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At least 19 recordsLinked to original sources
PubMed1994

Systemic absorption and anticholinergic activity of topically applied tropicamide.

We studied the plasma levels and systemic anticholinergic activity of tropicamide after ocular administration in eight women. Two 40 microliters drops of 0.5% tropicamide were instilled into the lower cul-de-sac of one eye of the subjects and concentrations and respective muscarinic receptor occupancy of tropicamide in plasma were monitored using radioligand binding techniques. Tropicamide was rapidly absorbed systemically with the mean peak concentration in plasma being 2.8 +/- 1.7 ng/ml (mean +/- SD) at five minutes after instillation. Tropicamide disappeared rapidly from the systemic circulation: drug concentration in plasma was 0.46 +/- 0.51 ng/ml (mean +/- SD) at 60 minutes and below 240 pg/ml at 120 minutes after instillation. Tropicamide bound to muscarinic receptors of rat brain with an apparent equilibrium binding constant (Ki-value in plasma) 220 +/- 25 nM (mean +/- SD, n = 3). Tropicamide occupied maximally 8% of muscarinic receptors in plasma after ocular application. The low affinity of tropicamide for muscarinic receptors and its negligible receptor occupancy in plasma can explain the low incidence of systemic side-effects of tropicamide eyedrops.

Absorption↗
PubMed1990

Time course of cycloplegia induced by a new phenylephrine-tropicamide combination drug.

A motorized and computer-interfaced phoropter was used to track the development of cycloplegia and recovery of accommodation over a 60-min period, after the topical application of a phenylephrine 5%-tropicamide 0.8% drug combination (Phenyltrope). Phenyltrope was introduced into the Canadian market about 2 years ago (Compendium of Pharmaceuticals and Specialties, 1987), and advertised as a fast acting cycloplegic and mydriatic drug. Here we report the results of our investigation of the depth of action and the temporal aspects of cycloplegia for this drug combination as a function of iris color. We also compare the action spectrum of Phenyltrope to that of tropicamide 1% under similar test conditions. Our results indicate that the latency for cycloplegia was shorter for tropicamide, the maximum rate of accommodative loss similar for both drugs, and the resultant cycloplegia at 20 min deeper for Phenyltrope. Recovery from induced cycloplegia was greater for tropicamide 60 min after drug administration. For both Phenyltrope and tropicamide, no significant differences in any of the parameters investigated were observed as a function of iris color. We conclude that even though Phenyltrope induced a measurably deeper cycloplegia than did tropicamide, the amount of residual accommodation present at 20 min (about 38%) is insufficient for most refractive purposes.

Accommodation, Ocular↗
PubMed1996

Pupillary response to tropicamide in patients with Alzheimer disease.

PURPOSE: To determine whether pupillary responses to dilute tropicamide could be used as a diagnostic test for Alzheimer disease (AD). The authors also investigated whether concurrent use of an oral acetylcholinesterase inhibitor (tacrine) alters the pupillary response to dilute tropicamide in patients with AD, and whether pupillary responses to dilute tropicamide differ in young versus older control subjects. METHODS: Pupillary diameter and area of both eyes were measured in light and darkness, at 10-minute intervals for 40 minutes after random instillation of 0.01% tropicamide to one eye. Four groups of subjects were studied: 9 patients with AD, 10 who were treated with tacrine, 11 older control subjects, and 10 young control subjects. RESULTS: Mean change in anisocoria was not significantly different among groups at any of the measurement time points. Mean percent change in diameter of the treated eyes showed a trend toward faster maximum dilatation in the AD groups, but change in pupillary measurements did not identify individuals with AD. CONCLUSION: Pupillary response to dilute tropicamide did not effectively distinguish individual patients with AD from young or older control subjects.

Adult↗
PubMed1982

Mydriatic effectiveness of dilute combinations of phenylephrine and tropicamide.

The effects of two solutions, each consisting of a combination of tropicamide and phenylephrine at lower than conventional concentrations, were studied in 79 students at Pacific University College of Optometry. Clinically effective diameters (CED's), measured when the eye was illuminated for direct ophthalmoscopy, were followed for 90 min after mydriatic instillation. Intraocular pressure (IOP), systolic arterial blood pressure (sBP), and the systolic BP/IOP ratio were also monitored for 90 min. Both combination A (0.25% tropicamide + 1.25% phenylephrine) and combination B (0.125% tropicamide + 2.0% phenylephrine) produced CED's as large as produced by 0.5% tropicamide in the opposite eye. By combining a low concentration of a sympathomimetic with a parasympatholytic agent, it is possible to achieve mydriasis superior to that produced by 0.5% tropicamide or 2.5% phenylephrine while reducing the risk of systemic or ocular side effects.

