Treatment of open angle glaucoma and ischemic retinopathy with dopamine antagonists

The Effects of Droperidol in Perforating Keratoplasty

PURPOSE

To evaluate the intraoperative and postoperative effects of droperidol administered with general anesthesia during perforating keratoplasty.

METHODS

A prospective, randomized, double-masked clinical trial. Twenty-seven patients undergoing penetrating keratoplasty under general anesthesia were included. Patients were assigned randomly to two groups. Fifteen subjects received droperidol during induction of general anesthesia. Twelve control patients received general anesthesia without droperidol.

RESULTS

Droperidol significantly reduced fellow eye intraocular pressure (p < 0.0001). Intraoperative anterior chamber depth was significantly deeper with droperidol (p = 0.0002). Iris bulging was observed in 25% of the control group and 0% with droperidol. There was significantly less postoperative nausea in the droperidol group (p = 0.038). There was less postoperative vomiting in the droperidol group, although the difference was not significant (p = 0.07). Postoperative wound gaping was observed in 2 patients; both of them did not receive droperidol.

CONCLUSIONS

Droperidol effectively reduces intraoperative and postoperative complications in keratoplasty surgery.

Effects of some natural flavonoids on retinal function recovery after ischemic insult in the rat

PURPOSE

There are six natural flavonoids studied recently and their effects on ocular blood flow measured with colored microsphere technique. It was found that three out of six compounds showed strong positive effects in increasing the ocular blood flow. In this study, we tried to find out whether these results can be translated on their effects to improve retinal function recovery after ischemic insult.

METHODS

Electroretinography was used to measure the b-wave recovery as an indication of retinal function recovery.

RESULTS

Naringenin, hesperetin, and rutin were found to produce marked positive effects on b-wave recovery, whereas naringin, hesperidin, and quercetin showed poor recovery of b-wave after ischemic insult of the retina.

CONCLUSION

It was found that the compounds that showed strong increase of ocular blood flow also showed marked increase of retinal function recovery, whereas those that showed poor increase of ocular blood flow also showed poor effects on the retinal function recovery.

Structure-activity relationship (SAR) between some natural flavonoids and ocular blood flow in the rabbit

PURPOSE

Flavonoids with two to five hydroxy groups, with or without sugar, and/or methoxy groups were studied on their effects to affect ocular blood flow.

METHODS

Colored microsphere technique was used to determine the ocular blood flow in rabbit eyes.

RESULTS

Flavonoids with three free hydroxy (OH) groups seemed to produce the optimal effects in increasing ocular blood flow (naringenin and hesperitin, Pfalts and Bauer, Waterbury, CT). Whether the OH groups are below three (naringenin, hesperitin, Pfalts and Bauer, Waterbury, CT) or above four (Quercetin, Pfalts and Bauer, Waterbury, CT), they produced no effects on the ocular blood flow. When OH groups are four (rutin, Aldrich, Milwaukee, WI), it produced mixed effects on ocular blood flow. The attachment of rutinose and/or methoxy group in the structure did not affect the ocular blood flow one way or the other.

CONCLUSION

The ocular blood flow is increased significantly by the number of OH group in the molecule, with three the best to increase the ocular blood flow.

Effects of Dihydrogenation of Flavones and Number of Hydroxy Groups in the Molecules on Ocular Blood Flow in Rabbits and Retinal Function Recovery in Rats

PURPOSE

It has been found that the number of hydroxy groups in the molecule of flavones and flavanones affect the ocular blood flow significantly. However, the effects of dihydrogenation of flavones into flavanones on ocular blood flow and retinal function recovery have not been studied and required investigation.

METHODS

The colored microsphere technique and electroretinography method were used for the study of ocular blood flow and retinal function, respectively.

RESULTS

Maximum effects on ocular blood flow were obtained when there were 3 hydroxy groups in the molecule of flavones and flavanones. Dihydrogenation of flavones to flavanones increased the ocular blood flow further. The same is true for retinal function recovery after ischemic insult.

CONCLUSION

These results indicate that hydrogenation is an excellent way to convert natural flavones into more potent compounds of flavanones.

