Disposition and bioavailability of the β1-adrenoceptor antagonist talinolol in man

In an open randomized crossover study, the pharmacokinetics and bioavailability of the selective β₁-adrenoceptor antagonist talinolol (Cordanum®—Arzneimittelwerk Dresden GmbH, Germany) were investigated in twelve healthy volunteers (five female, seven male; three poor and nine extensive metabolizers of the debrisoquine hydroxylation phenotype) after intravenous infusion (30 mg) and oral administration (50 mg), respectively. Concentrations of talinolol and its metabolites were measured in serum and urine by HPLC or GC-MS. At the end of infusion a peak serum concentration (C_max) of 631 ± 95 ng mL^?1 (mean ± SD) was observed. The area under the serum concentration-time curve from zero to infinity (AUC_0-∞) was 1433 ± 153 ng h mL^?1. The following parameters were estimated: terminal elimination half life (t_1/2), 10.6 ± 3.3 h; mean residence time, 11.6 ± 3.1 h; volume of distribution, 3.3 ± 0.5 L kg^?1; and total body clearance, 4.9 ± 0.6 mL min^?1 kg^?1. Within 36 h 52.8 ± 10.6% of the administered dose was recovered as unchanged talinolol and 0.33 ± 0.18% as hydroxylated talinolol metabolites in urine. After oral administration a C_max of 168 ± 67 ng mL^?1 was reached after 3.2 ± 0.8h. The AUC_0-∞ was 1321 ± 382 ng h mL^?1. The t_1/2 was 11.9 ± 2.4 h. 28.1 ± 6.8% of the dose or 55.0 ± 11.0% of the bioavailable talinolol was eliminated as unchanged talinolol and 0.26 ± 0.17% of the dose as hydroxylated metabolites by kidney. The absolute bioavailability of talinolol was 55 ± 15% (95% confidence interval, 36–69%). Talinolol does not undergo a relevant first-pass metabolism, and its reduced bioavailability results from incomplete absorption. Talinolol disposition is not found to be altered in poor metabolizers of debrisoquine type.     

The pharmacokinetics and absolute bioavailability of selegiline in the dog

Selegiline is beneficial to Parkinsonian patients as an adjunct to levodopa therapy. Currently no pharmacokinetic data are available for selegiline in the literature, mainly due to lack of analytical methods that can measure concentrations below 10 ng mL^?1 in plasma. A sensitive fluorimetric assay based on inhibition of rat brain monoamine oxidase-B (MAO-B) in vitro has been developed to measure selegiline in plasma as low as 0.25 ng mL^?1. The pharmacokinetics of selegiline were investigated following intravenous and oral administration to four female mongrel dogs. Each dog received 1 mg kg^?1 selegiline in solution via gavage or by an intravenous route separated by one week. The mean terminal half-life, volume of distribution of the central compartment, and systemic clearance of selegiline were 60.24 ± 9.56 min, 6.56 ± 0.56 L kg^?1, and 159.91 ± 19.28 mL min^?1 kg^?1, respectively. After oral administration selegiline appeared to be absorbed rapidly with a t_max and C_max of 25 ± 5.8 min and 5.2 ± 1.36 ng mL^?1, respectively. The absolute bioavailability of selegiline in the dog was 8.51 ± 3.31%.     

硫酸沙丁胺醇缓释胶囊人体药代动力学和生物利用度

目的　研究健康受试者单剂量和多剂量口服硫酸沙丁胺醇缓释胶囊的人体生物利用度和药代动力学。方法　以英国Glaxo公司生产的硫酸沙丁胺醇控释片为参比制剂,HPLC-UV法测定20名健康男性志愿受试者按交叉试验单剂量和多剂量口服硫酸沙丁胺醇缓释胶囊和控释片后血浆中沙丁胺醇的浓度。结果　单剂量服用硫酸沙丁胺醇缓释胶囊和控释片后,二者的C_max,T_max和T_1/2均无显著性差异,缓释胶囊的相对生物利用度为99.68%±10.27%。多剂量给药达稳态时,缓释胶囊和控释片的C^ss_max,C^ss_min,波动度(DF),均无显著性差异。结论　两种制剂具有生物等效性,缓释胶囊有与控释片相似的缓释特征。     

