Fundamental Aspects and Relevance of Components in Antihistamine Eye Drops.

Ocular allergy covers a series of immune-allergic inflammatory diseases of the ocular surface, with different degrees of involvement and severity. These pathologies are caused by a variety of IgE- and non-IgE-mediated immune mechanisms and may involve all parts of the external eye, including the conjunctiva, cornea, eyelids, tear film, and commensal flora. The most frequent is allergic conjunctivitis, a condition with different clinical forms that are classified according to the degree of involvement and the presence or absence of proliferative changes in the palpebral conjunctiva, associated atopic dermatitis, and mechanical stimuli by foreign bodies, including contact lenses. Treatment guidelines for allergic conjunctivitis propose a stepwise approach that includes medications for both ophthalmic and oral administration depending on symptom severity, allergic comorbidities, and degree of control. In the case of antihistamines, eye drops are the most prescribed ophthalmic formulations. To avoid disrupting the delicate balance of the ocular surface, topical ophthalmic medications must be well tolerated. The primary aim of this article is to review the physicochemical characteristics and other features of excipients (preservative agents, buffers, pH adjusters, viscosity enhancers, wetting agents or cosolvents, antioxidants, tonicity adjusters, and osmo-protectants) and active compounds (ocular antihistamines) that must be considered when developing formulations for ophthalmic administration of antihistamines. We also provide a brief overview of antihistamine eye drops that could be of interest to professionals treating ocular allergy and encourage the use of preservative-free formulations when possible.

Fundamental Aspects and Relevance of Components in Antihistamine Eye Drops

Ocular allergy covers a series of immune-allergic inflammatory diseases of the ocular surface, with different degrees of involvement and severity. These pathologies are caused by a variety of IgE- and non–IgE-mediated immune mechanisms and may involve all parts of the external eye, including the conjunctiva, cornea, eyelids, tear film, and commensal flora. The most frequent is allergic conjunctivitis, a condition with different clinical forms that are classified according to the degree of involvement and the presence or absence of proliferative changes in the palpebral conjunctiva, associated atopic dermatitis, and mechanical stimuli by foreign bodies, including contact lenses. Treatment guidelines for allergic conjunctivitis propose a stepwise approach that includes medications for both ophthalmic and oral administration depending on symptom severity, allergic comorbidities, and degree of control. In the case of antihistamines, eye drops are the most prescribed ophthalmic formulations.To avoid disrupting the delicate balance of the ocular surface, topical ophthalmic medications must be well tolerated. The primary aim of this article is to review the physicochemical characteristics and other features of excipients (preservative agents, buffers, pH adjusters, viscosity enhancers, wetting agents or cosolvents, antioxidants, tonicity adjusters, and osmo-protectants) and active compounds (ocular antihistamines) that must be considered when developing formulations for ophthalmic administration of antihistamines. (AU)

El término alergia ocular engloba un conjunto de enfermedades inflamatorias de la superficie ocular de origen inmunoalérgico, con distintos niveles de afectación y gravedad. Están causadas por una variedad de mecanismos inmunes, mediados o no por IgE y pueden involucrar a todos los componentes de la superficie ocular, incluyendo conjuntiva, córnea, párpados, película lagrimal y flora comensal. De estos trastornos, el más común es la enfermedad alérgica conjuntival. En su clasificación se incluyen distintas formas clínicas según el nivel de afectación y la presencia o no de cambios proliferativos en la conjuntiva palpebral, asociación con dermatitis atópica, y estímulos mecánicos por cuerpo extraño, incluyendo lentes de contacto. Las guías terapéuticas para el tratamiento de la conjuntivitis alérgica proponen un tratamiento escalonado, tanto en administración oftálmica como oral, en función de la gravedad de los síntomas, las comorbilidades alérgicas del paciente y el logro de un control adecuado. En general, cuando los síntomas oculares predominan o se presentan de forma aislada, se prefieren las formulaciones oftálmicas de antihistamínicos de administración tópica y, dentro de estas, los colirios. Para mantener el equilibrio de la superficie ocular, las formulaciones tópicas oftálmicas deben mostrar una buena tolerancia. El objetivo principal de este artículo es revisar las características y otras propiedades de los excipientes (conservantes, tampones, agentes para ajustar el pH, viscosizantes, agentes humectantes o cosolventes, antioxidantes, isotonizantes y osmoprotectores) y sustancias activas (antihistamínicos oculares) que deben ser considerados cuando se formulan los preparados de administración tópica oftálmica de agentes antihistamínicos. (AU)