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Biomedical subjects

G M Conzelman

Publications and source records attributed to G M Conzelman.

At least 19 recordsLinked to original sources
PubMed1991

Pharmacokinetic properties of enrofloxacin in rabbits.

The pharmacokinetic properties of the fluoroquinolone antimicrobial enrofloxacin were studied in New Zealand White rabbits. Four rabbits were each given enrofloxacin as a single 5 mg/kg of body weight dosage by IV, SC, and oral routes over 4 weeks. Serum antimicrobial concentrations were determined for 24 hours after dosing. Compartmental modeling of the IV administration indicated that a 2-compartment open model best described the disposition of enrofloxacin in rabbits. Serum enrofloxacin concentrations after SC and oral dosing were best described by a 1- and 2-compartment model, respectively. Overall elimination half-lives for IV, SC, and oral routes of administration were 2.5, 1.71, and 2.41 hours, respectively. The half-life of absorption for oral dosing was 26 times the half-life of absorption after SC dosing (7.73 hours vs 0.3 hour). The observed time to maximal serum concentration was 0.9 hour after SC dosing and 2.3 hours after oral administration. The observed serum concentrations at these times were 2.07 and 0.452 micrograms/ml, respectively. Mean residence times were 1.55 hours for IV injections, 1.46 hours for SC dosing, and 8.46 hours for oral administration. Enrofloxacin was widely distributed in the rabbit as suggested by the volume of distribution value of 2.12 L/kg calculated from the IV study. The volume of distribution at steady-state was estimated at 0.93 L/kg. Compared with IV administration, bioavailability was 77% after SC dosing and 61% for gastrointestinal absorption. Estimates of predicted average steady-state serum concentrations were 0.359, 0.254, and 0.226 micrograms/ml for IV, SC, and oral administration, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1985

Effects of ambient temperature on the half-life and dosage regimen of amikacin in the gopher snake.

Eight gopher snakes were given amikacin (5 mg/kg of body weight IM) and were housed at ambient temperatures of 25 C or 37 C. Snakes housed at 37 C had a larger volume of distribution, and a more rapid body clearance of amikacin while the apparent half-life was not changed significantly. The minimum inhibitory concentrations of amikacin against isolated snake pathogens were determined at both temperatures. Bacteria were twice as sensitive at 37 C than at 25 C. The data indicated that amikacin should be given IM at a dose schedule of 5 mg/kg (loading dose) followed by 2.5 mg/kg every 72 hours, and that snakes should be housed near the high end of their preferred optimum ambient temperature during treatment.

Amikacin↗
PubMed1981

Urine concentrations of gentamicin, tobramycin, amikacin, and kanamycin after subcutaneous administration to healthy adult dogs.

Gentamicin, tobramycin, amikacin, and kanamycin were given subcutaneously in separate trials to healthy adult dogs of both sexes. Daily dosage levels were as follows: gentamicin, 6.6 mg/kg of body weight; tobramycin, 3 mg/kg; amikacin, 15 mg/kg; and kanamycin, 11 mg/kg. Gentamicin, tobramycin, and amikacin were given in divided doses of 8-hour intervals for 5 consecutive 8-hour periods, whereas kanamycin was given in divided doses at 12-hour intervals for 4 consecutive 12-hour periods. Mean 8-hour urine concentrations +/- 1 SD were gentamicin, 107 +/- 33 microgram/ml, tobramycin, 66 +/- 39 microgram/ml; and amikacin, 342 +/- 153 microgram/ml. Mean urine concentrations (+/- 1 SD) for kanamycin were 473 +/- 306 microgram/ml in urine collected between 0 and 6 hours after dosing and 63 +/- 47 microgram/ml in urine collected 6 to 12 hours after dosing.

Amikacin↗
PubMed1980

Urine concentrations of five penicillins following oral administration to normal adult dogs.

