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At least 361 records · Page 20Linked to original sources
PubMed1986

Comparison of intraocular acetylcholine and carbachol.

Commercially available 1% acetylcholine chloride and 0.01% carbachol chloride, which are commonly used as miotics in intraocular surgery, have recently been reformulated. Comparative studies of these agents show similar miotic activity. However, in vitro perfusion of human corneas demonstrated that 1% acetylcholine chloride causes marked changes in endothelial function and ultrastructure as compared to carbachol or BSS Plus. This study showed that 0.01% carbachol chloride was less toxic to the corneal endothelium than 1% acetylcholine chloride and suggests that 1% acetylcholine should not be used in corneas with compromised endothelium as in primary corneal endotheliopathies.

Acetylcholine↗
PubMed1989

Effects of intraocular dapiprazole in the rabbit eye.

Dapiprazole produces miosis by blocking the alpha 1 receptors in the radial muscle of the iris; its intraocular effect has not yet been investigated. In this preliminary experimental animal study, we investigated the intracameral use of 0.2 ml of 0.005%, 0.0075%, 0.01%, and 0.05% dapiprazole to reverse mydriasis by 10% phenylephrine plus 0.5% tropicamide. With the 0.05% dapiprazole concentration, the values (mean +/- S.E.) of pupillary diameter were as follows: prior to the experiment, 5.3 +/- 0.31 mm; after mydriatics, 8.7 +/- 0.22 mm; after intraocular dapiprazole, 5.6 mm +/- 0.29. The results showed a dose-related miotic effect of dapiprazole. No difference in the toxicity parameters (inflammatory score, corneal thickness, endothelial cell counting, aqueous humor protein concentration, and intraocular pressure) was found between dapiprazole-treated eyes and saline-solution-treated eyes. Intraocular 0.01% and 0.05% dapiprazole is an effective miotic agent that may be helpful during surgery when the reversal of sympathomimetic mydriasis is needed.

Animals↗
PubMed2000

[4-[[N-(3-chlorophenyl)carbamoyl]oxy]-2-butynyl]-trimethylammonium (McN-A-343)-related compounds. Effect of the butynyl chain inclusion into an aromatic unit on the potency for muscarinic receptors.

A series of derivatives of the known M1 selective muscarinic receptor agonist McN-A-343 (1) was designed with the aim of investigating the effects of structural variations on both the butynyl chain and the phenyl ring of 1. The butynyl chain was replaced with an aromatic spacer, and the effects of such a modification on the stereoelectronic properties of the molecules were theoretically studied and considered compatible with muscarinic receptor affinity. Substituents on the phenyl ring of 1 were selected so as to vary their electronic and hydrophobic properties. This design strategy did not produce muscarinic M1 receptor agonists more potent than the prototype 1, even if some analogues displayed functional selectivity for different muscarinic receptor subtypes. Compounds 3 and 7 were selective agonists towards muscarinic M3 receptors, while compounds 14, 16 and 18 were selective muscarinic M2 receptor agonists. The most interesting derivative was 8, a full agonist at muscarinic M3 receptors devoid of activity at both muscarinic M1 and M2 subtypes. The pharmacological profile of the series was further characterized by studying the anticholinesterase and miotic activities of some representative compounds. Compounds 3-8 turned out to be weak acetylcholinesterase inhibitors, while derivatives 4, 6, 8 and 11 were able to significantly reduce the pupillary diameter in rabbit, indicating 8 as an effective miotic agent.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1990

The effect of Nd:YAG iridotomy on intraocular pressure in hypertensive eyes with shallow anterior chambers.

Eighty one eyes of 48 patients with raised IOP and shallow anterior chambers underwent Nd:YAG iridotomy to prevent further angle closure glaucoma and to remove any pupil block that might be contributing to the raised IOP. These eyes were followed for 18-34 months to assess the effect on IOP control. Seventy three eyes of 43 patients were asymptomatic. In eyes with no PAS none responded with drop in IOP but in eyes with well established PAS 69% showed a drop in IOP. By comparison eight eyes of five patients had a history of episodes of subacute angle closure glaucoma. All had PAS present pre-operatively. Iridotomy reduced IOP in 87.5% of the eyes in this group and rendered 100% symptom free. Permanent posterior synechiae between lens and iris were an invariable complication in those eyes that required long-term miotic treatment for IOP control following iridotomy. In asymptomatic eyes with chronic pressure elevation and narrow angles laser iridotomy is unlikely significantly to reduce the IOP. We recommend that in such eyes iridotomy should be reserved for those eyes with established closure of the angle by PAS in which IOP control can be achieved without the use of miotics.

