Calcium Dobesilate in the Treatment of Diabetic Retinopathy

Network pharmacology study of the mechanism underlying the therapeutic effect of Zhujing pill and its main component oleanolic acid against diabetic retinopathy

Diabetic retinopathy (DR) is the leading cause of blindness in the working population worldwide, with few effective drugs available for its treatment in the early stages. The Zhujing pill (ZJP) is well-established to enhance the early symptoms of DR, but the mechanism underlying its therapeutic effect remains unclear. In the present study, we used systems biology and multidirectional pharmacology to screen the main active ingredients of ZJP and retrieved DrugBank and Genecards databases to obtain 'drug-disease' common targets. Using bioinformatics analysis, we obtained the core targets, and potential mechanisms of action of ZJP and its main components for the treatment of DR. Molecular docking was used to predict the binding sites and the binding affinity of the main active ingredients to the core targets. The predicted mechanism was verified in animal experiments. We found that the main active ingredient of ZJP was oleanolic acid, and 63 common 'drug-disease' targets were identified. Topological analysis and cluster analysis based on the protein-protein interaction network of the Metascape database screened the core targets as PRKCA, etc. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that these core targets were significantly enriched in the pro-angiogenic pathway of the VEGF signaling pathway. Molecular docking and surface plasmon resonance revealed that ZJP and its main active component, oleanolic acid had the highest binding affinity with PKC-α, the core target of the VEGF signaling pathway. Animal experiments validated that ZJP and oleanolic acid could improve DR.

A single-dose, randomized crossover study in healthy Chinese subjects to evaluate pharmacokinetics and bioequivalence of two capsules of calcium dobesilate 0.5 g under fasting and fed conditions

OBJECTIVES

To compare the rate and extent of absorption of a launched generic calcium dobesilate capsule versus the branded reference formulation under fasting and fed conditions in healthy Chinese subjects, and to assess their bioequivalence and tolerability.

METHODS

This single-dose, open-label, randomized-sequence, 2-period crossover bioequivalence study was conducted on healthy Chinese volunteers aged 18 to 45 years. Subjects received a single 0.5 g dose of calcium dobesilate capsule under fasting or fed conditions, with a 3-day washout period between doses of the test (T) and reference (R) formulations. Blood samples were collected before and up to 24 hours after administration. The plasma concentration of calcium dobesilate was determined by a validated Liquid chromatography-tandem mass spectrometry method. Non-compartmental analysis was applied to identify the pharmacokinetic (PK) properties. The primary PK parameters including the maximal plasma concentration (Cmax), the area under the plasma concentration-time curve (AUC0-t), and the AUC extrapolated to infinity (AUC0-inf) were used for bioequivalence evaluation.

RESULTS

The mean of PK parameters for T and R capsules under fasting (fed) condition were: Cmax, 13.57 (6.71) and 12.59 (7.25) μg/mL; AUC0-t, 97.32 (79.74) and 96.97 (80.71) h*μg/mL; AUC0-inf, 101.68 (88.01) and 101.64 (87.81) h*μg/mL. The 90% confidence intervals (CIs) of GMRs under fasting (fed) condition were: Cmax, 97.91%-116.62% (88.63%-96.53%); AUC0-t, 97.15%-104.00% (96.58%-101.39%); and AUC0-inf, 97.19%-102.89% (98.67%-103.99%). These 90% CIs were all within the bioequivalence range of 80%-125%. All adverse events were mild.

CONCLUSION

In this study, the T calcium dobesilate 0.5 g capsule was bioequivalent to the reference product under both fasting and fed conditions. Taking food would slow down its rate and reduce its amount of absorption. Both formulations were generally well tolerated.

Effect of calcium dobesilate on retrobulbar blood flow and choroidal thickness in patients with non-proliferative diabetic retinopathy

INTRODUCTION

Diabetic retinopathy is one of the most common causes of blindness in work-aging adults and develops in one third of diabetic patients. Calcium dobesilate (CaD) treatment have protective effects on blood retinal barrier (BRB) and anti-oxidant as well as anti-inflammatory properties.

OBJECTIVES

To assess effects of CaD administration on retrobulbar blood flow and choroidal thickness in patients with diabetic retinopathy.

METHODS

In this quasi-experimental study, diabetic patients with diabetic retinopathy (DR) were recruited from Shahid Motahari and Poostchi ophthalmology clinic affiliated to Shiraz University of Medical Sciences. Patients were treated with CaD, 1 gr per day for seven days. Before and after CaD administration, retrobulbar blood flow and subfoveal choroidal thickness were assessed. Retrobulbar blood flow were evaluated by measuring peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) of ophthalmic artery (OA), central retinal artery (CRA) and short ciliary artery (SCA).

RESULTS

In this study, 26 DR patients with a mean age of 56.15 ± 8.93 years and mean diabetes mellitus duration of 15.04 ± 7.64 years were enrolled. Subfoveal choroidal thickness was significantly increased from 316.08 ± 61.69 to 327.81 ± 58.03 after CaD treatment (P value < 0.001). PSV of CRA and EDV of all arteries were significantly increased after CaD administration. In addition, RI of all arteries was significantly reduced after CaD treatment (P < 0.001).

