红霉素栓剂、氯霉素栓剂在马体内药物代谢动力学的研究

本文对我国健康蒙古马单剂量给与红霉素肛栓、氯霉素肛栓的药代动力学进行了观察,报道了红霉素肛栓的主要药代动力学参数(表观一级消除还率常数Ke=0.079hr~(-1),表观一级吸收速率常数Ka=3.263hr~1,表观分布容积Vd=0.6231/kg,体内廓清率Cl_D=0.0471/kg·hr,消除半衰期t1/2Ke=10.321hr,吸收半衰期t1/2Ka=0.243hr,有效浓度维持时间Tcp=6.50hr,峰浓度Cmax=0.742μg/ml,峰时间Tmax=1.281hr,“血药浓度—时间”曲线下的面积AUC=11.388μg/ml·hr)和生物利用度(F=0.8?),讨论了栓剂的临床意义。     

千里光提取物冻干粉药代动力学研究-抗炎药理效应法

为了探索千里光提取物冻干粉(SsE)的药物代谢动力学特征,首次采用耳肿胀度抑制率药理效应法测定SsE药动学参数。结果发现,在一定剂量范围内给小鼠腹腔注射SsE,能较迅速地产生药理效应,使耳肿胀度抑制率显著提高;SsE最低有效量为57.40 mg/kg,在小鼠体内代谢符合一级反应一室模型,模型表达式为:C=1 436.227 e^(-0.133 4 t)-1436.227 e^(-0.237 t),表观药动学参数为:一级消除速率常数Ke=0.133 4 h-1,消除半衰期t1/2Ke=5.194 9 h,一级吸收速率常数Ka=0.237 h-1,吸收半衰期t1/2Ka=2.924 1 h,血药峰浓度Cmax=1 436.227 mg/kg,达峰时间tmax=5.547 4 h,清除率Cl=0.055 3mg/kg.h,药-时曲线下面积AUC=16 826.35 mg/kg.h,表观分布容积V=0.414 2 mg/kg,滞后期t0=0.010 4 h。表明SsE具有良好的抗炎作用,在小鼠体内起效快,消除慢,生物利用度高,在机体内分布有限,较集中于血浆,组织摄入少。     

土霉素在鸡体内的生理房室模型研究

为预测土霉素在鸡体内的药动学特点,建立了土霉素在鸡体内的血流限速生理房室模型。结果显示,土霉素在鸡体内的药动学参数:Tmax(达峰时间)为2.22h,Cmax(峰浓度)为0.62μg/mL,AUC(药时曲线下面积)为7.61(μg/mL)×h,Ka(吸收速率常数)为1.21h-1,Ke(消除速率常数)为0.10h-1,T1/2Ka(吸收半衰期)为0.57h,T1/2Ke(消除半衰期)为6.73h,V(表观分布容积)为6.38L/kg,CL(血浆清除率)为0.66L/h·kg。其结果表明,土霉素在鸡体内的药动学特点为:吸收迅速,分布广泛,消除缓慢。因此,运用生理房室模型可以预测药物的药动学参数。     

头孢噻呋-大蒜素脂质体在大鼠体内的药代动力学

对头孢噻呋与大蒜素单一、配伍及其配伍后脂质体的药代动力学进行研究,采用高效液相色谱法测定给药后不同时间的血药浓度.用BAPP2.0药代动力学分析软件对所测得的结果进行分析,得出以下药代动力学结果:在大鼠体内均呈一室代谢模型.脂质体中药物的半衰期大于单一的药物半衰期,脂质体中药物的吸收速率常数Ka明显大于消除速率常数Ke(Ka头孢噻呋=6.29 h-1> Ke头孢噻呋=1.03 h-1;Ka大蒜素=1.12 h-1> Ke大蒜素=0.11 h-1),说明脂质体中药物的吸收迅速.吸收速率大于消除速率,可以使药物在体内迅速达到有效血药浓度以后维持较长的作用时间.结果表明,头孢噻呋-大蒜素脂质体肌肉注射缓释效果明显.     