Adult↗
PubMed1996

Effect of locally applied prazosin on the kinetics of the pupillary light reflex.

The effect of locally applied prazosin on pupillometric measures was studied in healthy volunteers, in an attempt to identify the role of alpha 1-adrenoceptors in the recovery time of the light reflex. Prazosin antagonized the mydriatic effect of phenylephrine, but did not alter that of tropicamide. Miotic responses to a range of light stimuli were measured under ambient temperature conditions of 22 degrees C and 40 degrees C. The 40 degrees C condition was associated with shorter recovery times of the light reflex; prazosin increased the recovery time under both temperature conditions. Response amplitude was not affected by the temperature condition or prazosin. The results are consistent with the hypothesis that sympathetic neuromuscular transmission is involved in the redilatation of the pupil following a miotic response to light stimulation.

Adolescent↗
PubMed1980

[Treatment of narrow-angle glaucoma with timolol (author's transl)].

The authors report on seven patients with narrow-angle glaucoma treated for up to six months with Timolol eye drops. Prior to treatment with Timolol the patient's eyes had remained unregulated despite miotics therapy, or it had been impossible to continue with miotics due to subjective intolerance. Timolol eye drops achieved a significant lowering of pressure in all seven patients and satisfactory pressure stabilization was achieved either with Timolol eye drops alone or in combination with pilocarpine or Carbachol eye drops. In one patient who had unregulated glaucoma and who was on Carbachol/acetazolamide therapy, satisfactory stabilization was achieved by additional application of Timolol.

Aged↗
PubMed1980

[Long-term treatment of angle-closure glaucoma with bupranolol eye drops (author's transl)].

In this study we report on the effect of Bupranolol eye drops on 10 patients who, prior to treatment, experienced decompensation of their glaucoma in spite of the use of miotics or who were not given biotics treatment because of their occupation or because of severe subjective complaints. Treatment with Bupranolol is given for six months and results in clear reduction of intraocular pressure in all patients, so that satisfactory control can be achieved with Bupranolol eye drops either alone or in combination with a miotic agent. As a rule, Bupranolol is tolerated well by all patients.

Adult↗
PubMed1989

Argon laser-induced ocular hypertension: animal model of ocular inflammation.

There is substantial evidence that prostaglandins (PG's) mediate acute elevations of intraocular pressure (IOP) due to laser irradiation of the iris. In the present study, we determined the optimal laser parameters needed to produce the maximal rise in IOP in anesthetized rabbits. Application of argon laser (0.75 watts, 0.5 sec. duration, and 8 spots of 500 micron size) to the iris of pigmented rabbits elicited an acute rise in IOP and miosis accompanied by an increase in aqueous protein concentration. This response was followed by a delayed ocular hypotension that lasted for more than 3 days and returned to baseline by day 5. The onset of ocular hypertension occurred within 15 min. and remained elevated for at least 90 min. The laser induced rise in IOP was related more to the number of laser spots applied to the iris than to the intensity of the total laser energy utilized. Pretreatment with either indomethacin or flurbiprofen produced a dose dependent inhibition of ocular hypertensive response and significantly reduced aqueous protein concentration. Indomethacin (0.01-30 mg/kg) was administered intraperitonially 1 hr. before laser treatment and flurbiprofen (0.03-0.3%) was administered topically 45 and 15 min. prior to laser application. The hypertensive response was reduced by more than 90% of control after both drugs, whereas the delayed hypotension was significantly antagonized only at the highest dose of indomethacin. Neither indomethacin nor flurbiprofen altered the maximum miotic response to laser irradiation of the iris. However, 0.3% flurbiprofen and 30 mg/kg indomethacin significantly increased the recovery rate of the miotic pupil. The results of this study support the contention that argon laser induced ocular hypertension may provide a quantitative assessment of inhibition of prostaglandin mediated responses.

Animals↗
PubMed1990

Review: mediation of the ocular response to injury.

