Formulation and in vivo evaluation of ocular insert containing phenylephrine and tropicamide

Diclofenac sodium ion exchange resin complex loaded melt cast films for sustained release ocular delivery

Purpose: The goal of the present study is to develop polymeric matrix films loaded with a combination of free diclofenac sodium (DFS_free) and DFS:Ion exchange resin complexes (DFS:IR) for immediate and sustained release profiles, respectively.

Methods: Effect of ratio of DFS and IR on the DFS:IR complexation efficiency was studied using batch processing. DFS:IR complex, DFS_free, or a combination of DFS_free+DFS:IR loaded matrix films were prepared by melt-cast technology. DFS content was 20% w/w in these matrix films. In vitro transcorneal permeability from the film formulations were compared against DFS solution, using a side-by-side diffusion apparatus, over a 6 h period. Ocular disposition of DFS from the solution, films and corresponding suspensions were evaluated in conscious New Zealand albino rabbits, 4 h and 8 h post-topical administration. All in vivo studies were carried out as per the University of Mississippi IACUC approved protocol.

Results: Complexation efficiency of DFS:IR was found to be 99% with a 1:1 ratio of DFS:IR. DFS release from DFS:IR suspension and the film were best-fit to a Higuchi model. In vitro transcorneal flux with the DFS_free+DFS:IR_(1:1)(1 + 1) was twice that of only DFS:IR_(1:1) film. In vivo, DFS solution and DFS:IR_(1:1) suspension formulations were not able to maintain therapeutic DFS levels in the aqueous humor (AH). Both DFS_free and DFS_free+DFS:IR_(1:1)(3 + 1) loaded matrix films were able to achieve and maintain high DFS concentrations in the AH, but elimination of DFS from the ocular tissues was much faster with the DFS_free formulation.

Conclusion: DFS_free+DFS:IR combination loaded matrix films were able to deliver and maintain therapeutic DFS concentrations in the anterior ocular chamber for up to 8 h. Thus, free drug/IR complex loaded matrix films could be a potential topical ocular delivery platform for achieving immediate and sustained release characteristics.

Mydriatics release from solid and semi-solid ophthalmic formulations using different in vitro methods

The aim of the present paper was the development of semi-solid (hydrogels) and solid (film) ophthalmic formulations for the controlled release of two mydriatics: phenylephrine and tropicamide. The formulations - based on polyvinylalcohol and hyaluronic acid - were characterized, and release studies were performed with three different in vitro set-ups, i.e. Franz-type diffusion cell, vial method and inclined plane; for comparison, a solution and a commercial insert, both clinically used to induce mydriasis, were evaluated. Both gels and film allowed for a controlled release of drugs, appearing a useful alternative for mydriatics administration. However, the release kinetic was significantly influenced by the method used, highlighting the need for optimization and standardization of in vitro models for the evaluation of drug release from ophthalmic dosage forms.

Flexible Coils with a Drug-Releasing Hydrophilic Coating: A New Platform for Controlled Delivery of Drugs to the Eye?

Delivery of drugs to the front-side of the eye is routinely done through eye drops. It is known that approximately 80% of each eye-drop is lost, as a result of rapid clearance of the tear fluid via the naso-lacrymal canal. Consequently, repeated administration through several droplets is usually necessary to achieve a desired effect, such as widening of the pupil prior to corneal surgery. A new ocular drug delivery device was studied. The new device is believed to provide a basis for a more convenient and efficient method for ocular drug delivery. The device is a metallic coil with a hydrophilic, drug-containing polymeric coating. The coil is placed in the conjuctival fornix (under the lower eye-lid) and the drug is slowly released by diffusion into the tear fluid. The capacity of the device could be increased by using the lumen of the coils as a depot for the drug to be released. Preliminary experiments with the new device were performed largely in vitro and in vivo. The latter experiments involved the release of a fluorescent dye and atropine (a potent mydriatic agent) in the eye of several healthy volunteers. The first results obtained with the new device indicate its potential utility. More research and development work is required to define the optimal design of the coil in order to minimize the risk of irritation. Furthermore, the parameters that define the kinetics of the intraocular drug release must be defined and optimized with respect to the exact application.

