Effect of Storage Conditions on Stability of Ophthalmological Compounded Cysteamine Eye Drops

Cysteamine Eye Drops in Hyaluronic Acid Packaged in Innovative Single-Dose Systems, Part II: Long-Term Stability and Clinical Ocular Biopermanence

BACKGROUND

Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in several tissues and organs causing, among others, severe eye symptoms. The high instability of cysteamine eye drops makes it difficult to develop formulations with an acceptable shelf life to be prepared in hospital pharmacy departments. Previously, a new compounded formulation of cysteamine eye drops in hyaluronic acid (HA) packaged in innovative single-dose systems was developed.

METHODS

Long-term stability at -20 °C of this formulation was studied considering the content of cysteamine, pH, osmolality, viscosity, and microbiological analysis. The oxygen permeability of single-dose containers was also studied and an ocular biopermanence study was conducted in healthy volunteers measuring lacrimal stability and volume parameters.

RESULTS

Data confirm that cysteamine concentration remained above 90% for 120 days, all parameters remaining within the accepted range for ophthalmic formulations. The permeability of the containers was reduced over time, while ocular biopermanence was maintained despite the freezing process and storage time.

CONCLUSIONS

0.55% cysteamine hydrochloride formulation in HA and packaged in single-dose containers preserved at -20 °C is stable for 120 days protected from light, presenting high potential for its translation into clinical practice when commercial presentations are not available.

Capillary electrophoresis in parenteral nutrition control - validation of two analytical methods: Amino acids/glucose/glucose-1-phosphate and K/Na/Ca/Mg

OBJECTIVES

Production of parenteral nutrition bags (PNBs) involves many nutrients: complete control of the production process decreases the risk of error. This study aimed to develop and validate two analytical methods by capillary electrophoresis (CE) for simultaneous detection of: glucose, amino acids (Primene®) and glucose-1-phosphate (Phocytan®) (anionic method, AM) on one hand; and on the other hand potassium, sodium, calcium and magnesium (cationic method, CM).

METHODS

Methods were developed using capillary electrophoresis with diode array detection (CE-DAD) (CE 7100, Agilent), indirect photometric detection, 56 cm long capillary and two different buffers (pH=12.1 for AM and pH=3.2 for CM). These methods were validated according to guidelines from the Société Française des Sciences et Techniques Pharmaceutiques (SFSTP).Analytical parameters were optimised: temperature was regulated at 15°C and the current settled to - 15kV, for a 21 minute analysis time for AM. Conditions were settled to 25°C and 30kV for CM so the analysis time dropped to 7 minutes.Accuracy profiles were established and recovery rates (RR), Repeatability and Reproducibility Coefficient of Variation (respectively RaCV and RoCV) were calculated.Capability was also calculated for each nutrient and concentration range according to guidelines from the Evaluation and Research Group on Protection in a Controlled Atmosphere (GERPAC).

RESULTS

Methods were successfully validated with: RR between 99.2 and 101.9%, RaCV between 1.5 and 3.1%, and RoCV between 2.4 and 4.1% for AM, and RR between 97.5 and 102.7%, RaCV between 0.5 and 2.3%, and RoCV between 0.6 and 2.8% for CM.Accuracy profiles were established with 95% β probability, except for glucose-1-phosphate (90%). Acceptance limits were settled to ±1 0% of target value. Capabilities are defined as "good" or "very good".

CONCLUSIONS

The methods developed by this research will ensure the composition of PNB is compliant to PNB formulas. These results show CE is an appropriate method for PNB quantitative control.CE utilisation for controlling other hospital preparations seems to be a relevant alternative to conventional methods such as liquid chromatography.