CONCLUSION

CaD treatment may improve the ophthalmic blood flow and increase the subfoveal choroidal thickness in DR patients. These results may be suggestive of protective effects of CaD on endothelium function as well as microvascular circulation.

Efficacy of calcium dobesilate in treating Chinese patients with mild-to-moderate non-proliferative diabetic retinopathy (CALM-DR): protocol for a single-blind, multicentre, 24-armed cluster-randomised, controlled trial

INTRODUCTION

Calcium dobesilate (CaD) has been used in the treatment of diabetic retinopathy (DR) due to its potential in protecting against retinal vascular damage. However, there is limited evidence exploring its efficacy in combating DR progression. This study is aimed at evaluating whether CaD could prevent DR progression into an advanced stage among Chinese patients with mild-to-moderate non-proliferative DR (NPDR).

METHODS AND ANALYSIS

This study is a single-blind, multicentre, cluster-randomised, controlled superiority trial. A total of 1272 patients with mild-to-moderate NPDR will be enrolled and randomly assigned at a 1:1 ratio into the control group (conventional treatment group) and the intervention group (conventional treatment plus CaD (500 mg three times per day) for 12 months). Patients will be followed at 1, 3, 6 and 12 months after randomisation and receiving treatments, with the severity of DR assessed by the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. The primary endpoint is the progression of DR during follow-up, which is defined as an increase of two or more steps in the ETDRS scale. The secondary endpoints include the concomitant changes in visual acuity, presence, number, location and type of retinal lesions, and retinal blood vessel diameter as well as the arteriovenous ratio at different visits.

ETHICS AND DISSEMINATION

Each local ethics committee (first Vote: Ethical Review Committees of Zhongda Hospital of Southeast University (2019ZDSYLL132-P01)) has approved the study. The results will be published in high impact peer-reviewed scientific journals aimed at the general reader.

TRIAL REGISTRATION NUMBERS

NCT04283162.

Calcium dobesilate reduces VEGF signaling by interfering with heparan sulfate binding site and protects from vascular complications in diabetic mice

Inhibiting vascular endothelial growth factor (VEGF) is a therapeutic option in diabetic microangiopathy. However, VEGF is needed at physiological concentrations to maintain glomerular integrity; complete VEGF blockade has deleterious effects on glomerular structure and function. Anti-VEGF therapy in diabetes raises the challenge of reducing VEGF-induced pathology without accelerating endothelial cell injury. Heparan sulfate (HS) act as a co-receptor for VEGF. Calcium dobesilate (CaD) is a small molecule with vasoprotective properties that has been used for the treatment of diabetic microangiopathy. Preliminary evidence suggests that CaD interferes with HS binding sites of fibroblast growth factor. We therefore tested the hypotheses that (1) CaD inhibits VEGF signaling in endothelial cells, (2) that this effect is mediated via interference between CaD and HS, and (3) that CaD ameliorates diabetic nephropathy in a streptozotocin-induced diabetic mouse model by VEGF inhibition. We found that CaD significantly inhibited VEGF₁₆₅-induced endothelial cell migration, proliferation, and permeability. CaD significantly inhibited VEGF₁₆₅-induced phosphorylation of VEGFR-2 and suppressed the activity of VEGFR-2 mediated signaling cascades. The effects of CaD in vitro were abrogated by heparin, suggesting the involvement of heparin-like domain in the interaction with CaD. In addition, VEGF₁₂₁, an isoform which does not bind to heparin, was not inhibited by CaD. Using the proximity ligation approach, we detected inhibition of interaction in situ between HS and VEGF and between VEGF and VEGFR-2. Moreover, CaD reduced VEGF signaling in mice diabetic kidneys and ameliorated diabetic nephropathy and neuropathy, suggesting CaD as a VEGF inhibitor without the negative effects of complete VEGF blockade and therefore could be useful as a strategy in treating diabetic nephropathy.

Effect of astaxanthin on metabolic cataract in rats with type 1 diabetes mellitus

OBJECTIVE

The purpose of this study was to investigate the effect of astaxanthin on metabolic cataract in rats with type 1 diabetes and its antioxidant capacity to lens.

METHODS

Rats were randomly divided into four groups (n = 8): control group, diabetes mellitus (DM) group, low-dose astaxanthin (DM + AL) and low-dose astaxanthin (DM + AH) group. A rat model of type I diabetes mellitus was established by intraperitoneal injection of 60 mg/kg streptozotocin (STZ). After successful modeling, rats in the administration group were given different doses of astaxanthin (AST) for 12 weeks. The lens opacity of rats was observed by slit-lamp camera system. The double antibody sandwich method was used to detect the levels of advanced glycation end product (AGE), lipid peroxide/malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) in the lens. Hematoxylin-eosin (HE) staining was used to examine the morphologic changes in the lens.

