A comparison of active ingredients and preservatives between brand name and generic topical glaucoma medications using liquid chromatography-tandem mass spectrometry

Quality of dorzolamide hydrochloride and timolol maleate containing eye drops distributed online

Patient safety risks associated with the online purchase of medications, especially in case of ophthalmic preparations, are significant. Our study aimed to carry out quality assessment of dorzolamide hydrochloride (DZA) and timolol maleate (TIM) eye drops preserved with benzalkonium chloride (BAC) via online test purchases. Three samples were purchased online, while control preparations were acquired through authorized national drug supply chain. Our method was based on the International Pharmaceutical Federation (FIP) Inspection Checklist and integrated the evaluation of packaging and labelling. Sterility was established according to the European Pharmacopoeia (Ph. Eur.), while qualitative and quantitative quality was assessed with high-performance liquid chromatographic (HPLC) analysis. Several signs of falsification were recognized upon visual inspection of the online samples. All the products were clear, colourless, slightly viscous solutions. They were free from visible contaminants. The samples were sterile as no evidence of microbial growth was found. A quick and inexpensive HPLC analysis, optimized by the authors showed that active ingredients and the preservative deviated significantly (p < 0,05) with more than 10% from the values stated on the labels for at least one component (DZA: 99.3-113.1%, TIM: 112.8-139.2%, BAC: 82.4-97.7%). Development of comprehensive and reliable quality assessment methods are vital to increase public safety of pharmaceutical products sold online. A complex approach, integrating visual inspection, labelling assessment, microbiological analysis coupled with qualitative and quantitative methods provide a most reliable method. Due to its limited feasibility and cost-effectiveness, raising public awareness and limiting illegal online sellers should be the primary approaches to protect patients from substandard and falsified medicinal products sold via the internet. Particularly important for health professionals to understand this market and its public health concern, and to raise patient awareness of the risks associated with uncontrolled online purchase of medication.

Comparative effects of latanoprost and latanoprostene bunod on intraocular pressure and pupil size in ophthalmologically normal Beagle dogs

OBJECTIVE

To compare effects of latanoprost, a topical prostaglandin analogue (PGA) commonly used to treat glaucoma and lens instability in dogs, and latanoprostene bunod, a novel PGA with a nitric oxide-donating moiety, on intraocular pressure (IOP) and pupil diameter (PD).

ANIMALS STUDIED

Ten ophthalmologically normal Beagle dogs.

PROCEDURES

Dogs were treated twice a day for 5 days in a randomly selected eye with either latanoprost or latanoprostene bunod. After a 6-week washout period, dogs were treated with the opposite drug. IOP and PD were measured at treatment times, at midday on days 1 and 5, and for 6 days post-treatment.

RESULTS

Both drugs significantly decreased IOP and PD. At midday on day 5 of treatment, mean IOP in eyes treated with latanoprost was 4.5 mmHg lower than the fellow eye and 3.0 mmHg lower than the same eye at baseline, while mean IOP in eyes treated with latanoprostene bunod was 5.5 mmHg lower than the fellow eye and 3.6 mmHg lower than baseline. Mean PD was 0.94 mm in eyes treated with latanoprost and 0.76 mmHg in eyes treated with latanoprostene bunod. There was no significant difference between the two drugs for either parameter at that time point (p = .372 and .619, respectively, for IOP relative to control and to baseline; p = .076 for PD) or when analyzed longitudinally. Significant diurnal variation in PD was noted and may have implications for treatment of lens' instability.

CONCLUSIONS

Latanoprost and latanoprostene bunod produce similar IOP reduction and miosis in normal canine eyes.

Reasons for the Underutilization of Generic Drugs by US Ophthalmologists: A Survey

Introduction

Cross-sectional survey of 92 board-certified practicing Midwestern ophthalmologists to determine why prescribing habits favor brand-name drugs over generics and to identify approaches for increasing generic drug utilization.

