Ophthalmic oil-in-water nanoemulsions (NEs) are a complex technological platform, representing an advancement in the treatment of dry eye disease. In addition to enabling the incorporation of poorly soluble active pharmaceutical ingredients (APIs), NEs provide prolonged residence time of APIs and other formulation components and consequent replenishment and stabilization of the compromised tear film. Ophthalmic NEs have been on the market for over 20 years, but considering their complexity, as well as the complex nature of the ocular surface, they are still a poorly understood advanced dosage form. The objective of this study was to develop a biorelevant in vitro method that would be able to predict the behavior of ophthalmic NEs after application. With that goal, NE formulations differing in critical material attributes and critical formulation variables were employed and subjected to simulated tear turnover and blinking. By gradually increasing the complexity of the in vitro method, we were able to detect key parameters influencing NE stability. The undertaken study presents a step forward in the development of in vitro tools that are fundamental to the reliable, cost and time-effective development of innovative and generic topical ophthalmic NEs.

Long-acting injectables (LAIs) are widely used for chronic conditions such as schizophrenia, opioid use disorder, and HIV. Their prolonged efficacy improves adherence and reduces dosing frequency. Among these systems, poly(lactide-co-glycolide) (PLGA)-based formulations are commonly used to deliver drugs ranging from small molecules to peptides and proteins. In vitro release (IVR) tests play a critical role in evaluating drug product performance for both immediate- and prolonged-release dosage forms. However, there is a lack of standardized compendial IVR methods for the assessment of LAIs. This lack impedes the development of new drug products in this area and also complicates their regulatory approval process. Considering the complexity of drug release mechanisms and the diversity of various formulation design approaches, it is not possible to devise a universal IVR method that is applicable to all LAI products. The in vitro release test applied for quality control should be simple, robust, reproducible, and discriminatory. On the other hand, more complex biorelevant media and methods are often used during development to better reflect physiological conditions. This article provides a comprehensive review of compendial and non-compendial methods used for in vitro release testing of PLGA-based LAIs (microspheres and in situ forming implants), with the goal of aiding the development and standardization of future methodologies.

Long‑acting injectables (LAIs) are widely used for chronic conditions such as schizophrenia, opioid use disorder and HIV. Their prolonged efficacy improves adherence and reduces dosing frequency. Among these systems, poly(lactide‑co‑glycolide) (PLGA)‑based formulations are commonly used to deliver drugs ranging from small molecules to peptides and proteins. In vitro release (IVR) tests play a critical role in evaluating drug product performance for both immediate release and prolonged release dosage forms. However, there is a lack of standardized compendial IVR methods for the assessment of LAIs. This lack impedes the development of new drug products in this area and also complicates their regulatory approval process. Considering the complexity of drug release mechanisms and the diversity of various formulation design approaches, it is not possible to devise a universal IVR method which would be applicable to all LAI products. The in vitro release test applied for quality control should be simple, robust, reproducible and discriminatory. On the other hand, more complex biorelevant media and methods are often used during development to better reflect the physiological conditions. This article provides a comprehensive review of compendial and non-compendial methods used for in vitro release testing of PLGA-based LAIs (microspheres and in situ forming implants), with the goal of aiding the development and standardization of future methodologies.

Background: TV-44749 is a subcutaneous (sc) long-acting injectable (LAI) formulation of olanzapine that recently demonstrated efficacy and safety as a treatment for schizophrenia in adults without the occurrence of post-injection delirium/sedation syndrome (PDSS) in the phase 3 SOLARIS trial (NCT05693935). TV-44749’s sc route of administration and formulation were designed to provide prolonged olanzapine release over a monthly dosing interval and to avoid the risk of post-injection delirium/sedation syndrome (PDSS). It was designed as a copolymer in situ-forming depot technology to provide a LAI formulation that could withstand physiological and environmental factors that could affect controlled-release kinetics. Methods: To evaluate the robustness of the TV-44749 formulation, an in vitro release (IVR) study in human plasma was conducted, comparing TV-44749 to the commercially available intramuscular (im) long-acting injection formulation of olanzapine pamoate monohydrate. In addition, in vivo studies in rats were conducted to assess the effect of injection site manipulation following TV-44749 sc injection on olanzapine release from the depot. Results: The IVR study showed that upon contact with human plasma, copolymers comprising TV-44749 formulation instantly precipitate and form a solid matrix that entraps olanzapine particles. This prevents an uncontrolled release of olanzapine. Additionally, in vivo rat studies found that manipulation of the injection site after TV-44749 administration, by either heating or rubbing at different time-points, resulted in no meaningful effect on overall olanzapine exposure. Conclusions: The presented findings support the robustness of the TV-44749 formulation in maintaining controlled-release properties, even under conditions that could otherwise compromise release performance.