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PubMed1977

Intraocular pressure reduction during treatment with pilocarpine and systemic propranolol. A comparative double-masked study.

Propranolol, pilocarpine, and placebo were tested on eight patients with ocular hypertension. The trial was performed in a randomized double-masked cross-over manner utilizing the double dummy technique. After 1 week's treatment with 40 mg propranolol administered orally twice daily a statistically significant decrease in intraocular pressure (IOP) was seen. Also after application of 2% pilocarpine eyedrops three times a day IOP was significantly reduced. Propranolol decreased the IOP to about the same extent as pilocarpine. Simultaneous administration of propranolol and pilocarpine caused a further decrease in IOP which was statistically significant compared with the corresponding values during administration of pilocarpine alone. The combination of pilocarpine and propranolol lowered IOP slightly more than propranolol alone. The difference was not, however, statistically significant. During treatment with propranolol a significant decrease in heart rate was observed and a slight reduction of systemic blood pressure. It is concluded that propranolol can additively decrease IOP during treatment with pilocarpine.

Adult↗
PubMed1999

Effects of dipivefrin and pilocarpine on pupil diameter, automated perimetry and LogMAR acuity.

BACKGROUND: A study was carried out to ascertain, in ophthalmologically normal subjects, the short-term effects of dipivefrin hydrochloride 0.1% on visual performance and make comparisons with pilocarpine. METHODS: Twelve normal volunteers aged 20-26 years attended on three occasions. One eye, randomly selected, received one drop of either pilocarpine 2%, dipivefrin or saline 0.9%. High- and low-contrast LogMAR acuity at 6 m and pupil diameter (measured by infra-red pupillometry) were recorded at baseline (T0) and at intervals up to 90 min following instillation of drops. Program 30-2 of the Humphrey Visual Field Analyzer (HFA) was run at T0 and at 60 min after treatment instillation (T60). Saline was always instilled at visit 1, to allow for learning effects. On visits 2 and 3 either pilocarpine or dipivefrin was randomly instilled into the treated eye. RESULTS: Pilocarpine significantly worsened the field global indices mean deviation (P < 0.001) and pattern standard deviation (P < 0.01) compared with T0. There was no significant change with dipivefrin. A significant (P = 0.01) pupil dilation from 5.44 mm (SD 0.79) at T0 to 6.19 mm (SD 1.09) at T90 occurred with dipivefrin. Pilocarpine caused significant miosis. No significant changes in LogMAR values were found with dipivefrin. Pilocarpine significantly (P < 0.01) increased LogMAR values (i.e. reduced acuity) compared with dipivefrin. At T30 the mean increase in LogMAR was 0.76 (SD 0.30) for high and 0.83 (SD 0.11) for low contrast. By T90 recovery of acuity was virtually complete. CONCLUSIONS: In normals dipivefrin causes mydriasis but does not affect the central visual field global indices (as assessed by STATPAC), or high- and low-contrast LogMAR acuity. Pilocarpine adversely affects the visual field and both measures of acuity. Knowledge of these effects is of value in glaucoma therapy and when monitoring the progression of visual loss.

Adult↗
PubMed2000

The additive intraocular pressure-lowering effect of latanoprost 0.005% daily once and pilocarpine 2% t.i.d. in patients with open-angle glaucoma or ocular hypertension. a 6-month, randomized, multicenter study. German Latanoprost Study Group.

