Corneal Penetration of Low-Dose Atropine Eye Drops

Preservatives and pH in low-dose atropine formulations for clinical trials

Over a century ago, atropine has been tested to arrest myopia progression with good results. In recent years, many randomized clinical trials have tested different concentrations against placebo. Three recent such studies with low-dose atropine showed that it was less effective than previous studies, even the last one showing no difference in myopia progression between the treated and control group. Previous randomized studies had been performed in Asian populations, and these last three were extended to Western Caucasian populations, based on the initial observation that differences in iris pigmentation could be a factor for a difference in effectiveness. We have noticed that the three last studies in the West have used the same patented formulation, while previous studies have preferred compounded low-dose atropine. Here we review how the power of hydrogen (pH) and preservatives could account for differences in drug penetration to the eye, possibly explaining the differences between studies.

Atropine: Updates on myopia pharmacotherapy

The prevalence of myopia has rapidly increased over the last 30 years, with the World Health Organization estimating a worldwide incidence of 23%, projected to increase to 50% by 2050. The myopia epidemic has prompted a reincarnation in efforts to overcome this challenge. The exploration of atropine use in myopia was a result due to a lack of treatment in effect. This study aimed at reviewing the role of atropine in the management of myopia worldwide based on currently available findings. A literature search was conducted using PubMed/MEDLINE and Google Scholar for studies published up to April 2022 inclusive. Articles with high or medium clinical relevance were selected for this review. Multiple studies have demonstrated the relevance and efficacy rates of different concentrations of atropine, despite still insufficiently explained the exact site and mechanism of action of atropine in slowing myopia progression. Currently available findings highlight that topical atropine opened a new page in pharmacotherapy of myopia and have shown a high therapeutic effect on myopia progression in Asian and European child population, irrespective of ethnicity. There is potential for myopia control with fewer side effects using lower concentrations but still exists a room for improvement, underscoring the requirement of modified atropine topical preparations with increased bioavailability, potentially with nanoparticle formulations, to enable the effective management of myopia.

Evaluation of the Levels of Low-dose Topical Atropine (0.01%) in Aqueous and Vitreous Humor in Human Eyes

SIGNIFICANCE

This is the first human study that confirmed penetration of 0.01% topical atropine in aqueous and vitreous humor in live human eyes. This supports the possible mode of action of atropine via posterior ocular structures. This knowledge will help improve the outcomes in myopia management.

PURPOSE

The purpose of this study was to evaluate penetration of low-dose atropine 0.01% in aqueous and vitreous humor.

METHODS

In this cross-sectional interventional pilot study, 48 cataract cases were divided into four groups (12 each), and 30 epiretinal membrane/macular hole cases were divided into three groups (10 each). One drop of 0.01% atropine was put in the eye to be operated. Aqueous humor samples were taken from patients undergoing cataract surgery at 60 ± 15 minutes in group 1, 120 ± 15 minutes in group 2, 240 ± 15 minutes in group 3, and 360 ± 15 minutes in group 4. Vitreous humor samples were taken from patients undergoing vitreoretinal surgery for epiretinal membrane/macular hole at 120 ± 15 minutes in group 1, 240 ± 15 minutes in group 2, and 360 ± 15 minutes in group 3. The assay of atropine was performed using liquid chromatography-mass spectrometry.

RESULTS

Median concentrations of atropine in aqueous samples were 1.33 ng/mL (min-max, 0.6 to 6.46 ng/mL; interquartile range [IQR], 3.05 ng/mL) at 60 minutes, 2.60 ng/mL (min-max, 0.63 to 4.62 ng/mL; IQR, 1.97 ng/mL) at 120 minutes, 1.615 ng/mL (min-max, 0.1 to 3.74 ng/mL; IQR, 1.62 ng/mL) at 240 minutes, and 1.46 ng/mL (min-max, 0.47 to 2.80 ng/mL; IQR, 1.73 ng/mL) at 360 minutes, and those in vitreous samples were 0.102 ng/mL (min-max, 0 to 0.369 ng/mL; IQR, 0.366 ng/mL) at 120 minutes, 0.1715 ng/mL (min-max, 0 to 0.795 ng/mL; IQR, 0.271 ng/mL) at 240 minutes, and 0.2495 ng/mL (min-max, 0 to 0.569 ng/mL; IQR, 0.402 ng/mL) at 360 minutes, respectively.

CONCLUSIONS

Measurable concentration of low-dose topical atropine (0.01%) was noted in aqueous and vitreous humor after instillation of a single drop of low-dose atropine. Muscarinic receptors located in the posterior segment such as the choroid and retina could be the possible site of action of low-dose atropine in myopia.

Compounded 0.01% Atropine-What's in the Bottle?

OBJECTIVE

To describe the labeling, packaging practices, and characteristics of compounded 0.01% ophthalmic atropine.

METHODS

A convenience sample of parents of children who had previously been prescribed low-concentration atropine for myopia management were randomized to obtain 0.01% atropine ophthalmic solution from one of nine compounding pharmacies. The products were analyzed for various important quality attributes. The main outcomes were labeling practices, concentration of atropine and degradant product tropic acid, pH, osmolarity, viscosity, and excipients in 0.01% atropine samples obtained from nine US compounding pharmacies.

