Diabetic Retinopathy - Treatment
Pycnogenol -
updated: 15 March 2008
Pycnogenol for diabetic retinopathy. A review
Int Ophthalmol. 2001;24(3):161-71
Schönlau F, Rohdewald P.
Diabetic retinopathy represents a serious health threat to a rapidly growing number of patients with diabetes mellitus. The retinal microangiopathy is characterised by vascular lesions with exudate deposits and haemorrhages causing vision loss. Pycnogenol, a standardised extract of the bark of the French maritime pine (Pinus pinaster), is known to increase capillary resistance. Pycnogenol has been tested for treatment and prevention of retinopathy in five clinical trials with a total number of 1289 patients since the late 1960's. All but one of these studies have been reported in French and German and, today, are of limited accessibility, giving the impetus for reviewing them in detail in this article. There were two open case studies and two double blind studies (one controlled against calcium dobesilate and another against placebo) and, finally, one multi-center field study with 1169 diabetics. All of these studies unequivocally showed that Pycnogenol retains progression of retinopathy and partly recovers visual acuity. Treatment efficacy of Pycnogenol was at least as good as that of calcium dobesilate. Pycnogenol was shown to improve capillary resistance and reduce leakages into the retina. Tolerance was generally very good and side effects were rare, mostly referring to gastric discomfort. In conclusion, treatment with Pycnogenol had a favourable outcome in the majority of the patients with diabetic retinopathy.
Publication Types:
Online - Abstract
Treatment of vascular retinopathies with Pycnogenol
Phytother Res. 2001 May;15(3):219-23
Spadea L, Balestrazzi E.
The aim of our study was to investigate the effects of Pycnogenol on the progression of diabetic retinopathy and other vascular retinal disorders. The study consisted of a double-blind phase in which 20 patients were recruited and randomly treated with placebo or Pycnogenol (50 mg x 3/day for 2 months) and an open phase in which another 20 patients were treated with Pycnogenol at the same dose schedule. In total, 40 patients with diabetes, atherosclerosis and other vascular diseases involving the retina were enrolled; 30 of them were treated with Pycnogenol and 10 with placebo. The results demonstrated a beneficial effect of Pycnogenol on the progression of retinopathy. Without any treatment (placebo) the retinopathy progressively worsened during the trial and the visual acuity significantly decreased; on the contrary, the Pycnogenol-treated patients showed no deterioration of retinal function and a significant recovery of visual acuity was also obtained. The fluorangiography showed an improvement of retinal vascularization and a reduced endothelial permeability and leakage in the Pycnogenol, but not in the placebo-treated, patients. The ophthalmoscopy and the electroretinogram (ERG) also confirmed the beneficial effects of Pycnogenol. The mechanism of action of Pycnogenol may be related to its free radical (FR) scavenging, anti-inflammatory and capillary protective activities. It has been suggested that Pycnogenol may bind to the blood vessel wall proteins and mucopolysaccharides and produce a capillary 'sealing' effect, leading to a reduced capillary permeability and oedema formation.
Publication Types:
Online - Abstract
Effects of low-carbohydrate diet and Pycnogenol treatment on retinal antioxidant enzymes in normal and diabetic rats
J Ocul Pharmacol Ther. 2006 Feb;22(1):10-8
Kamuren ZT, McPeek CG, Sanders RA, Watkins JB 3rd.
Because chronic hyperglycemia of uncontrolled diabetes mellitus may lead to increased reactive oxygen species and decreased enzymatic antioxidant defenses responsible for pathological processes in diabetic retinopathy, this study examined the hypothesis that a low-carbohydrate, high-fat diet, either alone or in combination with Pinus maritima can reduce hyperglycemia, restoring a more balanced, oxidative condition. Normal and streptozotocininduced diabetic rats were fed either a regular or low-carbohydrate diet for 30 or 90 d. In addition, normal and diabetic rats on the chronic (90-d) low-carbohydrate diet were treated with daily intraperitoneal Pinus maritima doses (10 mg/kg) for 14 consecutive days. Retinas were fractionated to assay activities of glutathione peroxidase, glutathione reductase, and gamma-glutamyl transferase. After 30 d, the low-carbohydrate diet reduced glycemic parameters and normalized aspartate aminotransferase activity in diabetic animals, suggesting less organ damage. No differences were observed between males and females in any measured glycemic parameters. Whereas all diabetic control animals developed cataracts bilaterally, no treated diabetic animals developed cataracts. There were no deleterious effects on retinal antioxidant defenses with either a 30-d or chronic low-carbohydrate diet. When diet was combined with Pinus maritima treatment, both retinal glutathione peroxidase and glutathione reductase activities increased, suggesting that a low-carbohydrate diet plus Pinus maritima may be an effective antioxidant and antihyperglycemic therapy, reducing the risk of diabetic retinopathy and cataract formation.
Publication Types:
Online - Abstract
Effects of antioxidant treatment on normal and diabetic rat retinal enzyme activities
J Ocul Pharmacol Ther. 2005 Feb;21(1):28-35
Dene BA, Maritim AC, Sanders RA, Watkins JB 3rd.
Diabetes mellitus is characterized by hyperglycemia and, in chronic disease, by microvascular pathologies, especially in the kidney, peripheral nerve, and eye. Although hyperglycemia can be controlled with insulin and/or antihyperglycemic medications, diabetic retinopathy continues to be the leading cause of blindness in the United States. Because increased oxidative stress may be a cause of retinopathy, this study examined the hypothesis that administration of exogenous antioxidants can restore a more balanced oxidative condition. Normal and 30-day streptozotocin-induced diabetic Sprague-Dawley rats received daily intraperitoneal doses (10 mg/kg) of beta-carotene, alpha-lipoic, and Pycnogenol individually or in combinations for 14 days, after which retinae were dissected and fractionated for the assay of activities of glutathione reductase, glutathione peroxidase, gamma-glutamyl transferase, and superoxide dismutase. In normal rats, treatment with antioxidant combinations led to a decrease in gamma-glutamyl transferase activity; beta-carotene plus pycnogenol treatment decreased the activity of both glutathione-related enzymes. Decreased retinal gamma-glutamyl transferase activity of diabetic rats was normalized by the administration of pycnogenol alone or in combination with beta-carotene. In diabetic rats, retinal glutathione reductase activity increased after treatment with beta-carotene alone or with pycnogenol. Treatment with pycnogenol and alpha-lipoic acid alone or in combination decreased the activity of glutathione peroxidase, while this activity was increased after treatment with a combination of all antioxidants. Elevated activity of superoxide dismutase in diabetic retina was normalized by treatment with alpha-lipoic acid and with pycnogenol and beta-carotene in combination, but not with all three together. Antioxidants can access the retina and, once there, can alter antioxidant enzyme activities. In both normal and diabetic rats, combinations of antioxidants have different effects on retinal antioxidant enzyme activities than do individual antioxidants.
Publication Types:
Online - Abstract
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