PURPOSE: To compare the additional intraocular pressure-lowering effect of latanoprost 0.005% administered once daily with that of pilocarpine 2% administered three times daily in patients with primary open-angle glaucoma or ocular hypertension currently on monotherapy with timolol 0.5% twice daily. METHODS: In a 6-month, multicenter, randomized, open-label study 242 patients with POAG or OH whose IOP was not controlled with timolol 0.5% b.i.d. were enrolled. Eyes had not been treated with pilocarpine and latanoprost for at least 2 years. An analysis of covariance with diurnal IOP change from baseline to month 6 for study eyes was performed. RESULTS: Four patients on latanoprost 0.005% and 35 on pilocarpine 2% did not complete the study (P<0.001). Two hundred and forty patients were included in the intent-to-treat analysis. For both treatments the diurnal IOP reduction after 6 months was statistically significant (P<0.001). IOP (mean+/-SD) was reduced from 23.3+/-2.8 to 17.8+/-2.8 (-5.6) mmHg in the latanoprost 0.005% group and from 23.0+/-3.2 to 18.5+/-2.4 (-4.8) mmHg in pilocarpine 2% t.i.d.-treated eyes. The mean difference of -0.8 mmHg (per protocol, PP) and -1.6 mmHg (intend-to-treat, ITT) was statistically significant (P<0.04, PP; P<0.001, ITT) in favor of latanoprost 0.005%. Two eyes treated with latanoprost showed an iris color change. Thirty-six patients in the latanoprost group and 106 in the pilocarpine 2% group reported ocular adverse events (P<0.001). CONCLUSION: From the data we conclude that the additivity of latanoprost 0.005% is at least as effective as pilocarpine 2% t.i.d. in reducing IOP when added to eyes currently on monotherapy with timolol 0.5% b.i.d. Latanoprost was better tolerated than pilocarpine 2% eye drops in this study. The increase in iris pigmentation requires further investigation.

Adrenergic beta-Antagonists↗
PubMed1987

A double-masked study of timolol and pilocarpine combined.

In a double-masked, randomized, multicenter study, 25 patients received timolol 0.5%-pilocarpine 2% twice a day, 25 received timolol 0.5%-pilocarpine 4% twice a day, and 25 received pilocarpine 4% four times a day. The combination drugs showed an immediate, significant reduction in intraocular pressure of 7.2 mm Hg (25%) and 10.7 mm Hg (37%), respectively. The lowered intraocular pressure level was maintained throughout the three-week test period. With pilocarpine alone, intraocular pressure was reduced 5.3 mm Hg (19%). The mean intraocular pressure 12 hours after the last dose compared to two hours after the last dose was significantly higher both in patients receiving pilocarpine four times a day and in patients receiving timolol 0.5%-pilocarpine 4% twice a day (5.1 and 3.6 mm Hg, respectively), but not in patients receiving timolol 0.5%-pilocarpine 2% twice a day (2.6 mm Hg).

Clinical Trials as Topic↗
PubMed1991

Effects of pilocarpine on salivary flow in patients with Sjögren's syndrome.

Pilocarpine, a muscarinic-cholinergic agonist drug, has been reported to stimulate salivary flow in patients with salivary gland dysfunction. Previous studies involved heterogeneous groups of patients with salivary gland dysfunction and examined the short-term, single-dose, tablet form of pilocarpine. In this single-blind, placebo-controlled study we examined the long-term effects of pilocarpine administration on patients with definitively diagnosed Sjögren's syndrome (SS). Nine subjects with SS who received pilocarpine, and nine age- and sex-matched SS control subjects who received a placebo, participated. Baseline predosing sialometric and clinical data were obtained for all subjects. The study group used 2% pilocarpine as a liquid ophthalmic drop preparation, four drops three times per day, for 6-weeks. Identically appearing placebo solution with the same dosing schedule and duration was used for the control subjects. Sialometric and clinical examinations were performed. The results indicated a significant overall increase in both whole unstimulated salivary flow (0.15 +/- 0.03 ml/min in study subjects vs 0.02 +/- 0.001 ml/min in control subjects; p less than 0.001) and parotid stimulated salivary flow (0.14 +/- 0.04 ml/min in study subjects vs 0.009 +/- 0.002 ml/min in control subjects; p less than 0.001) in the pilocarpine group as compared with the placebo group. The results of this study support the use of pilocarpine to increase salivary flow in patients with SS.

Adult↗
PubMed1993

Possible involvement of the spinal substance P system in pilocarpine-induced scratching in mice.

