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Objective

To determine the pharmacokinetics of gentamicin sulfate in healthy llamas after IV administration of a single bolus and after repeated parenteral administration.

Design

Prospective clinical trial.

Animals

19 clinically normal, adult male llamas for the single-dose trial and 10 of the 19 llamas for the multiple-dose trial.

Procedure

In the first trial, llamas were given gentamicin (5 mg/kg of body weight, IV) as a single bolus, and serum gentamicin concentration was monitored over the next 48 hours. 2 months later, llamas were given gentamicin (2.5 mg/kg) IV for the first day, then IM every 8 hours for 7 days. Serum gentamicin concentration and indices of renal function and damage were monitored during the 7 days.

Results

There were no significant dose- or time-related differences in clearance of the drug; volume of distribution; apparent coefficients of the distribution and elimination phases, α and β, respectively; mean residence time; or distribution (t½α) and elimination phase (tt/2β) half-lives. The 5 mg/kg IV kinetic study revealed t½β, of 14.5 ± 5.06 minutes and t½β of 166 ± 20.5 minutes. The 2.5 mg/kg IV kinetic study revealed t½α of 17.7 ± 6.59 minutes and t½β of 165 ± 40.3 minutes. Peak serum gentamicin concentration averaged 10.10 μg/ml in the multiple-dose trial, and trough concentration averaged 1.50 μg/ml.

Conclusions

Dose effects were not observed for gentamicin clearance, volume of distribution, or half-lives. Multiple dosing at 2.5 mg/kg every 8 hours does not appear to cause renal impairment in healthy llamas.

Clinical Relevance

Gentamicin pharmacokinetic variables in llamas appear to resemble those in other ruminant species. (Am J Vet Res 1996;57:1193–1199)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To compare results for sodium and potassium determination on llama urine, using flame emission spectrophotometry (flame photometry), atomic absorption spectrophotometry (AAS), indirect ion-selective electrode potentiometry (ISE), and direct ISE.

Design

Llama urine samples encompassing a wide range of electrolyte concentrations were analyzed for sodium and potassium concentrations, using 4 analytical methods, and results were compared statistically to assess correlation, bias, and potential interferents.

Sample Population

10 healthy male llamas.

Procedure

Urine specimens were obtained from llamas fitted with urine collection apparatus at defined intervals over a 24-hour period. Urine samples were centrifuged, and supernatants were frozen at −70 C until analysis. Analytical procedures were done, using standard laboratory protocols. Means, correlation coefficients, and bias were calculated, and differences were evaluated by ANOVA, with significance set at P < 0.05.

Results

There was strong correlation and good agreement among sodium values obtained by flame photometry, AAS, and indirect ISE. Sodium values obtained by use of direct ISE correlated poorly with other methods; urine is not an acceptable specimen for this method. Only AAS and indirect ISE had good correlation (r > 0.9) for potassium values. Data did not suggest presence of a potassium chelator in llama urine; urine potassium values measured by indirect ISE were significantly higher (by 150 to 200 mmol/L) than those measured by other methods.

Clinical Relevance

Urine electrolyte analysis in llamas resulted in less agreement between methods than is generally found for serum. Data collection for patient monitoring or research analysis should be restricted to a single method to avoid differences in results attributable to analytical variance. (Am J Vet Res 1996;57:25-30

Free access
in American Journal of Veterinary Research

SUMMARY

Indices of renal function and damage were measured in 12 healthy male adult llamas fed a diet of mixed alfalfa/grass hay (mixed hay) and water ad libitum. Using a collection bag fitted over the preputial area, urine samples were collected at 6, 12, and 24 hours. Serum samples were obtained concurrently to determine endogenous creatinine clearance (cl), total (te) and fractional excretion (fe) of electrolytes (Na, K, Cl, P), electrolyte cl, urine and serum osmolality, urine enzyme activities (γ-glutamyltransferase and N-acetyl-β-D-glucosaminidase), and urine protein concentration. Urine production was quantified. Three months later, 10 of the 12 llamas were fed a grass hay diet and water ad libitum. Similar samples were obtained, and similar measurements were made.

Urine production was higher when the llamas were fed the mixed hay diet. Total urine volume for llamas fed mixed hay ranged from 628 to 1,760 ml/24 h, with a median of 1,307.5 ml/24 h, compared with a range of 620 to 1,380 ml/24 h and a median of 927.50 ml/24 h for llamas fed grass hay. Median urine osmolality was higher in llamas fed mixed hay (1,906 mOsm/kg of body weight, with a range of 1,237 to 2,529 mOsm/kg), compared with llamas fed grass hay (1,666 mOsm/kg, with a range of 1,163 to 2,044 mOsm/kg). Creatinine cl did not vary significantly over time for either diet. Median creatinine cl was higher for llamas fed mixed hay, compared with llamas fed grass hay-0.78 ml/min/kg, with a range of 0.20 to 1.83 ml/min/kg vs 0.45 ml/min/kg, with a range of 0.13 to 3.17 ml/min/kg. Clearances for K and a varied significantly among the periods. However, median Cl for Na and P did not vary over time for either diet. Overall values for these electrolytes in llamas fed mixed hay and grass hay diets were: clNa, 0.001 and 0.002 ml/min/kg and clP, 0.0006 and 0.0004 ml/min/kg, respectively. The FE rates of K, cl, and P did not vary significantly over time for either diet. Median respective FE for these electrolytes in the llamas fed mixed hay and grass hay diets include: feK, 84.90 and 63.10%; feCl, 0.85 and 1.30%; and feP, 0.10 and 0.10%. Fractional excretion of Na varied over time for both diets and could not be expressed accurately as an overall median. Median respective te of electrolytes for llamas fed the mixed hay and grass hay diets were: teNa, 0.007 and 0.03 mEq/kg/h; teCl, 0.04 and 0.06 mEq/kg/h; and teP, 0.0002 and 0.00 mg/kg/h; teK varied significantly (P < 0.05) over time for both diets. Urine γ-glutamyltransferase activity changed significantly (P < 0.05) over time. Urine N-acetyl-β-D-glucosaminidase activity was influenced by an interaction between diet and time. Median urine protein concentration was 26.0 mg/dl, with a range of 11.0 to 73.0 mg/dl for llamas fed mixed hay, and was 28.0 mg/dl, with a range of 16.0 to 124.0 mg/dl for Hamas fed grass hay.

Free access
in American Journal of Veterinary Research