Pharmacokinetics of hydromorphone hydrochloride in healthy dogs

ObjectiveTo assess the pharmacokinetics of hydromorphone administered intravenously (IV) or subcutaneously (SC) to dogs.Study designRandomized experimental trial.AnimalsSeven healthy male neutered Beagles aged 12.13 ± 1.2 months and weighing 11.72 ± 1.10 kg.MethodsThe study was a randomized Latin square block design. Dogs were randomly assigned to receive hydromorphone hydrochloride 0.1 mg kg⁻¹ or 0.5 mg kg⁻¹ IV (n = 4 dogs) or 0.1 mg kg⁻¹ (n = 6) or 0.5 mg kg⁻¹ (n = 5) SC on separate occasions with a minimum 14-day washout between experiments. Blood was sampled via a vascular access port at serial intervals after drug administration. Serum was analyzed by mass spectrometry. Pharmacokinetic parameters were determined with computer software.ResultsSerum concentrations of hydromorphone decreased quickly after both routes of administration of either dose. The serum half-life, clearance, and volume of distribution after IV hydromorphone at 0.1 mg kg⁻¹ were 0.57 hours (geometric mean), 106.28 mL minute⁻¹ kg⁻¹, and 5.35 L kg⁻¹, and at 0.5 mg kg⁻¹ were 1.00 hour, 60.30 mL minute⁻¹ kg⁻¹, and 5.23 L kg⁻¹, respectively. The serum half-life after SC hydromorphone at 0.1 mg kg⁻¹ and 0.5 mg kg⁻¹ was 0.66 hours and 1.11 hours, respectively.Conclusions and clinical relevanceHydromorphone has a short half-life, suggesting that frequent dosing intervals are needed. Based on pharmacokinetic parameters calculated in this study, 0.1 mg kg⁻¹ IV or SC q 2 hours or a constant rate infusion of hydromorphone at 0.03 mg kg⁻¹ hour⁻¹ are suggested for future studies to assess the analgesic effect of hydromorphone.     

Pharmacokinetics and pharmacodynamics of guanidine hydrochloride in an hereditary myasthenia gravis-like disorder in dogs

The pharmacokinetic parameters of guanidine hydrochloride were analysed in dogs with an hereditary neuromuscular transmission disorder by the use of 14C-guanidine hydrochloride. The content of intravenously administrated 14C-guanidine hydrochloride in plasma, urine and faeces was determined by liquid scintillation counting. The drug was rapidly distributed in the organism with a plasma half-life of 7-8 h and most was eliminated in the urine. The clinical and electrophysiological effects of guanidine hydrochloride on the muscular weakness and fatigue induced by exercise were determined after oral and intravenous administration. Guanidine hydrochloride improved muscle-function, but had no apparent effect when administered during an attack of weakness. An effective level of guanidine in plasma (2-10 micrograms/ml) changed the muscle response evoked by trains of repetitive stimulation. The myasthenic decrement during short stimulation trains was unchanged.     

Pharmacokinetics of oxytetracycline hydrochloride in rabbits

Pharmacokinetics of oxytetracycline HCl (OTC) was studied in rabbits. After 10 mg of OTC/kg of body weight was administered IV, the distribution half-life was 0.06 hour, terminal half-life was 1.32 hours, volume of distribution area was 0.861 L/kg, and total body clearance was 0.434 L/kg/h. After 10 mg of OTC/kg was given IM, the absorption half-life was 2.09 hours, extent of absorption was 71.4%, and total body clearance of the absorbed fraction was 0.576 L/kg/h. Based on these kinetic data, a dosage of 15 mg of OTC/kg, every 8 hours was developed. This dose given IM for 7 consecutive days resulted in observed steady-state maximum and minimum concentrations (mean +/- SD) of 4.7 +/- 0.3 micrograms/ml and 3.2 +/- 0.6 micrograms/ml, respectively. Twice this dose (30 mg of OTC/kg, every 8 hours) given IM caused anorexia and diarrhea.     