Methods

A survey was sent to members of state ophthalmology societies, private practice groups, and individual ophthalmologists to evaluate basic demographic/practice information, knowledge and opinions on generic drugs, frequency of drug representative visits, understanding of the Food and Drug Administration’s process of evaluating generics, knowledge of patients’ financial status and preferences, and action items that would increase generic utilization.

Results

Three factors increase the likelihood of ophthalmologists switching patients to generic drugs: increased knowledge of (1) generic options, (2) price differences between brand-names and generics, and ((3) patient preference for generics. The following four factors decrease the likelihood of ophthalmologists switching patients to generic drugs: (1) increased disease severity, (2) feeling that patient outcomes may be affected by choice of brand-name versus generic, (3) personal preference for taking a brand-name drug over a generic for their own hypothetical eye disease even if both were free, and (4) increased personal preference for taking a brand-name drug for their hypothetical eye disease.

Conclusion

Ophthalmologists should continue to update themselves on generic medication options, become familiar with the price difference of generics versus brand-name drugs for commonly prescribed medications, and seek patients’ opinions on generics and correct them when possible to increase generic utilization. In addition, studies evaluating the clinical equivalence of generic drugs relative to brand-name drugs should be performed and may help increase generic utilization.

Evaluation of Generic versus Original Prostaglandin Analogues in the Treatment of Glaucoma: A Systematic Review and Meta-Analysis

TOPIC

An evaluation of the efficacy and tolerability of generic prostaglandin analogues (PGAs) compared with their original counterpart.

CLINICAL RELEVANCE

This systematic review was initiated to enlighten ophthalmologists and patients in the use of original and generic ophthalmic solutions.

METHODS

A literature search was conducted on PubMed, EMBASE, MEDLINE, Clinicaltrials.gov, and the World Health Organization International Clinical Trials Registry Platform, along with a manual search, from the marketing of the first PGA, latanoprost, in 1995 to the present. Randomized controlled trials comparing an original PGA with its generic counterpart were included. The last literature search was conducted in June 2019. Risk of bias was assessed by 2 independent reviewers using the Cochrane Handbook for Systematic Reviews Tool. The primary outcome was reduction of intraocular pressure (IOP) from baseline. Secondary outcomes included tolerability, ocular surface health, quality of life, disease progression, and cost-effectiveness. Meta-analysis of the primary outcome was planned.

RESULTS

Of 385 screened articles, 6 were included in a broad characterization and in the meta-analysis. A total of 619 patients were enrolled. The duration of the studies ranged from 3 to 16 weeks. Meta-analysis of all 6 studies denied any clinically significant difference in efficacy, and the 95% confidence interval included nil (-0.50 to 0.04 mmHg). The evidence was of moderate certainty because of unclear or high risk of bias in all studies. There were no reported differences in tolerability.

CONCLUSIONS

Trials comparing original and generic PGAs did not show a clinically significant difference in IOP-lowering effect or tolerability. However, the quality of the trials is suboptimal. Overall, there is uncertainty, and further research is needed to confirm equivalence.

The Use of Generic Medications for Glaucoma

The use of generic medicines has grown considerably in recent years providing considerable cost savings. In England, generic items represented 11.7% of prescriptions for glaucoma and ocular hypertension in 2009, increasing to 55.2% of prescriptions in 2018. Generics can be brought to the market quickly and at low cost as manufacturers are not required to repeat animal or clinical research on active ingredients already approved for safety and efficacy. Although there is no regulatory requirement for studies comparing branded and generic eye drops, several randomised crossover studies have been performed comparing branded and generic prostaglandin analogues. While most have shown similar intraocular pressure lowering, studies are of short duration and have not evaluated visual field endpoints. Furthermore, differences in inactive ingredients, pH, viscosity, levels of particulate matter, and degradation over time have been reported. Other potential problems with generic eye drops include differences in bottle design affecting adherence, problems with supply, and the possibility that reduced revenue for innovator companies will lead to reduced investment in new drug development. This article reviews the potential advantages and disadvantages of generic antiglaucoma medications.