In-vivo Distribution and Erythrocyte Binding Characteristics of Cyclosporin in Renal Transplant Patients

The pharmacokinetic parameters of cyclosporin, a potent immunosuppressive agent, show large intra-and inter-individual variability, possibly because of the different analytical methods used. A recently developed cyclosporin-specific radioimmunoassay has been used to study the in-vivo distribution and binding characteristics of cyclosporin in whole blood, plasma and erythrocytes of fifteen renal transplant patients. The profiles of cyclosporin concentration-time curves after an oral dose of cyclosporin had either one peak (ten patients, group A) or two (five patients, group B). Essentially no difference was observed between the two groups in the relationship between equilibrium cyclosporin concentrations in erythrocyte and plasma as a function of whole-blood concentration. The equilibrium in-vivo cyclosporin concentrations in erythrocytes and plasma were, however, markedly lower than those previously observed under in-vitro conditions. The ratio of cyclosporin concentration in erythrocytes (C_E) to that in plasma (C_P) changed with time, in inverse proportion to the change in cyclosporin concentration in blood, over the range 0.63-2.80 in individual patients with an average of 1.36 ± 007 (mean ± s.e.m.) for group A and 1.42 ± 0.23 for group B. The apparent cyclosporin binding affinity (K_d) to erythrocytes under in-vivo conditions averaged 452.2 ± 47.6 nm (543.5 ± 57.2 ng mL^?1) for group A and 419.4 ± 41.2 nm (504.1 ± 49.5 ng mL^?1) for group B, whereas apparent cyclosporin binding capacity (B_max) of the blood cell averaged 0.83 ± 0.07 nmol mL^?1 for group A and 0.78 ± 0.07 nmol mL^?1 for group B. Significantly reduced average K_d (262.7 ± 40.2 nm or 315.8 ± 48.9 ng mL^?1, P < 001) and B_max (0.56 ± 008 nmol mL^?1, P < 005) values were observed during the period after T_max (4–12 h after the drug ingestion) in group A patients. Apparent K_d and B_max, determined by a nonlinear regression technique, were 131.6 ± 29.4 and 1088.0 ± 114.7 nm (158.2 ± 35.4 and 1307.8 ± 137.9 ng mL^?1) and 0.178 ± 0.024 and 0.814 ± 0.078 nmol mL^?1, respectively, during the 4–12 h period in group A patients. These findings reveal distinct differences in in-vivo distribution of cyclosporin and the binding characteristics of the compound to erythrocytes from those previously observed under in-vitro conditions. The significantly lower K_d of cyclosporin binding to erythrocytes during the elimination phase suggests a potential effect of cyclosporin-containing erythrocytes or of cyclosporin contained in erythrocytes during cyclosporin treatment.     

Mucoadhesive bilayer buccal tablet of carvedilol-loaded chitosan microspheres: in vitro,pharmacokinetic and pharmacodynamic investigations

A multiple-unit system comprising mucoadhesive bilayer buccal tablets of carvedilol-loaded chitosan microspheres (CMs) was developed to improve bioavailability and therapeutic efficacy of carvedilol. Drug-loaded CMs were prepared by spray drying, evaluated for powder and particle characteristics, and optimized batch of CMs was compressed into bilayer buccal tablets using Carbopol. Tablets were evaluated for physicochemical parameters, in vitro drug release, in vivo pharmacokinetic and pharmacodynamic studies. Optimized formulation, CMT1 (CMT, chitosan microsphere tablet) showed maximum mucoadhesive force (50?±?1.84?dyne/cm²), exhibited 73.08?±?3.05% drug release and demonstrated zero-order kinetics with non-Fickian release mechanism. Pharmacokinetic studies in rabbits showed significantly higher C_max (71.26?±?6.45?ng/mL), AUC_0–10 (AUC, area under the curve 390.75?±?5.23?ng/mL/h) and AUC_0–∞ (664.72?ng/mL/h) than carvedilol oral tablet. Pharmacodynamic studies confirmed reduction in mean arterial pressure, heart rate, body weight and triglyceride on administration of bilayer buccal tablet compared to oral carvedilol tablet. Multiple-unit system exhibited enhanced bioavailability and sustained release of carvedilol, indicating its improved therapeutic potential for the treatment of hypertension.     