Adult↗
PubMed1993

Comparison of cyclopentolate versus tropicamide cycloplegia in children.

This double masked study compares the cycloplegic effects of tropicamide 1% and cyclopentolate 1% in 20 nonstrabismic, nonamblyopic, hyperopic 6- to 12-year-old children with a mean refractive error = +1.48 +/- 1.10 diopters (D). Unlike previous studies which used only amplitude of accommodation to measure the depth of cycloplegia, this study compares refractive error as determined by retinoscopy, distance subjective refraction, and distance autorefraction (Canon R-1). In addition, we compare the amplitude of accommodation as measured by subjective push-up and objective autorefraction methods. There is no statistically significant difference between cyclopentolate and tropicamide for either cycloplegic retinoscopy or distance subjective refraction. Autorefraction measurement of refractive error shows a statistically significant but clinically unimportant bias (0.14 +/- 0.30 D) toward more hyperopia with cyclopentolate. Both drops reveal latent hyperopia, and the mean latencies are not statistically different between the two cycloplegic agents. Latent hyperopia is not systematically related to the degree of hyperopia after tropicamide, but this relation is significant after cyclopentolate. No differences were found between refractive results with either agent at 30 min compared to 60 min after drop instillation. When measured objectively with the autorefractor, accommodation is inhibited more effectively by cyclopentolate than by tropicamide. Our results suggest that although tropicamide is not as effective as cyclopentolate in inhibiting accommodation it is, nevertheless, a useful cycloplegic agent for measuring distance refractive error of low to moderate hyperopia in school-aged children.

Accommodation, Ocular↗
PubMed1996

The effects of tropicamide on mydriasis in young rats exhibiting a natural deficit in passive-avoidance responding.

The young rat at post-natal day 18-22 exhibits a natural deficit in passive-avoidance responding that can be corrected with the acute systemic administration of different cholinomimetic drugs, such as tacrine. In order to evaluate the generality of this apparent cholinergic hypofunction, different doses of the anticholinergic agent tropicamide, were administered either systemically or dropped directly into the eye of young or adult rats. Tropicamide produced mydriasis in a dose-dependent manner. The ED50 for tropicamide dropped into the eye was 0.025% for adult rats and 0.12% for young rats. When doses between 0.3 and 100 mg/kg were delivered systemically, the mean time course for recovery to baseline pupil size was accelerated in young rats. The average time to recovery across all doses was 112 +/- 27 min (mean+/-SE) for young rats and 274 +/- 70 min for adults. When subcutaneous tacrine was given immediately to young rats after training in a passive-avoidance response (PAR) task, retention was enhanced at testing 24 hours later in a dose-dependent manner. The response latencies were statistically different from saline-treated controls at doses of 0.003 and 0.01 mg/kg. This was not observed in adult rats. Taken together these results suggest that the PAR, along with the mydriacyl response of the young rat to tropicamide, may be regulated by a system of subsensitive cholinergic receptors.

Aging↗
PubMed1990

Reduced mydriasis from repeated doses of tropicamide and cyclopentolate.

Pupils are often dilated for examination the day before surgery and again on the day of surgery. The following experiment was performed to determine the effect of serial doses of two commonly used mydriatic agents: on two consecutive days the pupil of one of the eyes of 28 subjects was dilated with tropicamide 1%, and the pupil of one of the eyes of 30 subjects was dilated with cyclopentolate hydrochloride 1%. The other eyes in both groups were dilated only on the second day, and thus served as controls. Pupil sizes were measured from photographs before and after dilation. The pupils of the eyes treated twice with either drug did not dilate as well after the second dose as those of the control eyes (P less than .005 for tropicamide, P less than .001 for cyclopentolate). The pupils of the eyes twice-treated with tropicamide were an average of 0.15 mm smaller than the control pupils; those twice-treated with cyclopentolate were 0.36 mm smaller. For subjects treated with cyclopentolate, this decreased mydriasis was related to age (P less than .05) and to eye color (P less than .025): the younger and blue-eyed subjects dilated less on the second day than the older and brown-eyed subjects. If full mydriasis is required at surgery, pupils should probably not be dilated with either tropicamide or cyclopentolate the day before surgery.