North American cost analysis of brand name versus generic drugs for the treatment of glaucoma

Background

According to the World Health Organization, glaucoma is a leading cause of irreversible blindness worldwide. By 2020, 80 million people will be affected by glaucoma in the world, which represents a significant financial burden to society. Glaucoma medications alone make up 38-52% of the total direct cost. The purpose of this research is to conduct a cost-minimization analysis to evaluate brand-name medications versus generic medications for treating glaucoma patients.

Methods

The per-bottle cost (in Canadian dollars) of brand-name drugs for glaucoma was obtained from the wholesaler, McKesson Canada, and, for generic drugs, from the Ontario Drug Benefit (ODB) Formulary. Further, a wastage adjustment fee, a pharmacy mark-up, and an ODB dispensing fee ($CAD) was added to the cost of both brand and generic. Previously published frequencies of medication prescription were utilized to calculate the average annual cost for each class of brand and generic. For each medication class and for mono-, bi-, and tri-drug therapy, the cost differential between brands and generics over a six-year period was computed and analyzed from third-party payer perspective.

Results

In descending order, the average annual government-funded health care system costs were: combination drugs such as Cosopt^® ($748.23) were the most expensive, followed by prostaglandin analogs ($246.36), carbonic anhydrase inhibitors (CAIs) ($45.04), α-agonist ($30.34), β-blockers ($29.29), and cholinergic agonists ($16.51). Brand-name mono-drugs are 34% more expensive compared to generics. Brand-generic percentage cost differential for various medication classes over a six-year period was the highest for prostaglandin analogous (44%), followed by β-blockers (35%), α-agonist (31%), cholinergic agonists (22%), combination drugs (10%), and CAIs (1%).

Conclusion

Brand-name drugs are relatively more expensive than their generic counterparts, with variable cost differentials depending on drug class.

Preservative-Free Prostaglandin Analogs and Prostaglandin/Timolol Fixed Combinations in the Treatment of Glaucoma: Efficacy, Safety and Potential Advantages

Glaucoma therapy-related ocular surface disease (OSD) is a serious pathology with a broad spectrum of insidious clinical presentations and complex pathogenesis that undermines long-term glaucoma care. Preservatives, especially benzalkonium chloride (BAK), contained in topical intraocular pressure-lowering medications frequently cause or aggravate OSD in glaucoma. Management of these patients is challenging, and to date often empirical due to the scarcity of controlled long-term clinical trials. Most of the available data are extracted from case series and retrospective analysis. Preservative-free prostaglandins and prostaglandin/timolol fixed combinations are novel options developed to remove the harmful impact of preservatives, especially BAK, upon ocular tissues. Based on what is currently known on the value of preservative-free antiglaucoma therapies it is tempting to speculate how these new therapies may affect the future medical management of all glaucoma patients. This article provides a comprehensive and critical review of the current literature on preservative-free prostaglandins and preservative-free prostaglandin/timolol fixed combinations.

Prospective study comparing Xalatan® eye drops and two similar generics as to the efficacy and safety profile

PURPOSE

To evaluate the efficacy and safety between two generic prostaglandins Lataz-Xalaprost (Greece) and the corresponding original drops (Xalatan^®).

MATERIAL AND METHODS

In this prospective randomized study, 60 patients diagnosed with open-angle glaucoma or ocular hypertension were enrolled, who had never received antiglaucoma treatment. Subjects were divided randomly into three groups (Xalatan, Lataz, and Xalaprost groups) and they were studied over 16 weeks. At each visit, the mean applanation tonometry values and tear break-up time were measured. The Ocular Surface Disease Index questionnaire was used to evaluate patient's symptoms.