IT administration of pilocarpine in the spinal subarachnoid space of mice produced a dose-related hindlimb scratching. When coadministered with substance P IT, the pilocarpine-induced scratches were enhanced by high doses of substance P but not by subthreshold doses. This characteristic behavioral response was inhibited dose dependently by IT coadministration of spantide [D-Arg1, D-Trp7,9,Leu11] substance P. Significant antagonistic effects of [D-Phe7,D-His9] substance P (6-11), a selective antagonist for substance P receptors, and substance P (1-7), a substance P N-terminal fragment, were observed against the pilocarpine-induced scratching. Pretreatment with substance P antiserum resulted in the reduction of the response to pilocarpine. When coadministered IT with pilocarpine, atropine potently inhibited pilocarpine-induced scratching. These results demonstrate that not only muscarinic receptors but also substance P-containing neurons in the mouse spinal cord may be involved in elicitation of the scratching behavior following IT injection of pilocarpine.

Afferent Pathways↗
PubMed1990

Dopamine D1 receptor modulation of pilocarpine-induced convulsions.

The contribution of dopaminergic mechanisms to the generalization of epileptic activity was studied in rats given pilocarpine after pretreatment with selective dopamine agonists. At the dose of 200 mg/kg, pilocarpine produced limbic stereotypes but not convulsions or seizure-related brain damage. Pilocarpine, 200 mg/kg, following pretreatment with the D1 agonist (RS)-2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3 benzazepine, but not its (S)-enantiomer, induced convulsive activity as revealed by behavioral, electroencephalographic alterations and widespread brain damage. These features were identical to those produced by a higher, convulsant dose of pilocarpine (400 mg/kg). On the other hand, pretreatment with the D2 agonist 4,4a,5,6,7,8,8a,9-octahydro-5-n-propyl-2H-pyrazolo-3,4-g-quinoline failed to induce convulsions. Furthermore, the D1 receptor antagonist (R)-(+)-8-chloro-2,3,4,5-n-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine -7-ol prevented the convulsive activity induced by both 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3 benzazepine plus pilocarpine (200 mg/kg) and pilocarpine (400 mg/kg), given alone. However, neither dopamine agonists nor antagonists altered the limbic stereotypes induced by pilocarpine, suggesting a dopamine system involvement primarily in the mechanisms of epilepsy generalization. The results suggest that pharmacological manipulation of dopaminergic transmission may provide an alternative approach to therapy of secondarily generalized epilepsy.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed2005

Comparison of pilocarpine-induced and stimulus-driven accommodation in phakic eyes.

With the recent introduction of potentially accommodative intraocular lenses (IOL), there is a need for methods to evaluate their accommodative potential. In most studies assessing IOL movement, pilocarpine is used to stimulate contraction of the ciliary muscle. The aim of this study is to determine if pilocarpine-induced ciliary muscle contraction is comparable to physiological stimulus-driven accommodation in young and presbyopic subjects. Ten emmetropic young subjects (23-25 years) and 11 emmetropic presbyopic subjects (51-62 years) were included in this study. Anterior chamber depth (ACD) and lens thickness (LT) were assessed with partial coherence interferometry (PCI). A moveable stimulus was coupled to the PCI equipment for measurement of biometric lens changes. ACD was measured with the stimulus at infinity and then at the subjects individual nearpoint, and after application of two drops of 2% pilocarpine. In young subjects, there was no significant difference in lens change between nearpoint and pilocarpine stimulation. Presbyopic subjects showed no relevant lens change when accommodating at the nearpoint, however, under pharmacologically induced ciliary muscle contraction with pilocarpine, there was a significant forward shift of the anterior and posterior lens pole, leading to a translational forward lens shift of about 150 microm. This study demonstrates that pilocarpine acts "physiologically" in young phakic subjects, but is a "superstimulus" in presbyopic phakic subjects. Therefore, IOL movement may be overestimated when using pilocarpine to stimulate accommodation.

Accommodation, Ocular↗
PubMed2005

Pilocarpine's effects on the blood-aqueous barrier of the human eye as assessed by high-resolution, contrast magnetic resonance imaging.

