Pilocarpine HCl Research Articles

Understanding Perspectives on Presbyopia and Use of Pilocarpine HCl 1.25% Twice Daily from Participants of the Phase 3 VIRGO Study.

The phase 3, randomized, vehicle-controlled, 14-day VIRGO study evaluated the efficacy and safety of twice-daily dosing of pilocarpine hydrochloride ophthalmic solution 1.25% (Pilo) in presbyopia. On VIRGO exit, a companion study was conducted to assess the patient experience with presbyopia and satisfaction with Pilo. Recruited individuals completed the Presbyopia Patient Satisfaction Questionnaire (PPSQ) plus a three-part exit survey, or a live interview. The PPSQ evaluated respondents' experience with Pilo. Survey parts 1 and 2 evaluated experience managing presbyopia before and during VIRGO, respectively; part 3 assessed future possibilities of using Pilo in real-world situations. The interview further informed the interviewees' experience with presbyopia and Pilo. The primary endpoint was responders (%) in each rating category of the PPSQ items 1-7; the secondary endpoints were summary of categorical (survey) and qualitative (interviews) responses. The PPSQ and survey included 62 participants who received Pilo (N = 28) or vehicle (N = 34) in VIRGO; the interview included ten participants (Pilo, N = 4; vehicle, N = 6). Per the PPSQ, 64.3% of Pilo users reported vision improvement, including 17.9% with complete improvement; ≥ 46.4% were satisfied/very satisfied with their ability to perform daily activities, see up close unaided, and read in dim light. Among vehicle users, these percentages were 35.3%, 0%, and ≤ 23.5%, respectively. In both subgroups, ≥ 67.9% were interested in using Pilo or Pilo and eyeglasses/contact lenses in the future. Per the interview, vehicle users (n = 6/6) found the eyedrop easy to use but none experienced meaningful near-vision improvements, stopped using other correction method(s) part of the day, were satisfied with the eyedrop, preferred it over their previous correction method(s), or would continue using it if prescribed. Conversely, 75% (n = 3/4) of Pilo users responded positively to each of these six criteria. Findings validate the VIRGO results and improve our understanding of the patient experience, demonstrating improved vision and satisfaction with Pilo (vs. vehicle) when performing daily activities.

Development and characterization of niosomes loaded mucoadhesive biodegradable ocular inserts for extended release of pilocarpine HCl

Abstract Background Pilocarpine HCl is a non-selective muscarinic receptor agonist that is prescribed for the treatment of glaucoma. The use of pilocarpine conventional eye drops is associated with several side effects, such as loss of visual acuity, and the need for several applications due to rapid drainage away via the nasolacrimal duct, especially for elderly people. Such adverse effects can lead to low patient compliance and poor clinical outcomes. Therefore, the aim of this project was to develop, optimise and characterise a biodegradable pilocarpine HCl ocular insert using niosomes as a drug delivery vehicle. To achieve that, various polymers such as hydroxypropyl methylcellulose (HPMC), polyvinyl alcohol (PVA), and a blend of both were investigated to prepare the ocular inserts using solvent casting technique. The niosomes of pilocarpine HCl were prepared using span-60 and cholesterol by thin film hydration method. The produced noisome-loaded ocular inserts were characterised using various analytical techniques, including Fourier Transform Infrared (FTIR), X-ray Diffractions (XRD), thermal analysis, particle size analysis, weight and content uniformity, surface pH and drug release profile, among others. Results The results indicated that drug-free ocular inserts of the two polymers (HPMC + PVA) were better than single polymer-based ocular inserts (HPMC or PVA alone). The formed niosomes demonstrated good entrapment efficiency of 49.7% ± 7.0, with an average particle size of 325.7 ± 3.5 nm. The FTIR analysis showed no interaction between the compositions of niosomes. Four optimal formulations with various co-polymer ratios and pilocarpine content were further evaluated. Pilocarpine-containing niosomes-loaded ocular inserts provided uniformity in pilocarpine content (89–96%), with 34.8% moisture content and an average pH of 7. The release profile of niosomes-loaded inserts demonstrated an initial burst release within 2 h ranging from 26.54% (T4) to 41.22% (T2), and continuous sustained release for the next 24 h (68.32 ± 5.11% (T4) to 82.11 ± 6.01% (T2)). Conclusions This work successfully optimised biodegradable ocular inserts containing slow-release pilocarpine HCl encapsulated in niosomes for the treatment of glaucoma without dose dumping, resulting in a user-friendly drug delivery system. Graphical abstract

Pilocarpine HCl 1.25% for treatment of presbyopia after laser vision correction: pooled analysis of two phase 3 randomized trials (GEMINI 1 and 2).