On the importance of Bloom number of gelatin to the development of biodegradable in situ gelling copolymers for intracameral drug delivery

To overcome the drawbacks associated with conventional antiglaucoma eye drops, this work demonstrated the feasibility of an effective alternative strategy to administer pilocarpine directly via intracameral injections of drug-containing biodegradable in situ gelling GN copolymers composed of gelatin and poly(N-isopropylacrylamide). Specifically, this study aims to understand the importance of Bloom number of gelatin, a physicochemical parameter, to the development of GN carriers for intracameral drug delivery in glaucoma therapy. Our results showed that both imino acid and triple-helix contents increased with increasing Bloom index from 75-100 to 300. The drug encapsulation efficiency in response to temperature-triggered phase transition in GN copolymers was affected by the Bloom index of gelatin. In addition, the differences in protein secondary structure significantly influenced the degradation rates of GN carriers, which were highly correlated with drug release profiles. The increase in released pilocarpine concentration led to a high intracellular calcium level in rabbit ciliary smooth muscle cell cultures, indicating a beneficial pharmacological response to a drug. Irrespective of Bloom number of gelatin, all carrier materials exhibited excellent in vitro and in vivo biocompatibility with corneal endothelium. In a glaucomatous rabbit model, intracameral injections of pilocarpine-containing GN synthesized from gelatins with various Bloom numbers had different abilities to improve ocular hypertension and induce pupillary constriction, indicating distinct antiglaucoma efficacies due to in vivo drug release. It is concluded that the effects on pharmacological treatment using GN carriers for intracameral pilocarpine administration demonstrate a strong dependence on the Bloom number of gelatin.

Novel in situ gelling ocular films for the opioid growth factor-receptor antagonist-naltrexone hydrochloride: fabrication, mechanical properties, mucoadhesion, tolerability and stability studies

Naltrexone hydrochloride (NTX) is an innovative drug used in ophthalmology for treatment of ocular surface diseases such as impaired corneal wound healing and severe dry eye. Poor chemical stability has been a major limitation for development of NTX in solution form. The aim of this study was to develop and characterise NTX in situ ocular films for enhanced chemical stability and improved ocular tolerability. The films were prepared from different amorphous polymers and characterised for physicochemical compatibility, moisture-sorption, surface pH, mechanical properties, sterilisability, surface morphology, mucoadhesion, in vitro release, conjunctival irritation and accelerated stability at 40°C/75% relative humidity for 3 months. Glycerin (GLY)-plasticised films exhibited significantly better mechanical properties, compared with polyethylene glycol (PEG) 400 and triethylcitrate (TEC)-plasticised formulations. Superior mucoadhesion was recorded for F7 and F9 plasticised with GLY and PEG 400, respectively. The stability of NTX was significantly enhanced more than 18-times, compared with the solution form. Combination of carboxymethylcellulose sodium (CMC) and sodium alginate (ALG) in a film formulation demonstrated minimal % moisture sorption, good mechanical properties, in vitro release, excellent chemical stability and minimal conjunctival irritation lending them as promising ocular formulations.

Evaluation of the Efficacy and Safety of the Ophthalmic Insert Mydriasert in Patients Undergoing Retinal Angiography

Purpose

To verify the efficacy to obtain mydriasis and cardiovascular safety of Mydriasert (ophthalmic insert containing tropicamide and phenylephrine) in diabetic and nondiabetic patients undergoing retinal angiography by comparing it with usually administered eyedrops (tropicamide 1% and phenylephrine 10%).