Pharmacokinetics of imipenem in dogs

OBJECTIVE: To determine the plasma pharmacokinetics of imipenem (5 mg/kg) after single-dose IV, IM, and SC administrations in dogs and assess the ability of plasma samples to inhibit the growth of Escherichia coli in vitro. ANIMALS: 6 adult dogs. PROCEDURE: A 3-way crossover design was used. Plasma concentrations of imipenem were measured after IV, IM, and SC administration by use of high-performance liquid chromatography. An agar well antimicrobial assay was performed with 3 E coli isolates that included a reference strain and 2 multidrug-resistant clinical isolates. RESULTS: Plasma concentrations of imipenem remained above the reported minimum inhibitory concentration for E coli (0.06 to 0.25 microg/mL) for a minimum of 4 hours after IV, IM, and SC injections. Harmonic mean and pseudo-standard deviation half-life of imipenem was 0.80 +/- 0.23, 0.92 +/- 0.33, and 1.54 +/- 1.02 hours after IV, IM, and SC administration, respectively. Maximum plasma concentrations (Cmax) of imipenem after IM and SC administration were 13.2 +/- 4.06 and 8.8 +/- 1.7 mg/L, respectively. Time elapsed from drug administration until Cmax was 0.50 +/- 0.16 hours after IM and 0.83 +/- 0.13 hours after SC injection. Growth of all 3 E coli isolates was inhibited in the agar well antimicrobial assay for 2 hours after imipenem administration by all routes. CONCLUSIONS AND CLINICAL RELEVANCE: Imipenem is rapidly and completely absorbed from intramuscular and subcutaneous tissues and effectively inhibits in vitro growth of certain multidrug-resistant clinical isolates of E coli.     

Pharmacokinetics of kanamycin in dogs

The pharmacokinetics of kanamycin were studied in beagle dogs. A parenteral preparation of kanamycin sulphate (5% aqueous solution), which was given at a dosage level of 10 mg/kg of body weight, was the drug product used. The disposition curve which resulted from the intravenous administration of a single bolus dose of the drug was completely described by the biexponential equation:
C _p= 50e^{-0.1977 t} + 36.3e^{-0.0128 t} where C _p represents concentration of the drug in the serum at time t (in minutes) and the experimental constants are mean values. Pseudo-distribution equilibrium was rapidly attained and the apparent volumes of the central and peripheral compartments of the two-compartment open model were the same ( ca 125 ml/kg). Body clearance (mean ± S.D., n = 6) of kanamycin was 3.21 ±0.72 ml/kg/min. The half-life of the drug was short (58.18 ± 18.43 min) and independent of the route of parenteral (intravenous and intramuscular) administration. Absorption of kanamycin from the intramuscular site was rapid, with a half-time of 9.08 ± 1.10 min. A systemic availability of 89.1 ± 15.8% was obtained. Based on the bioavailability and disposition kinetics a dosage regimen consisting of the intramuscular injection of the dose (10 mg/kg) at 6 h intervals is proposed. An intravenous infusion rate of 48 μg/kgymin is predicted to establish a steady state serum concentration of 15 μg/ml, which is a therapeutic level of the antibiotic for susceptible micro-organisms.     

Pharmacokinetics of fenbendazole in dogs

Fenbendazole was administered to dogs at a dose rate of 20 mg/kg body weight on a single occasion in gelatin capsules, on 5 consecutive days in feed, and on a single occasion as an alginate suspension. It was also administered at a dose rate of 100 mg/kg body weight on a single occasion in feed. Following single administration of 20 mg/kg fenbendazole mean maximum concentrations (Cmax) of the parent drug and its known active sulphoxide metabolite were 0.42 +/- 0.05 and 0.31 +/- 0.05 microgram/ml, respectively. Mean times until maximum concentrations were achieved (tmax) were 12.67 +/- 4.18 and 15.33 +/- 2.81 h, respectively, and areas under the plasma concentration-time curves (AUC) were 5.83 +/- 0.65 and 4.60 +/- 0.57 microgram.h/ml, respectively. Administration in feed increased the apparent bioavailability and administration for 5 consecutive days provided sustained plasma concentrations, generally greater than 0.2 microgram/ml. Administration as an alginate did not increase bioavailability or extend the persistence in plasma. It did increase the tmax to 16.80 +/- 2.93 and 20.00 +/- 2.53 h for fenbendazole and its sulphoxide metabolite, respectively. Increasing the dose from 20 mg/kg to 100 mg/kg did not substantially increase the Cmax or AUC.     

强痛宁在犬血浆中的药代动力学研究

强痛宁及其衍生物是目前临床医学中应用最为广泛的麻醉性镇痛药物.近年来,随着动物麻醉特别是复合麻醉的发展,在动物医学领域对强痛宁研究和应用越来越广泛.本研究采用高效液相色谱法-紫外检测器测定犬血浆中强痛宁浓度的方法.并用MCPKP自动化药动学分析程序对实验数据进行分析.分析结果表明:实验犬静脉注射2μg/kg强痛宁后,血药经时过程符合无吸收的三宣开放性模型,其理论方程为:Cp(t)=11.911 e-0.6020t+7.040 e-0.091 70t+5.013 e-0.005 093t;主要药动学参数:t1/2π为1.591 min、t1/2α7.892 min、t1/2β为140.283 min;kel为0.00 902 min-1;V1为153.372 mL/kg、VB为306.535 mL/kg;CL为2.379 mL·kg-1·min-1;AUC为906.040μg·min·L-1;TCP为237.503 min.     