Pharmacokinetics and Cardiovascular Effects of YM-21095, a Novel Renin Inhibitor,in Dogs and Monkeys

Abstract— The pharmacokinetics and cardiovascular effects of YM-21095 ((2 RS), (3S)-3-[N^α-[1,4-dioxo-4-morpholino-2-(1-naphthylmethyl)-butyl]-l-histidylamino]-4-cyclohexyl-1-[(1-methyl-5-tetrazolyl)thio]-2-butanol), a potent renin inhibitor, have been studied in beagle dogs and squirrel monkeys. Plasma levels of YM-21095 after 3 mg kg^?1 intravenous dosing to dogs declined biphasically and fitted a two-compartment model. Kinetics were as follows: t½α = 4·9±0·2 min, t½β = 2·76±0·79 h, Vd_ss = 3·86±1·04 L kg^?1, plasma clearance = 2·22 ± 0·39 L kg^?1, and AUC= 1445 ± 266 ng h mL^?1. After 30 mg kg^?1 oral dose, maximum plasma concentration, t_max and AUC of YM-21095 were 28·8 ± 9·6 ng mL^?1, 0·25 h and 23·6 ± 7·7 ng h mL^?1, respectively. Systemic bioavailability as determined on the basis of the ratio of AUC after intravenous and oral dose was 0·16 ± 0·04%. In conscious, sodium-depleted monkeys, YM-21095 at an oral dose of 30 mg kg^?1 lowered systolic blood pressure and inhibited plasma renin activity without affecting heart rate and plasma aldosterone concentration. Maximum plasma concentration of YM-21095 after 30 mg kg^?1 oral dose to monkeys was 71·8 ± 41·5 ng mL^?1, which was reached 0·5 h after the dose. At equihypotensive doses, captopril and nicardipine increased plasma renin activity markedly and slightly, respectively. These results suggest that oral absorption of YM-21095 is low in dogs and monkeys, and YM-21095 shows a blood pressure lowering effect by inhibiting plasma renin activity in sodium-depleted monkeys.     

Repeated dose pharmacokinetics of pancopride in human volunteers

The aim of this study was to assess the pharmacokinetic profile of pancopride after repeated oral dose administration of 20 mg pancopride in tablet form once a day for 5 d in 12 healthy male volunteers. Plasma levels were measured by HPLC using a solid phase extraction method and automated injection. The minimum quantification limit of pancopride in plasma was 2 ng mL^?1. The maximum plasma concentration (mean ± SD) after the first dose was 92.5 ± 41.5 ng mL^?1 and t_max was 1.7 ± 0.9 h. The elimination half-life (t_1/2) was 14.3 ± 6.9 h. The area under the concentration-time curve from zero to infinity (AUC) was 997 ± 396 ng h mL^?1. The maximum plasma concentration (mean ± SD) at steady state (day 5) was 101.8 ± 36.9 ng mL^?1 and t_max was 2.2 ± 1.2 h. The elimination half-life (t_1/2) was 16.3 ± 2.7 h and the minimum plasma concentration (C) was 16.6 ± 6.9 ng mL^?1. The area under the concentration-time curve during the dosing interval (AUC) was 995 ± 389 ng h mL^?1. The average plasma concentration at steady state (C) was 43.3 ± 16.1 ng mL^?1 and the experimental accumulation ratio (R_AUC) was 1.34 ± 0.19, whereas the mean theoretical value (R) was 1.40 ± 0.29. The results obtained showed a good correlation between the experimental plasma levels and the expected values calculated using a repeated dose two-compartment model assessed by means of the Akaike value. It is concluded that the pharmacokinetics of pancopride are not modified after repeated dose administration. The safety parameters showed no clinically relevant alterations.     