Methods

This was a prospective randomized study. A total of 154 eyes of 77 patients were randomly divided into 2 groups: group 1 consisted of 78 eyes, group 2 consisted of 76 eyes, and the patients were monitored for pupillary dilation, blood pressure, heart rate, and possible adverse effects at 0, 20, 40, 60, and 90 minutes.

Results

No severe adverse effects were observed in either group. In the entire sample studied, the mean pupillary diameter was greater in the eyedrops group after 20 and 40 minutes, while mydriasis was similar in the 2 groups after 60 minutes. The diabetic patients treated with Mydriasert had less mydriasis than those treated with eyedrops after 20 and 40 minutes, and diabetic patients showed less mydriasis than the nondiabetic patients after 60 and 90 minutes. There was no significant between-group difference in mean heart rate or systolic and diastolic blood pressure at any of the time points.

Conclusions

Mydriasert assures an adequate degree of mydriasis for retinal angiography in both diabetic and nondiabetic patients. There are no differences in efficacy or safety between the insert and the usually administered eyedrops, but the low total drug dose administered with the insert reduces the risk of cardiovascular side effects.

Towards the use of hydrogels in the treatment of limbal stem cell deficiency

Corneal blindness caused by limbal stem cell deficiency (LSCD) is a prevailing disorder worldwide. Clinical outcomes for LSCD therapy using amniotic membrane (AM) are unpredictable. Hydrogels can eliminate limitations of standard therapy for LSCD, because they present all the advantages of AM (i.e. biocompatibility, inertness and a biodegradable structure) but unlike AM, they are structurally uniform and can be easily manipulated to alter mechanical and physical properties. Hydrogels can be delivered with minimum trauma to the ocular surface and do not require extensive serological screening before clinical application. The hydrogel structure is also amenable to modifications which direct stem cell fate. In this focussed review we highlight hydrogels as biomaterial substrates which may replace and/or complement AM in the treatment of LSCD.

Preparation of Fluconazole β-Cyclodextrin Complex Ocuserts: In Vitro and In Vivo Evaluation

The main purpose of the present study was to develop ocuserts of Fluconazole β-CD (beta-cyclodextrin) complex and to evaluate both in vitro and in vivo. Fluconazole was made complex with β-CD, and the release rate was controlled by HPMC K(4)M and ethyl cellulose polymers using dibutyl Phthalate as permeability enhancer. Drug-polymer interactions were studied by Fourier transform infrared spectroscopic studies. The formulated ocuserts were tested for physicochemical parameters of in vitro release and in vivo permeation in rabbits. The optimized formulations (F-5 and F-8) were subjected to stability studies. The formulated ocuserts were found to have good physical characters, thickness, diameter, uniformity in weight, folding endurance, less moisture absorption, and controlled release of drug both in vitro and in vivo. The optimized formulations retained their characteristics even after stability studies. The study clearly showed that this technique was an effective way of formulating ocuserts for retaining the drug concentration at the intended site of action for a sufficient period of time and to elicit the desired pharmacological response.

Development of an ex vivo method for evaluation of precorneal residence of topical ophthalmic formulations

This paper describes the development of an ex vivo perfusion method for the evaluation of topical ophthalmic formulations. The perfusion system developed consisted of a perfusion chamber, two precision pumps to control the in/out flow rates to simulate the tear flow rate, and a fluorescence microscope imager. Freshly excised rat cornea was used as a biomembrane. Fluorescein (FITC) was used as a marker. Residence time was determined by measuring fluorescence intensity over time after application of the formulation to the cornea. In addition, viscoelastic properties of the formulations were measured and correlated to the retention times. The perfusion method easily differentiated formulations based on the retention time on the cornea: For example, a 0.3% hydroxypropyl methylcellulose formulation had a short retention time of <10 min. Addition of 0.25% carboxymethylcellulose increased the retention time from less than 10 min to over 16 min, and addition of 0.1% Carbopol further increased retention time to over 40 min. For alginate formulations, the retention time was significantly longer in the presence of 0.06% calcium chloride than that of 0.006% calcium chloride. The longer residence time at a higher Ca++ concentration can be attributed to the greater elastic modulus associated with the gel. Interestingly, however, a hyaluronate formulation displayed a very long retention time but has low viscoelastic moduli. This suggests that the mucoadhesive properties may not always be discernable by the rheological properties. The ex vivo perfusion method may in fact provide more meaningful information with regard to retention times of formulations.