Structural Requirements of Flavonoids for Increment of Ocular Blood Flow in the Rabbit and Retinal Function Recovery in Rat Eyes

PURPOSE

We have recently reported that the effect of a flavonoid on ocular blood flow depends upon the number of hydroxy (OH) groups in its backbone structure. To elucidate the structural features on the number and type of functional groups present in the flavonoid molecule plus the number of OH groups, flavonoids with four to five OH groups, with or without methoxy groups, were studied on their effects to affect the ocular blood flow and the retinal function recovery.

METHODS

A colored microsphere technique was used to determine the ocular blood flow in albino rabbit eyes and electroretinography was used to measure the retinal function recovery.

RESULTS

Flavonols with four free OH groups produced no effects on the ocular blood flow (fisetin, kaempferol), whereas flavanone and flavones with four free OH groups and without the C2-C3 double bond produced the rapid increment on ocular blood flow (dihydrofisetin and luteolin, respectively). Similarly, flavonols with five free OH groups produced no effects on the ocular blood flow (morin, quercetin). Yet, flavanone with five free OH groups and without the C2-C3 double bond produced the rapid increment on ocular blood flow (dihydroquercetin). Flavanols with five free OH groups and without the C2-C3 double bond and the carbonyl group produced no effects on the ocular blood flow (catechin). Flavonols with four free OH groups and a methoxy group on the 7 position produced no effects on the ocular blood flow (Rhamnetin). Flavonols with four free OH groups and a methoxy group at the 5 (5-methylquercetin) or 3' position (isorhamnetin) produced positive effects on the ocular blood flow also. Flavonol with five methoxy groups but no OH group produced positive effects on the ocular blood flow (pentamethylquercetin). Flavonols with an excessive number of OH groups, having both a catechol-like structure in the C ring and a catechol at the B ring, produced no effect on the ocular blood flow (rhamnetin, quercetin). Parallel results were obtained on retinal function recovery after ischemic insult.

CONCLUSION

The presence of OH groups at certain positions and the double bond at C2-C3 in the flavonoid molecules, which produces lipophilic action, can affect the increment on ocular blood flow and retinal function recovery. O-methylation can increase ocular blood flow and retinal function recovery as well.

Effects of N-nitropyrazoles on ocular blood flow of rabbits and retinal function recovery of rat eyes after ischemic insults

Twelve compounds of N-nitropyrazoles were studied for their effects on ocular blood flow in rabbits and retinal function recovery in rat eyes after ischemic insults. Of the twelve N-nitropyrazoles examined, nine increased choroidal blood flow while five increased retinal blood flow significantly. On the other hand, all twelve compounds increased blood flow in iris and ciliary muscle without exception. As for retinal function recovery after ischemic insult in rat eyes, eight out of the twelve compounds showed more significant facilitation than the control. The structure activity relationship of the N-nitropyrazoles to increase ocular blood flow and to facilitate retinal function recovery after ischemic insults were discussed.

Effects of dopamine antagonists in human eye accommodation

The purpose of this study was to evaluate the effects of dopamine antagonists in accommodation of the human eye. The dopamine antagonist drugs used in this experiment include 0.5% metoclopramide and 0.25% droperidol. Eighteen healthy subjects were enrolled; they were randomly assigned, in double-masked fashion, to receive topical administration of a single drop of either 0.5% metoclopramide or 0.25% droperidol in one eye, with the fellow eye receiving isotonic saline as control. The accommodative abilities of both eyes were measured before instillation, and also at 3 and 6 hr after instillation of drugs, respectively. We studied the latency of reaction, the rate of accommodation, the average accommodative power, the rate of recovering and the total recovering time as the five parameters for evaluating the accommodative ability of each eye. The results showed that there were significant changes in two parameters: the rate of accommodation and rate of recovering, whereas there were no significant changes in the other three parameters: latency of accommodation, average power of accommodation and total recovering time. In conclusion, the dopamine antagonists may have some effects on the rate of accommodation but not the degree of accommodation. Further studies with higher concentrations of these dopamine antagonists on dose-response relationships are needed before exact drug efficacy can be drawn.