To evaluate the efficacy of topical pilocarpine HCl 1.25% (Pilo) in treating presbyopia in individuals with or without a history of laser vision correction (laser-assisted in situ keratomileusis [LASIK] or photorefractive keratectomy [PRK]). Multiple clinical sites. Pooled analysis of 2 identically designed prospective, randomized, vehicle-controlled studies (GEMINI 1 and 2). Adults aged 40 to 55 years with presbyopia received once-daily Pilo or vehicle bilaterally for 30 days. Responder rates for ≥3-line improvement in mesopic, high-contrast, binocular distance-corrected near visual acuity (DCNVA) were determined on day 30. Among participants with a history of LASIK/PRK (n = 39 in the Pilo group, n = 41 in the vehicle group), responder rates for ≥3-line improvement in DCNVA on day 30 at hours 0.25, 0.5, 1, 3, 6, 8, and 10, respectively, were 16.7%, 38.9%, 41.7%, 37.8%, 16.2%, 13.9%, and 8.3% with Pilo and 0.0%, 2.6%, 10.5%, 5.1%, 7.7%, 2.6%, and 0.0% with vehicle. Responder rates in the LASIK/PRK subgroup were significantly higher with Pilo than vehicle at hours 0.25 ( P = .0087), 0.5 ( P = .0001), 1 ( P = .0022), and 3 ( P = .0005). In contrast, there were no significant differences in responder rates between Pilo-treated participants with and without LASIK/PRK. Among non-LASIK/PRK participants in the Pilo group (n = 336), responder rates for ≥3-line improvement in DCNVA on day 30 at hours 0.25, 0.5, 1, 3, 6, 8, and 10, respectively, were 16.8%, 32.7%, 39.0%, 28.0%, 17.4%, 12.6%, and 10.5%. Pilo treatment effectively and similarly improved DCNVA in presbyopes with or without a history of laser vision correction.

The Role of Pilocarpine Eye Drops in the Management of Presbyopia: A Systematic Review

Introduction: Presbyopia is characterized by progressive loss of accommodation resulting in loss of visual acuity and is known to affect quality of life. Mainstay treatment include reading spectacles, contact lenses, and a series of surgical techniques. Until recently, pharmacologic treatment have been available. In this paper, we aim to review the role of pilocarpine eye drops in managing presbyopia. Methods: A comprehensive literature search was performed using Medline, EMBASE, and grey literature databases for articles from inception until 06 June 2024. Search terms included “presbyopia”, “presbyopia correction/treatment”, “pilocarpine”, and “pharmacological presbyopia treatment”. All relevant articles examining the efficacy and side effects of pilocarpine formulations and written in the English language were included in the review. Results: The initial search yielded 587 publications, of which 19 met our inclusion criteria and were included in analysis. Pilocarpine, a parasympathomimetic drug, increases the power of accommodation by increasing the lens thickness via the muscarinic receptors on the iris and ciliary muscles. Clinical trials utilizing pilocarpine eye drops in the management of presbyopia have reported positive outcomes in terms of near visual acuity. Pilocarpine HCL ophthalmic 1.25% formulation; Vuity™ and 0.4% formulation, Qlosi™ are currently the only approved pharmacologic treatment options shown to be effective in managing presbyopia. Conclusion: Overall, pilocarpine eye drops appear to be an effective option in improving near visual acuity in presbyopia patients. Long term follow-up data on the use of pilocarpine-based eye drops is not available. With the increase in the number of users overtime, the long-term effects of its prolonged use may be determined. Further research is needed to optimize the concentrations and combinations of pilocarpine and other substances to maximize efficacy and minimize adverse effects.