RESULTS

There was a statistically significant difference (p < 0.001) in the mean values of the intraocular pressure between the baseline and the last visit (Xalatan group: from 23.11 ± 1.61 mmHg to 15.81 ± 1.22 mmHg, Lataz group: from 23.26 ± 1.33 mmHg to 15.80 ± 1.47 mmHg, and Xalaprost group: from 23.08 ± 1.45 mmHg to 16.08 ± 1.38 mmHg). Both generic eye drops showed mean percentage intraocular pressure reduction comparable to the standards of prostaglandin analogues (Xalatan: 31.57%, Lataz: 32.06%, and Xalaprost: 30.34%). Xalatan reduced the tear break-up time less, followed by Lataz and then by Xalaprost (Xalatan: from 8.5 to 8 s, Lataz: from 8.2 to 7.4 s, and Xalaprost: from 8.7 to 7.7 s). Xalatan presented the best safety profile, followed by Lataz and least was Xalaprost, according to Ocular Surface Disease Index questionnaire's results.

CONCLUSION

No significant difference was recorded in the effectiveness of each generic prostaglandin compared to the original. Furthermore, no patient had to change medication. The differences that arose in the safety profile of the three eye drops suggest a prompt closer initial monitoring of patients who are administered generic eye drops.

Comparative cost evaluation of brand name and generic ophthalmology medications in Ontario

Medication cost for the same indication can vary considerably and can affect patient compliance. In this comparative cost analysis of commonly prescribed ophthalmology medications, the differences in cost between generic and brand name medications as well as different medications within an individual drug class were evaluated. Eye preparations from the Ontario Drug Benefit Formulary were identified, and further agents commonly prescribed by ophthalmologists were included. The standardized prescription drug cost, which includes the cost of the medication, mark-up, and dispensing cost, was provided by Ontario Shoppers Drug Mart stores in July 2016 for 103 common medications using typical dosages and durations. Based on medication class, the highest and lowest cost medications were antiallergy agents (Zaditor [ketotifen], Vasocon [naphazoline]), antibiotic ophthalmic solutions (Vigamox [moxifloxacin], generic ciprofloxacin), oral antibiotics (Cipro [ciprofloxacin], generic cephalexin), antibiotic ophthalmic ointments (generic erythromycin, Tobrex [tobramycin]), antiviral treatment (Valtrex [oral valacyclovir], Viroptic [topical trifluridine]), blepharitis treatment (Zithromax [oral azithromycin], generic oral tetracycline), beta-adrenergic inhibitors (Timoptic [topical timolol], generic topical timolol), topical prostaglandin analogues (Xalatan [latanoprost], generic travoprost), oral carbonic anhydrase inhibitors (methazolamide, acetazolamide), topical carbonic anhydrase solutions (Trusopt preservative-free [dorzolamide], Azopt [brinzolamide]), topical alpha-adrenergic agonists (Alphagan [brimonidine], generic brimonidine), topical muscarinic agonists (Isopto carpine [pilocarpine], Diocarpine [pilocarpine]), topical combination glaucoma agents (Cosopt [dorzolamide-timolol], generic dorzolamide-timolol), topical lubricants (Lacri-lube, Isopto tears), topical nonsteroidal anti-inflammatory drugs (Acuvail [ketorolac], Ilevro [nepafenac]), and steroids (Durezol [difluprednate], Pred mild [prednisolone]). Substantial cost differences exist between ophthalmology medications of the same class. We encourage ophthalmologists to be aware of the associated costs of the medications they prescribe and to use this information in their decision making.