The purpose of this research was to reassess the effects of topical pilocarpine on the integrity of the blood-aqueous barrier, using high resolution, magnetic resonance imaging, and the standard intravenous contrast agent gadolinium dimeglumine. It has long been known that topical pilocarpine gives rise to an increase in protein levels in the anterior chamber of the eye. This protein scatters light and is referred to clinically as 'flare'. Prior studies concluded that pilocarpine-induced flare resulted from disruption of the blood-aqueous barrier. These studies relied upon indirect methods that precluded direct visualization of the posterior chamber of the eye. Five normal, human volunteers (age 22-40) received a single drop of 3% pilocarpine in one eye, following baseline measurements of pupil size and anterior chamber 'flare'. These measurements were repeated every 15 min for 45 min. The subject was then positioned in the magnet and the eye that received pilocarpine was taped closed and covered with a 3 in.-diameter receive-only surface coil. The open contralateral eye focused on a target to maintain fixation of the imaged eye. A baseline image of the eye was obtained and the contrast agent was administered intravenously. A series of additional images was obtained during the following 60 min to track the movement of contrast material from the bloodstream into the tissues and compartments of the eye. Percent enhancement was calculated from selected regions of interest in the images, including the ciliary body, and the anterior and posterior chambers. Within the 45 min after administration of pilocarpine, pupil size in mm decreased from (mean+/-s.d.) 5.7+/-1.5 to 2.5+/-0.5 (p=0.0106). During this period, average flare/s.d. (photons msec-1) increased from 3.7+/-1.1 to 12.5+/-4.7 (p=0.0151). In all cases, MRI images showed rapid enhancement of the ciliary body, followed by a progressive increase in signal in the anterior chamber but not the posterior chamber. These studies confirm that topical pilocarpine gives rise to 'flare' in the anterior chamber. But the lack of enhancement in the posterior chamber strongly suggests that the presence of this added protein in the anterior chamber is not the result of increased permeability of the blood-aqueous barrier of the ciliary body. These studies also introduce the novel concept that not all clinically observed flare is the result of blood-aqueous barrier compromise.

Adult↗
PubMed1999

Comparison of dorzolamide and pilocarpine as adjunctive therapy in patients with open-angle glaucoma and ocular hypertension.

Many patients with glaucoma or ocular hypertension initially receive beta-blocker monotherapy to control intraocular pressure (IOP), but some of these patients will require an additional IOP-lowering agent within 1 year. This active-controlled, double-masked, randomized, multicenter, 12-week study compared the effectiveness and tolerability of dorzolamide hydrochloride ophthalmic solution 2% TID with those of pilocarpine hydrochloride 2% QID as adjunctive therapy to timolol maleate ophthalmic gel-forming solution (TG) 0.5% QD as measured by changes in IOP and occurrence of adverse events. One hundred ninety-four patients with open-angle glaucoma or ocular hypertension participated in this study. Their mean age was approximately 63 years. Slightly more than one half were white, and approximately one third were black. After a 3-week run-in period during which all patients received TG 0.5% QD, patients with an IOP of > or = 22 mm Hg at the morning trough measurement were randomly assigned to receive additional double-masked therapy with either dorzolamide or pilocarpine. The primary outcome measure was the mean change in IOP at the morning trough measurement from baseline to week 12. The secondary outcome measure was the mean change in IOP at the morning peak measurement from baseline to week 12. There was no significant difference in IOP-lowering effect between the 2 drugs at either morning trough or morning peak. The mean change in IOP at morning trough was -3.17 mm Hg (-12%) in patients receiving dorzolamide; it was -3.45 mm Hg (-13%) in patients receiving pilocarpine. The mean change in IOP at morning peak was -2.25 mm Hg (-10%) for patients who received dorzolamide and -2.51 mm Hg (-11%) for those who received pilocarpine. In the pilocarpine group, 62 (63%) patients experienced > or =1 adverse event compared with 35 (36%) patients in the dorzolamide group (P < 0.001). Twenty-one (21%) patients in the pilocarpine group discontinued treatment because of an adverse event compared with 2 (2%) patients in the dorzolamide group (P < 0.001). These results demonstrate that dorzolamide and pilocarpine were equally effective as adjunctive therapy in lowering IOP but that dorzolamide was better tolerated.

