Intramuscular and oral disposition of enrofloxacin in African grey parrots following single and multiple doses.

The intramuscular (IM) and oral (PO) disposition of enrofloxacin, a new fluoroquinolone antimicrobial drug, were evaluated in African grey parrots. Peak enrofloxacin concentration, mean (+/- SEM), at 1 h following a 15-mg/kg IM dose was 3.87 (+/- 0.27) micrograms/ml and declined with a mean residence time of 3.05 h. Peak enrofloxacin plasma concentrations at 2 to 4 h following oral doses of 3, 15, and 30 mg/kg were 0.31 (+/- 0.11), 1.12 (+/- 0.11), and 1.69 (+/- 0.23) micrograms/ml, respectively, and declined with a mean residence time of 3.44-5.28 h. The relative bioavailability of the 15-mg/kg oral dose was 48%. An equipotent metabolite, ciprofloxacin, was detected in plasma at concentrations ranging from 3 to 78% of those of enrofloxacin. Enrofloxacin concentrations and area under the curve were significantly lower, the mean residence time significantly shorter and the ciprofloxacin/enrofloxacin ratios higher, following 10 days of oral treatment at 30 mg/kg every 12 h. Following 10 days of treatment, no significant biochemical changes were noted; however, polydipsia and polyuria occurred in treated birds, but resolved quickly upon discontinuation of enrofloxacin administration. These studies indicate that a rational starting dose for enrofloxacin in psittacines (7.5-30 mg/kg BID) should be higher than those in other domestic animals.

Plasma concentrations of enrofloxacin in African grey parrots treated with medicated water.

Plasma concentrations of enrofloxacin were measured four times during a 7-day treatment period in African grey parrots that were fed with enrofloxacin-medicated drinking water. Water medicated at doubling doses of 0.09, 0.19, 0.38, 0.75, 1.5, and 3.0 mg/ml achieved mean concentrations (+/- SEM) of 0.10 (+/- 0.05), 0.12 (+/- 0.05), 0.12 (+/- 0.03), 0.15 (+/- 0.05), 0.30 (+/- 0.11), and 0.20 (+/- 0.06) micrograms/ml, respectively. A portion of the administered enrofloxacin was metabolized to an equipotent metabolite, ciprofloxacin. Mean ciprofloxacin concentrations paralleled enrofloxacin concentrations but were lower, ranging from 0.04 to 0.27 micrograms/ml. Acceptance of medicated water was adequate at lower doses; however, at doses of 1.5 and 3.0 mg/ml, acceptance was unsatisfactory, and mean weight loss in these groups was significantly higher than the control group. Based on the concentrations achieved in these preliminary trials and the susceptibility patterns of gram-negative bacteria isolated from psittacine birds, drinking water medicated with enrofloxacin at 0.19-0.75 mg/ml might be effective for treating highly susceptible gram-negative bacterial infections in African grey parrots.

Potential use of long-acting injectable oxytetracycline for treatment of chlamydiosis in Goffin's cockatoos.

To determine the potential use of parenteral therapy in the treatment of chlamydiosis in psittacine birds, the disposition and toxicity of a long-acting oxytetracycline (OTC) was evaluated in Goffin's cockatoos. Following intramuscular and subcutaneous administration of 50 to 100 mg/kg body weight, plasma OTC concentrations of 7 to 15 micrograms/ml were obtained 3 hr following injection and declined with a terminal half-life between 8.9 to 14.7 hr. Plasma concentrations in excess of 1.0 microgram/ml were maintained for 48 to 68 hr. Multiple-dose treatment of 100 mg/kg subcutaneously every 3 days for 30 days caused focal necrosis and scabs at the injection site but no other clinical or serological evidence of adverse effects. Long-term treatment did not result in accumulation or alteration in the disposition of OTC. Based on this study, a dosage regimen of 50 to 100 mg/kg of OTC subcutaneously every 2-3 days would safely maintain plasma concentrations in excess of 1.0 microgram/ml and could potentially be used as an alternative to medicated feeds or daily oral dosing regimens for the treatment of chlamydiosis in psittacine birds.