Medical Management of Glaucoma in the 21st Century from a Canadian Perspective

Glaucoma is a medical term describing a group of progressive optic neuropathies characterized by degeneration of retinal ganglion cells and retinal nerve fibre layer and resulting in changes in the optic nerve head. Glaucoma is a leading cause of irreversible vision loss worldwide. With the aging population it is expected that the prevalence of glaucoma will continue to increase. Despite recent advances in imaging and visual field testing techniques that allow establishment of earlier diagnosis and treatment initiation, significant numbers of glaucoma patients are undiagnosed and present late in the course of their disease. This can lead to irreversible vision loss, reduced quality of life, and a higher socioeconomic burden. Selection of therapeutic approaches for glaucoma should be based on careful ocular examination, patient medical history, presence of comorbidities, and awareness of concomitant systemic therapies. Therapy should also be individualized to patients' needs and preferences. Recent developments in this therapeutic field require revisiting treatment algorithms and integration of traditional and novel approaches in order to ensure optimal visual outcomes. This article provides an overview of recent developments and practice trends in the medical management of glaucoma in Canada. A discussion of the surgical management is beyond the scope of this paper.

Keratitis in six dogs after topical treatment with carbonic anhydrase inhibitors for glaucoma

CASE DESCRIPTION

6 dogs (10 eyes) with keratitis following long-term topical treatment with a carbonic anhydrase inhibitor (CAI) were evaluated. In 4 dogs (6 eyes), CAI treatment was discontinued. Three dogs (4 eyes) underwent enucleation because of end-stage corneal disease. One dog was treated differently in each eye and thus was represented in both aforementioned groups.

CLINICAL FINDINGS

Following initiation of treatment with a CAI (ie, brinzolamide or dorzolamide), the median time to development of severe ocular signs was 266 days (range, 133 to 679 days). Clinically severe ocular signs included ulcerative and nonulcerative perilimbal keratitis or severe diffuse keratitis with marked vascularization. The keratitis was refractory to treatment with anti-inflammatory medications. Histologic and immunohistochemical examination of enucleated globes was performed in 3 affected dogs and in 1 dog with keratitis that recovered. Corneal lesions included 2 distinct inflammatory infiltrates with plasma cells predominating in the anterior stroma and both T cells and neutrophils in the epithelium. Stromal plasma cells and overlying epithelium exhibited strong positive immunoreactivity for IgG.

TREATMENT AND OUTCOME

Topical CAI treatment was discontinued in 4 dogs after a median of 209 days (range, 44 to 433 days), and in these dogs, clinical improvement was evident within 2 to 4 days of CAI treatment cessation. Signs of keratitis resolved in 12 to 25 days in these 4 dogs, and median follow-up time after CAI discontinuation was 25.5 months (range, 6 to 42 months), during which time signs of corneal disease did not recur.

CLINICAL RELEVANCE

On the basis of this small series, presumed topical CAI-associated keratitis in dogs appeared to be an uncommon immune-mediated disease that was not responsive to corticosteroid treatment. Affected patients improved rapidly, but only after discontinuation of CAI treatment. In dogs with glaucoma, clinicians should consider the development of punctate keratopathy and severe diffuse keratitis as potential adverse effects related to topical administration of CAIs, even after previously uneventful long-term use.

Evaluation of Physical Properties of Generic and Branded Travoprost Formulations

PURPOSE

Comparative evaluation of pharmaceutical characteristics of three marketed generic vs branded travoprost formulations.

MATERIALS AND METHODS

Three generic travoprost formulations and one branded (Travatan without benzalkonium chloride) formulation (10 vials each), obtained from authorized agents from the respective companies and having the same batch number, were used. These formulations were coded and labels were removed. At a standardized room temperature of 25°C, the drop size, pH, relative viscosity, and total drops per vial were determined for Travatan (Alcon, Fort Worth, TX, USA) and all the generic formulations. Travoprost concentration in all four brands was estimated by using liquid chromatography-coupled tandem mass spectrometry LCMS.

RESULTS

Out of the four formulations, two drugs (TP 1 and TP 4) were found to follow the United States Pharmacopoeia (USP) limits for ophthalmic formulation regarding drug concentration, while the remaining two drugs failed due to the limits being either above 110% (TP 2) or below 90% (TP 3). Two of them (TP 1 and TP 2) had osmolality of 313 and 262 mOsm respectively, which did not comply with the osmolality limits within 300 mOsm (+ 10%). The pH of all the formulations ranged between 4.7 and 5.9, and the mean drop size was 30.23 ± 6.03 uL. The total amount of drug volume in the bottles varied from 2.58 ± 0.15 to 3.38 ± 0.06 mL/bottle.