Adult↗
PubMed1989

A pupillographic evaluation of a phenylephrine HCl 5%-tropicamide 0.8% combination mydriatic.

A continuously recording high-resolution pupillometer was used to measure changes in pupil size and pupil reactivity to temporally modulated light, following topical application of a phenylephrine HCl 5%-tropicamide 0.8% combination mydriatic (Phenyltrope). A controlled light stimulus induced pupillary changes in the left eye while changes in the consensual pupillary responses were measured in the mydriatic-treated right eye. The effects on pupil light reactivity of a single drop of the combination mydriatic were also compared to those caused by one drop of tropicamide 1% alone. Phenyltrope was introduced onto the ophthalmic market ostensibly offering faster mydriasis because of its combined effect of both the parasympathetic and sympathetic innervation to the pupil. In the present study, we looked for any differences in the pupil reaction times and amplitudes as a function of time after drug administration, iris coloration and type of mydriatic instilled. Our results show that while the combination is a fast acting mydriatic providing a large and stable pupillary dilation in subjects with either blue or brown irides, it does not differ appreciably in efficacy from the mydriatic effect of tropicamide 1% alone in healthy subjects between 20 to 36 years of age. Applications of our findings to the clinical environment are presented.

Administration, Topical↗
PubMed1983

Tropicamide-induced mydriasis in densely pigmented eyes.

Clinically effective diameters (CED's) corresponding to illumination intensities used in direct ophthalmoscopy were determined in 30 young adults with densely pigmented irides after instillation of 1 drop of 0.5% tropicamide. All subjects were of Asian, Pacific Island, or Hispanic origin. The maximum CED was attained by 30 min and was maintained without significant change for the next 60 min. Ninety percent of the subjects had maximum CED's of 6.0 mm or more, and 57% had CED's of 7.0 mm or more. These figures correspond to the entrance pupil diameters and are free from the effects of corneal magnification. The average CED's for these densely pigmented eyes did not differ in a statistically significant manner from corresponding mean CED's for 97 less densely pigmented Caucasian eyes during the interval of 30 to 90 min after instillation of tropicamide. Tropicamide at 0.5% concentration appears to be an effective mydriatic for use in these densely pigmented eyes with procedures requiring intensities of illumination similar to those used in direct ophthalmoscopy.

Adult↗
PubMed1985

Sector pupil dilation with phenylephrine and tropicamide.

A comparison of sector pupil dilation produced with 2.5% phenylephrine and 1.0% tropicamide was carried out on nine subjects. We found that 2.5% phenylephrine produced a significant increase in the vertical as compared to the horizontal diameter at 10, 20, 30, 40, and 50 min after instillation of the drug with the maximum vertical diameter occurring at 40 min. The pupil diameter in the vertical and horizontal meridians before drug instillation was 3.7 mm +/- 0.2 (mean +/- SE) whereas at 40 min the vertical and horizontal diameters were 6.7 mm +/- 0.4 and 5.2 mm +/- 0.3, respectively. Instillation of 1% tropicamide produced equal dilation of the vertical and horizontal diameters, which was maximum at 40 min. Before drug instillation, the pupils were 3.7 mm +/- 0.2 (mean +/- SE) in both the horizontal and vertical meridians. At 50 min the pupil diameter was 7.0 mm +/- 0.2 in both meridians in the eye that received tropicamide.

Adult↗
PubMed1994

Dapiprazole clinical efficiency for counteracting tropicamide 1%.

We evaluated the clinical usefulness of dapiprazole in reversing the effects of tropicamide 1.0%. Our study was random, masked with placebo, and used one eye of each subject as a control. Thirty subjects were given dapiprazole as directed by the manufacturer 30 min after being dilated by one drop each of proparacaine 0.5%, tropicamide 1.0%, and then 5 min later another drop of tropicamide 1.0%. Pupil diameter, amplitude of accommodation, conjunctival injection, and intraocular pressure were evaluated. Each of these variables was measured: (1) before instillation of the diagnostic agents; (2) before the instillation of dapiprazole; and (3) at 30, 60, 120, and 180 min after the final instillation of dapiprazole. The average pupillary recovery time for dapiprazole-treated eyes was significantly less than for nontreated eyes. Accommodation also showed faster recovery. Comfortable reading ability returned after approximately 43 min with dapiprazole vs. 66 min without dapiprazole. All of our subjects exhibited conjunctival hyperemia after the administration of dapiprazole. This persisted throughout the 180 min observation period after its administration.