The structure of the anterior segment of the eye provide aqueous humour for metabolic traffic, regulation of intraocular pressure and the maintenance of a functional permeability barrier to separate internal compartments from general systemic influences. Irritative and injurous insults to the eye elicit an acute defensive miotic and vascular response which upsets the aqueous dynamics and provokes the influx of blood plasma proteins into the aqueous chambers. These events are initiated by antidromic activation of sensory elements within the anterior segment, releasing substance P and calcitonin gene-related peptide (CGRP) which, in lower mammals at least, stimulate respectively the miotic and vascular reactions. Considerable species differences can be found in the responsiveness of the eye to injury and in the effects of exogenous CGRP and substance P.

Animals↗
PubMed1993

Vascular effects of calcitonin gene-related peptide (CGRP) and cholecystokinin (CCK) in the monkey eye.

The effects of cholecystokinin (CCK) and calcitonin gene-related peptide (CGRP) on ocular blood flow were studied in monkeys using the labelled microsphere method. Intracameral administration of 800 pmole CGRP increased the blood flow significantly in the conjunctiva, ciliary body and sclera. There was no significant change in the choroid and retina. CCK-33 (800 pmole) caused no significant effects on the blood flow in the tissues examined, when compared to the control eyes. A miotic response was however noted, consistent with previous results. Neither peptide caused significant changes in the intraocular pressure. These results suggest that CGRP has a vasodilatory effect in some parts of the monkey eye, whereas CCK-33 is a miotic with no marked effect on ocular blood flow.

Animals↗
PubMed1999

Effects of 0.2% brimonidine on ocular anterior structures.

The aim of the study was to evaluate the effect of an alpha2-adrenergic agonist, 0.2% brimonidine, on a number of echobiometry and ultrasound biomicroscopy ocular parameters. Ten healthy subjects ranging in age from 20 to 40 years (mean age 29+/-3.39) were recruited into this prospective open-label trial. After instillation of 0.2% brimonidine eye drops, the following parameters were assessed: refraction, visual acuity, pupil diameter, intraocular pressure, five A-scan echobiometric parameters and 15 ultrasound biomicroscopy parameters. As early as the first hour after administration of the drug, a marked ocular hypotensive effect was detected associated with a miotic effect, without any refractive or visual acuity alterations. The A-scan echobiometry parameters were unchanged, while, as far as the ultrasound biomicroscopy variables were concerned, we observed an increase in iris-lens contact distance and a reduction in iris root thickness with a resulting increase in posterior chamber depth and in iris-ciliary process distances. No changes were observed in either the anterior chamber or the anterior iris profile. Brimonidine 0.2% proved to be an ocular hypotensive agent which is also endowed with a mild miotic effect, without giving rise to refractive or visual acuity alterations. The drug does not alter the thickness and position of the lens and does not facilitate pupil block; it reduces the iris thickness with an increase in posterior chamber depth and in iris-ciliary process distance but with no changes in anterior chamber depth or chamber angle width.

Adrenergic alpha-Agonists↗
PubMed1992

A review of the clinical pharmacokinetics of pilocarpine, moxisylyte (thymoxamine), and dapiprazole in the reversal of diagnostic pupillary dilation.

An alpha-adrenergic blocking drug, dapiprazole, is now marketed in eyedrop form. Dapiprazole is being promoted as an agent suitable for reversing the diagnostic mydriasis produced by tropicamide or tropicamide and phenylephrine. The mechanism of action of dapiprazole is thought to be the same as that of moxisylyte (thymoxamine). The human pharmacokinetics for these drugs are reviewed and compared to pilocarpine. Published data indicate that either dapiprazole (0.5%) or moxisylyte (0.5%) enhance recovery from the mydriasis produced by tropicamide, phenylephrine, or their combination. However, because the published studies differ substantially in the doses of these mydriatics or in the miotics actually used, it is not possible to make any firm recommendations on how many drops of these new miotics should be instilled.

Adrenergic alpha-Antagonists↗
PubMed1986

An unusual case of cyproheptadine (Periactin) overdose in an adolescent female.