Pharmacy compounded pilocarpine: An adequate solution to overcome shortage of pilogel® discs for sweat testing in patients with cystic fibrosis

To respond to shortage of pilocarpine discs due to CE-licensing problems a pharmacy compounded pilocarpine HCL solution was developed and validated for use in CF diagnosis.The aim of this study was to compare the results from a pharmacy compounded pilocarpine HCL solution versus Pilogel® discs for the measurements of sweat chloride concentrations.Ten pediatric and adult patients with CF underwent a sweat test using both Pilogel® discs and pilocarpine HCL solution.The average difference between both methods was -3.25 mmol/L (95% Limits of Agreement: -7.19 [95% CI: -9.19;-5.19] and 0.69 [95% CI: -1.31;2.69] mmol/L. Passing-Bablok regression showed that zero was enclosed with the 95% CI of the calculated intercept (0.15 [95% CI: -1.70;1.42] mmol/L).These data show a good agreement in chloride concentrations obtained using the two pilocarpine products. Therefore, the pharmacy compounded pilocarpine HCL solution can be used as an alternative for Pilogel® discs during times of shortage.

Safety and Efficacy of Twice-Daily Pilocarpine HCl in Presbyopia: The Virgo Phase 3, Randomized, Double-Masked, Controlled Study

To evaluate the safety, efficacy, and pharmacokinetics of pilocarpine hydrochloride 1.25% (Pilo hereafter) compared with vehicle when administered bilaterally, twice daily (6 hours apart) for 14 days in participants with presbyopia. Phase 3, randomized (1:1), controlled, double-masked, multicenter study. Participants (40-55 years of age) had objective and subjective evidence of presbyopia affecting daily activities with mesopic, high-contrast, binocular distance-corrected near visual acuity (DCNVA) of 20/40 to 20/100. The primary/key secondary endpoint was the proportion of participants gaining ≥3 lines in mesopic/photopic, high-contrast, binocular DCNVA on day 14 (last study visit), hour 9 (3 hours after the second dose), with no more than a 5-letter loss in mesopic/photopic corrected distance visual acuity with the same refractive correction. Key safety measures included treatment-emergent adverse events (TEAEs) and some ocular measurements. Pilocarpine plasma levels were assessed in approximately 10% of enrolled participants. Overall, 230 participants were randomized to Pilo twice daily (N=114) and vehicle (N=116). The proportion of participants achieving the primary and key secondary efficacy endpoints was statistically significantly greater with Pilo twice daily than vehicle, with between-treatment differences of 27.3% (95% CI=17.3, 37.4) and 26.4% (95% CI=16.8, 36.0), respectively. The most common TEAE was headache, reported in 10 participants (8.8%, Pilo group) and 4 participants (3.4%, vehicle group). Pilocarpine's accumulation index on day 14 was ≤1.11 after the second dose. Near-vision improvements were statistically greater with Pilo twice daily than with vehicle, without compromising distance acuity. The safety profile of Pilo twice daily was consistent with that of Pilo once daily, and systemic accumulation was minimal, supporting twice daily administration.

Ameliorating effect of ketogenic diet on acute status epilepticus: Insights into biochemical and histological changes in rat hippocampus.

This study aimed to evaluate the potential neuroprotective effects of ketogenic diet (KD) against the neuronal disruptions induced by SE in lithium-pilocarpine rat model of status epilepticus (SE). Four groups of female rats include; groups I and III received standard diet and groups II and IV received KD for 3 weeks. Groups I and II were left untreated, while groups III and IV were injected with LiCl (127 mg/kg, i.p.) followed by pilocarpine HCl (10mg/kg, i.p.) 18-24h later, repeatedly, till induction of SE. 72 h post-SE, KD effectively ameliorated the balance between excitatory (glutamate) and inhibitory (GABA) neurotransmitters and the oxidative stress indices, increased adenine nucleotides and decreased immunoreactivity of iNOS, TNFα, glial fibrillary acidic protein, and synaptophysin. Thiswas in association with improvement in inflammatory response and neuronal tissue characteristics in hippocampus of SE rats. Histological changes showed preservation of neuronal integrity. These findings highlight the protective effects of KD in the acute phase post-SE via ameliorating biochemical and histological changes involved. PRACTICAL APPLICATIONS: Epilepsy is the fourth most common neurological disorder that requires lifelong treatment. It stigmatizes patients and their families. The use of the ketogenic diet (KD) as a therapy for epilepsy developed from observations that fasting could reduce seizures. From 1920s, the KD was a common epilepsy treatment until it was gradually superseded by anticonvulsant drugs so that by the 1980s it was rarely used. However, there has been a resurgence of interest and usage of the KD for epilepsy since the turn of the century. Despite its long history, the mechanisms by which KD exhibits its anti-seizure action are not fully understood. Our study aims to identify the mechanism of KD which may help further studies to achieve the same benefits with a drug or supplement to overcome its unpalatability and gastrointestinal side effects.