Pharmacokinetics of intravenous tramadol in dogs

The purpose of this study was to determine the pharmacokinetics of tramadol and the active metabolite mono-O-desmethyltramadol (M1) in 6 healthy male mixed breed dogs following intravenous injection of tramadol at 3 different dose levels. Verification of the metabolism to the active metabolite M1, to which most of the analgesic activity of this agent is attributed to, was a primary goal. Quantification of the parent compound and the M1 metabolite was performed using gas chromatography. Pharmacodynamic evaluations were performed at the time of patient sampling and included assessment of sedation, and evaluation for depression of heart and respiratory rates. This study confirmed that while these dogs were able to produce the active M1 metabolite following intravenous administration of tramadol, the M1 concentrations were lower than previously reported in research beagles. Adverse effects were minimal, with mild dose-related sedation in all dogs and nausea in 1 dog. Analgesia was not documented with the method of assessment used in this study. Tramadol may be useful in canine patients, but additional studies in the canine population are required to more accurately determine the effective clinical use of the drug in dogs and quantification of M1 concentrations in a wider population of patients.     

Pharmacokinetics of allopurinol in Dalmatian dogs

The pharmacokinetics of allopurinol were studied in Dalmatian dogs. Eight dogs were given allopurinol orally at a dose of 10 mg/kg for seven doses prior to sample collection. After a period of at least two weeks, four of these dogs and four additional Dalmatians were later given a single intravenous (i.v.) dose of allopurinol (6 mg/kg) prior to sample collection.Allopurinol was found to follow first-order absorption and elimination kinetics. In the i.v. kinetic study, the elimination constant (K_el) = 0.31±0.03 per h, the half-life (t_½) = 2.22±0.20 h, the initial concentration (C₀) = 5.26±0.34 μg/mL and the specific volume (V_d) = 1.14±0.07 L/kg. Clearance of allopurinol was estimated to be 0.36±0.03 L/kg·h. In the oral kinetic study, the absorption rate constant (K_ab) = 1.06±0.13 per h, the elimination rate constant (K_el) = 0.26±0.01 per h, the absorption half-life (t_½ab) = 0.66±0.06 h, and the elimination half-life (t_½el) = 2.69±0.14 h. Peak plasma concentrations (C_max) = 6.43±0.18 μg/mL were obtained within 1 to 3 h (mean time of maximum concentration (T_max) = 1.9±0.1 h). The volume of distribution corrected by the fraction of dose absorbed (V_d/F) was estimated to be 1.17±0.07 L/kg.Good agreement was obtained between mean kinetic parameters in the oral and i.v. studies. There was little variation between individual dogs in the i.v. study, whereas the rate of absorption and elimination of orally administered allopurinol was more varied among individual dogs. Because of this, and the fact that the magnitude of hyperuricosuria varies among Dalmatians, it is not possible to specify an exact dose of allopurinol that will effectively lower the urinary uric acid concentration to acceptable values in all Dalmatians with hyperuricosuria; rather, the dose must be titrated to the needs of each dog.     

Pharmacokinetics of disodium-fosfomycin in mongrel dogs

Pharmacokinetic variables of fosfomycin were determined after administration of buffered disodium-fosfomycin intravenously (IV), intramuscularly (IM), subcutaneously (SC) and orally (PO), in mongrel dogs, at 40 and 80 mg/kgday for three days. Renal integrity was also assessed by measuring key serum variables. Day 1, day 2 and day 3 plasma concentration vs. time profiles were undistinguishable, but there appears to be a lineal increase in serum concentrations vs. time with the dose. A non-accumulative kinetic behavior was observed after three days with both doses and most pharmacokinetic variables remain unaltered. Considering a MIC range from 1 mirog/mL to 16 microg/mL of fosfomycin in serum for sensitive bacteria, and a negligible plasma protein binding of fosfomycin (<0.5%), useful plasma concentrations can only be achieved after the SC injection of 80 mg/kg every 12h, having a C(max)=18.96+/-0.3 microg/mL; a T(1/2beta)=2.09+/-0.06 microg/mL and a bioavailability of 84-85%. No alterations were observed in serum variables of kidney-related biochemical values.     

Pharmacokinetics of doxycycline in dogs.