A 13-year-old female ingested an acute overdose of cyproheptadine hydrochloride (Periactin) and presented for treatment. She manifested all the classic signs and symptoms of an acute antihistamine overdose, including psychosis, except for miotic, minimally reactive pupils. The patient was supportively managed. All sequelae of the ingestion resolved within four days, and the child was released from the hospital. We discuss the unusual presentation of miotic pupils in an acute cyproheptadine overdose.

Adolescent↗
PubMed1995

Evaluation of retinal toxicity of acetylcholine in rabbit eyes.

PURPOSE: In vitreoretinal surgery, pupillary constriction may be required at the termination of a procedure especially if mechanical pupillary dilation was used in eyes filled with gas or silicone oil. A miotic agent instilled into the anterior chamber will sink and come into direct contact with retina in the aphakic or pseudophakic vitrectomized eye. Therefore, the retinal toxicity of acetylcholine, a miotic used for pupillary constriction, was studied. METHODS: Eight Dutch pigmented rabbit eyes were vitrectomized, had air-fluid exchange, and were injected with a 20% mixture of SF6. Subsequently eyes were randomly selected to have injections of 0.75 ml of 10 mg/ml acetylcholine (Miochol, Iolab Corp., Claremont CA) versus 0.75 ml of lactated Ringer's solution. Short-term (2 weeks) and long-term (6 weeks) retinal toxicity was assessed by ophthalmoscopy, electroretinogram, and histology by light and electron microscopy at both times. RESULTS: Ophthalmoscopy, electroretinographic tracings, histology, and electron microscopy disclosed no significant abnormalities. CONCLUSIONS: Acetylcholine does not appear to have significant retinal toxicity even when undiluted solutions are in direct contact with the retina. We therefore postulate that intraoperative use of acetylcholine in previously vitrectomized eyes filled with gas or silicone is safe.

Acetylcholine↗
PubMed2003

Effects of ABCB1 (multidrug resistance transporter) gene mutations on disposition and central nervous effects of loperamide in healthy volunteers.

OBJECTIVE: Mutations in the ABCB1 gene have been associated with decreased expression and net function of P-glycoprotein (P-gp). We investigated the modulation of the central nervous effects of loperamide resulting from ABCB1 genetic variants. METHODS: On two occasions, 20 healthy volunteers received 24 mg loperamide suspension orally and, in a double-blind randomized two-way crossover fashion, 800 mg quinidine or placebo orally 1 h before loperamide. Pupil size was measured for 5 h following loperamide administration, and plasma concentrations of loperamide and quinidine were measured for 6 h. Single nucleotide polymorphisms and haplotypes including G2677T(A) (exon 21) and C3435T (exon 26) were analysed for their relation to plasma concentrations of quinidine and loperamide and to the miotic effects of loperamide. RESULTS: Loperamide plasma concentrations with quinidine co-administration were about twice as high as those without quinidine. The ABCB1 haplotype G2677/T3435 was associated with the highest loperamide plasma concentrations, which were about 1.5 times higher than in non-carriers of this haplotype. Plasma concentrations of quinidine did not differ among carriers and non-carriers of genetic variants. When quinidine was co-administered with loperamide, pupil size decreased. Without quinidine it changed only minimally. The ABCB1 TT3435 genotype was associated with the most pronounced increase of the miotic effects of loperamide when quinidine was co-administered. This was accompanied by a tendency toward higher plasma loperamide in TT3435 carriers. CONCLUSIONS: Our data support a functional importance of the ABCB1 mutations for plasma concentrations and central nervous actions of the opioid loperamide.

Administration, Oral↗
PubMed1990

Cholecystokinin causes contraction of the pupillary sphincter in monkeys but not in cats, rabbits, rats and guinea-pigs: antagonism by lorglumide.

The effects of intracameral injections of cholecystokinin (CCK) on the pupil size were determined in monkeys, cats, rabbits, rats and guinea-pigs. In animals under muscarinic cholinergic blockade, CCK caused miosis in monkeys but not in the other species investigated. In monkeys CCK-8 was more potent than CCK-33, which was, however, much more potent than non-sulphated CCK-8. These observations indicate that peripheral type A receptors mediated the miotic response. The effect of CCK-8 was not appreciably influenced by pretreatment with indomethacin, 3 mg kg-1 body wt, indicating that prostaglandins were not involved in the response. Nerve blockade with 0.9 micrograms tetrodotoxin intracamerally had no clear effect on the dose-response relationship for CCK-8. The effect of the peptide thus seems to be directly on receptors on the pupillary sphincter muscle. Pretreatment with lorglumide caused a dose-dependent rightward shift of the dose-response curve, indicating competitive antagonism. The results indicate that in monkeys, but not in rabbit, cats, rats and guinea-pigs, CCK is a potent miotic with a direct effect on the pupillary sphincter mediated by type A CCK receptors on the muscle.

