathies are multifactorial diseases with complex pathologies that eventually lead to vision loss. Animal models facilitate the understanding of the pathophysiology and identification of novel treatment options. However, each animal model reflects only specific disease aspects and understanding of the specific molecular changes in most disease models is limited. Here, we conducted transcriptome analysis of murine ocular tissue transduced with recombinant Adeno-associated viruses (AAVs) expressing either human VEGF-A, TNF-α, or IL-6. VEGF expression led to a distinct regulation of extracellular matrix (ECM)-associated genes. In contrast, both TNF-α and IL-6 led to more comparable gene expression changes in interleukin signaling, and the complement cascade, with TNF-α-induced changes being more pronounced. Furthermore, integration of single cell RNA-Sequencing data suggested an increase of endothelial cell-specific marker genes by VEGF, while TNF-α expression increased the expression T-cell markers. Both TNF-α and IL-6 expression led to an increase in macrophage markers. Finally, transcriptomic changes in AAV-VEGF treated mice largely overlapped with gene expression changes observed in the oxygen-induced retinopathy model, especially regarding ECM components and endothelial cell-specific gene expression. Altogether, our study represents a valuable investigation of gene expression changes induced by VEGF, TNF-α, and IL-6 and will aid researchers in selecting appropriate animal models for retinopathies based on their agreement with the human pathophysiology.
Assuntos
Doenças Retinianas , Fator de Necrose Tumoral alfa , Humanos , Camundongos , Animais , Fator de Necrose Tumoral alfa/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Interleucina-6/genética , Perfilação da Expressão GênicaRESUMO
Purpose: Retinopathies display complex pathologies, including vasculopathies, inflammation, and fibrosis, leading ultimately to visual impairment. However, animal models accurately reflecting these pathologies are lacking. In this study, we evaluate the suitability of using Adeno-associated virus (AAV)-mediated long-term expression of cytokines to establish retinal pathology in the murine retina. Methods: We administered recombinant, Müller-glia targeted AAV-ShH10 into the mouse vitreous to induce retinal expression of either human vascular endothelial growth factor (VEGF)-A165, tumor necrosis factor alpha (TNF-α), or interleukin-6 (IL-6) and evaluated consequent effects by optical coherence tomography, fluorescein angiography, and histology. Results: Intravitreal injection of AAVs resulted in rapid and stable expression of the transgenes within 1 to 6 weeks. Akin to the role of VEGF-A in wet age-related macular degeneration, expression of VEGF-A led to several vasculopathies in mice, including neovascularization and vascular leakage. In contrast, the expression of the proinflammatory cytokines TNF-α or IL-6 induced retinal inflammation, as indicated by microglial activation. Furthermore, the expression of TNF-α, but not of IL-6, induced immune cell infiltration into the vitreous as well as vasculitis, and subsequently induced the development of fibrosis and epiretinal membranes. Conclusions: In summary, the long-term expression of human VEGF-A165, TNF-α, or IL-6 in the mouse eye induced specific pathologies within 6 weeks that mimic different aspects of human retinopathies. Translational Relevance: AAV-mediated expression of human genes in mice is an attractive approach to provide valuable insights into the underlying molecular mechanisms causing retinopathies and is easily adaptable to other genes and preclinical species supporting drug discovery for retinal diseases.
Assuntos
Fator de Necrose Tumoral alfa , Fator A de Crescimento do Endotélio Vascular , Animais , Dependovirus/genética , Humanos , Interleucina-6/genética , Camundongos , Retina , Fator de Necrose Tumoral alfa/genética , Fator A de Crescimento do Endotélio Vascular/genéticaRESUMO
Rho-associated kinase (ROCK) activation was shown to contribute to microvascular closure, retinal hypoxia, and to retinal pigment epithelium (RPE) barrier disruption in a rat model of diabetic retinopathy. Fasudil, a clinically approved ROCK inhibitor, improved retinal perfusion and reduced edema in this model, indicating that ROCK inhibition could be a promising new therapeutic approach for the treatment of diabetic retinopathy. However, due to its short intravitreal half-life, fasudil is not suitable for long-term treatment. In this study, we evaluated a very potent ROCK1/2 inhibitor (BIRKI) in a depot formulation administered as a single intravitreal injection providing a slow release for at least four weeks. Following BIRKI intravitreal injection in old Goto-Kakizaki (GK) type 2 diabetic rats, we observed a significant reduction in ROCK1 activity in the retinal pigment epithelium/choroid complex after 8 days and relocation of ROCK1 to the cytoplasm and nucleus in retinal pigment epithelium cells after 28 days. The chronic ROCK inhibition by the BIRKI depot formulation restored retinal pigment epithelial cell morphology and distribution, favored retinal capillaries dilation, and reduced hypoxia and inner blood barrier leakage observed in the diabetic retina. No functional or morphological negative effects were observed, indicating suitable tolerability of BIRKI after intravitreous injection. In conclusion, our data suggest that sustained ROCK inhibition, provided by BIRKI slow-release formulation, could be a valuable treatment option for diabetic retinopathy, especially with regard to the improvement of retinal vascular infusion and protection of the outer retinal barrier.