Adjuvants, Pharmaceutic↗
PubMed1993

Influence of pupil size, anisocoria, and ambient light on pilocarpine miosis. Implications for supersensitivity testing.

BACKGROUND: This study determines how pupil size, anisocoria, and ambient light influence miotic responses to dilute pilocarpine. The aim is to establish whether mechanical properties of the iris affect miotic behavior using a cholinergic agonist and, if so, to define a more specific clinical definition of supersensitivity testing for suspected tonic pupil disorders. METHODS: The right pupil of 42 normal subjects was first dilated with phenylephrine to create an experimental anisocoria. Then, pilocarpine 0.1% was placed in both eyes. Net constriction of the larger right pupil was determined by subtracting the amount of pilocarpine-induced constriction of the control left pupil from the amount of pilocarpine-induced constriction of the experimental right pupil. Pupil diameters were measured in room light and darkness. RESULTS: In only a few subjects, the larger right pupil became smaller than the left pupil after pilocarpine administration. Net constriction of the right pupil was greater when determined in room light than in darkness. The amount of net constriction of the right pupil showed good correlation with the degree of baseline anisocoria when evaluated in room light, but not so in darkness. CONCLUSION: Pupil size, degree of anisocoria, and light conditions influence the amount of pilocarpine-induced change in anisocoria. If a patient's larger pupil becomes the smaller pupil in darkness after dilute pilocarpine is applied to both eyes, then it is likely that such a response occurred independent of mechanical properties of the iris, and likely represents a supersensitive response. Ophthalmology.

Adolescent↗
PubMed1997

Effects of pilocarpine and kainate-induced seizures on N-methyl-D-aspartate receptor gene expression in the rat hippocampus.

The effects of pilocarpine- and kainate-induced seizures on N-methyl-D-aspartate receptor subunit-1 messenger RNA and [3H]dizocilpine maleate binding were studied in the rat hippocampal formation. Pilocarpine- but not kainate-induced seizures decreased N-methyl-D-aspartate receptor subunit-1 messenger RNA level in dentate gyrus at 24 and 72 h after drug injection. Both convulsants decreased the messenger RNA level in CA1 pyramidal cells at 24 and 72 h, the effects of kainate being more profound. Kainate also decreased the N-methyl-D-aspartate receptor subunit-1 messenger RNA level in CA3 region after 24 and 72 h, whereas pilocarpine decreased the messenger RNA level at 72 h only. At 3 h after kainate, but not pilocarpine, an increased binding of [3H]dizocilpine maleate in several apical dendritic fields of pyramidal cells was found. Pilocarpine reduced the [3H]dizocilpine maleate binding in stratum lucidum only at 3 and 24 h after the drug injection. Pilocarpine but not kainate induced prolonged decrease in N-methyl-D-aspartate receptor subunit-1 gene expression in dentate gyrus. However, at the latest time measured, kainate had the stronger effect in decreasing both messenger RNA N-methyl-D-aspartate receptor subunit-1 and [3H]dizocilpine maleate binding in CA1 and CA3 hippocampal pyramidal cells. The latter changes corresponded, however, to neuronal loss and may reflect higher neurotoxic potency of kainate. These data point to some differences in hippocampal N-methyl-D-aspartate receptor regulation in pilocarpine and kainate models of limbic seizures. Moreover, our results suggest that the N-methyl-D-aspartate receptor subunit-1 messenger RNA level is more susceptible to limbic seizures than is [3H]dizocilpine maleate binding in the rat hippocampal formation.

Animals↗
PubMed1997

Pilocarpine, a salivary gland radioprotectant, does not inhibit cytotoxic effect of gamma-radiation on squamous cell carcinoma in vitro.