氨基丁三醇前列腺素F2α在奶牛体内的药代动力学研究

将18头健康成年中国荷斯坦奶牛随机分成高、中、低3组,每组每头分别肌肉注射氨基丁三醇前列腺素F2α注射液10(50mg),5(25mg),2.5mL(12.5mg),采用酶联免疫吸附法(ELISA)测定血药浓度,用残数法逐头奶牛拟合药动学曲线方程并计算药动学参数,研究氨基丁三醇前列腺素F2α在奶牛体内的药代动力学。结果表明,药时数据符合有吸收一室模型,高,中,低组的主要药动学参数:吸收速率常数Ka分别为(18.22±2.17),(15.30±0.64),(20.09±5.03)h-1;吸收半衰期t1/2Ka分别为(0.04±0.004),(0.05±0.002),(0.04±0.01)h;分布和消除速率常数Ke分别为(1.32±0.14),(1.27±0.12),(1.40±0.16)h-1;消除半衰期t1/2Ke分别为(0.53±0.06),(0.55±0.05),(0.50±0.06)h;达峰时间tmax均为0.17h;达峰质量浓度Cmax分别为(6.34±0.59),(5.94±0.27),(4.81±0.16)μg/L;药时曲线下面积AUC0~t分别为(14.40±2.19),(10.14±1.07),(13.15±4.34)μg/(L·h)。奶牛单剂量肌肉注射氨基丁三醇前列腺素F2α注射液后,机体对药物吸收迅速,消除快,浓度约10min达到峰值,100min后达到注射前的水平。根据药时曲线峰浓度,AUC值及相关的临床药效学试验结果,建议临床使用剂量为5mL(25mg)。     

硫酸锌在肉鸡体内药代动力学研究

实验研究了30日龄肉鸡单剂量52.86 mg/kg·BW剂量灌服1％硫酸锌溶液不同时间采血,应用火焰原子吸收分光光度法测定血药浓度,经微机处理得出血药浓度及药动学参数,血药浓度-时间曲线符合一级吸收一室开放模型,最佳药时方程:Ci=27.63626 (e-0.166907t-e-0.0.35005t).主要药动学参数:t1/2Ka为1.98014 hrs,t1/2Ke为4.15290 hrs,tp为4.52561hrs,Cmax为7.36195μg/L,AUC为86.62806(μg/L)·h.根据单剂量给药参数,计算出多剂量给药参数.     

阿维菌素长效注射液(油悬剂)与普通注射液在绵羊体内的药代动力学比较研究

本文描述了阿维菌素长效注射液与阿维菌素普通注射液(阿福丁注射液)药物动力学的比较研究。绵羊血浆经提取、纯化、真空干燥和荧光衍生化后,用荧光高效液相色谱法进行检测。用3P87药代动力学分析软件对所测得的结果进行分析,得出以下药代动力学结果:阿维菌素长效注射液和阿福丁注射液在绵羊体内均呈二室代谢模型。长效注射液以1mg/kg体重进行颈部皮下注射得到以下药动学参数:吸收半衰期t1/2α=9.59h,消除半衰期t1/2β=292.97h,达峰时间tmax=47.46h,最大血药浓度Cmax=13.91ng/mL,曲线下面积AUC=6235.48ng/(mL·h),消除率ClB=0.034L/(kg·h),表观分布容积Vd=13.7L/kg。将阿福丁注射液以0.2mg/kg体重进行颈部皮下注射得到以下药动学参数:吸收半衰期t1/2α=9.05h,消除半衰期t1/2β=144.34h,达峰时间tmax=12.63h,最大血药浓度Cmax=8.52ng/mL,曲线下面积AUC=1017.35ng/(mL·h),消除率ClB=0.22L/(kg·h),表观分布容积Vd=14.5L/kg。研究结果表明:阿维菌素长效注射液比普通注射液吸收慢、消除慢,在体内维持有效血药浓度的时间长,长效注射液维持有效血药浓度(0.5ng/mL血浆)的时间长于49d,而阿福丁注射液不足21d。     

三氮脒注射液在山羊体内的药动学比较

研究新制剂三氮脒注射液在山羊体内的药动学特征。用三氮脒和三氮脒注射液给山羊单剂量(3.5mg·kg-1)肌内注射,采用高效液相色谱法测定山羊体内三氮脒含量,3P97软件拟合血药浓度-时间曲线,计算药动学参数。三氮脒和三氮脒注射液药动学参数符合一级吸收二室模型,主要药动学参数分别为:达峰浓度(Cmax)为(5.97±0.37)μg·mL-1和(7.63±0.41)μg·mL-1;达峰时间(Tmax)为(0.22±0.03)h和(0.40±0.10)h;吸收半衰期(t1/2ka)为(0.13±0.04)h和(0.04±0.01)h;药时曲线下面积(AUC)为(53.96±6.87)μg·mL-1*h和(77.43±6.71)μg·mL-1*h。三氮脒注射液与三氮脒相比,具有吸收缓慢、分布广、安全性好和作用时间长等特点,此结论为临床合理使用剂型提供依据和指导。     