RESUMO
OBJECTIVES: The purpose of this study was to characterise the plasma protein binding of BI 1356. METHODS: BI 1356 (proposed trade name ONDERO) is a novel dipeptidyl peptidase 4 (DPP-4) inhibitor, which is under clinical development for the treatment of type 2 diabetes. DPP-4 is expressed in various tissues but soluble DPP-4 is also present in plasma. Therefore, binding to soluble DPP-4 may influence the pharmacokinetics of BI 1356. Plasma protein binding of BI 1356 was determined in vitro for wild type mice and rats and the results compared with those for DPP-4 knockout mice and DPP-4 deficient Fischer rats. In addition, protein binding of BI 1356 was examined in plasma from healthy human volunteers and renal excretion of the compound in the DPP-4 knockout mice was compared with that occurring in wild type mice. KEY FINDINGS: The results showed that BI 1356 exhibited a prominent concentration-dependent plasma protein binding due to a saturable high affinity binding to the DPP-4 target in plasma. Differences in renal excretion of BI 1356 between DPP-4 knockout mice and wild type mice suggested that saturable binding of BI 1356 to DPP-4 in the body also influenced elimination. CONCLUSIONS: High affinity, but readily saturable binding of BI 1356 to its target DPP-4 accounted primarily for the concentration-dependent plasma protein binding at therapeutic plasma concentrations of BI 1356.
Assuntos
Dipeptidil Peptidase 4/metabolismo , Inibidores da Dipeptidil Peptidase IV/metabolismo , Purinas/metabolismo , Quinazolinas/metabolismo , Algoritmos , Animais , Diabetes Mellitus Tipo 2/tratamento farmacológico , Dipeptidil Peptidase 4/sangue , Dipeptidil Peptidase 4/genética , Inibidores da Dipeptidil Peptidase IV/química , Inibidores da Dipeptidil Peptidase IV/farmacologia , Feminino , Humanos , Cinética , Linagliptina , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Estrutura Molecular , Ligação Proteica , Purinas/química , Purinas/farmacologia , Quinazolinas/química , Quinazolinas/farmacologia , Ratos , Ratos Endogâmicos F344RESUMO
BI 1356 (INN: linagliptin) is an inhibitor of dipeptidyl peptidase-4 (DPP-4). This study investigated whether saturable binding of BI 1356 to its target DPP-4 occurs in tissues and whether drug accumulation occurs at these sites in vivo. In order to test these hypotheses, the tissue distribution of BI 1356 was determined in wild-type and DPP-4 deficient rats at different dose levels by means of whole body autoradiography and measurement of tissue radioactivity concentrations after single i.v. dosing of [(14)C]-radio labeled BI 1356. The accumulation behavior of drug-related radioactivity in tissues was further explored in an oral repeat dose study. Tissue levels of [(14)C]BI 1356 related radioactivity were markedly lower in all investigated tissues of the DPP-4 deficient rats and the difference of the dose-dependent increase of radioactivity tissue levels between both rat strains indicates that tissue distribution at low doses of BI 1356 is dominated by binding of BI 1356 to DPP-4 in tissues. As the binding to DPP-4 is strong but reversible, the tissue binding results in a long terminal half-life in several tissues including plasma. The binding capacity to DPP-4 is, however, limited. In the rat, saturation of DPP-4 binding is suggested at an intravenous dose above 0.01-0.1 mg/kg [(14)C]BI 1356. As the DPP-4 binding capacity is saturated already at low doses, accumulation of BI 1356 in tissues is unlikely, despite the long persistence of low amounts in the body.