Anticonvulsive evaluation and histopathological survey of thalidomide synthetic analogs on lithium-pilocarpine-induced status epilepticus in rats.

Background and purpose:Status epilepticus is a severe neurological disorder that can be life-threatening. Thalidomide and its analogs have shown promising results to confront pentylenetetrazole-induced seizures. This study aimed to evaluate the potential effects of three synthesized thalidomide derivatives on lithium-pilocarpine-induced status epilepticus.Experimental approach:To induce status epilepticus, rats received lithium chloride (127 mg/kg, i.p.) and pilocarpine HCl (60 mg/kg, i.p.) 20 h after lithium chloride injection. Thirty min before pilocarpine HCl administration, rats received hyoscine N-butyl bromide (1 mg/kg, i.p.) and concurrently one of the test compounds (5B, 5C, and 5D), diazepam, thalidomide, or vehicle (4% DMSO) to evaluate their anti-epileptic effects. Epileptic seizures scores were assessed through the Racine scale. Twenty-four h after injection of pilocarpine, brain samples were extracted for further histopathological evaluation.Findings/Results:Results revealed that among tested compounds (5B, 5C, and 5D), only compound 5C (1 mg/kg) exhibited excellent anti-epileptic activity comparable to diazepam (10 mg/kg). Compound 5D (100 mg/kg) only demonstrated comparable anti-epileptic activity to thalidomide (1 mg/kg). Compound 5B did not have any anti-epileptic activity even at the dose of 100 mg/kg. The histopathological survey showed that compound 5C has more neuroprotective effects than diazepam and thalidomide in the cortex of the brain. In the cornu ammonis 1 region, thalidomide had higher protective properties and in the cornu ammonis 3 and dentate gyrus areas, diazepam had higher efficacy to prevent necrosis.Conclusion and implications:Compound 5C is a good candidate for further studies regarding its potency, compared to thalidomide and diazepam.

Combinations of Pilocarpine and Oxymetazoline for the Pharmacological Treatment of Presbyopia: Two Randomized Phase 2 Studies.

PurposeTo determine the safety, efficacy, and tolerability of combinations of pilocarpine (Pilo) and oxymetazoline (Oxy) ocular drops dosed once daily and identify the optimal concentration of each for the pharmacologic treatment of presbyopia.DesignTwo concurrent Phase 2, multicenter, double-masked, randomized, vehicle-controlled studies, 1 short-term and 1 extended study.ParticipantsEmmetropic individuals affected by presbyopia and in good general health.MethodsUncorrected near visual acuity (UNVA) was measured throughout both studies with various concentrations and combinations of Pilo (0%, 0.5% 1.0%, and 1.5%) and Oxy (0%, 0.0125%, 0.05%, and 0.125%). For safety, uncorrected distance visual acuity (UDVA) was measured, treatment-emergent adverse events (TEAEs) were recorded, and a temporal/supraorbital headache assessment was completed.Main Outcome MeasuresThe primary efficacy end point was mean change from baseline in UNVA.ResultsIn the short-term study, Pilo was shown to produce a significant dose response in the average increase of letters (P < 0.001), whereas Oxy did not have a significant impact (P = 0.4797). The addition or increase in concentration of Oxy did not reduce incidence or severity of headaches when compared with Pilo alone. Efficacy results from the extended study supported the results from the short-term study. As early as 15 minutes postadministration, a dose response could be seen, with peak effect at 1 hour. Peak improvement increased from day 1 to day 14 and was maintained up to day 28. The most common TEAE was headache. There was no clinically significant reduction in UDVA. A polynomial regression model was developed and determined that the optimal concentration range of Pilo is between 1.16% and 1.32%.ConclusionsOn the basis of the results of the 2 Phase 2 studies, AGN-190584, a reading drop containing an optimized concentration of pilocarpine HCl (1.25%) delivered using a proprietary formulation, was developed and is currently under investigation in Phase 3 studies.