RESULTS

The severity of cataract in the lens was obviously increased after induced by STZ, whereas it was significantly decreased after treatment with AST (p < .05, respectively). In addition, in the AST groups, the levels of AGE and MDA in the lens tissue were notably decreased when compared with those in the DM group (p < .05, respectively). However, the levels of GSH, SOD, and CAT were increased in the AST group in comparison with those in the DM group (p < .05, respectively).

CONCLUSIONS

Astaxanthin may play an antioxidant role in the lens. Additionally, it exerts a protective function in the lens by delaying the development and progression of metabolic cataract and inhibiting the oxidative stress of lens in diabetic rats.

Calcium Dobesilate and Micro-vascular diseases

Micro-vascular diseases and its associated complications continue to be a significant health problem worldwide. Vascular lesions from microvascular involvement lead to impaired blood flow and contribute to damage and dysfunction of one or more target organs, that is, the heart, kidneys, eyes, and nervous system. Calcium Dobesilate Drug (CAD) is an established vasoactive and angioprotective drug that has shown a unique, multitarget mode of action in several experimental studies and in different animal models of diabetic microvascular complications. CAD has been widely used as an antioxidant and a vascular protective agent. At present, the application of Calcium Dobesilate is mainly related to Micro-vascular damage-related diseases, such as diabetic retinopathy (DR) and diabetic nephropathy (DN), and it is found to significantly improve the related symptoms. Its beneficial effects make it an attractive therapeutic compound especially in the early stages of these diseases. Scholars at home and abroad have studied the effectiveness, safety, and mechanisms of the related diseases, furthermore, the subjects involved patients and animal models, they have found some new clinical effects of this medicine. This paper makes a brief summary of a research progress of clinical application about Vascular injury related diseases and other aspects.

Sweet Stress: Coping With Vascular Dysfunction in Diabetic Retinopathy

Oxidative stress plays key roles in the pathogenesis of retinal diseases, such as diabetic retinopathy. Reactive oxygen species (ROS) are increased in the retina in diabetes and the antioxidant defense system is also compromised. Increased ROS stimulate the release of pro-inflammatory cytokines, promoting a chronic low-grade inflammation involving various signaling pathways. An excessive production of ROS can lead to retinal endothelial cell injury, increased microvascular permeability, and recruitment of inflammatory cells at the site of inflammation. Recent studies have started unraveling the complex crosstalk between retinal endothelial cells and neuroglial cells or leukocytes, via both cell-to-cell contact and secretion of cytokines. This crosstalk is essential for the maintenance of the integrity of retinal vascular structure. Under diabetic conditions, an aberrant interaction between endothelial cells and other resident cells of the retina or invading inflammatory cells takes place in the retina. Impairment in the secretion and flow of molecular signals between different cells can compromise the retinal vascular architecture and trigger angiogenesis. In this review, the synergistic contributions of redox-inflammatory processes for endothelial dysfunction in diabetic retinopathy will be examined, with particular attention paid to endothelial cell communication with other retinal cells.

The Effect of Calcium Dobesilate on Liver Damage in Experimental Obstructive Jaundice

Purpose/Aim of the study: Inflammation and oxidative stress are two significant factors affecting the degree of liver damage in obstructive jaundice. The aim of this study was to evaluate the effect of calcium dobesilate (CaDob), an effective antioxidant and anti-inflammatory drug, on damage to liver caused by experimental obstructive jaundice.

MATERIALS AND METHODS

30 rats in total were randomly placed into three groups, each group consisting of 10 rats. The sham group (Group 1) only received solely laparotomy. In the control group (Group 2), ligation was applied to the biliary tract and no treatment was implemented. In the CaDob group (Group 3), following ligation of the biliary tract, 100 mg/kg/day CaDob was implemented via an orogastric tube for a 10-day period. Liver tissue and blood samples were taken for histopathological and biochemical examination.

RESULTS

The CaDob group had significantly lower test values for serum liver functions when compared to the control group. Statistically lower levels of tissue malondialdehyde (MDA) and fluorescent oxidation products (FOP) were detected in the CaDob group, and the CaDob group had significantly higher levels of sulfydryl (SH) than the control group. Histopathological scores in the CaDob group were found out to be statistically less than the scores the control group received (p < 0.05).

CONCLUSIONS

CaDob treatment repaired the histpatological changes induced by bile duct ligation. The hepatoprotective effects of CaDob can be associated with its antioxidant properties of the drug.

[Modern approach to early diagnosis and pathogenetic treatment of diabetic retinopathy]

AIM

To improve the approach to pathogenetic treatment of diabetic retinopathy (DR) through early diagnosis and a new method for predicting disease progression.