Assuntos
Inibidores da Dipeptidil Peptidase IV/farmacocinética , Purinas/farmacocinética , Quinazolinas/farmacocinética , Animais , Autorradiografia , Sítios de Ligação , Inibidores da Dipeptidil Peptidase IV/administração & dosagem , Relação Dose-Resposta a Droga , Meia-Vida , Linagliptina , Masculino , Purinas/administração & dosagem , Quinazolinas/administração & dosagem , Ratos , Ratos Endogâmicos F344 , Distribuição TecidualRESUMO
Linagliptin (BI 1356) is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor in clinical development for the treatment of type 2 diabetes. It exhibits non-linear pharmacokinetics and shows concentration-dependent plasma protein binding to its target, DPP-4. The aim of this study was to investigate the impact of saturable binding of linagliptin to plasma and tissue DPP-4 by comparing the pharmacokinetics of linagliptin in wildtype and DPP-4 deficient Fischer rats using non-compartmental and model-based data analysis. The non-compartmental analysis revealed a significantly reduced AUC in DPP-4 deficient rats compared with wildtype rats when single intravenous doses Assuntos
Dipeptidil Peptidase 4/sangue
, Dipeptidil Peptidases e Tripeptidil Peptidases/sangue
, Purinas/farmacologia
, Quinazolinas/farmacologia
, Animais
, Sítios de Ligação
, Diabetes Mellitus Tipo 2/tratamento farmacológico
, Diabetes Mellitus Tipo 2/enzimologia
, Diabetes Mellitus Tipo 2/metabolismo
, Inibidores da Dipeptidil Peptidase IV/farmacologia
, Linagliptina
, Ratos
, Ratos Endogâmicos F344
RESUMO
A new chemical class of potent DPP-4 inhibitors structurally derived from the xanthine scaffold for the treatment of type 2 diabetes has been discovered and evaluated. Systematic structural variations have led to 1 (BI 1356), a highly potent, selective, long-acting, and orally active DPP-4 inhibitor that shows considerable blood glucose lowering in different animal species. 1 is currently undergoing clinical phase IIb trials and holds the potential for once-daily treatment of type 2 diabetics.
Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Inibidores da Dipeptidil Peptidase IV , Hipoglicemiantes/síntese química , Piperidinas/síntese química , Purinas/síntese química , Quinazolinas/síntese química , Administração Oral , Animais , Células CACO-2 , Cristalografia por Raios X , Dipeptidil Peptidase 4 , Cães , Humanos , Hipoglicemiantes/farmacocinética , Hipoglicemiantes/farmacologia , Linagliptina , Macaca fascicularis , Macaca mulatta , Masculino , Modelos Moleculares , Piperidinas/farmacocinética , Piperidinas/farmacologia , Purinas/farmacocinética , Purinas/farmacologia , Quinazolinas/farmacocinética , Quinazolinas/farmacologia , Ratos , Ratos Wistar , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
PURPOSE: The ocular half-life of intravitreally (IVT) injected drugs is of major relevance for the suitability of a drug intended for chronic intraocular treatment, as the half-life determines the dosing frequency. Thus, half-life extension principles are very attractive as they can reduce the IVT dosing frequency. In this study, we investigated the ocular pharmacokinetics (PK) of the IVT injected Nanobody® BI-X and whether the noncovalent binding of BI-X to vitreous albumin could increase its ocular half-life. METHODS: Wistar rats were dosed IVT with 3 µg BI-X alone or coadministered with human serum albumin (HSA), and the ocular exposure was measured in a pilot experiment using whole eye homogenates. New Zealand White rabbits received IVT injections of 500 µg BI-X alone or coadministration with HSA. Concentrations of BI-X were determined in aqueous humor, vitreous body and plasma and pharmacokinetic parameters were calculated. RESULTS: Ocular concentrations of BI-X in rats were about 10- or 3-fold higher at 24 and 72 h, respectively, when dosed with HSA. In rabbits, coadministration with albumin led to an about 3-fold increased vitreous half-life and an about 5-fold higher exposure in vitreous humor. CONCLUSION: As small amounts of albumin are present in the vitreous body of healthy human eyes and the albumin concentration is even increased under disease conditions like diabetic retinopathy, high affinity binding to albumin may be a promising strategy to extend the half-life of IVT injected drugs, allowing for longer dosing intervals.