加丽素红中角黄素在鸡体内的药代动力学研究

本试验旨在探讨加丽素红中角黄素在鸡体内的药代动力学特征.选取19周龄的海兰蛋鸡12只,单次灌胃口服加丽素红9.6 mg/kg BW,在72 h内不同时间段分10次采集静脉血,用高效液相色谱法测定鸡血清中角黄素的质量浓度,并利用3P97药代动力学程序软件处理血药浓度-时间数据.结果如下:加丽素红经口服给药后,角黄素在鸡体内的血药浓度-时间数据符合一级吸收一室模型,其理论方程为C=0.471(e-0.036-e-0.190),主要药代动力学参数为:吸收半衰期t1/2(Ka)=(3.643±0.205)h,消除半衰期t1/2(Ke)=(19.263±1.312)h,达峰时间Tmax=(10.795±1.007)h,达峰浓度Cmax=(0.259±0.048)μg/mL,血药浓度-时间曲线下面积AUC=(10.607±1.029)μg/(mL·h),总体清除率CLB=(0.905±0.076)L/(kg·h),表观分布容积Vd=(2.515±0.133)L/kg.上述结果表明,角黄素在鸡体内血药浓度的变化表征了加丽素红在鸡体内代谢的变化规律,具有吸收分布较迅速、达峰快、体内分布广泛、消除速度较慢等特点.     

盐酸苯噁唑在鹿体内的药代动力学研究

本研究的主要目的是建立鹿血浆盐酸苯嗯唑浓度反相高效液相色谱紫外检测法,探讨盐酸苯噁唑在鹿血浆中的药代动力学.6只临床健康的梅花鹿,同一环境下饲养后肌内注射盐酸苯恶唑(0.44 mg·kg-1),颈静脉采血8 mL后分离血浆,通过建立的高效液相色谱检测法,测定各采血时间的血浆药物浓度.结果表明,盐酸苯噁唑单剂量肌内注射给药后,药代动力学符合吸收一室模型,药代动力学参数吸收半衰期(t1/2Ka)、消除半衰期(t1/2Ke)分别为(2.09±0.34)、(13.18±0.24)min,血浆药时曲线下面积(AUC0→∞)为(70±3.50)(μg·mL-1)·min,最大血药浓度(Cmax)为(4.70±0.50)μg·mL-1,血药达峰时间(Tpeak)为(12.46±0.12)min.试验结果提示,盐酸苯噁唑在鹿体内吸收快,消除迅速,4 h后血浆中无药物残留.     

Stereoselective pharmacokinetics of ketamine and norketamine after racemic ketamine or S-ketamine administration in Shetland ponies sedated with xylazine

The pharmacokinetics of ketamine and norketamine enantiomers after administration of intravenous (IV) racemic ketamine (R-/S-ketamine; 2.2 mg/kg) or S-ketamine (1.1 mg/kg) to five ponies sedated with IV xylazine (1.1mg/kg) were compared. The time intervals to assume sternal and standing positions were recorded. Arterial blood samples were collected before and 1, 2, 4, 6, 8 and 13 min after ketamine administration. Arterial blood gases were evaluated 5 min after ketamine injection. Plasma concentrations of ketamine and norketamine enantiomers were determined by capillary electrophoresis and were evaluated by non-linear least square regression analysis applying a monocompartmental model. The first-order elimination rate constant was significantly higher and elimination half-life and mean residence time were lower for S-ketamine after S-ketamine compared to R-/S-ketamine administration. The maximum concentration of S-norketamine was higher after S-ketamine administration. Time to standing position was significantly diminished after S-ketamine compared to R-/S-ketamine. Blood gases showed low-degree hypoxaemia and hypercarbia.     

