Plasma pharmacokinetics of intravenous and intramuscular furosemide in the camel (Camelus dromedarius)

Pharmacokinetics of furosemide in goats following intravenous, intramuscular, and subcutaneous administrations

Furosemide, a loop diuretic drug, is recommended for use in cases of edema, ascites, congestive heart failure, toxicosis, and acute renal failure in goats. However, its pharmacokinetics and bioavailability have not been reported yet in this species. The aim of this study was to determine the pharmacokinetics and bioavailability of furosemide in goats following intravenous (IV), intramuscular (IM), and subcutaneous (SC) administrations at a dose of 2.5 mg/kg. Six clinically healthy goats received furosemide by each route in a three-way crossover pharmacokinetic design with a 15-day washout period between administrations. The plasma concentrations of furosemide were determined using the high-performance liquid chromatography-UV method and analyzed by non-compartmental analysis. The elimination half-life following IV, IM, and SC administration was 0.71 (0.67-0.76) h, 0.69 (0.61-0.74) h, and 0.70 (0.67-0.79) h, respectively. The volume of distribution at steady state and total clearance for the IV route were 0.17 (0.16-0.19) L/kg and 0.30 (0.27-0.33) L/h/kg, respectively. The peak plasma concentrations of furosemide following IM and SC administrations were 11.19 (10.33-11.95) and 6.49 (5.92-7.00) μg/ml at 0.23 (0.16-0.25) and 0.39 (0.33-0.42) h, respectively. The bioavailability was 109.84 (104.92-116.99)% and 70.80 (55.77-86.67)% for the IM and SC routes, respectively. The pharmacokinetics of furosemide following the IV, IM, and SC administrations in goats demonstrated significant differences, which may have clinical and toxicological implications requiring further investigations.

The Effects of Furosemide on Behavioral and Hormonal Parameters in Male and Female Mice Subjected to Immobilization and Cold-Water Stress

Introduction

The diuretic agent furosemide (FUR, 25 and 50 mg/kg) has been shown in a single report to act as an anti-stressor agent in two models of acute stress in mice, viz. electric foot-shock stress and immobilization (IMS). The present work aimed to investigate the possible anti-stressor action of FUR on two models of acute stress in mice, cold-water stress (CWS) and IMS, and tried to determine whether gender has any impact on the effect of FUR.

Methods

FUR (40 mg/kg) was injected intraperitoneally, and after 30 minutes, mice were subjected to CWS (4°C for three minutes) or IMS (fixing movement for two and a half hrs using adhesive tape). Motor and exploratory activities, neuromuscular coordination, and thermal nociception were then tested. Blood was collected from the mice and used to measure the concentrations of three stress hormones (corticosterone, epinephrine and prolactin).

Results

Mice subjected to CWS and IMS had significantly reduced motor and exploratory activities, neuromuscular coordination, and increased nociception. CWS and IMS also significantly increased the plasma concentrations of the three hormones. FUR pretreatment significantly mitigated these stress-induced hormonal changes. There was no significant sex difference when CWS or IMS was applied.

Discussion

IMS and CWS stimuli in male and female mice caused significant elevations in the plasma concentrations of corticosterone, epinephrine, and prolactin, accompanied by a significant reduction of motor and exploratory activities, neuromuscular coordination, and thermal nociception. There were no sex differences when IMS was applied. In stressed mice, prior administration of FUR (40 mg/kg) significantly decreased the concentrations of stress hormones, and this effect significantly mitigated the stress-induced behavioural and motor changes.

