Administration In Beagle Dogs Research Articles

Toxicokinetics of naringin and its metabolite naringenin after 180-day repeated oral administration in beagle dogs assayed by a rapid resolution liquid chromatography/tandem mass spectrometric method

Toxicokinetic characteristics of naringin and its metabolite naringenin were investigated in beagle dogs after oral administration of naringin at the doses of 20, 100, or 500 mg/kg/day in a repeated-dose study for 1, 30, 90, and 180 days. Plasma concentrations of naringin and naringenin were determined by a rapid resolution liquid chromatography/electrospray ionization/tandem mass spectrometric method. The results showed that no differences in systemic exposure were observed between male and female beagle dogs. Systematic exposure exhibited dose-dependent increase for both naringin and naringenin. No significant accumulations were observed. Results would be taken into consideration for the interpretation of toxicology findings and provide a reference for clinical safety assessment.

Effect of particle size on solubility, dissolution rate, and oral bioavailability: evaluation using coenzyme Q10 as naked nanocrystals

In this paper work, four naked nanocrystals (size range 80–700 nm) were prepared without any surfactant or polymer using the solvent/nonsolvent method. The effects of particle size on their solubility, dissolution, and oral bioavailability were investigated. Solubility and dissolution testing were performed in three types of dissolution medium, and the studies demonstrated that the equilibrium solubilities of coenzyme Q10 nanocrystals and bulk drugs were not affected by the dissolution media but the kinetic solubilities were. Kinetic solubility curves and changes in particle size distribution were determined and well explained by the proposed solubilization model for the nanocrystals and bulk drugs. The particle size effect on dissolution was clearly influenced by the diffusion coefficients of the various dissolution media, and the dissolution velocity of coenzyme Q10 increased as particle size decreased. The bioavailability of coenzyme Q10 after oral administration in beagle dogs was improved by reducing the particle size. For 700 nm nanocrystals, the AUC0–48 was 4.4-fold greater than that for the coarse suspensions, but a further decrease in particle size from 700 nm to 120 nm did not contribute to improvement in bioavailability until the particle size was reduced to 80 nm, when bioavailability was increased by 7.3-fold.

An ultra-high sensitive bioanalytical method for plasma melatonin by liquid chromatography–tandem mass spectrometry using water as calibration matrix

For the endogenous substances with an ultra-low level in biological fluids, such as melatonin, the blank biological matrix is obviously not “blank”. This problem leads to a serious issue of the bioanalytical methods development and validation by liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). This work developed and validated an ultra-high sensitive bioanalytical method for plasma melatonin by LC–MS/MS using water as calibration matrix. The lower limit of quantitation of the method was verified to be 1.0 pg/mL and the method exhibited a linear range of 1–5000 pg/mL. Potential matrix effects, accuracy and precision were fully monitored and validated by two complementary quality control approaches respectively using water and the pooled plasma as matrix. The intra-run and inter-run precisions were less than 11.5% and 12.2%, respectively, and the relative error was below ±13.8% for all of 5 quality control levels. The method was successfully applied to investigate the daytime (8:00 AM–8:00 PM) baseline level of endogenous plasma melatonin, as well as the pharmacokinetic profiles of exogenous melatonin after oral administration in beagle dogs.

Toxicity of a novel anti-tumor agent 20(S)-ginsenoside Rg3: A 26-week intramuscular repeated administration study in Beagle dogs

The potential subchronic toxicity of a dammarane-type triterpenoid saponin with antitumor effect, 20(S)-Ginsenoside Rg3, was studied repeated intramuscular administration in Beagle dogs over a 26-week period. 20(S)-Ginsenoside Rg3 was administrated intramuscularly at 0, 0.70, 2.86 or 7.20mg/kg/day doses for 26weeks in both male and female dogs (n=4 for male and female dogs for each dose). During the test period as well as during the 8-week recovery period, clinical signs, mortality, body weights, food consumption, respiratory frequency, electrocardiogram, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, organ weights and histopathology were examined. In dogs treated with doses of 2.86 or 7.20mg/kg, hematological investigations revealed a dose-dependent increase in the total white blood cell (WBC) count and in the percentage of neutrophils, but a decrease in the percentage of lymphocytes. These effects were completely reversed during the recovery period, and no other adverse effects were observed. The no-observed-adverse-effect levels for both male and female dogs were considered to be 7.20mg/kg/day.

