Action of trimetazidine on retina of gerbils after ischemia reperfusion insult: determination of .OH, amino acids, and electroretinogram

Randomized clinical trial France DMLA2: effect of trimetazidine on exudative and nonexudative age-relatedmacular degeneration

PURPOSE

To evaluate the effect of trimetazidine (TMZ) in a randomized, double-blind, placebo-controlled clinical trial on the occurrence of choroidal neovascularization or geographic atrophy in age-related macular degeneration.

METHODS

A total of 1,086 patients from France, Belgium, and Spain with soft drusen and/or retinal pigment epithelium abnormalities in the study eye and choroidal neovascularization in the contralateral eye were randomly assigned to receive orally placebo or TMZ 70 mg daily (35 mg × 2) and followed-up for 3 years to 5 years.

RESULTS

Treatment duration ranged between 0.4 months and 67.8 months with a mean ± SD of 38 ± 16 months. Three hundred and fifty-eight patients developed choroidal neovascularization (incidence per 100 patient-years: TMZ 10.86; placebo 11.13). Trimetazidine did not prevent the choroidal neovascularization (hazard ratio = 0.97; 95% confidence interval, 0.77-1.20; P = 0.781). However, there was a trend favoring TMZ for retinal atrophy, a secondary endpoint (HR = 0.76; 95% confidence interval, 0.56-1.02; P = 0.069). Overall, the difference in atrophy incidence between TMZ and placebo was not statistically different. Differences within some prespecified subgroups of patients showed superiority of TMZ in men (HR = 0.50; 95% confidence interval, 0.28-0.89; p = 0.016), in patients aged ≤75 years (HR = 0.58; 95% confidence interval, 0.38-0.88; p = 0.010), or in patients presenting with isolated pigmentary changes (HR = 0.19; 95% confidence interval, 0.05-0.70; p = 0.005).

CONCLUSION

Trimetazidine failed to prevent choroidal neovascularization. Subgroup analyses suggest that this drug could be tested as preventive therapy for geographic atrophy, although the overall comparison showed no statistically significant differences in the progression of geographic atrophy.

Trimetazidine modulates AMPA/kainate receptors in rat vestibular ganglion neurons

Trimetazidine (1[2,3,4-trimethoxy-benzyl] piperazine, 2 HCl) is an anti-ischemic agent frequently administered as a prophylactic treatment for episodes of angina pectoris and chorioretinal disturbances. It is also employed as a symptomatic treatment of vertigo but its mechanism of action is yet to be defined. Using Fura-2 fluorescence photometry and whole-cell patch-clamp recordings we investigated the effect of trimetazidine on the [Ca(2+)](i) and current responses induced by the application of non-N-methyl-D-aspartate (NMDA) receptor agonists on low density vestibular ganglion neuronal cultures explanted from 3 day s postnatal rats. Trimetazidine blocked the [Ca(2+)](i) and current responses induced by 100 microM applications of both kainate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA). These responses were dependent on external Ca(2+) and were blocked by the voltage-dependent Ca(2+) channel blockers Ni(2+) and Cd(2+) . Trimetazidine only acts on the AMPA/kainate receptors and had no effect on K(+)-induced depolarizations. Dose-dependent curves were obtained for the inhibition by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and trimetazidine (IC(50) 7 microM and 0.7 microM) of kainate stimulations. After AMPA stimulation, dose-response inhibition curves showed an IC(50) of 3 microM for CNQX and 25 microM for trimetazidine. These results indicate that trimetazidine could be a potent antagonist of AMPA/kainate receptors in vestibular ganglion neurons. This may explain the protective role of trimetazidine in the inner ear suggesting an anti-excitotoxic activity.

Anti-excitotoxic activity of trimetazidine in the retina

The purpose of this study was to investigate the mechanism of the neuroprotective activity of trimetazidine in animal retina stressed by ischemia or kainate. Flash electroretinograms were recorded in guinea pigs after ischemia, induced by an acute increase in the intraocular pressure (IOP), or after an intravitreal injection of kainate. Treatment with trimetazidine per os afforded a significant protection of the electroretinogram against the ischemic as well as the excitotoxic insult as an antioxidant (dimethylthiourea) and a nitric oxide synthase inhibitor (nitroarginine) did. The effect of the drug on the extracellular accumulation of glutamate induced by chemical ischemia was studied by incubating rat retina in vitro. Trimetazidine was able to inhibit the extracellular glutamate accumulation, which represents the first step of the excitotoxic phenomenon. Then the compound activity on the glial uptake of glutamate was studied in a rat Müller cell line (rMC-1) in culture. Chemical ischemia inhibited the active 3H-glutamate transport, an effect that was reversed by trimetazidine, at micromolar concentrations. These results demonstrate that trimetazidine which is recognized as an efficient drug against ischemic injuries, is also capable of protecting the retina against excitotoxicity by reducing ischemia-induced accumulation of glutamate due in particular to glial transporter inhibition.

Influence of trimetazidine on the synthesis of complex lipids in the heart and other target organs

Trimetazidine exerts antianginal properties at the cellular level, without haemodynamic effect in clinical and experimental conditions. This cytoprotection was attributed to a decreased utilization of fatty acids for energy production, balanced by an increased incorporation in structural lipids. This study evaluated the influence of Trimetazidine on complex lipid synthesis from [2-(3)H] glycerol, in ventricular myocytes, isolated rat hearts and in vivo in the myocardium and several other tissues. In cardiomyocytes, Trimetazidine increased the synthesis of phosphatidyl-choline (+ 80%), phosphatidyl-ethanolamine (+ 210%), phosphatidyl-inositol (+ 250%) and cardiolipid (+ 100%). The common precursor diacylglycerol was also increased (+ 40%) whereas triacylglycerol was decreased (-70%). Similar results were obtained in isolated hearts with 10 microm Trimetazidine (phosphatidyl-choline + 60%, phosphatidyl-ethanolamine + 60%, phosphatidyl-inositol + 100% and cardiolipid + 50%), the last two phospholipids containing 85% of the radioactivity. At 1 microm, Trimetazidine still stimulated the phospholipid synthesis although the difference was found significant only in phosphatidyl-inositol and cardiolipid. In vivo studies (10 mg/kg per day for 7 days and 5 mg/kg, i.p. before the experiment) revealed significant changes in the intracellular lipid biosynthesis, with increased labelling of phospholipids and reduced incorporation of glycerol in nonphosphorous lipids. Trimetazidine increased the glycerol uptake from plasma to the other tissues (liver, cochlea, retina), resulting in an altered lipid synthesis. The anti-anginal properties of Trimetazidine involve a reorganisation of the glycerol-based lipid synthesis balance in cardiomyocytes, associated with an increased uptake of plasma glycerol that may contribute to explain the pharmacological properties reported in other organs.