Accommodation, Ocular↗
PubMed1989

Influence of thymoxamine eye-drops on the mydriatic effect of tropicamide and phenylephrine alone and in combination.

In a preliminary experiment in 12 healthy volunteers, one drop of thymoxamine 0.5% instilled into the conjunctival sac completely reversed the mydriasis produced by phenylephrine 2.5%, 5% and 10% after 20 minutes. In a second study in eight volunteers, thymoxamine 0.5% completely prevented the mydriasis produced by phenylephrine 2.5% and produced a miosis. It also completely reversed the mydriasis produced by tropicamide 0.5%. The mydriatic effect of tropicamide 0.5% plus phenylephrine 2.5%, however, was not completely reversed by thymoxamine 0.5% over a period of 180 minutes. Phenylephrine, tropicamide and thymoxamine are freely available for use by registered optometrists.

Adolescent↗
PubMed1992

Influence of ocular tropicamide on exercise testing.

This study was aimed to evaluate the effects of tropicamide 0.5% eye drops on cardiovascular parameters during exercise testing. The study group included 154 healthy subjects (mean age: 44.7 +/- 8 years). The subjects were divided into three groups according to the size of the pupils at the onset of exercise: A: pupils not dilated (n = 27), B: pupils partially dilated (n = 90) and C: pupils widely dilated (n = 37). They were compared to 66 healthy controls (age 43.8 +/- 8) who did not receive the drops. Rest and exercise parameters were affected in groups A and B, while the results of group C resembled those of the controls: (a) resting heart rate -66.7, 66.6, 70.9 and 69.3, respectively (p = 0.03); (b) heart rate at 50 and 100 W - 104, 107, 110 and 111 (p = 0.01) and 131, 131, 137, 139, respectively (p = 0.01); and (c) peak systolic blood pressure - 192, 186, 183, 175; respectively (p = 0.004). Reanalyzing the data by scoring of visual impairment gave identical results. As a whole, the study group achieved higher work loads than the controls (126 vs. 119 W; p = 0.03). We conclude that the instillation of ocular tropicamide has definite effects on cardiovascular parameters, both at rest and during exercise. Mainly, patients showed a lower heart rate at the initial levels of exercise. However, at symptom-limited level, tropicamide does not influence a patient's ability to achieve the target heart rate, and stress testing results are not altered by the drug.

Adult↗
PubMed1992

Effects of pilocarpine and tropicamide on blood-aqueous barrier permeability in man.

The time courses of changes in the effects of topical pilocarpine and tropicamide on the index of the blood-aqueous barrier permeability to plasma protein (Pin) were determined in normal volunteers. Before and after drug instillation in one eye, protein concentration in the anterior chamber (Ca) was determined from aqueous flare intensity with a laser flare-cell meter and from aqueous flow by fluorophotometry. The Pin was calculated from the Ca, plasma protein concentration, and aqueous flow. One percent pilocarpine produced a maximum increase of 21 +/- 10% in the Ca (mean +/- SEM, n = 10), no significant change in the aqueous flow (n = 5), and a maximum increase of 29 +/- 10% in the Pin (n = 10). Three percent pilocarpine produced a maximum increase of 55 +/- 11% in the Ca (n = 8), a maximum increase of 34 +/- 13% in the aqueous flow (n = 5), and a maximum increase of 74 +/- 18% in the Pin (n = 8). Tropicamide (0.4%) produced a maximum decrease of 17 +/- 7% in the Ca (n = 8), a maximum decrease of 15 +/- 11% in the aqueous flow (n = 8), and a maximum decrease of 24 +/- 13% in the Pin (n = 8). The results indicated that pilocarpine increased the blood-aqueous barrier permeability to plasma protein in a dose-dependent manner and that tropicamide reduced it.

Adult↗
PubMed1989

Ideal concentration of tropicamide with hydroxyamphetamine 1% for routine pupillary dilation.

