Inhibition of choroidal angiogenesis by calcium dobesilate in normal Wistar and diabetic GK rats

Endoplasmic Reticulum Stress Delays Choroid Development in the HCAR1 Knockout Mouse

The subretina, composed of the choroid and the retinal pigment epithelium (RPE), plays a critical role in proper vision. In addition to phagocytosis of photoreceptor debris, the RPE shuttles oxygen and nutrients to the neuroretina. For their own energy production, RPE cells mainly rely on lactate, a major by-product of glycolysis. Lactate, in turn, conveys most of its biological effects via the hydroxycarboxylic acid receptor 1 (HCAR1). Herein, the lactate-specific receptor, HCAR1, was found to be exclusively expressed in the RPE cells within the subretina, and Hcar1-/- mice exhibited a substantially thinner choroidal vasculature during development. Notably, the angiogenic properties of lactate on the choroid were impacted by the absence of Hcar1. HCAR1-deficient mice exhibited elevated endoplasmic reticulum stress along with eukaryotic translation initiation factor 2α phosphorylation, a significant decrease in the global protein translation rate, and a lower proliferation rate of choroidal vasculature. Strikingly, inhibition of the integrated stress response using an inhibitor that reverses the effect of eukaryotic translation initiation factor 2α phosphorylation restored protein translation and rescued choroidal thinning. These results provide evidence that lactate signalling via HCAR1 is important for choroidal development/angiogenesis and highlight the importance of this receptor in establishing mature vision.

Protective effects of pharmacological agents against aminoglycoside-induced nephrotoxicity: A systematic review

Introduction: Aminoglycosides have been long used for antibacterial treatment and are still commonly used in clinical practice. Despite their extensive application and positive effects, drug-related toxicity is considered as the main obstacle for aminoglycosides. Aminoglycosides induce nephrotoxicity through the endocytosis and accumulation of the antibiotics in the epithelial cells of proximal tubule. Most importantly, however, a number of pharmacological agents were demonstrated to have protective activities against nephrotoxicity in experimental animals.Areas covered: In the present systematic review, the authors provide and discuss the mechanisms and epidemiological features of aminoglycoside-induced nephrotoxicity, and focus mainly on recent discoveries and key features of pharmacological interventions. In total, 39 articles were included in this review.Expert opinion: The majority of studies investigated gentamicin-induced nephrotoxicity in animal models. Antioxidants, chemicals, synthetic drugs, hormones, vitamins, and minerals showed potential values to prevent gentamicin-induced nephrotoxicity. Indicators used to evaluate the effectiveness of nephroprotection included antioxidative indexes, inflammatory responses, and apoptotic markers. Among the nephroprotective agents studied, herbs and natural antioxidant agents showed excellent potential to provide a protective strategy against gentamicin-induced nephrotoxicity.

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.

A randomized, double-blind, placebo-controlled, clinical study on the efficacy and safety of calcium dobesilate in the treatment of chronic venous insufficiency

OBJECTIVE

To show the superiority of 500 mg calcium dobesilate vs. placebo in reduction of edema of the lower limbs in patients with chronic venous insufficiency, Clinical, Etiological, Anatomical and Pathophysiological classes C3/C4.

METHODS

A total of 351 patients were randomized (n = 174 calcium dobesilate, n = 177 placebo). Active treatment was 500 mg calcium dobesilate, three times daily for 12 weeks, with a 12-week follow-up.

RESULTS

At the end of treatment, the relative volume change in the most pathological leg was -0.6 ± 4.8% with calcium dobesilate compared to -0.3 ± 3.3% with placebo (p = 0.09). At the end of follow-up, this was -1.01 ± 5.4% for calcium dobesilate vs. -0.08 ± 3.5% for placebo (p = 0.002).

CONCLUSIONS

Calcium dobesilate treatment resulted in no significant volume change in the most pathological leg between baseline and end of treatment. However, the calcium dobesilate group showed a significantly greater volume decrease in the most pathological leg at the end of follow-up. Calcium dobesilate was well-tolerated, with a safety profile consistent with previously published data.

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.

Dramatic resolution of vitreous hemorrhage after an intravitreal injection of dobesilate

Vitreous hemorrhages are important clinical manifestations of proliferative diabetic retinopathy. Non-cleared vitreous hemorrhages could lead to hemosiderosis bulbi and glaucoma. Here, we describe the case of a type 2 diabetic patient presenting anterior segment and vitreous hemorrhages that resolved three days after treatment with a single intravitreal injection of dobesilate.