Pharmacokinetics and bioavailability of furosemide in sheep

The pharmacokinetics and bioavailability of furosemide were determined following intravenous (IV), intramuscular (IM), and subcutaneous (SC) administrations at 2.5 mg/kg dose in sheep. The study was conducted on six healthy sheep in a three-way, three-period, crossover pharmacokinetic design with a 15-day washout period. In first period, furosemide was randomly administered via IV to 2 sheep, IM to 2 sheep and SC to 2 sheep. In second and third periods, each sheep received furosemide via different routes of administration with the 15-day washout period. Plasma concentrations were determined using a high-performance liquid chromatography assay and analyzed by noncompartmental method. The mean total clearance and volume of distribution at steady state following IV administration were 0.24 L h^-1  kg^-1 and 0.17 L/kg, respectively. The elimination half-life was similar for all administration routes. The mean peak plasma concentrations of IM and SC administration were 10.33 and 3.18 μg/ml at 0.33 and 0.42 hr, respectively. The mean bioavailability of IM and SC administration was 97.91% and 37.98%, respectively. The IM injection of furosemide may be the alternative routes in addition to IV. However, further research is required to determine the effect of dose and route of administration on the clinical efficacy of furosemide in sheep.

Effects of two-dose intravenous administration of furosemide on clinical variables, electrocardiographic indices and serum electrolytes in dromedary calves

The intravenous (IV) usage of diuretic agents such as furosemide may cause changes in clinical signs, electrocardiographic (ECG) indices and serum electrolytes (sodium, potassium, chloride, calcium, phosphorus and magnesium) concentrations in dromedary calves. The purpose of this study was to evaluate the clinical, ECG and biochemical effects of two‐dose IV administration of furosemide in dromedary calves. A total of 21 clinically healthy male dromedary calves with the age of 5 (± 1) months and weight of 95 (± 5) kg were studied. The animals were randomly divided into three groups of control (normal saline), low‐dose furosemide (2.5 mg/kg) and high‐dose furosemide (5 mg/kg). Two IV injections with 12‐hr intervals were administered in all animals. The clinical and ECG parameters were measured at 0 (baseline), 2 (T2), 24 (T24) and 48 (T48) hours after drug administration. Serum concentrations of electrolytes were measured at T0, T24 and T48 hr. The results of this study showed no changes in clinical parameters (heart rate, rectal temperature, respiratory rate and Unruminal motility), ECG indices and also no significant changes in serum electrolytes levels. Under conditions with free access to fresh water, two‐dose IV injection of furosemide (2.5 and 5 mg/kg) could be administered in healthy dromedary calves.

Quantification of furosemide in camel plasma by high resolution mass spectrometry, application on pharmacokinetics

We developed and validated a high-resolution liquid chromatography mass spectrometry method for the quantification of furosemide in camel plasma which was used for a pharmacokinetic study in camels. Plasma samples were extracted by supported liquid extraction and furosemide and internal standard (furosemide-D5) were separated on a an Agilent Zorbax XDB C₁₈ column (50 × 2.1 mm i.d., 3.5 μm). Data was acquired in full-scan mode over a mass range of 200-400 Da in negative electrospray mode at a resolution of 70,000. Linear calibration curves were obtained over the concentration ranges of 1.0-10,000 ng/mL. The validated method was then successfully applied in evaluating the pharmacokinetics and metabolites of furosemide in six camels (Camelus dromedarus) and we were able to advice on a withdrawal time of furosemide treatment before racing.

The pharmacokinetics of nitazoxanide active metabolite (tizoxanide) in goats and its protein binding ability in vitro

The pharmacokinetics of tizoxanide (T), the active metabolite of nitazoxanide (NTZ), and its protein binding ability in goat plasma and in the solutions of albumin and alpha-1-acid-glycoprotein were investigated. The plasma and protein binding samples were analyzed using a high-performance liquid chromatography (HPLC) assay with UV detection at 360 nm. The plasma concentration of T was detectable in goats up to 24 h. Plasma concentrations vs. time data of T after 200 mg/kg oral administration of NTZ in goats were adequately described by one-compartment open model with first order absorption. As to free T, the values of t(1/2Ka), t(1/2Ke), T(max), C(max), AUC, V/F((c)), and Cl((s)) were 2.51 +/- 0.41 h, 3.47 +/- 0.32 h, 4.90 +/- 0.13 h, 2.56 +/- 0.25 microg/mL, 27.40 +/- 1.54 (microg/mL) x h, 30.17 +/- 2.17 L/kg, and 7.34 +/- 1.21 L/(kg x h), respectively. After beta-glucuronidase hydrolysis to obtain total T, t(1/2ke), C(max), T(max), AUC increased, while the V/F((c)) and Cl((s)) decreased. Study of the protein binding ability showed that T with 4 microg/mL concentration in goat plasma and in the albumin solution achieved a protein binding percentage of more than 95%, while in the solution of alpha-1-acid-glycoprotein, the percentage was only about 49%. This result suggested that T might have much more potent binding ability with albumin than with alpha-1-acid-glycoprotein, resulting from its acidic property.