Six adult dogs were given doxycycline hyclate at a dosage of 5 mg/kg of body weight intravenously so that pharmacokinetic parameters could be evaluated. Serum doxycycline concentrations were determined over a 48 h period using a modified agar well bioassay. Compartmental pharmacokinetic evaluation of the serum concentration time data indicated that doxycycline has a half-life of 10.36 h, a body clearance of 1.68 +/- 0.44 mL/min/kg, and a volume of distribution at steady state of 1.468 +/- 0.237 L/kg. Doxycycline pharmacokinetics are favorable for therapeutic use in the dog.     

Pharmacokinetics of tildipirosin in beagle dogs

The objective of this study was to investigate the pharmacokinetic profile of tildipirosin (TD) in 24 beagle dogs following intravenous (i.v.) and intramuscular (i.m.) administration, respectively, at 2, 4, and 6 mg/kg. Plasma samples at certain time points (0–14 days) were collected, and the concentrations of drug were quantified by UPLC‐MS/MS. Plasma concentration–time data and relevant parameters were described by noncompartmental through WinNonlin 6.4 software. After single i.m. injection at 2, 4, and 6 mg/kg body weight, mean maximum concentration (C_max) was 412.73 ± 76.01, 1,051 ± 323, and 1,061 ± 352 ng/ml, respectively. Mean time to reach C_max was 0.36 ± 0.2, 0.08 ± 0.00, and 0.13 ± 0.07 hr after i.m. injection at 2, 4, and 6 mg/kg, respectively. The mean value of T_1/2λz for i.m. administration at doses of 2, 4, and 6 mg/kg was 71.39 ± 28.42, 91 .33 ± 50.02, and 96.43 ± 45.02 hr, respectively. The mean residence times were 63.81 ± 10.96, 35.83 ± 15.13, and 38.18 ± 16.77 hr for doses of 2, 4, and 6 mg/kg, respectively. These pharmacokinetic characteristics after i.m. administration indicated that TD could be rapidly distributed into tissues on account of the high lipid solubility and then released into plasma. In addition, the absolute bioavailability of 2 mg/kg after i.m. injection was 112%. No adverse effects were observed after i.v. and i.m. administration.     

Pharmacokinetics of oral rufinamide in dogs

Wright, H. M., Chen, A. V., Martinez, S. E., Davies, N. M. Pharmacokinetics of oral rufinamide in dogs. J. vet. Pharmacol. Therap.  35 , 529–533. The objective of this study was to determine the pharmacokinetic properties and short‐term adverse effect profile of single‐dose oral rufinamide in healthy dogs. Six healthy adult dogs were included in the study. The pharmacokinetics of rufinamide were calculated following administration of a single mean oral dose of 20.0 mg/kg (range 18.6–20.8 mg/kg). Plasma rufinamide concentrations were determined using high‐performance liquid chromatography, and pharmacokinetic data were analyzed using commercial software. No adverse effects were observed. The mean terminal half‐life was 9.86 ± 4.77 h. The mean maximum plasma concentration was 19.6 ± 5.8 μg/mL, and the mean time to maximum plasma concentration was 9.33 ± 4.68 h. Mean clearance was 1.45 ± 0.70 L/h. The area under the curve (to infinity) was 411 ± 176 μg·h/mL. Results of this study suggest that rufinamide given orally at 20 mg/kg every 12 h in healthy dogs should result in a plasma concentration and half‐life sufficient to achieve the therapeutic level extrapolated from humans without short‐term adverse effects. Further investigation into the efficacy and long‐term safety of rufinamide in the treatment of canine epilepsy is warranted.     

Pharmacokinetics of flunixin meglumine in dogs

The pharmacokinetics of flunixin meglumine, a potent nonsteroidal anti-inflammatory agent, were studied in 6 intact, awake dogs. Plasma samples were obtained up to 12 hours after IV administration of flunixin meglumine. Flunixin concentration was determined, using high performance liquid chromatography. Plasma data best fit a 2-compartment model. Distribution half-life was 0.55 hour; elimination half-life was 3.7 hours; volume of distribution (area) was 0.35 L/kg; volume of distribution at steady state was 0.18 L/kg; volume of the central compartment was 0.079 L/kg; and total body clearance was 0.064 L/hr/kg. Flunixin concentrations obtained over a 6-hour period in 3 dogs with septic peritonitis did not differ significantly from those obtained from healthy dogs.     