Neuropeptides, trophic factors, and other substances providing morphofunctional and metabolic protection in experimental models of diabetic retinopathy

Vision is the most important sensory modality for many species, including humans. Damage to the retina results in vision loss or even blindness. One of the most serious complications of diabetes, a disease that has seen a worldwide increase in prevalence, is diabetic retinopathy. This condition stems from consequences of pathological metabolism and develops in 75% of patients with type 1 and 50% with type 2 diabetes. The development of novel protective drugs is essential. In this review we provide a description of the disease and conclude that type 1 diabetes and type 2 diabetes lead to the same retinopathy. We evaluate existing experimental models and recent developments in finding effective compounds against this disorder. In our opinion, the best models are the long-term streptozotocin-induced diabetes and Otsuka Long-Evans Tokushima Fatty and spontaneously diabetic Torii rats, while the most promising substances are topically administered somatostatin and pigment epithelium-derived factor analogs, antivasculogenic substances, and systemic antioxidants. Future drug development should focus on these.

Can calcium dobesilate be used safely for peripheral microvasculopathies that require neoangiogenesis?

Background

Calcium dobesilate (CaD) is a member of the synthetic veno-active drug family. Only a small number of reports are available that describe the micro-angiogenic effects of CaD in the current literature.

Material/Methods

The antiangiogenic potential of CaD was compared with bevacizumab (Bb), which is a potent angiogenesis inhibitor, in a chick chorioallantoic membrane model. Four different concentrations (10⁻⁷, 10⁻⁶, 10⁻⁵, and 10⁻⁴ M) of drug pellet were prepared for each drug. Changes in vessel formation were scored and compared for each drug according to the previous literature.

Result

The antiangiogenic behavior of CaD was lower than Bb, despite the significant dose-dependent manner of escalation. The anti-angiogenic scores of CaD were determined as 0.20, 0.47, 0.66, 1.0 in 10⁻⁷, 10⁻⁶, 10⁻⁵, and 10⁻⁴ M concentrations, respectively (average score >0.5 was significant).

Conclusions

According to the data obtained, this agent should be used carefully for cases in which angiogenesis plays an important role in healing.

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.

Dihydroxy-2,5 benzenesulphonate (dobesilate) elicits growth arrest and apoptosis in glioma cells

OBJECTIVES

Dihydroxy-2,5 benzenesulphonate (dobesilate) is used as an oral agent for treatment of vascular complications of diabetic retinopathy. We previously showed that blockade of fibroblast growth factor (FGF) driving angiogenesis with dobesilate inhibited new blood vessel formation in a mouse gelatine plug assay. In the present study we assessed the effects of dobesilate in rat glioma cells.

METHODS

Rat C6 cells line were grown as adherent cells in Dulbecco modified Eagle medium supplemented with 1% (v/v) fetal bovine serum and antibiotics. Calcium dobesilate was added in independent experiments at the following concentrations: 10, 25, 50, 75 and 100 microM, and cells were incubated for 24 hours. Effects of dobesilate in glioma cell proliferation and survival were assessed using crystal violet staining and TUNEL assay, respectively.

RESULTS

Incubation of glioma cells with dobesilate for 24 hours concentration-dependently decreased cell proliferation with an apparent IC50 of 25 microM, and this antiproliferative effect was related to a significant increase in glioma cell apoptosis.

CONCLUSIONS

The results suggest that dobesilate is a promising candidate leading to the development of a new adjuvant therapeutic strategy for gliomas.

Calcium Dobesilate in the Treatment of Diabetic Retinopathy

The incidence of diabetic retinopathy is still increasing in developed countries. Tight glycemic control and laser therapy reduce vision loss and blindness, but do not reverse existing ocular damage and only slow the progression of the disease. New pharmacologic agents that are currently under development and are specifically directed against clearly defined biochemical targets (i.e. aldose reductase inhibitors and protein kinase C-beta inhibitors) have failed to demonstrate significant efficacy in the treatment of diabetic retinopathy in clinical trials. In contrast, calcium dobesilate (2,5-dihydroxybenzenesulfonate), which was discovered more than 40 years ago and is registered for the treatment of diabetic retinopathy in more than 20 countries remains, to our knowledge, the only angioprotective agent that reduces the progression of this disease. An overall review of published studies involving calcium dobesilate (CLS 2210) depicts a rather 'non-specific' compound acting moderately, but significantly, on the various and complex disorders that contribute to diabetic retinopathy. Recent studies have shown that calcium dobesilate is a potent antioxidant, particularly against the highly damaging hydroxyl radical. In addition, it improves diabetic endothelial dysfunction, reduces apoptosis, and slows vascular cell proliferation.