비글견을 이용한 케토롤락트로메타민 서방형 펠렛 제제의 위궤양 증상 비교와 약물속도론적 평가

Ketrorolac tromethamine (KT), a nonsteroidal anti-inflammatory drug (NSAID) is required repeated administration due to its short blood half-life. To avoid dose-dependent side effects of KT, sustained-release pellets containing KT were prepared by coating with Eudragit RS 100 and Eudragit NE 30D. The in vitro and in vivo drug release behavior of KT from Eudragit RS 100 and NE 30D coated pellet (SR-A), Eudragit RS 100 coated pellet (SR-B) and conventional commercial immediate-release tablet (IR) was investigated. KT from SR-A and SR-B was slowly released over several hours, whereas IR showed rapid initial release in vitro. The pharmacokinetic study in vivo was performed by oral administration in beagle dogs. 5 mg IR was administered 3 times at intervals 5 hr. Five milligrams of IR was administered 3 times at intervals of 5 hr and 15 mg of SR-A and SR-B did once. After administering IR, KT concentration in blood showed high peak- trough fluctuation and stomach ulcer were discovered. On the other hand, SR-A and SR-B sustainedly released KT and reduced the occurrence of stomach ulcer. There sustained-release pellets will be effective system to minimize dosedependent of side effect and improve patient compliance.

2009 in Review

2009 in Review

Pharmacokinetic studies of meloxicam following oral and transdermal administration in Beagle dogs

The potential for topical delivery of meloxicam was investigated by examining its pharmacokinetic profiles in plasma and synovial fluid following oral and transdermal administration in Beagle dogs. The experiment was a two-period, crossover design using 6 Beagle dogs. Meloxicam tablets were administered orally at a dose of 0.31 mg/kg, and meloxicam gel was administered transdermally at a dose of 1.25 mg/kg. Drug concentrations in plasma and synovial fluid were determined by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The pharmacokinetic parameters were calculated using the Topfit 2.0 program. The pharmacokinetic results showed that AUC(0-t) (23.9+/-8.26 microg.h.mL(-1)) in plasma after oral administration was significantly higher than after transdermal delivery (1.00+/-0.43 microg.h.mL(-1)). In contrast, the ratio of the average concentration in synovial fluid to that in plasma following transdermal administration was higher than that for an oral delivery. The synovial fluid concentration in the treated leg was much higher than that in the untreated leg, whereas the synovial fluid concentration in the untreated leg was similar to the plasma concentration. The high concentration ratio of synovial fluid to plasma indicates direct penetration of meloxicam following topical administration to the target tissue. This finding is further supported by the differences observed in meloxicam concentrations in synovial fluid in the treated and untreated joints at the same time point. Our results suggest that transdermal delivery of meloxicam is a promising method for decreasing its adverse systemic effects.Acta Pharmacologica Sinica (2009) 30: 1060-1064; doi: 10.1038/aps.2009.73; published online 8 June 2009.

Pharmacokinetics of forsythoside after intravenous administration in beagle dogs

A high-performance liquid chromatography with ultraviolet detection method was established and validated for quantification of forsythoside concentrations in dog plasma. Following a single-step protein precipitation with perchloric acid, the forsythoside and internal standard were separated on a reversed-phase C18 column with water-glacial acetic acid-methanol as mobile phase at a flow rate of 1 mL/min with ultraviolet detection at 326 and 278 nm for forsythoside and IS, respectively. The calibration curve for forsythoside was linear over a range of 0.052-13.33 microg/mL with correlation coefficient of 0.999. The within- and between-batch precisions of analysis were < 8 % and accuracy was 95-107%. After intravenous administration of forsythoside at the doses of 5, 10, and 20 mg/kg, the C(max) values for forsythoside were estimated to be of 12.33, 22.90 and 54.45 microg/mL, respectively. The AUC increased with the increasing of doses, and the mean AUC(o-t) values were 5.69, 11.80, and 18.66 mg x h/L, respectively. Forsythoside was eliminated quickly and the mean T(1/2) values at doses of 5, 10, and 20 mg/kg were 1.36, 1.49, and 0.71 h, respectively. The pharmacokinetics of forsythoside in beagle dogs complied with linear kinetic course in the dose range.