Improvement of ocular blood flow and retinal functions with puerarin analogs

Ischemic retinopathy and, particularly, age-related macular degeneration (AMD) are difficult eye diseases to treat. Since the etiology of these diseases is inadequate blood circulation in the retina and choroid, drugs which can improve blood circulation to these tissues should be beneficial to these diseases. Since fovea is avascular, AMD is closely related to choroidal vascular abnormalities, and drugs which show strong effects to increase choroidal blood flow would be particularly useful. Puerarin and all its derivatives, except ET (puerarin disubstituted with -CH2CH2OH), showed marked increase of choroidal blood flow at various time periods. Even ET showed a tendency to increase choroidal blood flow, though it was not statistically significant. As for b wave recovery, all puerarin analogs showed strong recovery of retinal function after ischemic insult for 30 min. These results indicate that puerarin analogs could be used for the treatment of ischemic retinopathy, and AMD in particular.

Effects of crocin analogs on ocular blood flow and retinal function

Ischemic retinopathy and age-related macular degeneration are the leading ocular diseases that cause blindness. The etiology of these diseases is due in part to the reduction of blood flow in the retina and/or choroid. Crocin analogs isolated from Crocus sativus L. were found to significantly increase the blood flow in the retina and choroid and to facilitate retinal function recovery. Increased blood flow due to vasodilation presumably improves oxygenation and nutrient supply of retinal structures. These results indicated that crocin analogs could be used to treat ischemic retinopathy and/or age-related macular degeneration. It was noted that disaccharide analogs of crocin, such as crocin-1 and crocin-2, were less potent than monosaccharide analogs of crocin, such as crocin-3 and crocin-4, constituting an interesting structure-activity relationship.

Effects of some N-nitropyrazole derivatives on ocular blood flow and retinal function recovery after ischemic insult

Ocular blood flow and retinal function were determined in this study with colored microspheres and b-wave amplitude of electroretinography, respectively. It was found that N-nitropyrazole analogs can facilitate the retinal function recovery efficiently after ischemic insult primarily through increase of choroidal blood flow specifically. Since age-related macular degeneration (AMD) is caused mainly by the choroidal vascular abnormality and/or insufficiency, these N-nitropyrazole analogs are of potential use in the treatment of AMD.

Effects of dopamine D-1 and D-2 receptors on intraocular pressure in conscious rabbits

This investigation was designed as a randomized, placebo-controlled, double-masked, crossover study in NZW rabbits with normal intraocular pressure (IOP) to investigate dopaminergic effects on IOP. SKF 38393, a selective D1-receptor agonist, increased, and SDZ PSD-958, a selective D1-receptor antagonist, decreased IOP, respectively. The selective D2-receptor agonist quinpirole decreased IOP, whereas the selective D2 receptor antagonist metoclopramide had no significant effect. Combinations of quinpirole with SDZ PSD-958 decreased IOP in an additive manner. SDZ GLC-756, a mixed D1-receptor antagonist/D2-receptor agonist, decreased IOP in a dose-dependent manner with a maximum effect greater than the maximum effects produced either by the D1-receptor antagonist SDZ PSD-958 and the D2-receptor agonist quinpirole. The effect of SDZ GLC-756 could only be partially blocked by the selective D2-receptor antagonist metoclopramide suggesting that both D1-receptor blockade and D2-receptor stimulation participate in its IOP-lowering effect. Tonography suggests that SDZ GLC-756 has no significant effect on outflow facility. Furthermore, the results suggest that both D1 and D2 receptors each play an independent role in the regulation of IOP in rabbits. Thus, simultaneous blockade of D1 receptors and stimulation of D2 receptors may provide a new pharmacological approach for the treatment of ocular hypertension frequently associated with glaucoma.

Vaninolol: a novel compound for the treatment of glaucoma and ischemic retinopathy

Vaninolol has been confirmed as a selective beta 1-adrenergic blocking agent. The new compound was studied for its effects on intraocular pressure (IOP), the ocular blood flow and the retinal function in this report. Vaninolol showed marked delay in IOP recovery demonstrating that the agent possessed an ocular hypotensive action. This effect is equipotent or slightly more active than L-timolol. In addition, effects of vaninolol on the ocular blood flow of ocular hypertensive eyes were determined using the colored microspheres technique. It was found that vaninolol improved the ocular blood flow in ciliary body and retina, but not in iris and choroid. Further, vaninolol is able to improve the b-wave recovery in electroretinography significantly, indicating that it is possible to develop a new agent for the treatment of ischemic retinopathy.