Dose-dependent pharmacokinetics of gentamicin in sheep

Dose-related changes in the pharmacokinetics of gentamicin sulfate were investigated in 9 sheep given 3, 10, or 20 mg/kg of body weight IV in a crossover design with a 24-day washout period. The pharmacokinetics of the 3 mg/kg single dose were compared with that of the terminal phase pharmacokinetics of 3 mg of gentamicin/kg IV every 8 hours for 7 days in 8 additional sheep. Serum concentrations were monitored for 21 to 24 days after the dose. Polyexponential equations were fit to each data set. The number of exponential terms was determined by optimizing the fit for each data set. The pharmacokinetics of the 3 mg/kg single dose were mainly described by triexponential equations. The 10 mg/kg and the 20 mg/kg single doses and the 3 mg/kg multiple-dose data were described by a tetraexponential equation. The elimination rate constant was significantly smaller (P less than 0.05) after the larger single doses, and the serum gentamicin clearance increased as the dose increased (P less than 0.05). The crossover design sequence had a significant effect on serum gentamicin clearance and the area under the curve normalized to unit dose (P less than 0.01). The final exponential phase was not detectable with the present assay sensitivity under the 3 mg/kg single dose. The triexponential equation underpredicted the terminal serum concentrations determined after the 3 mg/kg multiple dose, whereas the 4 phase equation overpredicted the same terminal serum concentrations, perhaps reflecting saturation of the tissue pools that were mirrored by the serum gentamicin concentrations after 24 hours. The present study emphasized the complexity of the terminal phase gentamicin. pharmacokinetics and acknowledged the need for a long-term washout period when using the crossover design for gentamicin pharmacokinetic studies.     

Intravenous infusion of electrolyte solution changes pharmacokinetics of drugs: pharmacokinetics of ampicillin

The pharmacokinetics of ampicillin in dogs was determined after intravenous (i.v.) bolus and constant rate infusion. Ampicillin was administered to six beagle dogs as an i.v. bolus at 20 mg/kg and as a constant rate i.v. infusion (CRI) at 20 mg/kg during 8 h (0.042 mL/min/kg) in Ringer's lactate (Hartmann's) solution. The concentrations were determined by an LC/MS/MS method. After i.v. bolus, ampicillin total body clearance, apparent volume of distribution at steady‐state, mean residence time (MRT), and half‐life were 4.53 ± 0.70 mL/min/kg, 0.275 ± 0.044 L/kg, 61 ± 13 min, and 111 (85–169) min, respectively. The corresponding parameters calculated after CRI were 13.5 ± 1.06 mL/min/kg, 0.993 ± 0.415 L/kg, 73 ± 27 min, and 49 (31–69) min. Ampicillin concentration decreased by 30% in the Ringer's lactate infusion solution mostly during the first hour after preparation of the solution. Constant rate infusion of Ringer's lactate solution during 8 h caused significant changes in ampicillin pharmacokinetics. The results suggested that special attention should be given to drug pharmacokinetics when co‐administered intravenously with electrolyte solutions.     

Cardiovascular and renal effects of carvedilol in dogs with heart failure

To determine the acute effects of carvedilol (beta-blocker) on cardiovascular and renal function and its pharmacokinetics in dogs. Fifteen mature mongrel dogs (7-15 kg) of both sexes were used in these experiments. Eight dogs served as controls, and seven dogs served as iatrogenic mitral regurgitation (MR) experimental animals. Carvedilol (0.2, 0.4, and 0.8 mg/kg, P.O.) was administered, and the blood carvedilol concentration was analyzed by reverse-phase high-performance liquid chromatography. The response to isoproterenol or phenylephrine was also evaluated. Isoproterenol (0.025 microg/kg/min) was infused via the saphenous vein for 5 min, and phenylephrine (5 microg/kg) was injected with carvedilol (0.2, 0.4 mg/kg) or placebo for 4 days. The heart rate and arterial blood pressure were measured, and LV fractional shortening was measured by echocardiography. Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured by intravenous infusion of sodium thiosulfate and sodium para-aminohippurate. Carvedilol (0.2 mg/kg) decreased the heart rate, whereas renal function, arterial blood pressure, and left ventricular contractile function were not affected. Carvedilol (0.4 mg/kg) decreased heart rate, blood pressure, and renal function. The tachycardic response to isoproterenol was significantly diminished for 36 hr by 0.4 mg/kg carvedilol. Carvedilol 0.2 mg/kg inhibited this effect for 24 hr. Thus, it is necessary to titrate the dosage of carvedilol, it should be initiated at less than 0.2 mg/kg and titrated up to 0.4 mg/kg for heart failure dogs.     