A Subchronic Intravenous Toxicity Study of Magnesium Fructose‐1,6‐Diphosphate in Beagle Dogs

Magnesium fructose-1,6-diphosphate is a novel agent of antimyocardial ischaemia. In the present study, the subchronic toxicity of magnesium fructose-1,6-diphosphate was investigated after 13-week repeated intravenous administration in beagle dogs. The animals received doses of 0, 75, 150 and 300 mg/kg/day (three males and three females for each dose). During the study period, clinical signs, mortality, body weights, food consumption, electrocardiogram, urinalysis, haematology, clinical biochemistry, macroscopic findings, organ weights and histopathology were examined. The administration of magnesium fructose-1,6-diphosphate resulted in increased incidence of clinical signs, including salivation and emesis. These effects were transient and were noted in almost all dogs given 300 mg/kg/day and occasionally noted in the 150 mg/kg/day dose-treated animals. Serum magnesium in the 150 mg/kg/day and 300 mg/kg/day dose-treated animals was significantly increased after 6- and 13-week administration, but recovered at the end of a 2-week recovery period. At 6 weeks, a statistically significant decrease in serum electrolytes, including sodium and potassium, was observed in the treatment groups. There were no other treatment-related findings. Under the conditions of the present study, magnesium fructose-1,6-diphosphate did not show any evidence of target organ toxicity. The no-observed-adverse-effect level for 13-week intravenous administration of magnesium fructose-1,6-diphosphate to beagle dogs was considered 75 mg/kg/day based on observations of clinical signs and serum electrolytes.

Design and Evaluation of pH-Independent Pulsatile Release Pellets Containing Isosorbide-5-mononitrate

A three-layered, pH-independent pulsatile release pellets system containing isosorbide-5-mononitrate (ISMN) was studied. The process of the heart disease such as angina has a close relationship to the chronobiology, which gives rise to the need of a pulsatile drug deliver system for the anti-anginal drug. In this study, pellets containing ISMN were firstly prepared as the core, and then layered with a swelling layer followed by an water-insoluble control layer. The core pellets were formulated with microcrystalline cellulose (MCC) and lactose, and were prepared by extrusion-spheronization. The preparation was optimized by Box-Behnken experimental design, when taking the MCC/lactose ratio as swell as the operating conditions of extrusion-spheronization as variables. The experimental results demonstrated the relationships between formulation, operation and properties of the product, and meanwhile provided optimized values for the parameters. The core pellets were coated by a fluidized bed coater, and pellets with various coating types and coating levels were studied by in vitro dissolution tests. The effects of both swelling layer and control layer on the lag time and the drug release time were studied, in order to predetermine the lag time and release time. The pellets were also evaluated in vivo by studying the pharmacokinetics after oral administration in beagle dogs. The pellets achieved a lag time of 4.1 h in vivo, which had a good consistency with the in vitro results, and the relative bioavailability was nearly 100% comparing to the normal tablets.

Pharmacokinetics of Huperzine A after transdermal and oral administration in beagle dogs

Comparison of single and multiple dose pharmacokinetics between patches and conventional tablets of Huperzine A (Hup-A) was performed in beagle dogs to evaluate the patches’ controlled drug release characteristics in vivo, a newly developed transdermal system for treatment of Alzheimer disease. Results showed that transdermal administration of Hup-A prolonged T max value (24 h vs. 3 h, P < 0.01), lowered C max value (3.4 ± 0.2 ng mL −1 vs. 9.8 ± 1.0 ng mL −1, P < 0.01), and produced a relatively constant serum concentration within 84 h after a single transdermal dose of 4 mg/20 cm 2 Hup-A patches. Following application of the patches, Hup-A serum concentrations increased for approximately 12–24 h, reaching an average C max of 3.4 ± 0.2 ng mL −1. Thereafter, a serum concentration of at least 2.1 ng mL −1 was maintained for up to 84 h. The serum concentration was maintained within the range of 2.4–4.3 ng mL −1 during 2-week wearing period after multiple dosing, and the degree of fluctuation at the steady state of td and po administration was significantly different (0.51 vs. 1.99, P < 0.01). This study indicates that Hup-A patches exhibited good controlled-release properties in vivo, maintained a relatively constant serum concentration within 3.5 d after wearing, and are suitable for twice-weekly application.