Interspecies allometric scaling. Part I: prediction of clearance in large animals

Interspecies scaling is a useful tool for the prediction of pharmacokinetic parameters from animals to humans, and it is often used for estimating a first-time in human dose. The knowledge of pharmacokinetics in veterinary species is important for dosage selection, particularly in the treatment of large zoo animal species, such as elephants, giant cats and camels, for which pharmacokinetic data are scant. Therefore, the accuracy in clearance predictions in large animal species, with and without the use of correction factors (rule of exponents), and the impact of species selection in the prediction of clearance in large animal species was examined. Based upon this analysis, it was determined that there is a much larger risk of inaccuracies in the clearance estimates in large animal species when compared with that observed for humans. Unlike in humans, for large animal species, correction factors could not be applied because there was no trend between the exponents of simple allometry and the appropriate correction factor for improving our predictions. Nevertheless, we did see an indication that the exponents of simple allometry may alert us as to when the predicted clearance in the large animal may be underestimated or overpredicted. For example, if a large animal is included in the scaling, the predicted clearance in a large animal should be considered overestimated if the exponent of simple allometry is >1.3. Despite the potential for extrapolation error, the reality is that allometric scaling is needed across many veterinary practice situations, and therefore will be used. For this reason, it is important to consider mechanisms for reducing the risk of extrapolation errors that can seriously affect target animal safety, therapeutic response, or the accuracy of withdrawal time predictions.

Comparative plasma pharmacokinetics and tolerance of florfenicol following intramuscular and intravenous administration to camels, sheep and goats

Florfenicol, a monofluorinated analogue of thiamphenicol, has a broad antibacterial spectrum. The pharmacokinetics of florfenicol was studied following a single intravenous (i.v.) or intramuscular (i.m.) injection at a dose of 20 mg/kg body weight in healthy male camels, sheep and goats. The concentration of florfenicol in plasma was determined using a microbiological assay. Pharmacokinetic analysis was performed using a two-compartment open model. Following i.m. administration, the maximum plasma concentration of florfenicol (Cmax) reached in camels, sheep and goats was 0.84 +/- 0.08, 1.04 +/- 0.10 and 1.21 +/- 0.10 microg/ml, respectively, the the time required to reach Cmax (t(max)) in the same three respective species was 1.51 +/- 0.14, 1.44 +/- 0.10 and 1.21 +/- 0.10 h. The terminal half-life (t(1/2)beta) and the fraction of the drug absorbed (F%) in camels, sheep and goats were 151.3 +/- 16.33, 137.0 +/- 12.16 and 127.4 +/- 11.0 min, and 69.20% +/- 7.8% , 65.82% +/- 6.7% and 60.88% +/- 5.9%, respectively. The MRT in the same three respective species was 4.01 +/- 0.45, 3.42 +/- 0.39 and 2.98 +/- 0.32 h. Following i.v. administration, the terminal half-life (t(1/2)beta) and total body clearance (Clbeta) in camels, sheep and goats were 89.5 +/- 9.2, 78.8 +/- 8.3 and 71.1 +/- 8.9 min and 0.33 +/- 0.04, 0.30 +/- 0.03 and 0.27 +/- 0.03 L/h per kg, respectively. The area under the curve (AUC(0-infinity)) and the mean residence time (MRT) in the same three respective species were 60.61 +/- 6.98, 62.45 +/- 6.56 and 74.07 +/- 7.85 microg/ml per h, and 2.71 +/- 0.31, 2.34 +/- 0.25 and 2.11 +/- 0.23 h. These data suggest that sheep and goats absorb and clear florfenicol to a broadly similar extent, but the rate and extent of absorption of the drug tends to be higher in camels. Drug treatment caused no clinically overt adverse effects. Plasma enzyme activities and metabolites indicative of hepatic and renal functions measured 1, 2, 4 and 7 days following the drug treatment were within the normal range, indicating that the drug is safe at the dose used.