盐酸普萘洛尔缓释片与常释片的生物利用度比较研究

目的：通过双交叉试验证明盐酸普萘洛尔缓释片有缓释作用。方法：用HPLC方法,测定血清中普萘洛尔浓度,进行盐酸普萘洛尔缓释片与常释片的生物利用度比较及峰谷浓度波动研究。结果：12位健康男性受试者一次交叉口服缓释片和常释片(均为40 mg)后的C_max分别为62.4±23.3和95.9±12.6 ng.mL^-1,AUC分别为360.2±80.6和383.5±74.2 ng.h.mL^-1,缓释片相对于常释片的相对生物利用度为95%;12位受试者连续服缓释片和常释片后平均稳态浓度分别为42.2±12.2和32.7±7.1 ng.mL^-1,波动度(DF)分别为0.90±0.35和2.09±0.34。结论：两种制剂具生物等效性,且缓释片比常释片有峰谷浓度差异小、血药浓度波动幅度小的特点。     

Preparation,characterization and pharmacokinetic studies of linalool-loaded nanostructured lipid carriers

Context Linalool (LL) is associated with numerous pharmacological activities. However, its poor solubility usually results in poor bioavailability, and further limited its applications.

Objective To reduce volatilization and improve bioavailability of LL, linalool-loaded nanostructured lipid carriers (LL-NLCs) were prepared.

Materials and methods LL-NLCs were prepared using high-pressure homogenization method and optimized via response surface methodology-central composite design, followed by characterization, including particle size (PS), zeta potential (ZP), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and in vitro release study. Rats were administered 300?mg?×?kg?^??¹ LL with each preparation (LL-NLCs or LL) via oral gavage.

Results LL-NLCs had a PS of 52.72?nm with polydispersity index of 0.172, and ZP of –16.0?mV. The encapsulation efficiency and drug loading gave 79.563 and 7.555%, respectively. The cumulative release of LL from free LL reached 51.414% at 180?min, while LL from LL-NLCs was 15.564%. All the pharmacokinetics parameters of LL-NLCs were better than those of LL, including C_max (from 1915.45 to 2182.45?ng?×?mL?^??¹), AUC_0–t (from 76003.40 to 298948.46?ng?×?min?×?mL?^??¹) and relative bioavailability (393.34%). The t_1/2, MRT and t_max of LL-NLCs (110.50, 146.66 and 60?min) were also longer than that of LL (44.72, 45.66 and 40?min).

Discussion and conclusion LL-NLCs were for the first time prepared and its oral administration in rats thoroughly investigated. LL-NLCs exhibited sustained release effect and increased absorption of LL. Therefore, these findings might provide a potential possibility for clinical application of LL.     

Andrographolide Liquisolid using Porous-Starch as the Adsorbent with Enhanced Oral Bioavailability in Rats

Andrographolide (AGL) is the major component of Andrographispaniculata. The poor water solubility and low dissolution strongly affect its oral absorption. Liquisolid technology has been used to improve its dissolution and oral bioavailability. Liquisolid powders of AGL (AGL-LS-PSG) were obtained by firstly dissolving AGL in the mixture of NMP, PEG 6000 and Soluplus®, and solidified by absorption of the blend in porous starch. Angle of repose, Carr index and Hauser ratio presented good powder fluidity and compressibility characteristics of AGL-LS-PSG. The results of optical microscopic observation, PXRD and DSC analysis indicated that AGL has been completely adsorbed in porous starch granules and existed in an amorphous or molecularly dispersing state. AGL-LS-PSG can obviously increase the drug dissolution rate compared to commercial guttate pills and raw drug. In vivo pharmacokinetic behavior of AGL-LS-PSG was investigated following a single oral administration to rats. The C_max (0.37 ± 0.06 μg mL^?1) and AUC_0?2h (13.55 ± 2.67 μg h mL^?1) of AGL-LS-PSG were evidently increased compared to commercial guttate pills (C_max = 0.30 ± 0.21 μg mL^?1, AUC_0–2h = 9.88 ± 3.57 μg h mL^?1). This study indicated great potential of liquisolid technology in effectively improving the dissolution and bioavailability of AGL.     