Use of a mydriatic cocktail with a wick for preoperative mydriasis in cataract surgery: a prospective randomised controlled trial

PURPOSE

To investigate the efficacy of a standardised wick soaked in a mydriatic cocktail regimen and compare it with the pre-existing regimen of topical dilating drops.

DESIGN

Prospective, two armed, randomised, double blind, parallel assignment efficacy study.

PARTICIPANTS

In all, 150 eyes of 150 patients were dilated using the dilating cocktail regimen by using a Weck cell sponge. The control group comprised of 75 eyes of 75 patients dilated using the conventional mydriatic regimen.

INTERVENTIONS

A specially prepared mydriatic cocktail regimen consisting of 1 : 1 : 1 : 1 ratio of 2.5% phenylephrine, 0.5% moxifloxacin, 1% cyclopentolate, and 0.03% flurbiprofen eye drops was prepared. A standard sized wick (1 cm x 2 mm) made of Weck cell sponge was soaked in the cocktail for a minute and placed in the lower fornix with sterile forceps. In the control group, eyes were dilated with the above drops using topical instillation in every 15 min. The mydriasis was measured at 15, 30, and 45 min after instillation using the Procyon pupillometer under scotopic conditions (0.04 lux). The intraoperative maintenance of mydriasis was measured with calipers after nucleus delivery and after intraocular lens implantation.

MAIN OUTCOME MEASURES

Pupillary diameters at the end of 15, 30, and 45 min, and intraoperative maintenance of mydriasis in the two groups were compared using unpaired t-test.

RESULTS

There was a statistically significant difference (P<0.001) in dilation achieved at the end of 45 min in both groups. There was also a significant difference of 1-mm dilation between the two groups after nucleus delivery (P< 0.001), and a difference of 1.41 mm after intraocular lens implantation, which was statistically significant (P<0.001).

CONCLUSIONS

These results show that the mydriatic cocktail regimen delivered with a wick is a useful, economical, and timesaving regimen compared with the conventional method of preoperative mydriasis using topical drops.

[Efficacy and efficiency of preoperative mydriasis: drops versus ocular insert]

OBJECTIVE

The primary objective of this study was to compare eye drops and inserts in terms of the quality of preoperative mydriasis. The secondary objective was to evaluate the safety and ease of use of each modality.

PATIENTS AND METHODS

Prospective randomized and simple blinded study. Patients were randomized into two groups: the insert protocol (atropine 1%, diclofenac 0.1% collyrium and Mydriasert) or the eye drop protocol (atropine 1%, diclofenac 0.1%, tropicamide 0.5%, and phenylephrine 10% collyrium). Fifty-one patients were included: 25 in the insert protocol and 26 in the drop protocol. Mydriasis quality was evaluated by nurses and surgeons. The ease of use was estimated by the number of gestures required to obtain mydriasis and the difficulties encountered. Safety was evaluated at the patient's bedside.

RESULTS

Mydriasis of at least 6 mm was obtained in 92% of the patients in the insert protocol (23/25) and 85% of the patients in the drop protocol (22/26) (NS). Four patients lost their insert during the study. Of the patients in the insert group, 16% (4/25) experienced stinging in their eyes, as did 23% (6/26) of patients in the group using drops (NS). To reach effective mydriasis, the insert protocol required fewer nurse gestures per patient than the drop protocol (3.0 versus 8.3; p<0.001).