Cysteamine Eye Drops in Hyaluronic Acid Packaged in Innovative Single-Dose Systems: Stability and Ocular Biopermanence

Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in different tissues and organs causing, among other symptoms, severe ocular manifestations. Cysteamine eye drops are prepared in hospital pharmacy departments to facilitate access to treatment, for which vehicles that provide adequate biopermanence, as well as adaptable containers that maintain its stability, are required. Difficulties related to cysteamine preparation, as well as its tendency to oxidize to cystamine, show the importance of conducting rigorous galenic characterization studies. This work aims to develop and characterize an ophthalmic compounded formulation of cysteamine prepared with hyaluronic acid and packaged in innovative single-dose systems. For this task, the effect of different storage temperatures and the presence/absence of nitrogen on the physicochemical stability of the formulation and its packaging was studied in a scaled manner, until reaching the optimal storage conditions. The results showed that 0.55% cysteamine, prepared with hyaluronic acid and packaged in single-dose containers, is stable for 30 days when stored at −20 °C. In addition, opening vials every 4 h at room temperature after 30 days of freezing maintains the stability of the cysteamine formulation for up to 16 h. Moreover, ocular biopermanence studies were conducted using molecular imaging, concluding that the biopermanence offered by the vehicle is not affected by the freezing process, where a half-life of 31.11 min for a hyaluronic acid formulation stored for 30 days at −20 °C was obtained, compared with 14.63 min for 0.9% sodium chloride eye drops.

Limitations and Challenges in the Stability of Cysteamine Eye Drop Compounded Formulations

Accumulation of cystine crystals in the cornea of patients suffering from cystinosis is considered pathognomonic and can lead to severe ocular complications. Cysteamine eye drop compounded formulations, commonly prepared by hospital pharmacy services, are meant to diminish the build-up of corneal cystine crystals. The objective of this work was to analyze whether the shelf life proposed for six formulations prepared following different protocols used in hospital pharmacies is adequate to guarantee the quality and efficacy of cysteamine eye drops. The long-term and in-use stabilities of these preparations were studied using different parameters: content of cysteamine and its main degradation product cystamine; appearance, color and odor; pH and viscosity; and microbiological analysis. The results obtained show that degradation of cysteamine was between 20% and 50% after one month of storage in the long-term stability study and between 35% and 60% in the in-use study. These data confirm that cysteamine is a very unstable molecule in aqueous solution, the presence of oxygen being the main degradation factor. Saturation with nitrogen gas of the solutions offers a means of reducing cysteamine degradation. Overall, all the formulae studied presented high instability at the end of their shelf life, suggesting that their clinical efficacy might be dramatically compromised.

Recent Research in Ocular Cystinosis: Drug Delivery Systems, Cysteamine Detection Methods and Future Perspectives

Cystinosis is a rare genetic disorder characterized by the accumulation of cystine crystals in different tissues and organs. Although renal damage prevails during initial stages, the deposition of cystine crystals in the cornea causes severe ocular manifestations. At present, cysteamine is the only topical effective treatment for ocular cystinosis. The lack of investment by the pharmaceutical industry, together with the limited stability of cysteamine, make it available only as two marketed presentations (Cystaran® and Cystadrops®) and as compounding formulations prepared in pharmacy departments. Even so, new drug delivery systems (DDSs) need to be developed, allowing more comfortable dosage schedules that favor patient adherence. In the last decades, different research groups have focused on the development of hydrogels, nanowafers and contact lenses, allowing a sustained cysteamine release. In parallel, different determination methods and strategies to increase the stability of the formulations have also been developed. This comprehensive review aims to compile all the challenges and advances related to new cysteamine DDSs, analytical determination methods, and possible future therapeutic alternatives for treating cystinosis.

Development of cysteamine loaded liposomes in liquid and dried forms for improvement of cysteamine stability