Pharmacokinetics of reboxetine in healthy volunteers. Single oral doses,linearity and plasma protein binding

The pharmacokinetics of reboxetine, a new antidepressant agent, were found to be close to linear in a crossover study comparing administration of single 2, 3, 4 and 5 mg capsule doses in 15 healthy male volunteers, and in the same study the capsules were bioequivalent to the proposed therapeutic tablet formulation (4mg). Kinetic analysis was based on HPLC assay of reboxetine in plasma and urine collected up to 72 h after each administration. Plasma levels indicated a rapid absorption (t_max?2h) and an elimination half-life of about 13 h. Clearance and volume of distribution were modest (ratios to bioavailability: CL/F?29 mL min^?1; V_z/F?32L); urinary excretion was ～9% of dose, corresponding to a renal clearance of only 3 mL min^?1 (a value consistent with the rate of glomerular filtration of unbound drug). In vitro, binding to plasma proteins, estimated from radioactivity levels following dialysis of ¹⁴C-labelled reboxetine, appeared to be dominated by α₁-acid glycoprotein without marked saturation up to plasma concentrations of over 500 ng mL^?1 (2.8–3.1% unbound with human plasma from three additional volunteers; 1.8–2.0% for 2gL^?1 orosomucoid α₁-acid glycoprotein, and 46.4–47.4% for 40 gL^?1 albumin), whilst the mean C_max in the current study was much lower (164 ng mL^?1 after a 5 mg dose).     

RELATIVE BIOAVAILABILITY OF FOUR CLOMIPRAMINE HYDROCHLORIDE TABLET PRODUCTS

The relative bioavailability of clomipramine was determined in two single-blind, single-dose, randomized, crossover studies. In the first study, the relative bioavailability of the test product, 2×25 mg clomipramine hydrochloride tablets (Noristan Ltd.), with respect to the reference product, Anafranil^® 2×25 mg tablets (clomipramine HCl; Ciba—Geigy (Pty) Ltd.) was determined. In the second study, the relative bioavailability of the test product, 5×10 mg clomipramine hydrochloride tablets (Noristan Ltd.), with respect to the reference product, Anafranil^® 5×10 mg tablets (clomipramine HCl; Ciba—Geigy (Pty) Ltd.), was determined. The geometric mean values for the variable C_max were 31·.3 ng mL⁻¹ for the reference and 31·.6 ng mL⁻¹ for the test product in study 1. The geometric mean values for the variable AUC were 736 ng h mL⁻¹ and 753 ng h mL⁻¹ for the reference and test, respectively. In study 2, the geometric mean C_max values were 25·.8 ng mL⁻¹ and 23·.9 ng mL⁻¹ for the reference and test respectively; the geometric mean AUC values were 569 ng h mL⁻¹ and 547 ng h mL⁻¹. The 90% confidence intervals for the ‘test/reference’ mean ratios of the plasma clomipramine pharmacokinetic variables C_max and AUC_(0–∞) (as measures of the rate and extent of absorption of clomipramine, respectively) fall within the conventional bioequivalence range of 80–125% for both studies. The test products (clomipramine HCl) are therefore bioequivalent to the reference products (Anafranil^®) with respect to the rate and the extent of absorption of clomipramine in both 10 mg and 25 mg strengths.     

Preparation,characterization, and pharmacokinetics study of capsaicin via hydroxypropyl-beta-cyclodextrin encapsulation

Context: Capsaicin (CAP) is an effective drug in the treatment of pain and cancer. However, its practical administration has been limited due to poor aqueous solubility and bioavailability, as well as strong gastrointestinal irritation.

