Minimally invasive microneedles for ocular drug delivery.

Anterior and posterior segment eye diseases are highly challenging to treat, due to the barrier properties and relative inaccessibility of the ocular tissues. Topical eye drops and systemically delivered treatments result in low bioavailability. Alternatively, direct injection of medication into the ocular tissues is clinically employed to overcome the barrier properties, but injections cause significant tissue damage and are associated with a number of untoward side effects and poor patient compliance.

Microneedle-mediated intradermal nanoparticle delivery: Potential for enhanced local administration of hydrophobic pre-formed photosensitisers.

Introduction: To date, 5-aminolevulinic acid (ALA) has been the most widely used agent in topical photodynamic therapy (PDT). However, owing to the poor penetration of ALA into skin, ALA-PDT is inappropriate for difficult-to-treat deep skin neoplasias, such as nodular basal cell carcinoma. An alternative strategy to ALA-PDT is to use pre-formed photosensitisers, which can be activated at longer wavelengths, facilitating enhanced light penetration into skin.