PURPOSE: Pilocarpine, a salivary stimulant, has been shown to protect salivary glands from gamma-radiation-induced damage during the radiotherapy of head and neck tumors. This study was performed to determine whether pilocarpine affects the survival of squamous carcinoma cells, line SCC-25, following gamma-radiation treatment. METHODS AND MATERIALS: The survival of squamous carcinoma tumor cells, line SCC-25, following the exposure of cells to pilocarpine at concentration of 0-100 ng/ml given for 0-1 h prior to radiation at dose of 0-20 Gy was determined by an in vitro colony-formation assay. RESULTS: The survival fractions of SCC-25 cells were identical for the control and pilocarpine-treated samples at all tested conditions. Calculated Do and Dq values did not depend on the presence of pilocarpine and were not affected by the time of incubation prior to irradiation. CONCLUSION: Pilocarpine, at clinically relevant concentrations, given to the SCC-25 cells 1 h prior to or at the time of irradiation did not affect survival of SCC-25 cells in vitro. Pilocarpine does not sensitize or protect these tumor cells from the effects of y-radiation, suggesting that this agent should not compromise the tumoricidal effects of radiotherapy.

Carcinoma, Squamous Cell↗
PubMed2002

Pilocarpine-induced status epilepticus results in mossy fiber sprouting and spontaneous seizures in C57BL/6 and CD-1 mice.

Several rodent models are available to study the cellular mechanisms associated with the development of temporal lobe epilepsy (TLE), but few have been successfully transferred to inbred mouse strains commonly used in genetic mutation studies. We examined spontaneous seizure development and correlative axon sprouting in the dentate gyrus of CD-1 and C57BL/6 mice after systemic injection of pilocarpine. Pilocarpine induced seizures and status epilepticus (SE) after systemic injection in both strains, although SE onset latency was greater for C57BL/6 mice. There were also animals of both strains which did not experience SE after pilocarpine treatment. After a period of normal behavior for several days after the pilocarpine treatment, spontaneous tonic-clonic seizures were observed in most CD-1 mice and all C57BL/6 that survived pilocarpine-induced SE. Robust mossy fiber sprouting into the inner molecular layer was observed after 4-8 weeks in mice from both strains which had experienced SE, and cell loss was apparent in the hippocampus. Mossy fiber sprouting and spontaneous seizures were not observed in mice that did not experience a period of SE. These results indicate that pilocarpine induces spontaneous seizures and mossy fiber sprouting in both CD-1 and C57BL/6 mouse strains. Unlike systemic kainic acid treatment, the pilocarpine model offers a potentially useful tool for studying TLE development in genetically modified mice raised on the C57BL/6 background.

Animals↗
PubMed2002

Castration in female rats modifies the development of the pilocarpine model of epilepsy.

Previous studies have shown that the susceptibility to pilocarpine-induced status epilepticus (SE) in female rats changes according to estrous cycle phases. These studies have also shown that following pilocarpine administration changes occur in gonadal, hypophyseal and hypothalamic hormones that could contribute for the sequence of the epileptic events. Accordingly, the present work aimed to investigate the role of sexual hormones withdrawal on the development of the pilocarpine model of epilepsy in female rats. With this purpose, castrated and non-castrated adult female Wistar rats were injected with pilocarpine and some characteristic parameters of the experimental model were observed. The results showed increased mortality after pilocarpine injection in the castrated rats when compared with non-castrated females. The latency period for SE onset and for the first spontaneous seizure was decreased in castrated when compared with non-castrated animals. The mossy fiber sprouting measured by neo-Timm scale during the chronic period, reached grade 3 for castrated epileptic rats while the non-castrated epileptic rats showed grade 2. Our results indicate that castration interferes with the epileptogenesis in the pilocarpine model of epilepsy suggesting that female sexual hormones could have protective effects against pilocarpine-induced SE.

Animals↗
PubMed1997

Status epilepticus induced by pilocarpine and picrotoxin.

