Metabolites of furazolidone in urine of chickens.
Colostomized chickens were medicated with single oral doses of the antibacterial furazolidone. An average of 7.5 ± 3.0% of the dose was excreted in the urine within 12 hr. as compounds measured by a procedure in which they react to form 5-nitrofurfural phenylhydrazone. Chromatographic analysis delected four metabolites containing a furan ring. Only one metabolite reacted to form 5-nitrofurfural phenylhydrazone. Elimination of the metabolites with a furan ring was complete in 12 hr. Only traces of furazolidone were detected by the chromatographic procedure.
Furazolidone concentrations in plasma, milk and some tissues of Nubian goats.
The concentrations of furazolidone (FZ) in plasma and milk were measured in goats treated orally with the drug at a dose of 10 mg kg-1 daily for 5 days. The maximum plasma concentrations obtained were 1.57 +/- 0.52 micrograms ml-1 (n = 5) 8 h after the first dose, and 2.13 +/- 0.11 micrograms ml-1 (n = 4) 6 h after the fifth dose. The maximum milk concentration was 0.88 +/- 0.32 micrograms ml-1 (n = 4) 8 h following the administration of a single dose. Using a colorimetric method, FZ was not detectable in goats' liver or muscle after the recommended therapeutic dose (10 mg kg-1, 5 days). However, using an HPLC method, the drug was detected 24 h after the treatment in the gluteal muscle and liver at concentrations of 0.26 +/- 0.01 microgram g-1 (n = 5) and 0.10 +/- 0.02 microgram g-1 (n = 5), respectively. The drug concentrations decreased significantly (P less than 0.05-0.01) at 3, 5 and 7 days after treatment, and no measurable concentrations were found after 10 days.
Laboratory studies with nitrofurantoin. Relationship between crystal size, urinary excretion in the rat and man, and emesis in dogs.
Studies were conducted relating the effect of varying the crystal size of orally administered nitrofurantoin on absorption and urinary excretion in the rat and man and emesis in dogs. It was discovered that there is an optimal average crystal size of about 150 mesh, or its equivalent surface area falling between 80 to 200 mesh limits, which reduces emesis while still permitting ample urinary excretion for efficacy.