Nonionic surfactant vesicles (niosomes) for ocular drug delivery: Development, evaluation and toxicological profiling

Niosomes are emerging drug delivery systems that maintain the drug targeting advantages of liposomes, while overcoming the problems of low drug encapsulation and instabilities usually associated with liposomes. The purpose of this study was to systematically develop and characterise the physicochemical and biological toxicological properties of prepared niosomes based on method of production, method of drug incorporation, construct composition and drug loading. Briefly, drug-free and model drug pilocarpine HCl-loaded niosomes were prepared using combinations of Tweens and Spans by either thin film hydration (TFH) or ether injection (EI) methods. The resulting niosomes were characterised based on vesicle size, polydispersity, zeta potential, structural microscopy and drug entrapment. Toxicity of optimised niosomes was tested on HCE-2 cell-line as a model of the corneal epithelium. Results indicated that EI method produced smaller niosomes than TFH method, although the latter method produces niosomes with better stability over time. Significant increase in drug entrapment was observed when pilocarpine HCl was incorporated into the organic phase during manufacture. No corneal cellular toxicity was observed with optimal Span-60 niosomes, with high drug encapsulation. This study provides a mechanistic insight to the design, evaluation and toxicological screening of niosomes with potential for ocular drug delivery to the elderly.

Microneedle ocular patch: fabrication, characterization, and ex-vivo evaluation using pilocarpine as model drug

Context: Enhacing the ocular bioavailability of drugs after their topical application is a challenge.Objective: The objective of the study was to design, fabricate, and investigate the effectiveness of microneedle ocular patch (MOP) in delivering the model drug, pilocarpine HCl across the corneal membrane.Methods: MOP mimicked commercially available contact lens design elements having a diameter of 14.20 mm and a sagittal height of 3.85 mm with a convex curvature. The base of this patch contained an array of 25 pyramid-shaped microneedles measuring 521 ± 10 µm in length. Pilocarpine loaded MOP was prepared by micromolding technique using dissolvable polyvinyl alcohol and polyvinyl pyrrolidone matrix. MOP was characterized for physical and mechanical properties using a stereomicroscope, scanning electron microscope, and texture analyzer.Results: Histological examination after MOP application on excised human cornea showed penetration of microneedles with a required insertional force of 1.04 ± 0.17 N. Flux of pilocarpine across excised cornea was significantly (p < 0.05) greater after application of MOP (704 ± 149 µg/cm2/h) compared with solution formulation (188 ± 24 µg/cm2/h). Ex-vivo pilocarpine permeation study in porcine eye globe revealed significantly (p < 0.05) greater availability in aqueous humor within 30 min of application of MOP (249 ± 85 µg/ml) compared with solution formulation (46 ± 9 µg/ml).Conclusion: MOP can be developed as a potential ophthalmic drug delivery system.

Formulation and investigation of pilocarpine hydrochloride niosomal gels for the treatment of glaucoma: intraocular pressure measurement in white albino rabbits