Animals↗
PubMed1995

Adrenergic and imidazoline receptor-mediated responses to UK-14,304-18 (brimonidine) in rabbits and monkeys. A species difference.

Brimonidine is a relatively selective alpha-2 adrenoceptor agonist that is being developed for the treatment of glaucoma. Because brimonidine is chemically related to clonidine and has affinity for the nonadrenergic imidazoline receptor, its ocular effects may be unrelated to alpha-2 receptor activation. The objective of this study was to determine the pharmacology of the intraocular pressure (IOP) response to brimonidine in rabbits and monkeys and the side effects (miosis, cardiovascular depression) in monkeys. Conscious albino rabbits and cynomolgus monkeys were pretreated topically with the following receptor antagonists: rauwolscine (alpha-2), idazoxan (alpha-2, imidazoline), SKF 105854 (vascular postjunctional alpha-2), and prazosin (alpha-1). Intraocular pressure, pupil size, or blood pressure/heart rate was monitored noninvasively for 6 hours following dosing. Binding experiments were performed using [3H]brimonidine in membrane preparations from rabbit iris/ciliary body and from monkey cerebral cortex and brain stem. In rabbits, the ocular hypotensive response to brimonidine was unilateral and was inhibited by rauwolscine > idazoxan >> SKF 105854 = prazosin; this ranked order of potency correlated with displacement of [3H]brimonidine in the rabbit iris/ciliary body. In monkeys, brimonidine decreased IOP bilaterally and suppressed cardiovascular function suggesting a CNS site of action. Intraocular pressure and cardiovascular responses to brimonidine were inhibited by idazoxan >> rauwolscine > SKF 105854 = prazosin; a similar profile was obtained for displacement of [3H]brimonidine in monkey brain tissue. Both rauwolscine and idazoxan inhibited the miotic response to brimonidine in monkeys. Taken together, these results indicate that brimonidine stimulates an ocular alpha-2 adrenoceptor to decrease IOP in the rabbit and a CNS imidazoline receptor to decrease IOP, blood pressure, and heart rate in the cynomolgus monkey. The miotic response in the monkey is mediated by an alpha-2 adrenoceptor. The alpha-1 and vascular postjunctional alpha-2 adrenoceptors do not appear to play a role in mediating these responses.

Adrenergic alpha-2 Receptor Agonists↗
PubMed1996

Modified beta-cyclodextrin (SBE7-beta-CyD) with viscous vehicle improves the ocular delivery and tolerability of pilocarpine prodrug in rabbits.

The complexation of pilocarpine prodrug, O,O'-dipropionyl-(1,4-xylylene) bispilocarpate, with various beta-cyclodextrin (beta-CyD) derivatives was studied by the phase solubility method. The effects of coadministered sulphobutyl ether beta-CyD (SBE7-beta-CyD) with and without poly(vinyl alcohol) (PVA) on the miotic response and eye irritation of the prodrug were investigated in pigmented rabbits. The pilocarpine prodrug formed 1:1 inclusion complexes with variably substituted sulphobutyl ether derivatives of beta-CyD (SBE4-beta-CyD and SBE7-beta-CyD), and 1:1 and 1:2 complexes with hydroxypropyl-beta-CyD (HP-beta-CyD) at pH 7-4. Coadministered SBE7-beta-CyD eliminated the eye irritation due to the pilocarpine prodrug, but also decreased the miotic response. Ocular absorption of the prodrug was improved by increasing the viscosity of prodrug/SBE7-beta-CyD solution with PVA without inducing any eye irritation. Eye irritation due to viscous prodrug/SBE7-beta-CyD solutions was comparable with isotonic NaCl solution. We conclude that administration of pilocarpine prodrug in viscous SBE7-beta-CyD solution decreases substantially eye irritation while ocular absorption is not affected.

Animals↗