Objective: The objective of this study is to improve the solubility and oral bioavailability of CAP by reducing irritation via hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex formulation, in vitro and in vivo analysis.

Materials and methods: The complex (CAP-HP-β-CD) was developed via the magnetic stirring method and characterized using ultraviolet (UV) absorption spectrometry, infrared radiation (IR) spectroscopy, and differential scanning calorimetry (DSC). Rats were treated with CAP (90?mg?×?kg^?1) or CAP-HP-β-CD (corresponding to 90?mg?×?kg^?1 CAP) by gavage, and all the plasma samples were analyzed with high performance liquid chromatography (HPLC).

Results: The results of UV, IR, and DSC showed that an acceptable CAP-HP-β-CD (encapsulation efficiency, 75.83%; drug loading, 7.44%) was formulated. In vitro release study of CAP-HP-β-CD revealed that the cumulative release of CAP from HP-β-CD encapsulation was obviously enhanced (above 80% increases). Similarly, the in vivo pharmacokinetics parameters also increased, C_max (from 737.94 to 1117.57?ng?×?mL^?1), AUC_0– (from 5285.9 to 7409.8?ng?×?h?×?mL^?1) or relative bioavailability (139.38%). The gastric irritation bioassay further showed that the CAP-HP-β-CD was far better than free CAP.

Discussion and conclusion: CAP exhibited significant aqueous solubility and oral bioavailability, as well as minimal irritation effect after forming inclusion complex with HP-β-CD. Therefore, these findings could provide an equally important alternative option for the clinical use of CAP.     

Comparison of enantioselective disposition of rabeprazole versus lansoprazole in renal-transplant recipients who are CYP2C19 extensive metabolizers

The purpose of this study was to investigate the comparative pharmacokinetics of rabeprazole and lansoprazole enantiomers in renal-transplant recipients on tacrolimus who were CYP2C19 extensive metabolizers. Sixteen Japanese patients were randomly assigned after renal transplantation to receive repeated doses of one of the following two regimens for 28 days; tacrolimus, mycophenolate mofetil and prednisolone together with either 20?mg of racemic rabeprazole (n?=?8) or 30?mg of racemic lansoprazole (n?=?8). The mean C_max and AUC_0–24 of (R)-lansoprazole compared to (S)-lansoprazole in renal transplant recipients were 12-fold (954?±?522 vs. 167?±?137?ng?ml^?1, respectively) and 6.9-fold (4787?±?3454 vs. 451?±?354?ng?h?ml^?1, respectively) greater, and its elimination half-life was 2.1-fold (2.3?±?1.0 vs. 1.2?±?0.6?h, respectively) longer. In contrast, although the elimination half-life of (R)-rabeprazole was significantly longer than that of the (S)-enantiomer (2.1?±?0.5 vs. 1.3?±?0.9?h, respectively; P?C_max between the (R)- and (S)-enantiomer (186?±?40 vs. 200?±?92?ng?ml^?1, respectively). In conclusion, in renal-transplant recipients who are CYP2C19 extensive metabolizers, there is less stereoselective difference in the pharmacokinetic disposition between the (R)- and (S)-enantiomers of rabeprazole than those of lansoprazole.     

Bioequivalence of pyrantel pamoate dosage forms in healthy human subjects

Drugs that are largely restricted to the gastro-intestinal tract (GIT) for their therapeutic efficacy and that are not substantially absorbed into the body are usually inadequately studied in terms of systemic bioavailability. The possibility of systemic effects requires that bioavailabilities be studied to ensure against enhanced toxicity resulting from formulation differences. Pyrantel pamoate falls into this category. High-performance liquid chromatography was employed in this study to determine plasma levels of pyrantel in nine healthy human subjects after administration of tablet and suspension dosage forms. Mean peak plasma concentrations of 37.56 ± 9.37, 35.89 ± 8.94, and 36.22 ± 10.10 ng mL^?1 were obtained following administration of 750 mg pyrantel pamoate in three different formulations. The mean t_max values were 2.02 ± 0.12, 2.05 ± 0.356, and 2.05 ± 0.339 h respectively for the above dosage forms; the respective AUC_0–9 values were 81.01 ± 12.97, 94.59 ± 17.18, and 101.47 ± 19.59 h ng mL^?1. There was no statistically significant difference between the bioavailabilities of the dosage forms tested. Large inter-subject variations were observed. One subject experienced abdominal discomfort and one experienced dizziness. It was not possible to clearly correlate individual variations in absorption with the observed adverse effect because the number of incidents was low (two out of 27 treatments).     