CONCLUSION

There are wide variations in the physical properties of generic formulations available in India. Although some generic drugs are compliant with the pharmacopeia standards, this study underscores the need for a better quality control in the production of generic travoprost formulations. How to cite this article: Wadhwani M, Mishra SK, Angmo D, Velpandian T, Sihota R, Kotnala A, Bhartiya S, Dada T. Evaluation of Physical Properties of Generic and Branded Travoprost Formulations. J Curr Glaucoma Pract. 2016;10(2):49-55.

Evaluation of physical properties and dose equivalency of generic versus branded latanoprost formulations

The purpose of this study was to comparatively evaluate the pharmaceutical characteristics of various marketed generic formulations of prostaglandin analogue latanoprost in the Indian market. Three generics of latanoprost and one branded (Xalatan) formulation (five vials each) were obtained from authorized agents from the respective commercial sourcing having the same batch number. These formulations were coded, and the labels were removed. At a standardized room temperature of 25 °C, the concentration, osmolarity, drop size, pH, and total drops per vial were determined for Xalatan and all the generics of latanoprost. The concentration of various brands varied between 50.49 ± 0.36 and 58.90 ± 0.52 µg/ml as compared to the standard labeled concentration of 50 µg/ml on the latanoprost vials. The concentration of drugs in individual drop varied from 1.30 ± 0.05 to 1.78 ± 0.04 µg/drop. The volume of drug formulation per bottle varied from 2.4 ± 0.12 to 2.6 ± 0.09 ml/bottle. The number of drops per bottle varied from minimum of 88.60 ± 0.10 drops to maximum of 102.0 ± 4.3 drops across all the formulations, while the drop size varied from 25.72 ± 2.70 to 29.97 ± 1.38 µl. The osmolarity of 2/4 drugs was within 300 mOs M (±10 %). The specific gravity varied between 0.98 ± 0.01 and 1.007 ± 0.01, while pH was between 7.05 ± 0.004 and 7.13 ± 0.005. Two of the generic brands were outside the United States pharmacopoeia limits (±10%) for ophthalmic formulation, with concentration exceeding the limits by 3 % (p = 0.151) and 8 % (p = 0.008), respectively. This pilot study highlights that there are significant variations in the drug concentrations and physical properties of generic latanoprost formulations. Although none of the brands had concentrations below the recommended level, two of the brands had concentrations exceeding the limits by 3 and 8 %, respectively.

New prostaglandin analog formulation for glaucoma treatment containing cyclodextrins for improved stability, solubility and ocular tolerance

Latanoprost is a practically insoluble prostaglandin F2α analog considered a first-line agent for glaucoma treatment. From a pharmaceutical point of view, latanoprost is challenging to be formulated as an eye drop due to its poor water solubility and the presence of an ester bond that needs to be cleaved in vivo but maintained unchanged during storage. Cyclodextrins (CDs) are known to form complexes with hydrophobic drugs, influencing their stability, availability, solubility, and tolerance in a non-predictable manner. A variety of CDs including native α, β, and γCDs as well as substituted hydroxypropylβCD, hydroxypropylγCD, dimethylβCD, sulphatedβCD, and propylaminoβCD were screened and the most appropriate CD for the formulation of latanoprost for an ocular topical application was selected. Among the tested CDs, propylaminoβCD had the best trade-off between latanoprost stability and availability, which was confirmed by its complex constant value of 3129M(-1). Phase-solubility and NMR investigations demonstrated that the propylaminoβCD effectively formed a complex involving the ester group of latanoprost providing protection to its ester bond, while ensuring proper latanoprost solubilization. Furthermore, in vivo experiments demonstrated that the latanoprost-propylaminoβCD formulation led to lower ocular irritation than the commercial latanoprost formulation used as a reference. The latanoprost-propylaminoβCD formulation was demonstrated to successfully address the main stability, solubility, and tolerance limitations of topical ocular latanoprost therapy for glaucoma.