Penicillin G, penicillin V, ampicillin, hetacillin, and amoxicillin were administered separately per os to clinically normal adult dogs of both sexes at 8-hour intervals for five consecutive 8-hour test periods. All urine was collected from each dog during each test period and was assayed for antimicrobial activity. Daily doses of the antimicrobics used were as follows: penicillin G, 110,000 U/kg of body weight; penicillin V, 77 mg/kg; ampicillin, 77 mg/kg; hetacillin, 77 mg/kg; and amoxicillin, 33 mg/kg. Mean 8-hour urine concentrations (+/- 1 SD) were as follows: penicillin G, 294 +/- 210 U/ml; penicillin V, 148 +/- 98 micrograms/ml; ampicillin, 309 +/- 55 micrograms/ml; hetacillin, 300 +/- 156 micrograms/ml, and amoxicillin 201 +/- 93 micrograms/ml. Among the three antimicrobials administered at the same daily dosage, ie, penicillin V, ampicillin, and hetacillin, the mean urine concentrations of penicillin V were significantly lower (P < 0.01) than were concentrations of ampicillin and hetacillin. The mean urine concentrations of the latter two did not differ significantly (P > 0.05).

Administration, Oral↗
PubMed1980

Urine concentrations of chloramphenicol, tetracycline, and sulfisoxazole after oral administration to healthy adult dogs.

Chloramphenicol, tetracycline, and sulfisoxazole were administered (orally) in separate trials to clinically healthy adult dogs of both sexes at 8-hour intervals for five consecutive 8-hour test periods. All urine was collected from each dog during each test period and an aliquot from each period was assayed for antimicrobial activity. Daily doses of the antimicrobics were as follows: chloramphenicol 99 mg/kg of body weight, tetracycline 55 mg/kg, and sulfisoxazole 66 mg/kg. Mean 8-hour urine concentrations (+/- 1SD) for chloramphenicol were 124 +/- 40 micrograms/ml; for tetracycline, 138 +/- 65 micrograms/ml; and for sulfisoxazole, 1,466 +/- 832 micrograms/ml. The mean 8-hour percentages of the doses of drug eliminated in active form in the urine were 6.3 +/- 2.6% for chloramphenicol, 11.2 +/- 2.0% for tetracycline, and 68.5 +/- 2.1% for sulfisoxazole.

Administration, Oral↗
PubMed1979

Furosemide enhancement of experimental gentamicin nephrotoxicity: comparison of functional and morphological changes with activities of urinary enzymes.

Dogs were given gentamicin (10 mg/kg) intramuscularly every 8 hr for 10 days. Levels of serum creatinine rose by day 6 (0.91 +/- 0.08 vs. 0.75 +/- 0.02 mg/dl for controls, P less than 0.05) and of blood urea nitrogen by day 8 (24.3 +/- 4.80 vs. 16.1 +/- 0.90 mg/dl for controls, P less than 0.05). Gentamicin nephrotoxicity occurred earlier and was more marked when furosemide (2 mg/kg) was added: the level of serum creatinine by day 6 was 1.62 +/- 0.25 mg/dl (P less than 0.05), and the level of blood urea nitrogen by day 8 was 181 +/- 23.5 mg/dl (P less than 0.01). Elevations in the activities of the urinary enzymes beta-glucuronidase, N-acetyl-beta-glucosaminidase, and muramidase preceded rises in levels of serum creatinine and blood urea nitrogen. Examination of serial percutaneous renal biopsy specimens showed that gentamicin administration was associated with hyaline droplet degeneration, lysosomal changes, and, later, cell necrosis (primarily of the proximal tubules). Changes in renal morphology were more severe and occurred earlier when furosemide was administered concomitantly. In summary, furosemide enhanced gentamicin nephrotoxicity. Enzymuria was an early sign of gentamicin nephrotoxicity.

Acetylglucosaminidase↗
PubMed1978

Pharmacokinetics of penicillin G in the turkey.

Parmacokinetics of penicillin G was determined for the turkey. The study was prompted by the isolation of a sulfonamide-resistant strain of Pasteurella multocida from tissues of turkeys involved in an outbreak of fowl cholera and the subsequent discovery that little pharmacologic information was available concerning other antimicrobial agents in that species. Penicillin G was chosen for study because P multocida is susceptible to this antibiotic. The elimination of the antibiotic followed first-order kinetics, and the half-life was found to be 0.5 hours. Parenteral administration of benzathine-procaine penicillin G resulted in higher concentrations, which persisted for longer periods than did procaine or potassium salts of the antibiotic.

Animals↗