MATERIAL AND METHODS

The study enrolled 330 type 2 diabetes patients with DR (660 eyes), of whom women constituted 64.6%, men - 35.4%. The mean patient age was 62.3±2.3 years. Three groups were formed: the controls - 30 healthy volunteers (60 eyes) and 30 type 2 diabetes patients without ocular involvement (DR 0, 60 eyes); group 1 - 30 type 2 diabetes patients with DR I but no diabetic macular edema (DR I without DME, 60 eyes) that were treated with calcium dobesilate; group 2 - 240 type 2 diabetes patients, who had diabetic retinopathy of different stages (DR I, II, or III with DME, 480 eyes) and received laser retinal photocoagulation (LRP). The groups were all alike in terms of sex and age distribution. All patients underwent ophthalmic examination, including best corrected visual acuity (BCVA) and critical flicker fusion frequency (CFFF) testing, tonometry, biomicroscopy, MAIA fundus microperimetry, optical coherence tomography (OCT), and fluorescein angiography (FAG) of the retina. Traditionally we also determined blood sugar and glycated hemoglobin levels as well as vascular endothelial growth factor (VEGF-A) and monocyte chemoattractant protein (MCP-1) in tear fluid by ELISA.

RESULTS

In group 1, which was under conservative therapy with calcium dobesilate, there was an increase in BCVA by the average of 0.95±0.02 and CFFF by 42.5±0.2 Hz (p<0,05). The mean central retinal thickness decreased reliably down to 265.1±12.1 µm (p<0.05). Light sensitivity of the macula improved and scored 24.13±12.3 dB (p<0.05). In group 2, the mean central retinal thickness appeared to be 383.1±221 µm, which was reliably higher than that in healthy individuals (p<0.05) and in type 2 diabetes patients without diabetic retinopathy (DR 0) (p<0.05). Tear assessment 12 months after the treatment revealed a significant decrease in VEGF-A and MCP-1 concentrations - down to 655.1±86.1 pg/ml and 1133 pg/ml, respectively (p<0.05).

CONCLUSION

Conservative treatment with calcium dobesilate has proved effective in patients with DR I without DME as it ensures improvement and stabilization of the state of the retina (clinical and morphological) in one month already (judging from FAG and OCT findings). Laser treatment is rational in DR I, DR II, and DR III patients, whose condition is complicated with DME. Improvement and stabilization take, however, longer to be achieved - up to 1 year (according to FAG and OCT). Tear fluid assessment for particular participants in disease pathogenesis, such as VEGF-A and MCP-1, is a unique method for disease control and patient follow-up with account to different treatments. A new method for predicting the progression of diabetic retinopathy and diabetic macular edema has been suggested (RF patent for invention №2520826).

Administration of Traditional Chinese Blood Circulation Activating Drugs for Microvascular Complications in Patients with Type 2 Diabetes Mellitus

Traditional Chinese medicine (TCM) is an important complementary strategy for treating diabetes mellitus (DM) in China. Traditional Chinese blood circulation activating drugs are intended to guide an overall approach to the prevention and treatment of microvascular complications of DM. The core mechanism is related to the protection of the vascular endothelium and the basement membrane. Here, we reviewed the scientific evidence underpinning the use of blood circulation activating drugs to prevent and treat DM-induced microvascular complications, including diabetic nephropathy (DN), diabetic peripheral neuropathy (DPN), and diabetic retinopathy (DR). Furthermore, we summarized the effects and mechanism of TCM on improving blood rheology, inhibiting aggregation of platelet, forming advanced glycation end products (AGEs), regulating oxidative stress, reducing blood fat, and improving lipid metabolism. The paper provides a new theoretical basis for the clinical practice of TCM in the prevention and treatment of DM and its microvascular complications.

[Relationship of cystatin C, fibrinogen, and 24-hour urinary protein with renal pathological grade in children with Henoch-Schönlein purpura nephritis]

OBJECTIVE

To study the relationship of cystatin C (CysC), fibrinogen (Fbg), and 24-hour urinary protein with renal pathological grade in children with Henoch-Schönlein purpura nephritis (HSPN), and to explore their values.

METHODS

The clinical data of 48 children diagnosed with HSPN by renal biopsy from January 2011 to January 2015 were reviewed. According to renal pathological grading, in the 48 children with HSPN, 12 had stage IIa or lower, 12 stage IIb, 17 stage IIIa, and 7 stage IIIb or higher. The latex-enhanced immunoturbidimetric assay, turbidimetric measurement, and end-point method were used to determine the levels of serum CysC, Fbg, and 24-hour urinary protein, respectively. Pearson and Spearman correlation analyses were used to test the correlations between the indices and between the indices and renal pathological grade.

RESULTS

There were significant differences in the levels of serum CysC, Fbg, and 24-hour urinary protein between patients with different pathological grades (P<0.05). The level of each index increased with increasing pathological grade (P<0.05). In the 48 children with HSPN, the level of 24-hour urine protein was positively correlated with the levels of serum CysC (r=0.51, P<0.05) and Fbg (r=0.63, P<0.05). The level of Fbg was positively correlated with that of serum CysC (r=0.55, P<0.05). The levels of CysC, Fbg, and 24-hour urinary protein were all positively correlated with renal pathological grade (r=0.66, 0.64 and 0.68; respectively, P<0.05).

