Critical Evaluation of Key Elements in Manufacturing Procedures and Testing Methodologies for Ocular Anti-Infective Thin Film Inserts

Eye drops remain the principal topical treatment for ocular infections, yet rapid precorneal clearance, variable dose delivery and limited tissue penetration can restrict local drug availability and necessitate frequent administration. Conjunctival inserts have long been investigated as a means of extending ocular residence and thin film inserts offer a more adaptable solid dosage form that may provide a defined drug-containing unit, prolonged local exposure and hydration-dependent dissolution or transformation within the conjunctival sac. Clinical translation remains limited by substantial variability in formulation design, manufacturing control and performance testing. This review critically evaluates the manufacture and characterisation of ocular anti-infective thin film inserts, with the aim of identifying the principal factors that determine reproducibility, interpretability and progression beyond formulation feasibility. Film architecture, polymer selection and drug-loading strategy are considered in relation to the physicochemical characteristics of the active pharmaceutical ingredient and the intended behaviour of the finished insert. Solvent casting remains the most extensively investigated manufacturing approach, while extrusion, electrospinning and additive manufacturing broaden the available processing options. Across these methods, incomplete specification of material and process variables frequently restricts comparison and reproducibility. Testing procedures are similarly heterogeneous and often assess individual attributes without establishing how the finished insert performs under conditions relevant to conjunctival administration. Particular limitations concern dosage-unit uniformity, hydration and matrix transformation, drug-release models and the interpretation of antimicrobial activity. Progression towards clinically relevant products will require indication-led development in which manufacturing control, pharmaceutical quality, ocular compatibility and biorelevant performance evaluation are considered as connected elements. This approach may provide a stronger basis for determining whether the potential advantages of ocular anti-infective thin film inserts can be translated into reproducible and clinically useful dosage forms.