Multiple oral dosing of ketoconazole influences pharmacokinetics of quinidine after intravenous and oral administration in beagle dogs

In this study, we investigated the effect of multiple oral dosing of ketoconazole (KTZ) on pharmacokinetics of quinidine (QN), a CYP3A substrate with low hepatic clearance, after i.v. and oral administration in beagle dogs. Four dogs were given p.o. KTZ for 20 days (200 mg, b.i.d.). QN was administered either i.v. (1 mg/kg) or p.o. (100 mg) 10 and 20 days before the KTZ treatment and 10 and 20 days after start of KTZ treatment. Multiple oral dosing of KTZ decreased significantly alpha and beta, whereas increased t(1/2beta), V(1), and k(a). The KTZ treatment also decreased significantly both total body clearance (Cl(tot)) and oral clearance (Cl(oral)). No significant change in bioavailability was observed in the presence of KTZ. Co-administration of KTZ increased C(max) of QN to about 1.5-fold. Mean resident time after i.v. administration (MRT(i.v.)), and after oral administration (MRT(p.o.)) of QN were prolonged to about twofold, whereas mean absorption time (MAT) was decreased to 50%. Volume of distribution at steady state (V(d(ss))) of QN was unchanged in the presence of KTZ. These alterations may be because of a decrease in metabolism of QN by inhibition of KTZ on hepatic CYP3A activity. In conclusion, multiple oral dosing of KTZ affected largely pharmacokinetics of QN after i.v. and oral administration in beagle dogs. Therefore, KTZ at a clinical dosing regimen may markedly change the pharmacokinetics of drugs primarily metabolized by CYP3A with low hepatic clearance in dogs. In clinical use, much attention should be paid to concomitant administration of KTZ with the drug when given either p.o. or i.v.

Pharmacokinetics of PEG-hemoglobin SB1, a hemoglobin-based oxygen carrier, after its intravenous administration in beagle dogs.

The purpose of the present study was to investigate the pharmacokinetics of PEG-hemoglobin SB1, a modified bovine hemoglobin with polyethylene glycol, after its single and multiple administration in beagle dogs. For this purpose, the analytical method of free hemoglobin in the plasma was developed and validated. Excellent linearity (r2=0.999) was observed in the calibration curve data, with the limit of quantification of 0.005 g/dL. The precision and the deviation of the theoretical values for accuracy were always within +/-15% in both the between- and the within-day results. The method was tested by measuring the plasma concentrations following intravenous administration to beagle dogs and was shown to be suitable for pharmacokinetic studies. In a single dose study, the plasma half-life (t1/2) increased and the total body clearance (CLt) decreased with the dose (i.e., 0.017 to 0.75 gHb/kg as PEG-hemoglobin SB1) in both sexes. The volume of distribution at steady-state (Vd(ss)) showed no difference with the dose. In contrast, the values of t1/2, CLt and the area under the plasma concentration-time curve (AUC) after the multiple dose were significantly different from those of the single dose administration. The values of t1/2 in the multiple administration were about two times higher than that of the single dose. As a result, t1/2 of hemoglobin after the administration of PEG-hemoglobin SB1 was about 15-30 h, indicating the PEG modification of the hemoglobin lead to a prolongation of plasma concentration of the protein. Therefore, these observations suggested that the PEG modification of hemoglobin is potentially applicable in the hemoglobin-based therapeutics.