CONCLUSIONS

The levels of CysC, Fbg, and 24-hour urine protein can reflect the severity of renal injury, providing satisfactory prediction of the severity of renal injury in children with HSPN.

Compound Danshen Dripping Pill for Treating Early Diabetic Retinopathy: A Randomized, Double-Dummy, Double-Blind Study

This randomized, double-dummy, double-blind study was to observe the therapeutic effects of compound Danshen dripping pill (CDDP) in treating early diabetic retinopathy (DR). All the 57 type 2 diabetes cases in nonproliferative diabetic retinopathy (NPDR) stage were divided into two groups randomly: 28 cases treated with CDDP as the treated group and 29 cases treated with calcium dobesilate as the control group. The best corrected visual acuity (BCVA) in the treated group was significantly improved after treatment when compared to that before treatment (P < 0.05). Mean defect (MD) of visual field, hemorrhage area of the fundus, microaneurysm number, fluorescent leakage area, and capillary nonperfusion area evaluated by visual field, fundus photography, and fundus fluorescein angiography in the treated group had the same results as BCVA. However, there was no statistical difference in each index between the two groups. No obvious adverse events with clinical significance occurred. Our present study showed that CDDP has a similar improvement and safety to calcium dobesilate for NPDR. In future DR treatments, CDDP may function as the auxiliary drug.

Oxidative stress, mitochondrial damage and diabetic retinopathy

Diabetes has emerged as an epidemic of the 21st century, and retinopathy remains the leading cause of blindness in young adults and the mechanism of this blinding disease remains evasive. Diabetes-induced metabolic abnormalities have been identified, but a causal relationship between any specific abnormality and the development of this multi-factorial disease is unclear. Reactive oxygen species (ROS) are increased and the antioxidant defense system is compromised. Increased ROS result in retinal metabolic abnormalities, and these metabolic abnormalities can also produce ROS. Sustained exposure to ROS damages the mitochondria and compromises the electron transport system (ETC), and, ultimately, the mitochondrial DNA (mtDNA) is damaged. Damaged mtDNA impairs its transcription, and the vicious cycle of ROS continues to propagate. Many genes important in generation and neutralization of ROS are also epigenetically modified further increasing ROS, and the futile cycle continues to fuel in. Antioxidants have generated beneficial effects in ameliorating retinopathy in diabetic rodents, but limited clinical studies have not been encouraging. With the ongoing use of antioxidants for other chronic diseases, there is a need for a controlled trial to recognize their potential in ameliorating the development of this devastating disease.

Oxidative stress and epigenetic modifications in the pathogenesis of diabetic retinopathy

Diabetic retinopathy remains the major cause of blindness among working age adults. Although a number of metabolic abnormalities have been associated with its development, due to complex nature of this multi-factorial disease, a link between any specific abnormality and diabetic retinopathy remains largely speculative. Diabetes increases oxidative stress in the retina and its capillary cells, and overwhelming evidence suggests a bidirectional relationship between oxidative stress and other major metabolic abnormalities implicated in the development of diabetic retinopathy. Due to increased production of cytosolic reactive oxygen species, mitochondrial membranes are damaged and their membrane potentials are impaired, and complex III of the electron transport system is compromised. Suboptimal enzymatic and nonenzymatic antioxidant defense system further aids in the accumulation of free radicals. As the duration of the disease progresses, mitochondrial DNA (mtDNA) is damaged and the DNA repair system is compromised, and due to impaired transcription of mtDNA-encoded proteins, the integrity of the electron transport system is encumbered. Due to decreased mtDNA biogenesis and impaired transcription, superoxide accumulation is further increased, and the vicious cycle of free radicals continues to self-propagate. Diabetic milieu also alters enzymes responsible for DNA and histone modifications, and various genes important for mitochondrial homeostasis, including mitochondrial biosynthesis, damage and antioxidant defense, undergo epigenetic modifications. Although antioxidant administration in animal models has yielded encouraging results in preventing diabetic retinopathy, controlled longitudinal human studies remain to be conducted. Furthermore, the role of epigenetic in mitochondrial homeostasis suggests that regulation of such modifications also has potential to inhibit/retard the development of diabetic retinopathy.

Non-traditional systemic treatments for diabetic retinopathy: an evidence-based review

The rapid escalation in the global prevalence diabetes, with more than 30% being afflicted with diabetic retinopathy (DR), means it is likely that associated vision-threatening conditions will also rise substantially. This means that new therapeutic approaches need to be found that go beyond the current standards of diabetic care, and which are effective in the early stages of the disease. In recent decades several new pharmacological agents have been investigated for their effectiveness in preventing the appearance and progression of DR or in reversing DR; some with limited success while others appear promising. This up-to-date critical review of non-traditional systemic treatments for DR is based on the published evidence in MEDLINE spanning 1980-December 2014. It discusses a number of therapeutic options, paying particular attention to the mechanisms of action and the clinical evidence for the use of renin-angiotensin system blockade, fenofibrate and calcium dobesilate monohydrate in DR.