RESULTS

Twenty-four samples from nine pharmacies were analyzed. The median bottle size was 10 mL (range 3.5-15 mL), and eight of nine pharmacies used clear plastic bottles. Storage recommendations varied and were evenly split between refrigeration (33%), room temperature (33%), and cool, dark, dry location (33%). Beyond use dates ranged from 7 to 175 days (median, 91 days). Median pH of samples was 7.1 (range, 5.5-7.8). Median measured concentration relative to the prescribed concentration was 93.3% (70.4%-104.1%). One quarter of samples were under the 90% minimum target concentration of 0.01%.

CONCLUSIONS

An inconsistent and wide variety of formulation and labeling practices exist for compounding 0.01% atropine prescribed to slow pediatric myopia progression.

[Recommendations for Progressive Myopia in Childhood and Adolescence. Statement of the DOG, BVA and the Bielschowsky Society for Strabismus Research and Neuroophthalmology - Status June 2022]

Since the last and at the same time first statement of the German ophthalmological societies on the possibilities of reducing myopia progression in childhood and adolescence, many new details and aspects have emerged in clinical research. This second statement updates the previous document and specifies the recommendations on visual and reading behavior as well as on pharmacological and optical therapy options, which have been both refined and newly developed in the meantime.

[Recommendations for progressive myopia in childhood and adolescence. Statement of the DOG, BVA and the Bielschowsky Society for Strabismus Research and Neuroophthalmology : Status June 2022]

Since the last and at the same time first statement of the German ophthalmological societies on the possibilities of reducing myopia progression in childhood and adolescence, many new details and aspects have emerged in clinical research. This second statement updates the previous document and specifies the recommendations on visual and reading behavior as well as on pharmacological and optical therapy options, which have been both refined and newly developed in the meantime.

Balsam Poplar Buds: Extraction of Potential Phenolic Compounds with Polyethylene Glycol Aqueous Solution, Thermal Sterilization of Extracts and Challenges to Their Application in Topical Ocular Formulations

Phenolic compounds of natural origin have been valued for their beneficial effects on health since ancient times. During our study, we performed the extraction of phenolic compounds from balsam poplar buds using different concentrations of aqueous polyethylene glycol 400 solvents (10-30% PEG400). The aqueous 30% PEG400 extract showed the best phenolic yield. The stability of the extract during autoclave sterilization was evaluated. The extract remained stable under heat sterilization. Ophthalmic formulations are formed using different concentrations (8-15%) of poloxamer 407 (P407) together with hydroxypropyl methylcellulose (0.3%), sodium carboxymethyl cellulose (0.3%) or hyaluronic acid (0.1%). Physicochemical parameters of the formulations remained significantly unchanged after sterilization. Formulations based on 12% P407 exhibited properties characteristic of in situ gels, the gelation point of the formulations was close to the temperature of the cornea. After evaluating the amount of released compounds, it was found that, as the concentration of polymers increases, the amount of released compounds decreases. Formulations based on 15% P407 released the least biologically active compounds. Sterilized formulations remained stable for 30 days.

Efficacy and safety of traditional Chinese medicine decoction in the treatment of adolescent myopia: A protocol for systematic review and network meta-analysis

BACKGROUND

Adolescent myopia has become a major public health problem in Asian countries and even the world. Due to its unstable prognosis and numerous complications, it has caused serious social and economic burden. As a common treatment in Asia, Chinese medicine has been shown to be effective in controlling the development of myopia, but its evidence-based medical evidence is not sufficient. Therefore, the purpose of this study is to evaluate the efficacy and safety of traditional Chinese medicine (TCM) in the treatment of adolescent myopia through network meta-analysis, and to provide evidence for clinical and scientific research.

METHODS

We searched seven databases for randomized controlled trials of TCM decoction for adolescent myopia, including PubMed, the Cochrane Library, EMbase, China National Knowledge Infrastructure, China Biological Medicine, Chinese Scientific Journals Database, and wan-fang databases, from the date of the establishment of each database to January 31, 2022. The network meta-analysis will be implemented through Aggregate Data Drug Information System 1.16.8 and Stata 13.0 software. Primary outcomes include distant vision, intraocular pressure, and diopter. Mean differences or odds ratios will be used for statistical analysis. We will ensure the reliability of the results through node-split model and heterogeneity analysis. In addition, the Cochrane Collaboration's tool and Grading of Recommendations Assessment, Development and Evaluation system will be used for the methodological quality and the evidence quality.

RESULTS

This study will provide reliable evidence for the clinical selection of TCM decoction in the treatment of adolescent myopia.

CONCLUSION

The results of this study will evaluate the efficacy and safety of TCM decoction in the treatment of adolescent myopia, and provide decision-making references for future clinical and scientific research.

ETHICS AND DISSEMINATION

This study did not require ethical approval. We will disseminate our findings by publishing results in a peer-reviewed journal.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/VXQUP.