Fast-disintegration oral tablets having sustained release property

Fast-disintegrating (FD) tablets containing nicorandil-loaded dry emulsions were prepared and their controlled-release properties were examined and compared with the plain FD tablets (FD tablets without dry emulsions) and commercial tablets. The dry emulsions were prepared with myristyl alcohol and stearyl alcohol and their property was modified by mixing the ratio of the two alcohols. Disintegration time of the prepared FD tablets was sufficiently fast (i.e., 12 to 23 s). In vitro release of nicorandil from the FD tablets containing the dry emulsions was sustained over 6 h, while that from plain FD and commercial tablets was complete within 5 min. In vivo absorption of nicorandil from the tablets was evaluated by oral administration in beagle dogs. FD tablets containing dry emulsions showed a similar AUC, lower Cmax, and delayed Tmax compared to the plain FD and commercial tablets. These results suggest that the dry emulsion-loaded FD tablets can be utilized to improve the sustained-release property of active drugs.

Safety profile of thalidomide after 53 weeks of oral administration in beagle dogs.

Fifty-six adult beagle dogs (28 male, 28 female) were orally administered thalidomide at 43, 200, or 1000 mg/kg/day for 53 weeks. Sixteen (2/sex/dose group) and 32 (4/sex/dose group) dogs were euthanized and necropsied after 26 and 53 weeks of dosing, respectively. The remaining 8 animals (2/sex/group; high-dose and control groups) were dosed for 53 weeks, euthanized, and necropsied at 58 weeks after a 5-week recovery period. There were no deaths during the study. The only observed clinical signs attributable to thalidomide administration were green-colored urine, white-colored fecal residue presumed to be unchanged thalidomide, enlarged and/or blue coloration of female mammary tissue, and prolonged estrus. There were no thalidomide-related changes in body weights, food consumption, electrocardiography, ophthalmoscopy, neurological function, and endocrine function. The mostly slight and/or transient variations observed in some hematology and blood chemistry values of dosed dogs were considered to be toxicologically insignificant and were supported by the lack of histopathologic correlates. The only gross finding attributable to thalidomide was a yellow-green discoloration of the femur, rib, and/or calvarium that was observed at each euthanization interval including recovery. There was no microscopic correlate for this finding. No thalidomide-related microscopic changes were seen in any of the organs and tissues at 26 weeks. Mammary duct dilatation and/or glandular hyperplasia observed in females at 53 and 58 weeks and hepatic bile pigment exhibited by high-dose males at 53 weeks were microscopic changes considered to be thalidomide-related. There was no gross and histopathologic evidence of any tumors. In summary, thalidomide at up to 1000 mg/kg/day for 53 weeks did not induce any major systemic toxicity or tumors in dogs. The NOAEL was 200 mg/kg/day.

The Pharmacology of Physostigmine

The Pharmacology of Physostigmine

In Vivo Evaluation of Zidovudine (AZT)-Loaded Ethylcellulose Microspheres After Oral Administration in Beagle Dogs

The purpose of this study was to evaluate the in vivo performance of sustained-release zidovudine (AZT) microspheres after oral administration in Beagle dogs, and to establish an in vitro–in vivo correlation. Two AZT microsphere formulations as well as AZT powder were administered to four Beagle dogs. Plasma samples were analyzed by HPLC. The plasma concentration–time data was analyzed by both compartmental and noncompartmental pharmacokinetic analyses. Based on the calculated pharmacokinetic parameters, in vivo release profiles were simulated and compared with in vitro release profiles in three different release media. Significantly longer mean residence time (MRT) was observed after administration of the sustained-release microspheres compared with AZT powder. Significantly lower maximum (Cmax) concentration values and longer times to Cmax (tmax) values were also observed. Formulation I showed the longest MRT (4.4 h). AZT plasma concentration was maintained above the minimum effective concentration for ∼10h after administration of Formulation I. The relative bioavailability of the microsphere formulations with respect to AZT powder was not significantly different from 1. The in vitro release of the three formulations was slower in simulated gastric fluid compared with simulated intestinal fluid. The addition of enzymes and mucin to the release media significantly lowered the in vitro release rate of AZT from the microspheres formulations, but not from AZT powder. A good level of in vitro–in vivo correlation (Level A correlation) was achieved with a release medium that was composed of simulated gastric fluid with pepsin and mucin for 2h followed by simulated intestinal fluid with pancreatin and mucin for 8h. This in vitro model may be used to predict the in vivo release of AZT, in the further development of controlled-release AZT formulations.

