ABSTRACT
Eye drops, unlike cosmetics or chemicals, only cause minor irritations which often prove difficult to objectively observe and assess. A specular microscope with pachymeter is used to measure corneal thickness, and to examine and photograph corneal endothelium in ocular tolerance studies in the rabbit. Rabbits were instilled 5 times a day for 16 days with BKC aqueous solution, 0.01% or 0.1% and subjected after anaesthesia to 4 corneal inspections (before treatment, 7th and 14th days of treatment, 5th day after treatment). Only the 0.1% concentration provoked an increase in corneal thickness. Thickening progressed during the treatment period (5.3% on day 7, 26% on day 14) and strongly regressed 5 days after treatment stopped (3%). A slit lamp examination revealed very light or light corneal opacities, but the correlation between corneal thickening ratio and opacity was poor (r = 0.62).
Subject(s)
Benzalkonium Compounds/toxicity , Cornea/pathology , Animals , Cornea/drug effects , Corneal Opacity/chemically induced , Corneal Opacity/pathology , Drug Tolerance , Endothelium, Corneal/drug effects , Endothelium, Corneal/pathology , Evaluation Studies as Topic , Female , Male , Rabbits , Random Allocation , Vision Tests/instrumentationABSTRACT
Data on the pharmacokinetics of doxycycline in dogs and cats are reported. Doxycycline was given orally in the form of palatable tablets of Ronaxan. Tablets of 100 mg of doxycycline (as hyclate) were used in dogs, whereas cats were given tablets of 20 mg. The doses administered were 10 mg/kg in both species. The pharmacokinetics of doxycycline in dogs and cats were compared with those obtained in man (at a dosage of 3 mg/kg/day). It is concluded that a dosage of 10 mg/kg/day of doxycycline is required to obtain effective plasma concentrations in dogs and cats for 24 hours, when this dose is administered once daily.