Study: Claritin vs. Elestat in the drying contest

An open-label, investigator-masked, crossover study of the ocular drying effects of two antihistamines, topical epinastine and systemic loratadine, in adult volunteers with seasonal allergic conjunctivitis.
Clin Ther. 2007 Apr;29(4):611-6.
Ousler GW, Workman DA, Torkildsen GL.

CONCLUSIONS: These healthy adult volunteers with a history of seasonal allergic conjunctivitis had no clinical signs of ocular drying after 4 days of twice-daily treatment with topical epinastine. After 4 days of once-daily dosing, systemic loratadine was associated with clinical signs of ocular dryness, including decreased tear volume and tear flow. Use of loratadine was also associated with an increase in global fluorescein staining, indicating an increase in ocular surface damage.

TRANSLATION:
Elestat eyedrops twice a day did not cause visible drying, but Claritin (taken internally) once a day did.

Interesting....