The present study was focused on investigating niosomal gels loaded with cholinergic drug; pilocarpine HCl, for prolonged precorneal residence time and improved bioavailability for glaucoma treatment. Pilocarpine HCl niosomes were prepared using various nonionic surfactants (span 20, span 60 and span 80), in the presence of cholesterol in different molar ratios by ether injection method. The selected formulations were incorporated into carbopol 934 and locust bean gum-based gels. TEM analysis confirmed that niosomes formed were spherical in shape and has a definite internal aqueous space with uniform particle size. Formulation F4 composed of span 60 and cholesterol (1:1) gave the highest entrapment (93.26 ± 1.75%) and slower release results after 8 hours (Q8h = 60.35 ± 1.87%) among other formulations. The in-vitro drug permeation studies showed that there was a prolonged release of drug from niosomal gels as compared to niosomes itself. Considering the in-vitro drug release, niosomal gel formulation G2 was the best among the studied formulations. The release data were fitted to an empirical equation, which indicated that the release follows non-Fickian diffusion mechanism. The stability study revealed that incorporation of niosomes in gel increased their stability than the niosome itself. No signs of redness, inflammation, swelling or increased tear production were observed over the study period for tested formulation by Draize’s test. The intraocular pressure (IOP) lowering activity of G2 formulation showed relative bioavailability 2.64 times more than bioavailability of marketed Pilopine HS® gel. These results suggest that the niosomal gels containing pilocarpine HCl are promising ocular carriers for glaucoma treatment.

Solid-state epimerisation and disproportionation of pilocarpine HCl: Why we need a 5-stage approach to validate melting point measurements for heat-sensitive drugs.

Melting points for new drugs are reported in regulatory documents, e.g. investigational brochures, and frequently in published research; however, the authors do not typically consider that heat-induced degradation can affect the melting point measurement. Applying a single heating rate is not adequate, and thus many melting points in the literature and regulatory documentation are not valid. Our aim was to validate a five-stage approach for the melting point measurement of heat-sensitive drugs. These stages are; (1) observe melting; (2) record mass loss; (3) measure melting points at different heating rates; (4) characterise degradation and (5) test for potential isomerisation. Applying this approach to pilocarpine HCl illustrated the sensitivity of a melting point to thermal degradation. Due to salt disproportionation & loss of HCl gas, pilocarpine's melting point decreased by 14°C when the heating rate was lowered from 20 to 1°C/min. Epimerization occurred before melting was reached. Increasing the heating rate diminished disproportionation; however, this did not remove epimerization. Thus, the melting point of pilocarpine HCl of 205.5±0.4°C measured at 20°C/min represents the melt of a racemic mixture containing inactive isopilocarpine. Heating above the melting point accelerated degradation, a rate of 5°C/min recovered just 38±1% of pilocarpine. Such data predicted a shelf-life of 6.6years. Pilocarpine successfully validated the multistage approach by providing new knowledge concerning its thermal stability. Our 5-stage approach must be applied to all new drugs especially if their formulation requires heat. For example, thermal stability is an infrequently considered pre-requisite in the emerging field of 3D printing.

Δ9-Tetrahydrocannabinol Derivative-Loaded Nanoformulation Lowers Intraocular Pressure in Normotensive Rabbits.

PurposeΔ9-Tetrahydrocannabinol-valine-hemisuccinate, a hydrophilic prodrug of Δ9-tetrahydrocannabinol, synthesized with the aim of improving the ocular bioavailability of the parent molecule, was investigated in a lipid-based nanoparticle dosage form for ocular delivery.MethodsSolid lipid nanoparticles (SLNs) of Δ9-tetrahydrocannabinol-valine-hemisuccinate and Δ9-tetrahydrocannabinol, along with a nanoemulsion of Δ9-tetrahydrocannabinol-valine-hemisuccinate, were tested for glaucoma management in a normotensive rabbit model by using a multiple-dosing protocol. Marketed formulations of timolol maleate and pilocarpine HCl were also tested for their pharmacodynamic profile, post-single dose administration.ResultsA peak intraocular pressure (IOP) drop of 30% from baseline was observed in rabbits treated with SLNs loaded with Δ9-tetrahydrocannabinol-valine-hemisuccinate at 90 minutes. Treated eyes of rabbits receiving Δ9-tetrahydrocannabinol-valine-hemisuccinate SLNs had significantly lower IOP than untreated eyes until 360 minutes, whereas the group receiving the emulsion formulation showed a drop in IOP until 90 minutes only. In comparison to marketed pilocarpine and timolol maleate ophthalmic solutions, Δ9-tetrahydrocannabinol-valine-hemisuccinate SLNs produced a greater effect on IOP in terms of both intensity and duration. In terms of tissue concentrations, significantly higher concentrations of Δ9-tetrahydrocannabinol-valine-hemisuccinate were observed in iris-ciliary bodies and retina-choroid with SLNs.ConclusionΔ9-Tetrahydrocannabinol-valine-hemisuccinate formulated in a lipid-based nanoparticulate carrier shows promise in glaucoma pharmacotherapy.Translational RelevanceGlaucoma therapies usually focus on decreased aqueous humor production and increased outflow. However, such therapy is not curative, and there lies a need in preclinical research to focus efforts on agents that not only affect the aqueous humor dynamics but also provide neuroprotection. Historically, there have been bench-scale studies looking at retinal ganglion cell death post-axonal injury. However, for a smooth translation of this in vitro activity to the clinic, animal models examining IOP reduction, i.e., connecting the neuroprotective activity to a measurable outcome in glaucoma management (IOP), need to be investigated. This study investigated the IOP reduction efficacy of cannabinoids for glaucoma pharmacotherapy in a normotensive rabbit model, bringing forth a new class of agents with the potential of IOP reduction and improved permeation to the back of the eye, possibly providing neuroprotective benefits in glaucoma management.