Effect of adding oral calcium dobesilate to laser photocoagulation on the macular thickness in patients with diabetic macular edema: a randomized clinical trial

PURPOSE

To evaluate the effect of oral calcium dobesilate (Doxium) on macular thickness in clinically significant macular edema (CSME).

METHODS

Overall, 71 eyes of 40 patients with non-proliferative diabetic retinopathy and clinically significant macular edema were included. All patients were received laser treatment for macular edema. Coherence optical tomography was used to determine the retinal thickness. Patients were randomized into two groups: group A received three Doxium capsule daily and group B received three placebo capsule daily for six months.

RESULTS

The mean macular thickness before and after treatment in the group A was 340 and 257 micrometers respectively (24.5% reduced), and in the group B was 336 micrometers and 263 micrometers respectively (21.5% reduced). Macular thickness significantly decreased after treatment in both groups and the reduction in group A is higher but the difference of reduction between the two groups was not statistically significant (P>0.05).

CONCLUSION

In respect to the effect of adding oral Doxium to Laser Photocoagulation on the macular thickness in patients with diabetic macular edema, this study showed no statistically significant difference between Doxium and placebo.

Regression activity that is naturally present in vitreous becomes ineffective as patients develop proliferative diabetic retinopathy

AIMS/HYPOTHESIS

The realisation that targeting agents in the vitreous is an effective approach to treating patients with diabetic retinopathy (DR) has increased awareness that changes in the composition/bioactivity of the vitreous is a contributor to the pathogenesis of DR. The overall goal of this study was to test the hypothesis that the vitreous has regression activity, and that lysophosphatidic acid (LPA) contributes to such activity. LPA is a bioactive phospholipid present in many biological fluids, and has been recently appreciated for its ability to promote regression of blood vessels.

METHODS

Vitreous-mediated regression was monitored on tubes organised from primary retinal endothelial cells or neovessels that sprouted from retinal explants. LPA was quantified radioenzymatically.

RESULTS

Bovine and human vitreous promoted regression of retinal explant vessels and of tubes organised from primary retinal endothelial cells. LPA was a substantial component of this regression activity. Comparing the regression activities of vitreous from patients with different stages of DR revealed that, as patients developed proliferative diabetic retinopathy (PDR), vitreous lost its ability to promote regression, even though the amount of LPA did not change. The underlying mechanism was a PDR-vitreous-mediated insensitivity to LPA, which could be overcome pharmacologically.

CONCLUSIONS/INTERPRETATION

Our findings suggest that a decline in the responsiveness to regression factors such as LPA, which are naturally present in the vitreous, contributes to the pathogenesis of PDR.

Beyond AREDS: is there a place for antioxidant therapy in the prevention/treatment of eye disease?

Age-related macular degeneration (AMD), the major cause of blindness in adults (65 years of age and older), and diabetic retinopathy, the major cause of blindness in working adults, are chronic, progressive diseases with multifaceted etiologies that are not fully understood. Progression and lack of treatment of both diseases may lead to the advanced stage with neovascularization. Although the detailed cellular mechanisms leading to the development of AMD and diabetic retinopathy remain elusive, oxidative damage to the retina and its pigment epithelium are considered to be involved. Clinical studies have shown that the progression of AMD can be slowed down by nutritional antioxidants, but trials with antioxidants for diabetic retinopathy (very limited in number) have been inconclusive. Long-term administration of the AREDS antioxidants, the same nutritional antioxidants that have been demonstrated to slow the progression of AMD, have yielded exciting results in preventing the pathogenesis of retinopathy in diabetic rodents. These results suggest the merit of testing the AREDS antioxidants in a clinical trial to prevent the development and/or progression of diabetic retinopathy, with the possibility of reducing the impact of this common vision-threatening disease.

In vitro effect of calcium dobesilate on oxidative/inflammatory stress in human varicose veins

AIM

To determine whether calcium dobesilate can act in chronic venous insufficiency by similar antioxidant, anti-inflammatory mechanisms as in diabetic retinopathy.

METHODS

Calcium dobesilate was tested in vitro for its protective action against oxidative/inflammatory stress in human varicose veins. Varicose greater saphenous veins were obtained from 14 patients (11 men, 3 women) aged 53-65 years. Oxidative stress was induced exogenously in the vein segments, with the phenazine methosulphate (PMS)/NADH couple. Total antioxidant status (TAS) and malondialdehyde (MDA) contents were used as markers of oxidative stress.

RESULTS

Calcium dobesilate significantly prevented oxidative disturbances in the micromolar range. PMS/NADH-dependent TAS decrease was fully prevented with IC(50) = 11.4 ± 2.3 µmol/L (n = 6 veins), whereas MDA increase was fully prevented with IC(50) = (102 ± -3) µmol/L (n = 6 veins). Calcium dobesilate acted quali- and quantitatively like rutin, the reference compound. Comparison with pharmacokinetic data suggests that calcium dobesilate can act at therapeutic concentrations.