Stereoselective Pharmacokinetics of Bisoprolol After Intravenous and Oral Administration in Beagle Dogs

The stereoselective pharmacokinetics of bisoprolol, a highly β1-selective adrenoceptor blocking agent, was studied in dogs. After intravenous and oral administration of the racemate, there was a difference in the plasma concentration between S(−)- and R(+)-bisoprolol. The area under the curve (AUC) of concentration versus time of S(−)-bisoprolol was ∼1.5 times higher than that of R(+)-bisoprolol, and the elimination half–life of S(−)-bisoprolol was ∼1.4 times longer than that of R(+)-bisoprolol. However, no differences were observed in the volume of distribution, absolute bioavailability, and renal clearance between the two enantiomers. The plasma protein binding of S(−)-bisoprolol was also the same as that of the R(−)-isomer. No chiral inversion or enantiomer–enantiomer interaction was observed, when enantiomers were solely administered via the intravenous route. The comparison of the oxidative metabolic rate of two enantiomers using dog liver microsomes demonstrated that the metabolite was more slowly formed from S(−)- than from R(+)-bisoprolol. Consequently, we concluded that the stereoselective difference in the metabolic clearance between S(−)- and R(+)-bisoprolol caused the difference in the disposition of bisoprolol enantiomers.

Pharmacokinetics of Insect Repellent N,N-Diethyl-m-toluamide in Beagle Dogs following Intravenous and Topical Routes of Administration

The common topical insect repellent N,N-diethyl-m-toluamide (DEET) has caused serious adverse effects in the users of DEET products due to its high skin permeability. This study investigated the pharma-cokinetics of DEET following iv and dermal routes of administration in beagle dogs. The pharmacokinetics of DEET was linear over the dose range of 2.5–6.0mg/kg. Following the iv dosing, plasma DEET concentrations declined biexponentially with an elimination half-life of 2.56h. Volume of distribution at steady-state, systematic clearance, and mean residence time were estimated as 6.21L/kg, 2.66L/h/kg, and 2.34 h, respectively, indicating that DEET underwent extensive extravascular distribution and rapid elimination. After the dermal application of a commercial lotion and a new DEET lotion at 15mg of DEET/kg, plasma DEET concentrations peaked at 1–2h postdose. The DEET transdermal bioavailability and mean absorption time were 18.3% and 2.05 h, respectively, for the commercial lotion and 14.0% and 2.66 h, respectively, for the new lotion. The difference in DEET transdermal absorption between the two lotions suggested that commercial DEET products could be optimized for reduced DEET absorption for safer use.

Pharmacological properties of YM17E, an acyl-CoA:cholesterol acyltransferase inhibitor, and diarrheal effect in beagle dogs.

YM17E (1,3-bis[[1-cycloheptyl-3-(p-dimethylaminophenyl)ureido]methyl]ben zene dihydrochloride) was found to be a potent inhibitor of acyl-CoA:cholesterol acyltransferase (ACAT) in rabbit liver and intestine microsomes. Dixon plot analysis revealed that YM17E inhibited microsomal ACAT in a non-competitive manner. YM17E induced a marked decrease in serum cholesterol, especially in non-high-density lipoprotein (HDL) fractions, in cholesterol-fed rats and rats fed normal chow. Measurement of bile secretion after oral administration of YM17E in cholesterol-fed rats showed that the drug markedly accelerated the secretion of bile acids and neutral sterols. Furthermore, absorption of [3H]cholesterol from the gut of cholesterol-fed rats was significantly inhibited by YM17E. From these results, the hypocholesterolemic activity of YM17E in these animals resulted from both a decrease in cholesterol absorption from the gut and the stimulation of excretion of cholesterol from the liver into bile. However, YM17E caused secretory diarrhea in beagle dogs at near lipid lowering doses. When YM17E was administered at the same total dosage but divided into 5 daily administrations, the incidence of diarrhea was significantly reduced while its cholesterol lowering effect became stronger. These results suggest that the inhibition of intestinal and/or liver ACAT increases the risk of diarrhea development which, however, can be avoided by controlled drug administration in beagle dogs.