Preparation and characterization of polymeric and lipid nanoparticles of pilocarpine HCl for ocular application

Pilocarpine is used topically in the treatment of glaucoma. Various studies were performed to improve the bioavailability and prolong the residence time of drugs in ocular drug delivery. Drug loaded polymeric and lipid nanoparticles offer several favourable biological properties, such as biodegradability, nontoxicity, biocompatibility and mucoadhesiveness. Therefore, preparing positively-charged pilocarpine HCl-loaded polymeric and lipid nanoparticles was the purpose of this study. Nanoparticles were prepared by quasi-emulsion solvent evaporation technique. The non-biodegradable positively-charged polymer Eudragit® RS 100 and semi-solid lipid excipient Gelucire® 44/14 were used as a vehicle, the cationic lipid octadecylamine was used as a cationic agent. The formulations were evaluated in terms of particle size, size distribution, zeta potential measurement, thermal behavior (Differential Scanning Calorimetry DSC), entrapment efficacy and pH. Characterizations of nanoparticles were analyzed during the storage period of 6 months for stability tests. Polymeric and lipid nanoparticles could be prepared successfully promising their use for ophthalmic delivery.

Pilocarpine β-cyclodextrin Complexation and Niosomal Entrapment

Pilocarpine HCl and β-cyclodextrin kneading complex was entrapped in niosomes followed by dispersion in hydroxypropylmethylcellulose gel. In-vitro release studies showed that the product exhibited slow release compared with release of plain drug. In-vivo studies also showed miotic action for a longer duration indicating the slow and sustained release of the niosome-entrapped complex.

The lack of effects of zinc and nitric oxide in initial state of pilocarpine-induced seizures

In this study we investigated whether intracerebroventricular (i.c.v.) injection of L-NAME (a nitric oxide synthase inhibitor) or CaEDTA (an extracellular zinc chelator) or the combination of the two could affect the initial phase of pilocarpine induced (2 h) seizures. Two groups of rats were used. Animals from both groups were given with i.c.v. injections of either saline (10 microl), L-NAME (150 microg/10 microl), CaEDTA (100 mM/10 microl) or L-NAME and CaEDTA. One group received pilocarpine HCl (380 mg/kg i.p.) the other served as control. Pilocarpine HCl was injected intraperitoneally 10 min later. The behavior of the animals was observed for 2h and the intensity of their seizures was scored. The rats were then sacrificed and their brains were removed and analyzed for zinc ions by using the immersion autometallography and the TSQ fluorescence staining. All the animals which received pilocarpine HCl developed seizures. Despite treatment with L-NAME and/or CaEDTA we found that the latency and the intensity of seizures were similar in both groups investigated. The distribution of stainable zinc ions and the intensity of staining in hippocampus were not affected by pilocarpine and found unchanged after L-NAME and/or CaEDTA injections in both the control animals and the pilocarpine treated animals. The data suggest that the nitric oxide system and zinc ions do not affect pilocarpine-induced seizures in their initial state.