CONCLUSION

Calcium dobesilate protected human varicose veins against oxidative stress in vitro at levels that correspond to therapeutic concentrations. Further studies are required to investigate whether a similar action is found in varicose veins from patients orally treated with calcium dobesilate.

Calcium dobesilate and oxerutin: effectiveness of combination therapy

Objectives

Chronic venous insufficiency (CVI) is an important cause of discomfort and inability to work. Hydroxyethylrutosides (Venoruton®; 0-[beta-hydroxyethyl]-rutosides) has been used for decades for the treatment of CVI. Studies have reported symptomatic relief and a decreased capillary filtration after the administration of the oral preparations. Calcium dobesilate is a synthetic venoactive drug acting on several levels. It inhibits capillary permeability; it has antioxidant properties; and it inhibits the synthesis of prostaglandins and thromboxanes, reducing platelet and erythrocyte aggregation, as well as blood viscosity. The aim of this study is to determine whether the combination of both drugs is more effective in decreasing patients' complaints.

Methods

One hundred and fifty patients with primary venous insufficiency were randomized into three groups: Group A receiving calcium dobesilate only, Group B receiving oxerutin only and Group C receiving both calcium dobesilate and oxerutin. Patients were evaluated with a questionnaire before and four weeks after treatment regarding following parameters: itching, fatigue, heaviness, numbness, cramp, swelling and sensitiveness. Patients rated their symptoms from 0 to 4 (0: absent; 1: mild; 2: moderate; 3: severe; 4: very severe).

Results

Complaints, which were scored by patients before and after treatment, decreased. Among the single-drug groups, itching score decreased more in Group B, whereas scores of fatigue, heaviness, numbness, cramp and swelling decreased more in Group A. But the difference was not significant, statistically. But all complaints decreased significantly in Group C. Difference of scores after treatment revealed no statistical significance in Group A and B, but scores of Group C produced a significant difference when compared with Group A and B.

Conclusion

Results demonstrate that a combination of calcium dobesilate and oxerutin shows a better improvement of complaints. These observations have to be confirmed in larger series with objective tests. Changes of quality of life after a combination therapy might also be of interest.

Effect of calcium dobesilate on occurrence of diabetic macular oedema (CALDIRET study): randomised, double-blind, placebo-controlled, multicentre trial

BACKGROUND

Medical treatment for diabetic retinopathy could have an important role in prevention of complications such as visual loss. We aimed to assess the effect of calcium dobesilate on occurrence of diabetic macular oedema.

METHODS

We undertook a randomised, double-blind, placebo-controlled, multicentre study in 40 centres in 11 countries. We enrolled outpatients with adult-onset type 2 diabetes and mild-to-moderate non-proliferative diabetic retinopathy, and randomly allocated them via sealed envelopes either calcium dobesilate (1500 mg per day) or placebo. The primary endpoint was development of clinically significant macular oedema (CSME) within a follow-up period of 5 years. Patients who dropped out of the study early were censored. Analysis was by intention to treat.

FINDINGS

We enrolled 635 patients. 324 were randomly allocated calcium dobesilate and 311 were assigned placebo. In the calcium dobesilate group, 86 patients developed CSME compared with 69 in the placebo group. Accounting for censored cases, estimated cumulative 5-year CSME probability was 35% and 28%, respectively (hazard ratio 1.32, 95% CI 0.96-1.81; p=0.0844). Adverse events did not differ between treatment groups (78 [24%] on calcium dobesilate and 90 [29%] with placebo). No relevant drug-related complications were noted. Nine patients (3%) died in the calcium dobesilate group and eight (3%) deaths were recorded on placebo.

INTERPRETATION

Calcium dobesilate did not reduce the risk of development of CSME.

Randomized, double blind, placebo-controlled clinical trial to evaluate the lymphagogue effect and clinical efficacy of calcium dobesilate in chronic venous disease

The aims of the present study were to investigate the effect of calcium dobesilate on lymph flow and lymphovenous edema in patients with chronic venous disease. It was a randomized, placebo-controlled, double-blind clinical trial. Patients received 1 capsule of 500 mg calcium dobesilate every 8 hours (1.5 g/day) or placebo by 49 days. By the end of the treatment period, only the patients treated with calcium dobesilate had normalization of lymphogammagraphy (capture index and speed of lymph flow; 80 and 78%, respectively). Only patients treated with calcium dobesilate had statistically significant reduction in the perimeter of leg, calf, and ankle. Twenty-two out of 25 (88%) calcium dobesilate-treated patients presented clinical improvement versus 5 out of 24 (20.8%) in the placebo group. One patient on calcium dobesilate developed rash and one patient on placebo complained of vomiting. In the present study, calcium dobesilate normalized lymph physiology and improved symptoms in patients with chronic venous disease.

