Advancing Ophthalmic Drug Development: Overcoming Bioanalytical Challenges in Ophthalmology

The intricate structure of the eye poses several challenges for ophthalmic bioanalysis, including small sample volumes, low concentrations of analytes, and difficulty in obtaining a real blank matrix. This blog focuses on the challenges and strategies for ophthalmic bioanalysis after ocular drug delivery.

What are ophthalmic bioanalysis challenges after ocular drug delivery?

• Low exposure in plasma: Topical drug delivery is commonly used in terms of ocular drug delivery. However, due to the small area of topical drug delivery and various barriers, the drug concentration in the systemic circulation is typically low. To address this challenge, WuXi AppTec DMPK has developed a highly sensitive detection method of plasma drug concentration, providing an effective solution for evaluating systemic exposure after ocular topical administration.

  
  

• Nonspecific binding: Ophthalmic fluid samples (aqueous humor, vitreous humor, and tears) have low protein content. Therefore, drugs are prone to generate non-specific adsorption in these matrices.

  
  

• Difficulty in obtaining a blank matrix: Obtaining a blank matrix is also a major challenge due to the small volume of ocular tissue and the impossibility of using a large number of animals to obtain sufficient blank matrices. To tackle this challenge, suitable surrogate matrix and the purchase of commercialized matrices need to be selected.

What are bioanalysis challenges of tear sample?

The challenges of tear sample bioanalysis are mainly related to its unique collection methods, which currently mainly include two methods:

(1)  Capillary tube method: Accurately aspirating the sample and obtaining sufficient blank matrix for sample analysis pose challenges to the capillary tube collection method. We used organic reagents to dilute the tear samples and wetted the samples well in the sample tubes for accurate sampling. Meanwhile, organic reagents were also used as surrogate matrices to prepare standard curves and quality control samples for sample analysis.

(2)  Filter paper strip method: The challenges of the filter paper strip method involve how to extract the drugs from the filter paper strip sample to obtain a liquid state for injection and how to use the filter paper strip as a blank matrix for preparing standard curves and quality control samples. To deal with these two challenges, we designed the process and chose an alternative method to obtain standard curves and quality control samples.

What are ophthalmic bioanalysis challenges of drug binding to melanin?

The binding of drugs to melanin brings a potential risk of inaccurate detection concentrations and unstable false positives, which presents a significant challenge for bioanalysis. The strategy mainly includes three aspects: adding high concentration of salts, adjusting the pH, and adding a protease.

If you want to learn more details about the bioanalysis challenges and strategy of ophthalmology, please read the article now.

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