Preparation and evaluation of drug-loaded gelatin nanoparticles for topical ophthalmic use

Gelatin nanoparticles encapsulating pilocarpine HCl or hydrocortisone as model drugs were produced using a desolvation method. The influence of a number of preparation parameters on the particle properties was investigated. For the pilocarpine HCl-loaded spheres, an influence of the pH during particle preparation on the size was observed. Slightly negative zeta potential values were measured for all samples. In the case of pilocarpine HCl-loaded spheres, no influence of the gelatin type or the pH level was observed, which could be attributed to the shielding effect of ions present in the dispersion medium. When hydrocortisone was entrapped, a difference in zeta potential value between gelatin type A and gelatin type B particles was measured. A high pilocarpine HCl entrapment was established. Hydrocortisone was complexed with cyclodextrins in order to increase its aqueous solubility. The drug encapsulation was lower than in the case of pilocarpine HCl, but still amounted to approximately 30–40%. Compared to the aqueous drug solutions, a sustained release for both drugs was observed. The release kinetics of pilocarpine HCl are close to zero order, and no significant differences were measured between the various preparations. In the case of hydrocortisone, the release data suggests a difference in release rate depending on the type of cyclodextrin employed.

Pilocarpine permeability across ocular tissues and cell cultures: influence of formulation parameters.

In vitro permeation studies of drugs across biological barriers are promising tools for estimating the quality and quantity of drug transport in vivo. The objective of this work was to compare the permeability of the hydrophilic model drug pilocarpine-HCl (P-HCl) through different ocular tissues and cell cultures: isolated pig cornea (PCr) and sclera (PSc), rabbit conjunctiva (RCo), and rabbit conjunctival (RCoEC) or corneal epithelial cell culture (RCrEC). Furthermore, the study included investigations about the influence of the excipients benzalkonium chloride (BAC) and ethylene diamine tetra acetic acid disodium salt (EDTA) on the permeability of the small drug. In general, BAC caused a facilitated drug transport, while EDTA hardly influenced the P-HCl concentration on the acceptor side, except for RCoEC. Additionally, the impact of variation in buffer solution pH and tonicity on drug transport in both cell cultures was tested. The higher the tonicity of the buffer solution (80, 300, and 600 mOsm/kg) the lower the permeability coefficient (P(eff)). At different pH values (6.4, 7.4, and 8.4) the P(eff) showed a directly proportional demeanor. In summary, a good correlation between the isolated tissues and cell cultures with regard to P-HCl transport could be observed.

In vivo evaluation of submicron emulsions with pilocarpine: the effect of pH and chemical form of the drug

Submicron emulsions containing 2.0% w/v pilocarpine as pilocarpine HCl, soybean oil (10% w/v) and egg lecithin (1.2% w/v) were formulated. Emulsions at pH 5.0, 6.5 and 8.5 were applied to the rabbit's eye, and the reduction in pupil diameter was measured for 6 h. The miotic effect was compared with that obtained with aqueous solutions at the same pH. A prolonged miotic effect was observed when the submicron emulsion was used as a vehicle. After application of emulsions at pH 5.0, 6.5 or 8.5, the time when 20% reduction of pupil diameter was still observed was 3.9 +/- 1.1 h, 4.3 +/- 1.3 h and 5.3 +/- 0.8 h, respectively, while, after application of a solution, this parameter was shorter by 30-40%. AUC(0-6h) values were larger after application of the submicron emulsions in comparison to aqueous solutions; however, statistically significant differences were only observed for emulsions at pH 6.5. Although the bioavailability of the drug is pH dependent, emulsions at higher pH cannot be considered for clinical use because of pilocarpine degradation which occurs with a similar rate as in aqueous solutions. Introduction of pilocarpine into the oily phase in the form of pilocarpine base or its oleate did not improve either the physicochemical or the pharmacological properties of the formulations. Irrespective of the pH and chemical form of pilocarpine used for emulsion preparation, practically all drug was found in the aqueous phase of the emulsion; thus, partitioning to the oily phase was negligible.