Cyclodextrin-based nanosponges: effective nanocarrier for Tamoxifen delivery

The purpose of the present study was to develop Tamoxifen loaded β-cyclodextrin nanosponges for oral drug delivery. The three types of Tamoxifen loaded β-cyclodextrin nanosponges were synthesized by varying the molar ratios of β-cyclodextrin to carbonyldiimidazole as a crosslinker viz. 1:2, 1:4 and 1:8. The Tamoxifen nanosponge complex (TNC) with particle size of 400–600?nm was obtained by freeze drying method. Differential scanning calorimetry, Fourier transformed infra-red spectroscopy and X-ray powder diffraction studies confirmed the complexation of Tamoxifen with cyclodextrin nanosponge. AUC and C_max of TNC formulation (1236.4?±?16.12 µg·mL^?1 h, 421.156?±?0.91 µg/mL) after gastric intubation were 1.44 fold and 1.38 fold higher than plain drug (856.079?±?15.18 µg·mL^?1 h, 298.532?±?1.15 µg/mL). Cytotoxic studies on MCF-7 cells showed that TNC formulation was more cytotoxic than plain Tamoxifen after 24 and 48?h of incubation.     

Determination of cepharanthine in rat plasma by LC–MS/MS and its application to a pharmacokinetic study

Context: Cepharanthine (CPA) has been reported to possess a wide range of pharmacological activities.

Objective: This study investigates the pharmacokinetic characteristics after oral or intravenous administration of CPA by using a sensitive and rapid LC–MS/MS method.

Materials and methods: A sensitive and rapid LC–MS/MS method was developed for the determination of CPA in Sprague–Dawley rat plasma. Twelve rats were equally randomized into two groups, including the intravenous group (1?mg/kg) and the oral group (10?mg/kg). Blood samples (250?μL) were collected at designated time points and determined using this method. The pharmacokinetic parameters were calculated.

Results: The calibration curve was linear within the range of 0.1–200?ng/mL (r?=?0.999) with the lower limit of quantification at 0.1?ng/mL. After 1?mg/kg intravenous injection, the concentration of CPA reached a maximum of 153.17?±?16.18?ng/mL and the t_1/2 was 6.76?±?1.21?h. After oral administration of 10?mg/kg of CPA, CPA was not readily absorbed and reached C_max 46.89?±?5.25?ng/mL at approximately 2.67?h. The t_1/2 was 11.02?±?1.32?h. The absolute bioavailability of CPA by oral route was 5.65?±?0.35%, and the bioavailability was poor.

Discussion and conclusions: The results indicate that the bioavailability of CPA was poor in rats, and further research should be conducted to investigate the reason for its poor bioavailability and address this problem.     

Determination of dihydromyricetin in rat plasma by LC-MS/MS and its application to a pharmacokinetic study

Context: The pharmacokinetics properties of dihydromyricetin (DHM) are still unknown.

Objective: This study investigates the pharmacokinetic characteristics of DHM using a sensitive and reliable LC-MS/MS method.

Materials and methods: A rapid and sensitive LC-MS/MS method was developed for the determination of DHM in male Sprague–Dawley rat plasma. Twelve rats were equally randomized into two groups, including the intravenous group (2?mg/kg) and the oral group (20?mg/kg). Blood samples (250?μL) were collected at designated time points and analyzed using this method. The pharmacokinetic parameters were calculated using DAS 3.0 pharmacokinetic software.