Despite the high aqueous solubility of cysteamine, its unpleasant organoleptic properties, hygroscopicity, instability in solutions, and poor pharmacokinetic profile are the main drawbacks that limit its use for medical and cosmetic purposes. In this study, cysteamine-loaded liposomes were prepared using the ethanol injection method. Liposomes were characterized for their size, homogeneity, surface charge, and morphology. The incorporation ratios of cholesterol and phospholipids, the encapsulation efficiency and the loading ratio of cysteamine in liposomes were determined. Moreover, the stability of free and encapsulated cysteamine was assessed at different temperatures (4, 25, and 37 °C) in the presence and absence of light. Cysteamine-loaded liposomes were freeze-dried and reconstituted liposomes were characterized. Finally, the storage stability of the freeze-dried cysteamine-loaded liposomes was studied. Liposomes were nanometric, oligolamellar, and spherical. The encapsulation efficiency and the loading ratio of cysteamine varied between 12 and 40% in the different formulations. The encapsulation improved the stability of cysteamine in the various storage conditions. The dried form of cysteamine-loaded liposomes conserved the size of the vesicles and retained 33% of cysteamine present in the liposomal suspension before lyophilization. The freeze-dried liposomes formulations were stable after four months of storage at 4 °C.

Patient safety issues associated with the use of compounded medicines as alternatives to approved pharmaceutical products in Europe and how best practice can improve outcomes

BACKGROUND

Pharmaceutical compounding allows individuals with special requirements access to medicines. Compounding can also be used to provide cheaper alternatives to commercially produced medicines which may be less strictly regulated than those commercially produced as they do not require marketing authorisation.

OBJECTIVE

This review describes the issues and potential risks associated with compounded medicines and equally importantly identifies best practices.

METHODS

To establish reports about lack of effectiveness, adverse events and medication errors occurring with compounded pharmaceuticals, a literature search was conducted of PubMed, Embase and MEDLINE databases for relevant cases in European countries which were published between 2003 and 2018. Case reports/series that described instances of successful use of compounded medicines over the same period were also identified.

RESULTS

Overall, 12 case reports/case series describing problems associated with compounded medicines in Europe have been identified. Sources of patient risk associated with compounded medicines include lack of quality, safety and efficacy data, preparation and labelling errors, and improper storage and handling practices.

CONCLUSIONS

Several case reports/series describing instances of overdose, medication errors and adverse events associated with compounded medications were reviewed. The number of affected patients was relatively small, but many were children and two adult patients experienced permanent sequelae. The number of incidents associated with compounded medicines is unknown, and so these numbers should be interpreted with caution. When licensed medicines are available, the use of compounded medicines can put patients at unnecessary risk which should be avoided. Stricter regulation is necessary to prevent similar cases from occurring in the future as the European market for compounded medications grows. Pharmacists can promote best practices in compounding through professional organisations. Future recommended actions are: 1. Stricter regulation is necessary to prevent similar cases from occurring in the future as the European market for compounded medications grows. 2. A comprehensive pan-European survey to gain a greater understanding of compounding procedures and techniques. This would provide valuable information to the benefit of hospital systems and their patients. 3. The results of the survey can then be used to improve the knowledge and quality control of compounded medicines for the good of patient safety.

Ophthalmic Outcome in a Belgian Cohort of Cystinosis Patients Treated with a Compounded Preparation of Cysteamine Eye Drops: Retrospective Analysis

INTRODUCTION

Treatment of the anterior segment problems in cystinosis is challenging as oral cysteamine is ineffective in the treatment of corneal problems because of its avascular structure. Although cysteamine eye drops have been formulated to counter this issue, the stability of cysteamine in these off-licensed formulations and treatment compliance are major problems. The aim of this retrospective study was to determine the efficacy of a compounded preparation of aqueous 0.5% cysteamine eye drops in the management of corneal complications of cystinosis.

METHODS

Data of patients attending the multidisciplinary cystinosis clinic at the University Hospitals Leuven, Belgium between January 2015 and December 2018 were analyzed. All cystinosis patients were treated with the compounded preparation of aqueous 0.5% cysteamine eye drops and oral cysteamine.

RESULTS

A total of 12 patients were treated with the compounded preparation of aqueous 0.5% cysteamine eye drops, of whom 75% were aged > 18 years (n = 9). The mean instillation frequency of the cysteamine eye drops was 3.3 drops/eye per day, and the mean number of hospital visits was two per year. All patients showed photophobia, > 30% corneal infiltration, blepharospasm, eye pain and conjunctival hyperemia during the study period. None of these symptoms improved with treatment with aqueous compounded 0.5% cysteamine eye drops. The corneal cystine crystal score was ≥ 2 in all patients at the last  visit.