In this double-masked clinical study, we evaluated four concentrations of tropicamide (0.05%, 0.1%, 0.25%, and 0.5%) combined with hydroxyamphetamine 1% to find the combination that gives maximal pupillary dilation and inhibition of responsiveness to light and minimal paralysis of accommodation. With all concentrations, pupil size was maximal at 60 minutes, and there was no significant difference between the groups in mean pupillary diameter. Inhibition of the pupillary responses to light and loss of accommodation were directly related to the concentration of tropicamide. Tropicamide 0.25% combined with hydroxyamphetamine 1% was considered ideal for dilation and inhibition of the light response without inhibiting accommodation for near vision.

Accommodation, Ocular↗
PubMed1993

The effect of dapiprazole on accommodative amplitude in eyes dilated with 0.5 percent tropicamide.

BACKGROUND: Dapiprazole 0.5 percent (REV-EYES) eyedrops have recently become commercially available in the U.S. to reverse the diagnostic mydriasis produced by various concentrations and combinations of tropicamide and phenylephrine. Although a previous study has shown that dapiprazole increased accommodative amplitude after the administration of tropicamide, no attempt was made to control for differences in pupil size. METHODS: In the present single masked study, the accommodative amplitudes of forty-eight age-matched subjects previously dilated with 0.5% tropicamide were measured through a 3 millimeter artificial pupil following random instillation of dapiprazole in one eye and a placebo drop in the other eye. RESULTS: Area under the curve analysis determined that the magnitude of accommodative response to dapiprazole was significant at p < 0.001 (paired t-test). The McNemar test also showed that the accommodative amplitude was greater in eyes treated with dapiprazole at all observation points (p < 0.005), beginning at 15 mins after the instillation of the test drug. CONCLUSIONS: The results demonstrate that dapiprazole accelerates the return of accommodation independent of pupil size.

Accommodation, Ocular↗
PubMed1995

Reversal of tropicamide mydriasis with single instillations of pilocarpine can induce substantial pseudo-myopia in young adults.

Pupillary dilation for diagnostic purpose has become an increasingly common procedure in UK optometry in recent years and the consensus seems currently to militate against the routine use of miotics; an eye that is judged safe to dilate is thought to be at minimal risk during the natural recovery phase to normal pupil size. Nevertheless, the optometrist does, on occasion, need to consider whether there might be some advantage in minimising the sometimes debilitating effects of cycloplegia and mydriasis produced in young adults by tropicamide. In this context we compare the effects of single instillations of two miotic agents: the alpha-adrenoceptor antagonist thymoxamine HCl (0.5%), and the parasympathomimetic pilocarpine HCl (1 and 2%). Tropicamide was used to induce mydriasis in a group of 12 volunteer student subjects aged 20-26 years (7 males, 5 female; mean 21.67 years) selected to provide low (L; n = 4), medium (M; n = 4) and high (H; n = 4) iris pigment levels. Measurements of pupil diameter (Brocca pupillometer), Snellen visual acuity and accommodative amplitude (near point rule) were made every 3 min over a 90 min recording period for 4 trials: (1) a control condition whereby a miotic was not employed; (2) thymoxamine HCl 0.5% was instilled after 30 min; (3) and (4) pilocarpine 1% and 2% was instilled after 30 min, respectively. Tropicamide induced a mean increase in pupil area from 25 to 50 mm2 after 22 min which was generally sustained over the 90 min period and was enhanced for the lower pigment groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Accommodation, Ocular↗
PubMed1978

Antimuscarinic effects of stereoisomers of tropicamide on rabbit iris sphincter.

The antimuscarinic activity of optical isomers of tropicamide were compared on the isolated rabbit iris sphincter. The increasing concentrations of both the (--)- and (+)-isomer shifted the dose-response curve of carbachol to the right in a parallel fashion. The competitive reversible muscarinic blocking effects of both isomers were confirmed by pA2 plots. The pA2 values from the nonpigmented irides for (--)- and (+)-tropicamide were 7.88 and 6.18, respectively. Thus the (+)-isomer has only 1/50 the blocking activity of the (--)-isomer. Although both isomers are slightly less active in the pigmented iris, the activity difference between the isomers was high. From the nonpigmented iris, the blocking effect of the active (--)-tropicamide was readily reversed by washing, whereas reversal of this isomer's effect from the pigmented iris was relatively slow.

Animals↗