Oxidative stress and diabetic retinopathy

Oxygen metabolism is essential for sustaining aerobic life, and normal cellular homeostasis works on a fine balance between the formation and elimination of reactive oxygen species (ROS). Oxidative stress, a cytopathic consequence of excessive production of ROS and the suppression of ROS removal by antioxidant defense system, is implicated in the development of many diseases, including Alzheimer's disease, and diabetes and its complications. Retinopathy, a debilitating microvascular complication of diabetes, is the leading cause of acquired blindness in developed countries. Many diabetes-induced metabolic abnormalities are implicated in its development, and appear to be influenced by elevated oxidative stress; however the exact mechanism of its development remains elusive. Increased superoxide concentration is considered as a causal link between elevated glucose and the other metabolic abnormalities important in the pathogenesis of diabetic complications. Animal studies have shown that antioxidants have beneficial effects on the development of retinopathy, but the results from very limited clinical trials are somewhat ambiguous. Although antioxidants are being used for other chronic diseases, controlled clinical trials are warranted to investigate potential beneficial effects of antioxidants in the development of retinopathy in diabetic patients.

Effects of stobadine and vitamin E in diabetes-induced retinal abnormalities: involvement of oxidative stress

BACKGROUND

Because hyperglycemia-induced oxidative stress may be a cause of retinopathy, this study examined the hypothesis that administration of exogenous antioxidants, stobadine (ST) and vitamin E (vitE), can restore retinal abnormalities in experimental diabetes.

METHODS

Normal and streptozotocin (STZ)-induced male Wistar rats received daily intraoral doses of ST (24.7 mg/kg) and vitE (alpha-dl-tocopherol acetate, 400-500 IU/kg) individually or in combinations for 8 months. The biochemical parameters including aldose reductase enzyme (AR) activity and lipid peroxidation (MDA), and histopathological changes such as retinal capillary basement membrane thickness (RCBMT) and vascular endothelial growth factor (VEGF) expression were evaluated.

RESULTS

A 37.99% increase in RCBMT was observed in rats after 8 months diabetes duration. The increase in RCBMT was 12.34% in diabetic rats treated with ST and 23.07% in diabetic rats treated with vitE. In diabetic rats treated with antioxidant combination, just a 4.38% increase was observed in RCBMT. The excess VEGF immunoreactivity and increased MDA and AR activity determined in diabetic retina were significantly attenuated by individual antioxidant treatments. Although both antioxidants decreased blood glucose, HbA1c, fructosamine and triglyceride levels in diabetic rats, poor glycemic control was maintained in all experimental groups during the treatment period. However, the antioxidant combination led to almost complete amelioration in retinal MDA and RCBMT in diabetic rats.

CONCLUSIONS

The ability of antioxidant combination to arrest retinal abnormalities and lipid peroxidation even in the presence of poor glycemic control might advocate the key role of direct oxidative damage and the protective action of antioxidants in retinal alterations associated with diabetic retinopathy.

Effect of calcium dobesilate on progression of early diabetic retinopathy: a randomised double-blind study

BACKGROUND

The study was carried out to confirm the effect of calcium dobesilate (CaD) compared to placebo (PLA) on the blood-retinal barrier (BRB) permeability in early diabetic retinopathy (DR).

METHODS

Adults with type II diabetes and early diabetic retinopathy (below level 47 of ETDRS grading and PVPR between 20 and 50x10(-6)/ min, plasma-free fluorescein) were included in this double-blind placebo-controlled study. Treatment was 2 g daily for 24 months. The primary parameter, posterior vitreous penetration ratio (PVPR), was measured every 6 months by fluorophotometry. Secondary parameters were fundus photography, fluorescein angiography and safety assessments. Metabolic control was performed every 3 months.

RESULTS

A total of 194 patients started the treatment (98 CaD, 96 PLA) and 137 completed the 24-month study (69 CaD, 68 PLA). Both treatment groups were comparable at baseline, with ETDRS level 10 in about 59% of patients. Mean PVPR change from baseline after 24 months was significantly (P=0.002) lower in the CaD group [-3.87 (SD 12.03)] than in the PLA group [+2.03 (SD 12.86)], corresponding to a 13.2% decrease in the CaD group and a 7.3% increase in the PLA group. PVPR evolution was also analysed by HbA1c classes (<7%, between 7 and 9%, > or =9%) and results confirmed the superiority of CaD independently of the diabetes control level. A highly significant difference [CaD: -3.38 (SD 13.44) versus PLA: +3.50 (SD 13.70)] was also obtained in a subgroup of patients without anti-hypertensive and/or lipid-lowering agents (P=0.002 at 24 months). A further analysis of the secondary parameters showed significant changes in favour of CaD in the evolution from baseline to the last visit of haemorrhages (P=0.029), DR level (P=0.0006) and microaneurysms (P=0.013). Regarding safety, only 2.5% (n=5 patients/ events) of all adverse events reported were assessed as possibly or probably related to the test drug, while all serious adverse events were reported as unlikely. There was no statistical difference between groups.

CONCLUSION

Calcium dobesilate 2 g daily for 2 years shows a significantly better activity than placebo on prevention of BRB disruption, independently of diabetes control. Tolerance was very good.