CONCLUSION

With the protocol using an insert, preoperative mydriasis is not inferior to that obtained with drops only and is more efficient in terms of nurse time and number of gestures. Nurses should be trained in appropriate handling of the insert and avoiding the loss of the device.

Pharmacodynamics of a new ophthalmic mydriatic insert in healthy volunteers: potential alternative as drug delivery system prior to cataract surgery

Cataract surgery requires a satisfactory degree of mydriasis throughout the entire operation. A phase I, open-labelled, randomised, cross-over trial was conducted in 18 healthy volunteers to compare mydriasis obtained with subsequent administration of phenylephrine 10% and tropicamide 0.5% eyedrops or a new insoluble-matrix retropalpebral ophthalmic insert containing 5.38 mg phenylephrine and 0.28 mg tropicamide. Phenylephrine serum concentrations were measured over 6 hr following each treatment administration. Secondary end-points included cardiovascular, general and local tolerance and quantification of bacterial colonisation of the conjunctiva and the cultured insert, respectively. When normalized to the pupil diameter after conventional treatment, the diameter achieved with the insert was 1.13 (95% confidence interval, 0.94-1.48, P=0.38). Moreover, standard eye drops provided faster effective mydriasis than the insert, starting 30 min. as compared to 90 min. upon treatment administration (P<0.01, repeated-measures ANOVA). Phenylephrine concentrations remained almost undetectable for both treatments and no change in heart rate or blood pressure were observed throughout the study. Only three superficial punctuate keratitis were diagnosed with the insert and two with the eye drops. No significant bacterial contamination of conjunctiva swab and cultured insert was observed. The new insoluble-matrix retropalpebral ophthalmic mydriatic insert produced similar but delayed effective and prolonged mydriasis as compared to the standard delivery system. In addition to its potential usefulness in patients undergoing cataract surgery, such new ophthalmic delivery system may be an advantage in children who need to undergo fundus photography due to the single administration and excellent tolerance as well.

Étude de la dilatation pupillaire par l’insert ophtalmique Mydriasert®

PURPOSE

To evaluate the tolerance and efficiency of the Mydriasert(R) ophthalmic insert on pupil dilation.

METHOD

Two pharmaceutical forms of a combination of tropicamide and phenylephrine (HCl) were compared on both eyes of 80 patients. For each patient, one Mydriasert insert (Ioltech) was placed in the lower conjunctival sac of the eye. Dilation of the control eye was obtained using 0.5% tropicamide eye drops and 10% phenylephrine eye drops (Novartis Ophthalmics), which were instilled with three frequency regimens (5, 10 or 15 min). The pupil diameter was regularly measured until the maximal mydriasis had occurred.

RESULTS

Both subjective and objective tolerance of the insert was excellent. The size of the maximal mydriasis obtained when using the insert was significantly greater than that obtained when using the eye drops, regardless of the frequency of the instillation (p < 0.04). The difference in maximal pupil diameter ranged from +0.16 mm to +0.38 mm. Mydriasis kinetics was slower with the insert. The time necessary to obtain a maximal mydriasis was 47.3 min when the insert was used, whereas it was in the range of 31.4 to 38.5 minutes with the eye drops (p < 0.001). As far as pupil diameter is concerned, the superiority of the insert compared to the eye drops became observable only about 45 min after the insert had been placed in the eye. The relative efficacy of the insert compared to the eye drops did not correlate with patient features (p > or = 0.06).

CONCLUSION

Despite the small quantity of drug delivered by the insert, Mydriasert allows a much greater mydriasis compared to that usually obtained when the eye drops were used. However, a longer time lapse is necessary for this to occur.