Assuntos
Humor Aquoso/metabolismo , Albumina Sérica/farmacocinética , Anticorpos de Domínio Único/metabolismo , Corpo Vítreo/metabolismo , Animais , Sítios de Ligação , Relação Dose-Resposta a Droga , Meia-Vida , Humanos , Injeções Intravítreas , Masculino , Coelhos , Ratos , Ratos Wistar , Albumina Sérica/administração & dosagem , Albumina Sérica/química , Anticorpos de Domínio Único/administração & dosagem , Anticorpos de Domínio Único/químicaRESUMO
A major aspect of understanding functions of the globus pallidus (GP) within the basal ganglia is the significance of its dopamine innervation. Here, we used in vivo-microdialysis in rats to characterize pallidal dopamine release in response to a number of physiological and pharmacological stimuli known to activate dopamine neurons. Results reveal that an aversive stimulus, i.e. handling for 20 min, significantly increased dialysate dopamine in the globus pallidus to about 130% of baseline levels. Likewise, a novel and appetitive stimulus, i.e. presentation of unfamiliar, palatable food, significantly elevated pallidal dopamine to about 150% of baseline levels both in rats which did and did not consume the food reward. These findings provide evidence that increases of dopamine (DA) efflux may largely reflect stimulus saliency implicating an involvement of pallidal dopamine signalling in control of behaviour governed by salient stimuli. Results further showed that reverse microdialysis of D-amphetamine and cocaine in augmenting concentrations of 0.1-100 microM elevated dialysate dopamine in a concentration-dependent manner suggesting a role of pallidal dopamine in mediating behavioural effects of psychostimulant drugs.
Assuntos
Dopamina/metabolismo , Globo Pálido/efeitos dos fármacos , Globo Pálido/metabolismo , Animais , Apetite/fisiologia , Cromatografia Líquida de Alta Pressão , Cocaína/farmacologia , Dextroanfetamina/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Eletroquímica , Alimentos , Globo Pálido/anatomia & histologia , Manobra Psicológica , Ácido Homovanílico/metabolismo , Masculino , Microdiálise , Ratos , Técnicas EstereotáxicasRESUMO
BACKGROUND: Pyogenic infections of the lumbar spine are a rare but critical pathology, yet with considerably high mortality rates. In cases indicating surgical therapy, the implantation of titanium cages or autologous bone grafts represent today's gold standard. Although non-metallic implants such as poly-ether-ether-ketone (PEEK) have proven to be advantageous in diverse degenerative conditions, their saftey and practicability in lumbar spine infection remains questionable. Moreover, the efficacy of a single-step radical debridement of the infected disc space with subsequent fusion from a strictly posterior approach continues to be an issue of debate. We therefore sought to evaluate the feasibility, clinical and radiological outcome of a single-step TLIF procedure using oblique PEEK cages in the surgical management of patients with lumbar pyogenic spondylodiscitis. METHODS: From January 2009 through December 2013, all patients meeting the indication for surgical treatment of lumbar pyogenic spondylodiscitis were included. Patients demonstrating intact cortical bone on preoperative CT received a single-step radical debridement of the infected intervertebral disc space, posterior screw-and-rod instrumentation and implantation of an oblique PEEK cage using the TLIF technique. Oral antibiotics were continued for 12 weeks postoperatively and clinical and radiological results recorded throughout a minimum 1-year clinical follow-up. RESULTS: A total of 104 patients were admitted to receive surgical therapy for lumbar pyogenic spondylodiscitis. Within this patient population, 18 patients met the diagnostic criteria to receive the implantation of an oblique PEEK cage. Pathogens were detected in 13 cases with Staph. aureus being the predominant causative organism. All patients were discharged to recover in their domestic environment. Throughout the first year of clinical and radiological follow-up and beyond, none of the 18 patients demonstrated any signs of residual neurologic deficits or recurrent infection. Furthermore, two-plane conventional X-rays showed no significant implant subsidence or failure at any of the given time-points in up to 5 years postoperatively. CONCLUSIONS: In patients meeting the criteria for surgical treatment of lumbar pyogenic spondylodiscitis, the implantation of PEEK cages using a single-step TLIF approach is a safe and feasible procedure. Based on our experience, the concern of a recurrent infection when implanting non-metallic cages may be refuted in carefully selected patients.