We would like to thank Ilhan et al. for the interest in our study entitled “The beneficial effects of doxycycline, an inhibitor of matrix metalloproteinases, on sulfur mustard-induced ocular pathologies depend on the injury stage”.Citation1
We evaluated topical doxycycline for sulfur mustard-induced ocular injuries since it is the preferable route of administration for the eyes, although there is no commercially available topical doxycycline yet. During the acute phase (0–7 days), characterized by severe inflammation and corneal erosions, topical doxycycline treatment reduced the inflammation and did not delay the re-epithelization compared to the non-treated eyes.Citation1 Nevertheless there is data suggesting that orally administered doxycycline reaches the eyes,Citation2–5 and it was shown to be beneficial in ocular pathologies.Citation6–8 Based on this data and the unavailability of commercial topical treatment we evaluated the effect of oral doxycycline in our rabbit model for sulfur mustard induced ocular injury as well, but the results were beyond the scope of our article.Citation1 The results showed that during the acute phase, the beneficial effect of oral doxycycline (30 mg/kg × 1/day × 6 days) was not consistent. Regarding the late phase, prolonged oral treatment (30 mg/kg × 1/day × 8 weeks) reduced the incidence and the extent of the injury (incidence of 50–87% versus 17–28% in the non-treated group versus doxycycline-treated group, respectively).
In summary, we found that oral doxycycline was beneficial in reducing the severity of sulfur mustard-induced ocular injury, mainly the late injury. In case of multi-organ injuries following whole body exposure to sulfur mustard, more research is needed to evaluate the effect of oral doxycycline.
Declaration of interest
The authors state that they have no financial or conflicts of interest to disclose.
References
- Horwitz V, Dachir S, Cohen M, Gutman H, Cohen L, Fishbine E, et al. The beneficial effects of doxycycline, an inhibitor of matrix metalloproteinases, on sulfur mustard-induced ocular pathologies depend on the injury stage. Curr Eye Res 2014;39:803–812
- Krause U, Raunio V, Mustonen E. Aqueous humor penetration of alpha-deoxyoxytetracycline (doxycycline) in man. Am J Ophthalmol 1972;74:77–79
- Zachariah S. Effective penetration of doxycycline into the serum and aqueous humor. Ann Ophthalmol 1984;16:672–674
- Salminen L. Penetration of ocular compartments by tetracyclines. II. An experimental study with doxycycline. Albrecht Von Graefes Arch Klin Exp Ophthalmol 1977;204:201–207
- Smith VA, Khan-Lim D, Anderson L, Cook SD, Dick AD. Does orally administered doxycycline reach the tear film? Br J Ophthalmol 2008;92:856–859
- Dan L, Shi-long Y, Miao-li L, Yong-ping L, Hong-jie M, Ying Z, Xiang-gui W. Inhibitory effect of oral doxycycline on neovascularization in a rat corneal alkali burn model of angiogenesis. Curr Eye Res 2008;33:653–660
- Ralph RA. Tetracyclines and the treatment of corneal stromal ulceration: a review. Cornea 2000;19:274–277
- Perry HD, Hodes LW, Seedor JA, Donnenfeld ED, McNamara TF, Golub LM. Effect of doxycycline hyclate on corneal epithelial wound healing in the rabbit alkali-burn model. Preliminary observations. Cornea 1993;12:379–382