Comparative pharmacokinetics of salicylate in camels, sheep and goats

This study compared some pharmacokinetic parameters of DL-lysine-acetyl salicylate administered intravenously (i.v.) and intramuscularly (i.m.) at a dose of 20 mg/kg in camels, sheep and goats. The data was analyzed using a non-compartmental model. In camels, sheep and goats given the drug i.v., the t1/2 values were 43.1, 31.2 and 27.3; the clearance (Cl) values were 203.7, 261.1, and 280.4 ml/h/kg, while the area under the curve (AUC) were 100.1, 106.9 and 110.5 mg.h/L, respectively. In camels, sheep and goats given the drug by the i.m. route the mean peak plasma concentration (Cmax) were 0.94, 1.44 and 1.74 mg/ml, and the time to reach Cmax (tmax) were 2.94, 2.57 and 2.43h, respectively. The t1/2 values were 48.9, 38.2 and 36.0 min; the clearance (Cl) values were 261.3, 297.4 and 306.4 ml/h/kg, while the area under the curve (AUC) were 101.6, 117.3 and 123.7 mg.h/L, respectively. The drug bioavailability (F) in camels, sheep and goats were 71.3, 78.4 and 79.4% respectively. These findings suggest that the rate of absorption and elimination of the salicylate is slower in camels than in sheep and goats.

Comparative pharmacokinetics of theophylline in camels (Camelus dromedarius) and goats (Caprus hircus)

A comparative randomized crossover study was conducted to determine the pharmacokinetics of theophylline in male and female camels (Camelus dromedarius) and goats (Caprus hircus). Theophylline is an established 'probe drug' to evaluate the drug metabolizing enzyme activity of animals. It was administered by the intravenous (i.v.) route and then intramuscularly (i.m.) at a dose of 2 mg/kg. The concentration of the drug in plasma was measured using a high-performance liquid chromatography (HPLC) technique on samples collected at frequent intervals after administration. Following i.v. injection, the overall elimination rate constant (lambda z,) in goats was 0.006 +/- 0.00076/min and in camels was 0.0046 +/- 0.0008/min (P < 0.01). The elimination half-life (t 1/2 lambda z) in goats (112 .7 min) was lower than in camels (154.7 min) (P < 0.01). The apparent volume of distribution (Vz) and the total body clearance (Cl) in goats were 1440.1 +/- 166.6 ml/kg and 8.9 +/- 1.4 ml/min/kg, respectively. The corresponding values in camels were 1720.3 +/- 345.3 ml/kg and 6.1 +/- 1.0 ml/min/kg, respectively. After i.m. administration, theophylline reached a peak plasma concentration (Cmax) of 1.8 +/- 0.1 and 1.7 +/- 0.2 microg/ml at a post-injection time (Tmax) of 67.5 +/- 8.6 and 122.3 +/- 6.7 min in goats and camels, respectively. The mean bioavailability (T) in both goats and camels was 0.9 +/- 0.2. The above data suggest that camels eliminate theophylline at a slower rate than goats.

A survey of the literature (1995-1999) on the kinetics of drugs in camels (Camelus dromedarius)

Recent publications dealing mainly with the kinetics of antiparasitic and antibacterial agents, NSAIDs, and other drugs in camels are briefly reviewed. The kinetic data for most of these drugs indicated that they have longer absorption and elimination half-lives and slower systemic clearance in the camel compared to other animals. This corroborates earlier reports that suggested that the activities of drug-metabolizing enzymes and the capacity to biotransform and eliminate xenobiotics is lower in camels than in other ruminants. There is a clear need to establish basic kinetic data for the camel in order to avoid extrapolation of drug dosage regimens and withdrawal times from data for other animals, as this may result in irrational use of drugs in camels.