Impact of the introduction of generic latanoprost on glaucoma medication adherence

PURPOSE

To assess possible changes in medication adherence to prostaglandin analog (PGA) regimens among patients with open-angle glaucoma (OAG) after the initial introduction of generic PGAs.

DESIGN

Longitudinal cohort analysis.

PARTICIPANTS

Patients older than 40 years with OAG continuously enrolled in a nationwide managed-care network during 2009-2012 who used PGAs.

METHODS

Mean adherence rates were calculated for topical PGA use during the 18 months before the introduction of generic latanoprost (September 2009-February 2011) and the 18 months after generic latanoprost became available (July 2011-December 2012). The rates were compared between persons who continued to use brand-name PGAs once generic latanoprost became available and others who switched to generic latanoprost. Multivariable logistic regression identified variables associated with an improvement or worsening of adherence of ≥25%.

MAIN OUTCOME MEASURES

Mean adherence rates and odds of 25% or more improved or worsened adherence (with 95% confidence intervals [CIs]).

RESULTS

A total of 8427 patients met the study eligibility criteria. Compared with persons switching to generic latanoprost, patients who continued taking brand name PGAs were 28% less likely to have improved adherence (odds ratio [OR], 0.72; 95% CI, 0.55-0.94) and 39% more likely to have reduced adherence (OR, 1.39; 1.04-1.86) of ≥25%. Improved adherence after the generic drug's introduction was also associated with higher monthly medication copay in the pregeneric period (P = 0.02), lower copay after introduction of the generic drug (P < 0.0001), and black race (OR, 1.25; 95% CI, 1.04-1.50). Six-hundred twelve patients (7.3%) discontinued all antiglaucoma interventions when generic latanoprost became available.

CONCLUSIONS

Given that cost can significantly deter adherence, switching patients to generic medications may help improve patients' drug-regimen adherence. A considerable number of patients discontinued glaucoma drug use altogether when generic latanoprost became available. Ophthalmologists should work with insurers and pharmacists to prevent such discontinuation of use as generic forms of other PGA agents become available.

[Original preparations versus generics--latanoprost: how similar is different?]

BACKGROUND

To test the interchangeability of the commercially available (in Germany) latanoprost drugs and their generics respectively, the concentration of the active substance was tested. Guidelines of the European Medicines Agency postulate a sufficient bioequivalence, if the range of the agent is within 80-125% of the original drug.

METHODS

All compounds of latanoprost were procured registered. The concentration of latanoprost and benzalkoniumchloride was measured by high-performance liquid chromatography (HPLC) in a validated reference labroratory for 23 generics. In addition, the mean volume of drops and the pH of the formulation were measured. The packaging label and the readability of the enclosed information leaflet were checked.

RESULTS

All products contained less than 50 μg/ml latanoprost. The deviating reduction of the active substance (mean: - 7.39%, ± 2.8%) was accompanied by fluctions of the eyedrops' mass (mean: 0.03 g, ± 0.002 g). The concentration of benzalkonium chloride was mostly increased (median: 5.45%, min: - 2.5%, max: 11.5%). The pH of the original drug and the generics (median 6.78, min: 6.62, max: 6.81) was similar to the original drug, but was significantly different from an unpreserved formulation (pH 7.18). Due to type size, the packaging leaflet was illegible for humans with impaired vision.

CONCLUSIONS

Before prescribing generics in ophthalmology, different factors have to be considered, which might influence the amount of IOP lowering in effect. In the absence of healthcare research it is still unclear, how different bottle forms of eyedrops--such as appearance (e.g. Cyrillic characters) or pressure point (administration)--reduce the adherence of glaucoma patients.

