Tissue concentration of dimetridazole in laying hens.

After laying hens had been dosed orally with dimetridazole (DMZ) for 3 days (50 and 250 mg/kg body weight (b.w.)) or intramuscularly, also for 3 days (50 mg/kg b.w.), the residues were determined in serum, liver, breast and thigh muscle by liquid chromatography. The limit of determination was 0.01 micrograms/g. The maximum concentration of DMZ was found at 1 h following application. After oral doses (50 and 250 mg/kg b.w.) no residues were found in muscle (breast and thigh) at 48 and 72 h, respectively. After intramuscular injection, residues in thigh muscle were below 0.01 micrograms/g at 72 h but breast muscle (injection site) still had concentrations above this level. Bioavailability (F > 80%) and some pharmacokinetic parameters were determined. The elimination half-lives from serum were 2.56h and 2.69h, after both oral doses, respectively, and 2.88 h after intramuscular application.

Pharmacokinetics and anti-trichomonal efficacy of a dimetridazole tablet and water-soluble powder in homing pigeons (Columba livia).

The anti-trichomonal efficacy and pharmacokinetics of dimetridazole were investigated in the homing pigeon (Columba livia). Dimetridazole was formulated for drinking water medication and as a prolonged-release tablet. To suppress a Trichomonas gallinae infection successfully, medicated drinking water containing dimetridazole (400 mg/L) had to be administered for at least 3 days. A two-day treatment with a dimetridazole tablet (20 mg/tablet) in fasted, as well as in fed, pigeons was shown to be ineffective. After intravenous administration of 20 mg dimetridazole, the drug plasma concentration-time profile fitted a one-compartment open model with a mean half-life of 3.9 h. The absolute bioavailability of the tablet in fasted pigeons was 83.8%. The bioavailability of the tablet administered with food was reduced by 20%. Dimetridazole was rapidly metabolised to (1-methyl-5-nitroimidazol-2-yl) methanol.

Dimetridazole residues in pork tissue. II. Application of liquid chromatographic method to monitor elimination of drug and its major metabolite.

A study was conducted to monitor the elimination of dimetridazole (DMZ) and its major metabolite 2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI) in swine plasma and tissue, using a liquid chromatographic method with electrochemical detector sensitive to 0.5 ppb. The study consisted of 2 experiments. In the preliminary experiment, one young female piglet was fed medicated ration containing 125 ppm dimetridazole (DMZ) for 2 weeks, followed by a withdrawal period using regular ration for 5 days. Another, control, piglet was given regular diet throughout. Plasma concentrations of DMZ and its most important residue, HMMNI, were measured daily at 2 h after the morning feeding and, on days 8 and 15, several times during the day. The 2 h concentrations after 3 days loading ranged from 47 to 77 ppb for DMZ and 424 to 1081 ppb for HMMNI. A daily cycle in the plasma levels was seen for both substances. Upon withdrawal of medication, elimination of drug and metabolite was biexponential with a terminal half-life of 6.7 h. In the second experiment, 5 piglets were medicated as above and slaughtered 2, 6, 12, 25, and 49 h after withdrawal of the medication; the concentration of DMZ and HMMNI was measured in plasma, muscle, kidney, and liver. DMZ in the plasma amounted to 22 and 1.8 ppb at 2 and 6 h, while HMMNI declined from 535 ppb at 2 h to 0.75 ppb at 25 h. Most values for both substances found in muscle were close to those in the plasma; in kidney they amounted to 9-17% of the plasma levels.(ABSTRACT TRUNCATED AT 250 WORDS)