Pharmacokinetics and cardiopulmonary effects of fentanyl in isoflurane-anesthetized rhesus monkeys (Macaca mulatta)

OBJECTIVE: To determine pharmacokinetics and selected cardiopulmonary effects of fentanyl in isoflurane-anesthetized rhesus monkeys. ANIMALS: 6 adult male rhesus monkeys. PROCEDURE: Fentanyl (8 mg/kg of body weight, IV) was administered to 6 monkeys anesthetized with isoflurane. End-tidal isoflurane concentration and esophageal temperature were kept constant, and ventilation was mechanically assisted. Heart rate, rhythm, aortic blood pressure, and blood pH, gas, and fentanyl concentrations were determined before and for 8 hours after administration of fentanyl. Pharmacokinetics of fentanyl were derived by use of noncompartmental methods based on statistical moment theory. RESULTS: Heart rate and mean arterial pressure decreased transiently following fentanyl administration. Maximal decreases were observed 5 to 15 minutes after administration. Arterial pH, Paco2, and Pao2 ranged from 7.46 +/- 0.04 to 751 +/- 0.05 units, 29.2 +/- 3 to 34.6 +/- 4.4 mm Hg, and 412.6 +/- 105.3 to 482.9 +/- 71.2 mm Hg, respectively. The clearance, volume of distribution area, volume of distribution steady state, mean residence time, area under the curve, elimination rate constant, and half-life were 32.5 +/- 2.48 ml/kg/min, 9.04 +/- 1.91 L/kg, 70 +/- 1.2 L/kg, 218.5 +/- 35.5 min, 0.247 +/- 0.019 mg/ml/min, 0.004 + 0.001/min, and 192.0 +/- 33.5 min, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Transient but potentially clinically important decreases in heart rate and mean arterial pressure were observed following fentanyl administration. Distribution and clearance data were similar to those reported for dogs and humans.     

Pharmacokinetics and anesthetic and cardiopulmonary effects of propofol in red-tailed hawks (Buteo jamaicensis) and great horned owls (Bubo virginianus)

OBJECTIVE: To determine induction doses, anesthetic constant rate infusions (CRI), and cardiopulmonary effects of propofol in red-tailed hawks and great horned owls and propofol pharmacokinetics in the owls during CRI. ANIMALS: 6 red-tailed hawks and 6 great horned owls. PROCEDURE: The CRI dose necessary for a loss of withdrawal reflex was determined via specific stimuli. Anesthesia was induced by IV administration of propofol (1 mg/kg/min) and maintained by CRI at the predetermined dose for 30 minutes. Heart and respiratory rates, arterial blood pressures, and blood gas tensions were obtained in awake birds and at various times after induction. End-tidal CO2 (ETCO2) concentration and esophageal temperature were obtained after induction. Propofol plasma concentrations were obtained after induction and after completion of the CRI in the owls. Recovery times were recorded. RESULTS: Mean +/- SD doses for induction and CRI were 4.48 +/- 1.09 mg/kg and 0.48 +/- 0.06 mg/kg/min, respectively, for hawks and 3.36 +/- 0.71 mg/kg and 0.56 +/- 0.15 mg/kg/min, respectively, for owls. Significant increases in PaCO2, HCO3, and ETCO2 in hawks and owls and significant decreases in arterial pH in hawks were detected. A 2-compartment model best described the owl pharmacodynamic data. Recovery times after infusion were prolonged and varied widely. Central nervous system excitatory signs were observed during recovery. CONCLUSIONS AND CLINICAL RELEVANCE: Effects on blood pressure were minimal, but effective ventilation was reduced, suggesting the need for careful monitoring during anesthesia. Prolonged recovery periods with moderate-to-severe excitatory CNS signs may occur in these species at these doses.     

Effects of ketoconazole on the pharmacokinetics and pharmacodynamics of morphine in healthy Greyhounds

OBJECTIVE: To assess pharmacokinetics and pharmacodynamics of morphine and the effects of ketoconazole on the pharmacokinetics and pharmacodynamics of morphine in healthy Greyhounds. ANIMALS: 6 healthy Greyhounds, 3 male and 3 female. PROCEDURES: Morphine sulfate (0.5 mg/kg. IV) was administered to Greyhounds prior to and after 5 days of ketoconazole (12.7 +/- 0.6 mg/kg, PO) treatment. Plasma samples were obtained from blood samples that were collected at predetermined time points for measurement of morphine and ketoconazole concentrations by mass spectrometry. Pharmacokinetics of morphine were estimated by use of computer software. RESULTS: Pharmacodynamic effects of morphine in Greyhounds were similar to those of other studies in dogs and were similar between treatment groups. Morphine was rapidly eliminated with a half-life of 1.28 hours and a plasma clearance of 32.55 mL/min/kg. The volume of distribution was 3.6 L/kg. No significant differences in the pharmacokinetics of morphine were found after treatment with ketoconazole. Plasma concentrations of ketoconazole were high and persisted longer than expected in Greyhounds. CONCLUSIONS AND CLINICAL RELEVANCE: Ketoconazole had no significant effect on morphine pharmacokinetics, and the pharmacodynamics were similar between treatment groups. Plasma concentrations of ketoconazole were higher than expected and persisted longer than expected in Greyhounds.     

