Intraocular penetration of tri-tetracyclines after parenteral and subconjunctival administration

Ocular penetration of oral doxycycline in the horse

OBJECTIVE

To investigate intraocular penetration of orally administered doxycycline in the normal equine eye and to compare intraocular and serum doxycycline concentrations. Procedures Six mares were administered doxycycline at 10 mg/kg every 12 h by nasogastric tube for 5 days. Blood, aqueous, and vitreous samples were collected on days 1 and 5. All samples were assayed for doxycycline concentrations. Aqueous and vitreous samples were also assayed for protein quantitation.

RESULTS

Doxycycline was rapidly absorbed after the first dose (T(max) value of 1.42 +/- 1.28 h); and elimination of doxycycline occurred slowly (median t(1/2) = 10.88 h). Doxycycline could not be detected in the aqueous on days 1 and 5, nor could it be detected in the vitreous on day 1. On day 5, the mean vitreous doxycycline concentration was 0.17 +/- 0.04 microg/mL at 2 h after drug administration.

CONCLUSIONS

Repeated oral administration of doxycycline in the horse resulted in steady state serum concentrations of < 1 microg/mL; however, it did not result in appreciable concentrations of drug in the aqueous and vitreous in normal eyes.

Herpes simplex keratitis

This article reviews the current concepts for the diagnosis and treatment of Herpes simplex keratitis and its complications, discussing characteristics of the virus, the prevalence of the disease, chemical and clinical differentiation between Types I and II Herpesvirus hominis, and the many clinical presentations of Type I disease. The antiviral agents commonly in use are reviewed, covering the historical development of the drugs, indications for their use and the associated toxic and untoward reactions. An outline for the medical treatment of the different forms of Herpes simplex keratitis is given, as well as the indications for surgical intervention in the treatment of the disease. The surgical complications and results following keratoplasty are discussed.