Mucoadhesive ocular insert based on thiolated poly(acrylic acid): development and in vivo evaluation in humans

The aim of the study was to develop a mucoadhesive ocular insert for the controlled delivery of ophthalmic drugs and to evaluate its efficacy in vivo. The inserts tested were based either on unmodified or thiolated poly(acrylic acid). Water uptake and swelling behavior of the inserts as well as the drug release rates of the model drugs fluorescein and two diclofenac salts with different solubility properties were evaluated in vitro. Fluorescein was used as fluorescent tracer to study the drug release from the insert in humans. The mean fluorescein concentration in the cornea/tearfilm compartment as a function of time was determined after application of aqueous eye drops and inserts composed of unmodified and of thiolated poly(acrylic acid). The acceptability of the inserts by the volunteers was also evaluated. Inserts based on thiolated poly(acrylic acid) were not soluble and had good cohesive properties. A controlled release was achieved for the incorporated model drugs. The in vivo study showed that inserts based on thiolated poly(acrylic acid) provide a fluorescein concentration on the eye surface for more than 8 h, whereas the fluorescein concentration rapidly decreased after application of aqueous eye drops or inserts based on unmodified poly(acrylic acid). Moreover, these inserts were well accepted by the volunteers. The present study indicates that ocular inserts based on thiolated poly(acrylic acid) are promising new solid devices for ocular drug delivery.

Ophthalmic delivery of ciprofloxacin hydrochloride from different polymer formulations: in vitro and in vivo studies

Reservoir-type ocular inserts were fabricated using sodium alginate containing ciprofloxacin hydrochloride as the core (drug reservoir) that was sandwiched between the Eudragit and/or polyvinylacetate films. Ocular inserts were packaged in aluminium foil and sterilized by gamma radiation. These were tested for sterility as per British Pharmacopoeia (BP). Ocular inserts were evaluated for in vitro release rate studies, microbial efficacy, in vivo release studies, efficacy against induced bacterial conjunctivitis in rabbit's eyes, concentration in the aqueous humor, and stability studies as per the International Conference on Harmonization (ICH) guidelines. Ocular inserts passed the test for sterility. They showed zero-order release of the drug in the in vitro and in vivo release studies over a period of 120 hr. The drug was found to be active against selected microorganisms as was proved by microbial efficacy studies. A high correlation coefficient was found between in vitro and in vivo release rate studies. Better improvement was observed in artificially induced bacterial conjunctivitis in rabbit's eyes, compared with marketed eye drops and placebo. Drug concentration in the aqueous humor was found above Minimum Inhibitory Concentration (MIC-90) against selected microorganisms. Shelf-life of the product was found to be more than 2 years.

Ocular gelfoam disc-applicator for pupillary dilation in humans

This study investigates a gelfoam disc device as an alternative topical ophthalmic drug delivery system for pupillary dilation in humans. Gelfoam (Pharmacia & Upjohn) discs were impregnated with 0.60 mg of tropicamide racemate and 1.7 mg of 1-phenylephrine hydrochloride by an ethanol solvent evaporation method. Twenty randomly selected human subjects received baseline examinations, including blood pressure, pulse rate and biomicroscopy of the ocular surface. One impregnated gelfoam disc was placed in the inferior fornix of a randomly selected eye. Simultaneously, the fellow eye was treated with two topically administered drops, one from a phenylephrine hydrochloride 2.5% solution and one from a tropicamide 1% solution. A single, masked observer measured the pupillary diameter in both eyes at various time intervals under constant ambient conditions. Administration of the topical drops was repeated in the fellow eye. At maximum pupillary dilation, the disc was removed, and a post-dilation biomicroscopic exam was performed. Blood pressure and pulse rate were rechecked. The gelfoam-treated eyes' median change in dilation diameter was approximately 25% greater (a two-fold increase in pupillary area) (p< 0.001) at 15.2 min (median time to maximum dilation) than the topically treated fellow eyes. The median change in systolic blood pressure (+1.0 mmHg) and diastolic blood pressure (-1.0 mmHg) was not statistically significant (p>0.1). The average pulse rate was decreased 7 beats per minute (p=0.004). A gelfoam disc may serve as an ophthalmic drug delivery system for pupillary dilation or as a model for other multiple-dose topical drugs.