The pharmacokinetics of maropitant citrate dosed orally to dogs at 2 mg/kg and 8 mg/kg once daily for 14 days consecutive days

The pharmacokinetics of maropitant were evaluated in beagle dogs dosed orally with Cerenia^® tablets (Pfizer Animal Health) once daily for 14 consecutive days at either 2 mg/kg or 8 mg/kg bodyweight. Noncompartmental pharmacokinetic analysis was performed on the plasma concentration data to measure the AUC_0–24 (after first and last doses), C_t (trough concentration—measured 24 h after each dose), C_max (after first and last doses), t_max (after first and last doses), λ_z (terminal disposition rate constant; after last dose), t_1/2 (after last dose), and CL/F (oral clearance; after last dose). Maropitant accumulation in plasma was substantially greater after fourteen daily 8 mg/kg doses than after fourteen daily 2 mg/kg doses as reflected in the AUC_0–24 accumulation ratio of 4.81 at 8 mg/kg and 2.46 at 2 mg/kg. This is most likely due to previously identified nonlinear pharmacokinetics of maropitant in which high doses (8 mg/kg) saturate the metabolic clearance mechanisms and delay drug elimination. To determine the time to reach steady‐state maropitant plasma levels, a nonlinear model was fit to the least squares (LS) means maropitant C_t values for each treatment group. Based on this model, 90% of steady‐state was determined to occur at approximately four doses for daily 2 mg/kg oral dosing and eight doses for daily 8 mg/kg oral dosing.     

The pharmacokinetics of salicylate in dairy cattle are not altered by simultaneous intravenous ceftiofur sodium and DL-lysine-acetyl salicylate (Aspirin)

This study evaluated potential alterations to the pharmacokinetics of salicylate by concurrently administered ceftiofur sodium. The trial design was a crossover using 10 non-lactating, non-pregnant dairy cows. In the first period each cow received intravenously (IV) 26 mg/kg of DL-lysine acetyl salicylate (aspirin) followed immediately by 2 mg/kg ceftiofur sodium. In the second period each cow received 26 mg/kg of aspirin IV. Plasma samples were harvested for determination of salicylate concentration by HPLC. The data best fitted a single compartment open model, using weighted non-linear regression. No alterations to the pharmacokinetic parameters of salicylate in cattle by concurrently administered ceftiofur sodium were detected ( P <0.05). Using 90% confidence intervals, and testing for changes of > 20%. control values, elimination half-life ( t ₁/₂), apparent volume of distribution ( V _d), area under the plasma concentration versus time curve ( AUC ) and mean residence time ( MRT ) were not altered. For control animals the elimination rate constant ( k _el) and total body clearance ( Cl ) were 1.35/pm0.43 h⁻¹ and 20.2/pm6.1 ml/h.kg respectively (mean/pmSD). Since ceftiofur sodium did not affect the pharmacokinetics of salicylate, dose regimens for aspirin in cattle need not be altered when ceftiofur sodium is administered concurrently.     

Oral dosage regimen in the nonlinear pharmacokinetics of sulphadimethoxine in pigs

An oral high dosage regimen of sulphadimethoxine (SDM) was examined in pigs. The dose (50 mg/kg) in the therapeutic range, showed nonlinear pharmacokinetics, and administered by drench once a day for 4 days. The unbound plasma concentration-time profile was compared with that of the dosage regimen based on nonlinear pharmacokinetics, where a pharmacokinetic model and parameters were used except for the first order absorption rate constant (ka) and bioavailability (F). F and ka were obtained from oral and intravenous administration of 20 and 10 mg/kg of SDM. The unbound plasma concentration was observed almost within the setting range by the dosage regimen through the experimental period. This result suggested that the dosage regimen, based on the nonlinear pharmacokinetic model, resulted in an appropriate effect in the clinical use.