Results: The calibration curve was linear within the range of 0.5–200?ng/mL (r?>?0.998) with the lower limit of quantification at 0.5?ng/mL. After the intravenous injection, DHM reached a maximum concentration of 165.67?±?16.35?ng/mL, and t_1/2 was 2.05?±?0.52?h. However, DHM was not readily absorbed and reached C_max 21.63?±?3.62?ng/mL at approximately 2.67?h following the oral administration of DHM, and t_1/2 was 3.70?±?0.99?h. The MRT for the intravenous group and the oral group were 2.62?±?0.36 and 5.98?±?0.58?h, respectively. The AUC_(0-t) for the intravenous group and the oral group were 410.73?±?78.12 and 164.97?±?41.76?ng·L/mL, respectively, so the absolute bioavailability of DHM was 4.02% which was poor.

Discussion and conclusion: The results indicated that the bioavailability was poor. Further work needs to be conducted to investigate the reason for poor bioavailability and improve this situation.     

伏立康唑胶囊人体药动学及相对生物利用度研究

目的 研究健康受试者口服伏立康唑胶囊的药动学和相对生物利用度。方法 20名健康受试者随机服用伏立康唑受试胶囊剂和参比片剂各100 mg,用HPLC-MS/MS测定血浆中伏立康唑的浓度。结果 主要药动学参数,伏立康唑受试制剂与参比制剂的T_max分别为(0.75±0.15)和(0.84±0.25)h,C_max分别为(605.4±136.6)和(595.2±134.7)ng·mL^-1;t_1/2分别为(4.91±1.44)和(5.06±2.06)h,AUC_0-15分别为(1737.6±325.1)和(1750.6±352.8)ng·h·mL^-1。受试制剂与参比制剂的AUC_0-15和C_max经双单侧t检验,T_max经非参数检验,差异均无统计学意义。结论 统计学结果表明,2种制剂生物等效。     

Preparation and pharmacokinetics evaluation of oral self-emulsifying system for poorly water-soluble drug Lornoxicam

Abstract

The present work was performed aiming to develop a new solid self-emulsifying system (SMEDDS) for poorly water-soluble drug Lornoxicam and evaluate the bioavailability in Wister rats by oral gavage. Liquid SMEDDS of Lornoxicam was formulated with Labrafil M 1944 CS as oil phase, Kolliphor HS 15 as a surfactant and Transcutol HP as a cosurfactant after screening various vehicles. The microemulsion system selected from the phase diagram and optimized by central composite design (CCD) response surface method was transformed into solid-SMEDDS (S-SMEDDS) by lyophilization using sucrose as cryoprotectant. The formulations were further characterized by the particle size, poly dispersity index (PDI), self-emulsifying time, zeta potential, transmission electron microscope (TEM), differential scanning calorimeter (DSC), in vitro drug release and in vivo pharmacokinetics. Results of DSC studies confirmed that the drug was incorporated in the S-SMEDDS. The in vitro drug release from Lornoxicam SMEDDS was found to be greatly higher in comparison with that from the commercial tablets. It was indicated that SMEDDS might be effective in reducing the effect of pH variability of Lornoxicam and improving the release performance of Lornoxicam. HPLC system was applied to study the concentration of Lornoxicam in the plasma of the Wister rats after oral administration of Lornoxicam SMEDDS and Lornoxicam commercial tablets. The pharmacokinetics parameters of the rats were C_max 1065.91?±?224.90 and 1855.22?±?748.25?ngmL^?1, T_max were 2.5?±?0.4?h and 1.8?±?0.5?h, and AUC_0～t were 5316.35?±?323.62 and 7758.07?±?241.57?ngmL^?1?h, respectively. Calculated by AUC_0～∞, the relative bioavailability of Lornoxicam S-SMEDDS was 151.69?±?15.32%. It suggested that this S-SMEDDS could be used as a successful oral solid dosage form to improve the solubility and bioavailability of poorly water-soluble drug Lornoxicam as well.