盐酸多西环素缓释注射液在猪体内的药物动力学

健康猪6头,体质量(17.85±1.3)kg,按拉丁方设计进行单剂量静注、肌注盐酸多西环素注射液(普通制剂)和肌注盐酸多西环素缓释注射液,注射剂量按多西环素计均为20 mg/kg,比较盐酸多西环素缓释注射液和盐酸多西环素注射液在猪体内的药动学特征和生物利用度.用高效液相色谱法测定其血药浓度,试验所得的血药浓度-时间数据采用非房室模型统计矩原理分析处理.猪静注盐酸多西环素注射液的主要药物动力学参数为AUC(108.15±13,25)mg·h·L-1,MRT(5.56±1.08)h,CI(0.19±0.02)L·h-1·kg-1,Vd(ss)(1.04±0.09)L·kg-1,t1/2(4.07±0.65)h.猪肌注盐酸多西环素注射液和盐酸多西环素缓释注射液的主要药物动力学参数分别为MRT(15.18±2.13)h和(22.25±3.49)h;Tmax(1.135±0.44)h和(2.0±0.63)h;Cmax(3.32±0.33)mg·L-1和(3.10±0.29)mg·L-1;AUC(38.91±4.35)mg·h·L-1和(61.72±10.16)mg·h·L-1;F(36.66±7.88)%和(57.66±10.75)%.比较盐酸多西环素注射液和盐酸多西环素缓释注射液的主要药动学参数,除了Cmax以外,MRT、Tmax、AUC、F等主要参数均有显著的统计学意义(P＜0.05).这表明盐酸多西环素缓释注射液肌注后吸收缓慢.消除半衰期延长,临床用药48 h给药1次仍能维持对常见病原菌的有效血药浓度.     

盐酸多西环素在猪体内的药物动力学及其残留

试验建立了反相高效液相色谱(RT-HPLC)法测定盐酸多西环素的浓度,探讨了盐酸多西环素在猪体内的药物动力学和残留特征。结果表明,盐酸多西环素以2.5mg/kg单剂量肌内注射给猪(n=6),药物动力学模型符合有吸收一室模型,药物动力学参数:吸收半衰期(t1/2ka)、消除半衰期(t1/2ke)为(0.400±0.312)h、(9.530±0.956)h,药时曲线下面积(AUC)为(44.414±4.123)mg·h·L-1,最大血药浓度(Cmax)为(2.811±0.136)mg/L,达峰时间(Tp)为(1.910±0.213)h。另外,以相同剂量肌内注射给猪(n=6),每天1次,连续给药4d后,在不同时间测定盐酸多西环素在猪的肌肉、肝脏、肾脏、皮肤和脂肪中的残留量。在给药后16d,盐酸多西环素在各组织均能检测到,且残留均低于残留限量。盐酸多西环素注射液在猪体内消除缓慢,残留期较长,建议休药期不低于16d。     

Pharmacokinetics and pharmacodynamics of piroxicam in dogs

Piroxicam was administered to beagle dogs intravenously and orally at a dose rate of 0.3 mg/kg bodyweight. It had an elimination half-life of 40.2 hours, a volume of distribution of 0.29 +/- 0.02 litres/kg and a body clearance rate of 0.066 litres/hour. When administered orally it was 100 per cent bioavailable and maximum plasma concentrations were achieved quickly (3.1 +/- 1.0 hours). Piroxicam inhibited the generation of thromboxane B2 in the blood of dogs by more than 70 per cent and more than 50 per cent inhibition was maintained in most animals for 48 hours.     

头孢维星在犬体内的药动学及生物利用度研究

建立了一种头孢维星在犬血浆中的高效液相色谱检测法,并研究了头孢维星在犬体内的药动学特征及生物利用度。选用健康家犬12只,按单剂量(8 mg/kg b.w.)分别静脉注射或皮下注射头孢维星,利用建立的方法对头孢维星在犬血浆中的浓度进行测定,采用Win Nonlin5.2.1程序的非房室模型处理药时数据。结果显示,静脉注射组的主要药动学参数为t1/2β=129.15±35.79 h;MRT=152.56±44.95 h;λz=0.0059±0.0023 h-1;Cl=1.24±0.56 m L/(h·kg);AUC=6942.88±2462.48μg獉h/m L;V=170.20±28.09 m L/kg。皮下注射组的主要药动学参数为t1/2β=136.94±20.96 h;MRT=167.77±28.15 h;Tmax=0.83±0.26 h;Cmax=59.51±7.99μg/m L;λz=0.0052±0.0009 h-1;Cl=1.05±0.21 m L/(h·kg);AUC=7332.58±1118.30μg·h/m L;V=203.81±30.09 m L/kg;F=105.61%。结果表明,头孢维星在家犬体内表现出吸收迅速、消除缓慢、表观分布容积大、生物利用度高等药动学特点。