Introduction
The ongoing fight against HIV continues to rely on advances in treatment strategies that improve adherence, reduce side effects, and extend drug efficacy. Among the promising developments is the use of core-shell fiber systems for antiretroviral (ART) delivery. These nanoscale or microscale fibers, engineered with a core-shell architecture, offer unique control over drug release profiles, stability, and biocompatibility. In this article, we explore how core-shell fiber composition can influence the properties of ART formulations and what this means for patients and public health.
What are core-shell fibers?
Core-shell fibers consist of two distinct layers: a core that contains the active drug and a surrounding shell that modulates release, protection, and interaction with the biological environment. This design enables precise tuning of drug release rates, improves drug stability, and can reduce systemic exposure by localizing delivery. In the context of HIV, ART drugs embedded in core-shell fibers can potentially provide long-acting formulations with improved adherence and fewer dosing events.
Material considerations and design principles
The performance of core-shell ART fibers hinges on material selection for both the core and shell. Common polymer systems include biocompatible and biodegradable polymers such as poly(lactic-co-glycolic acid) (PLGA), poly(ε-caprolactone) (PCL), and natural polymers like chitosan. The shell often employs polymers with slower degradation or diffusion characteristics to regulate release. Design parameters include:
– Drug loading in the core and its distribution
– Shell thickness and porosity to control diffusion
– Interfacial compatibility between core and shell to prevent drug leakage or crystallization
– Mechanical properties suitable for the intended route of administration (e.g., implantable, injectable, or transdermal)
Impact on drug release and stability
One of the main advantages of core-shell fibers is the ability to engineer sustained drug release. By selecting appropriate core and shell materials, researchers can create a release profile that minimizes peaks and troughs in plasma ART concentrations, potentially reducing side effects and resistance risks. The shell can act as a barrier to environmental factors, protecting labile ART molecules from hydrolysis or degradation, which is particularly important for heat- or moisture-sensitive drugs. This enhanced stability translates into more reliable dosing regimens and better patient outcomes.
Pharmacokinetics, safety, and patient adherence
Long-acting ART via core-shell fibers could transform adherence patterns. Fewer dosing events—ranging from weekly to monthly or even longer intervals—can significantly reduce the burden on patients and healthcare systems. However, safety considerations include ensuring predictable clearance of the material after the drug is exhausted, minimizing local tissue reactions, and avoiding immune responses to the polymer components. Rigorous pharmacokinetic and toxicological evaluations are essential to determine the optimum balance between release duration and safety margins.
Clinical and public health implications
From a public health perspective, core-shell ART fibers have the potential to improve access to effective HIV therapy, particularly in settings with weak healthcare infrastructure or where daily pill burden hinders adherence. By enabling long-acting formulations, clinicians may offer more robust protection against viral rebound and reduce the risk of transmission at the population level. Moreover, customizable release could support combination therapies by co-encapsulating multiple ART agents with synchronized release, addressing drug–drug interactions and simplifying regimens for patients living with HIV.
Challenges and future directions
Despite the promise, several challenges remain. Manufacturing scalability, sterilization methods that preserve drug activity, and regulatory pathways for combination core-shell systems need addressing. The development pipeline must also consider variability in patient physiology, potential monolithic failure modes, and cost implications for widespread adoption. Ongoing research aims to optimize shell materials for precise diffusion control, improve core stability, and validate long-term safety in diverse populations.
Conclusion
Core-shell fiber composition represents a compelling strategy to advance antiretroviral delivery. By delivering ART drugs in a controlled, stable, and patient-friendly format, these systems could enhance adherence, reduce toxicity, and strengthen HIV treatment outcomes. As research progresses, collaboration across materials science, pharmacology, and clinical practice will be crucial to translating core-shell fiber technology from the lab bench to real-world patient care.