CONCLUSION

Treatment with the compounded preparation of aqueous 0.5% cysteamine eye drops, combined with oral cysteamine, was not effective in reducing corneal cystine crystal deposition and other ocular symptoms in these patients with cystinosis.

FUNDING

Recordati Rare Diseases.

The Ocular Status of Cystinosis Patients Receiving a Hospital Pharmacy-Made Preparation of Cysteamine Eye Drops: A Case Series

Introduction

Infantile nephropathic cystinosis (INC) is an autosomal recessive lysosomal disorder in which patients develop deposits of cystine crystals in their kidneys and corneas from a young age.

Methods

We conducted a retrospective analysis of children with INC seen by ophthalmologists at the Manchester Royal Eye Hospital between 2002 and 2018, to evaluate clinical findings, symptoms and treatment.

Results

Twenty-two children diagnosed with INC from age 0 (prenatally) to 11 years were assessed. All evaluable patients had corneal cystine crystal deposits, and 15 had mild to moderate photophobia. Ten patients had other ocular conditions including blepharitis/chalzion (n = 6), swollen optic nerve (n = 3), punctate epitheliopathy (n = 3), corneal scarring (n = 1),and elevated intraocular pressure (n = 2). Confocal imaging identified nerve abnormalities in two patients (enlarged corneal nerve + abnormal-looking tortuous nerves in one patient and beaded nerves in the sub-basal plexus in the other), both of whom had significant crystal deposition in the anterior stroma. Visual acuity was relatively unaffected. All 22 patients were receiving oral cysteamine, and 21 were applying cysteamine eye drops (galenic preparation of 0.55% concentration, compounded by a hospital pharmacy). Recommended application frequency was at least eight times per day in all patients with dosing information available.

Conclusions

This case series of patients with INC highlights the consistent pattern of corneal cystine crystal deposition, which is universally present from a young age in this condition, and the high incidence of photophobia even in young children. Corneal manifestations of INC persisted despite frequent administration of the hospital pharmacy-made eye drop preparation. Reasons for this lack of efficacy may include the lag period between diagnosis and first prescription of cysteamine eye drops and the difficulty in maintaining rigorous compliance with this treatment. In addition, the challenge for patients of maintaining optimal storage conditions may adversely affect the stability and efficacy of cysteamine within this preparation.

Funding

Editorial assistance was funded by Orphan Europe Ltd.

Novel approaches for improving stability of cysteamine formulations

Cystinosis is a genetic disorder that leads to the formation of cystine crystals in many organs in the body including cornea. Ocular manifestation of this disease is treated by eye drops of cysteamine which can easily oxidize into its disulfide cystamine. The rapid oxidation limits the shelf life as well the duration during which the drug can be used after opening the eye drop bottle. We evaluate two approaches of preventing the oxidation of cysteamine with the goal of increasing the time of use after opening the bottle to one month. The first approach integrates antioxidants such as catalase enzyme and vitamins C and E into the aqueous solution. Results show that catalase is the most effective additive as it decreases the oxidation rate by 58%, which on its own is not sufficient to reach targeted one month stability. The second approach focuses on incorporating diffusion barriers to prevent oxygen from reaching the cysteamine solution. This was accomplished by two methods: formulation of a hydrophobic layer which floats on the surface of the aqueous solution and integration of OMAC® oxygen-resistant material into the eye drop bottle. Both methods delay the onset of cysteamine degradation and decrease the rate of degradation. In particular, an eye drop bottle with three layers of OMAC® has less than 10% degradation after one month of opening the bottle and withdrawing a drop each day. By integrating all three methods, we designed a system where >90% of cysteamine remains in the active form for 70 days after opening the bottle. In addition, we examine the use of OMAC® as heat-sealed pouches for storage of cysteamine eye drop bottles during packaging to eliminate the need for the current approach of freezing the formulation during shipping. The results show that such heat-sealed pouches would keep cysteamine stable for over one year at ambient conditions.