Since its original description over 10 years ago, the pilocarpine model of status epilepticus (SE) has gained considerable attention. Much work has been done with the model in order to characterize the involvement of different brain structures in seizure genesis and spread. Electrophysiological studies of temporal lobe epileptic slices of both human and animal models, have failed to reveal hyperexcitability, unless blockade of GABAergic inhibition is performed. Thus, we have decided to evaluate potential contributions of picrotoxin, a GABAA channel blocker, on pilocarpine-induced SE. Animals injected with three-specific dose combinations (pilocarpine dose/picrotoxin dose), 150/0.5, 75/1.5 and 50/2.0 mg/kg, evoked status epilepticus (SE) within 23, 31 and 27 min, respectively. Ictal events and EEG spikes were initially observed either in the amygdala or in the hippocampus, with a later spread to cerebral cortex. Neuropathological analysis, performed 5-7 days after SE, has shown a high degree of cell loss predominantly in the piriform cortex, amygdala, hippocampus, thalamus and substantia nigra. Mortality rates for 150/0.5, 75/1.5 and 50/2.0 mg/kg (pilocarpine dose/picrotoxin dose) were 53, 42 and 51%, respectively. Single injections of 150 mg/kg of pilocarpine or 3 mg/kg of picrotoxin did not evoke any form of sustained epileptic activity. Previous studies in which simultaneous injections of other GABAA antagonists (i.e. bicuculline) and pilocarpine were performed, did not show clear evidences of a synergistic action between these two systems. The present study reveals a proconvulsant role for picrotoxin when co-administered with subconvulsant doses of pilocarpine. Possible mechanisms that might account for the interactions between the cholinergic and GABAergic systems in regard to epileptogenesis are discussed.

Amygdala↗
PubMed1999

Studies on the effect of pilocarpine incorporation into a submicron emulsion on the stability of the drug and the vehicle.

In order to obtain a novel ocular formulation with a potential for prolonging pilocarpine activity, the drug (2.0%) was incorporated into a submicron emulsion containing soya-bean oil and lecithin as emulgator. The effect of drug incorporation into the emulsion on its physical stability and on the other hand, the potential of the vehicle to reduce drug degradation at pH higher than 5.0 was studied. The pH was adjusted to 6.5 or 5.0 and the physicochemical stability of the formulations was observed. The mean diameter of oily particles in the resulting emulsions measured by a laser diffractometer was 0.6-0.7 micron and this was larger than in a drug-free emulsion where a 0.33 micron value was measured. The formulations were physically stable for 6 months at 4 degrees C, but progressing chemical degradation of pilocarpine was noted at pH 6.5. At that pH nearly 8% of pilocarpine was degraded to isopilocarpine and pilocarpic acid, both in the emulsion and in the solution. Thus, it may be concluded that pilocarpine in submicron emulsion is not protected against degradation. The presence of pilocarpine changes the physical stability of the vehicle since the formulation was easily destabilized during autoclaving or at room temperature. In the presence of higher concentration of lecithin (2.4%) or co-emulgators (poloxamer 2.0% or Tween 80 0.5%) the mean droplet size in the emulsions was the same as in a drug-free system. However the emulsions containing poloxamer were not stable during storage. Viscosity of pilocarpine emulsions can be increased by addition of methylcellulose or sodium carmellose (1.0%), but an intensive creaming occurs in these systems. Pilocarpine base is less suitable for emulsion preparation than hydrochloride salt, and emulsions prepared at pH 5.0 show the most satisfying stability.

Chemistry, Pharmaceutical↗
PubMed1987

Comparative intraocular levels of pilocarpine achieved with drops and repository preparations.

The concentrations of pilocarpine in aqueous humor and iris-ciliary body of rabbits following topical treatment with repository preparations or conventional drop therapy were measured using high performance liquid chromatography (HPLC). Higher concentrations of pilocarpine occurred both in aqueous humor and iris-ciliary body following topical administration of the 4% gel product than with 4% drops. At 1 hour after administration, 2% drops produced a higher concentration of pilocarpine in the aqueous humor than occurred with the 1.86% pilocarpine emulsion product; however, isopilocarpine present in the emulsion product entered the aqueous humor in equal amounts with the pilocarpine. At 4 hours, equal concentrations of pilocarpine were present in aqueous humor and iris-ciliary body samples with both the 2% drop and 1.86% emulsion therapy. Pilocarpine concentrations were maintained within the aqueous humor of the eye for longer durations with both the gel and emulsion repository preparations than with comparable drop therapy.

Animals↗