Stability of latanoprost in generic formulations using controlled degradation and patient usage simulation studies

PURPOSE

To evaluate the stability of latanoprost in generic formulations by using controlled degradation and patient usage simulation studies

METHODS

Standard latanoprost was subjected to controlled degradation studies. Latanoprost content was assessed by using MRM, and generated Degradation Products (DP) were analysed by using the Information Dependent Acquisition (IDA) protocol of positive ESI-LC-MS/MS. Latanoprost content and formation of DP were assessed in generic formulations and were compared with Xalatan(®) in a controlled patient usage simulation studies. The last few drops of latanoprost, present in containers used by patients were also evaluated.

RESULTS

Extreme pH conditions, oxidation, light and heat were found to be the significant factors for high degree of latanoprost degradation. Systematic analysis of 7 selected generics revealed that the latanoprost content varied from 90-330%. Concentration of the latanoprost in Xalatan was found to be 97% of the label claim. Degradation studies showed the formation of 3 novel and 3 already known impurities. Upon simulated patient usage, 2 of the generic formulations showed significant degradation of latanoprost. Generic formulations having thermally sealed gas tight packing showed good stability during patient usage. Overage of latanoprost was observed in generics with other than thermal sealing. Latanoprost bottles used by patients showed concentrations ranging from 20 to 250% of label claim (144% median).

CONCLUSION

This study revealed the presence of overage of latanoprost in some generic formulations and formation of degradation products. Packaging with gas tight containers may be one of the important factors for latanoprost stability, along with its storage at low temperature during patient usage.

Generic drugs for the treatment of ocular conditions: changing the treatment landscape

As global spending on medicinal products continues to rise, the availability of lower-cost generic substitutes is increasingly driving health care decision-making. US FDA does not require strict demonstration of human bioequivalence and/or therapeutic studies for the approval of generic ophthalmic compounds. Bioequivalence between generic and innovator compounds is presumed on the basis of matching active and inactive ingredient profiles. Generic compounds may differ from innovator agents with regards to performance under environmental stress, relative acidity and bottle size/rigidity. Matching ingredient profiles may therefore not result in consistently comparable drug compositions and clinical effects.

A randomized, prospective study of bimatoprost 0.01% or travoprost/timolol in patients previously treated with latanoprost and timolol to reduce intraocular pressure

PURPOSE

To compare the efficacy and safety of bimatoprost 0.01% with the fixed combination travoprost 0.004%/timolol 0.5% in subjects with stable intraocular pressure (IOP) control on latanoprost and timolol.

METHODS

This was a randomized, prospective, investigator masked, crossover study comparing bimatoprost 0.01% with travoprost/timolol in 40 subjects diagnosed with primary open-angle glaucoma. Subjects were randomized to bimatoprost 0.01% qpm or travoprost/timolol qam and followed for 12 weeks, at which time they were crossed over to the alternate medication and followed for another 12 weeks. Intraocular pressure and hyperemia (rated on a standardized, 5-point photographic scale) were evaluated as change from baseline to 12 weeks following each therapy, and subject preference was elicited at the end of the study.

RESULTS

Both treatments were well tolerated and the majority of patients achieved effective IOP control relative to baseline. After 12 weeks of treatment, mean reductions from baseline IOP were -1.68 mmHg OD (right eye) and -1.58 mmHg OS (left eye) with bimatoprost and -0.45 mmHg OD and -0.53 mmHg OS with travoprost/timolol, although the differences between drugs were not statistically significant. Hyperemia scores were significantly higher with the fixed combination of travoprost/timolol than bimatoprost 0.01% as measured at 8 am (both P<0.01). Subject preference at the end of the study was more than 3 to 1 in favor of bimatoprost, with most citing greater tolerability.

CONCLUSION

Bimatoprost 0.01% and travoprost/timolol are both effective at reducing IOP in subjects with stable IOP control on latanoprost and timolol, but bimatoprost 0.01% is associated with less hyperemia.