OBJECTIVE: To prepare the slow-release complex with rifampicin (RFP)-polylactic-co-glycolic acid (PLGA)-calcium phosphate cement (CPC) (RFP-PLGA-CPC complex), and to study its physical and chemical properties and drug release properties in vitro.
 METHODS: The emulsification-solvent evaporation method was adopted to prepare rifampicin polylactic acid-glycolic acid (RFP-PLGA) slow-release microspheres, which were divided into 3 groups: a calcium phosphate bone cement group (CPC group), a CPC embedded with RFP group (RFP-CPC group), and a PLGA slow-release microspheres carrying RFP and the self-curing CPC group (RFP- PLGA-CPC complex group). The solidification time and porosity of materials were determined. The drug release experiments in vitro were carried out to observe the compressive strength, the change of section morphology before and after drug release. 
 RESULTS: The CPC group showed the shortest solidification time, while the RFP-PLGA-CPC complex group had the longest one. There was statistical difference in the porosity between the CPC group and the RFP-CPC group (P<0.05); Compared to the RFP-PLGA-CPC complex group, the porosity in the CPC group and the RFP-CPC group were significantly changed (both P<0.01). There was significant difference in the compressive strength between the RFP- PLGA-CPC complex group and the CPC group (P<0.01), while there was significant difference in the compressive strength between the RFP-CPC group and the CPC group (3 days: P<0.05; 30 and 60 days: P<0.01). The change of the compressive strength in the CPC was not significant in the whole process of degradation. The sizes of PLGA microspheres were uniform, with the particle size between 100-150 μm. The microspheres were spheres or spheroids, and their surface was smooth without the attached impurities. There was no significant change in the section gap in the CPC group after soaking for 3 to 60 days. The microstructure change in the RFP-CPC group was small, and the cross section was formed by small particles. The pores of section in the RFP-PLGA-CPC complex group increased obviously, and PLGA microspheres gradually disappeared until the 60th day when there were only empty cavities left. The RFP-PLGA-CPC complex group had no obvious drugs sudden release, and the cumulative drug release rate was nearly 95% in the 60 days. The linear fitting was conducted for the drug release behavior of the complex, which was in accordance with zero order kinetics equation F=0.168×t.
 CONCLUSION The porosity of RFP-PLGA-CPC complex is significantly higher than that of CPC, and it can keep slow release of the effective anti-tuberculosis drugs and maintain a certain mechanical strength for a long time.
Bone Cements ; pharmacokinetics ; Calcium Phosphates ; pharmacokinetics ; Compressive Strength ; Delayed-Action Preparations ; pharmacokinetics ; Dental Cements ; pharmacokinetics ; Lactic Acid ; pharmacokinetics ; Materials Testing ; Microspheres ; Polyglycolic Acid ; pharmacokinetics ; Polylactic Acid-Polyglycolic Acid Copolymer ; Porosity ; Rifampin ; administration & dosage ; pharmacokinetics

Drug release from alpha-TCP cement containing tetracycline hydrochloride (TTCH) was studied in vitro. Results from X-ray diffraction study indicated that TTCH did not prevent the hydration of alpha-TCP. In vitro drug release study showed that TTCH release could sustain over 1200 h, and the release was controlled by two mechanisms: (1) diffusion of free TTCH molecules through the porous cement (square-root-of-time kinetics); (2) dissociation of TTCH from the apatite-TTCH complex (zero-order kinetics). The mechanism controlling release would changed with the variety of the antibiotic content of cement pellets, as a result of TTCH adsorption and bonding on calcium phosphates. The first mechanism was predominantly for low concentration system TTCH-loaded apatite cement systems at the initial release period, and for high concentration TTCH-loaded apatite cement systems. As for low concentration TTCH-loaded apatite cement systems at later release stage, drug release was controlled by the coupling of the two mechanisms.
Anti-Bacterial Agents ; pharmacokinetics ; Biocompatible Materials ; Bone Cements ; Calcium Phosphates ; Diffusion ; Drug Carriers ; In Vitro Techniques ; Tetracycline ; pharmacokinetics ; X-Ray Diffraction

The purpose of the current study was to examine the pharmacokinetic profiles and tissue distribution of clevidipine, an ultra-short-acting calcium antagonist in Beagle dogs and Sprague-Dawley rats, respectively. The pharmacokinetics and biodistribution of its primary metabolite H152/81 were also evaluated. Dogs received intravenous infusion of clevidipine at a dose rate of 17 μg/(kg·min), and rats were given intravenous administration of clevidipine at a dose of 5 mg/kg. Dog plasma and rat tissues were collected and assayed by HPLC-MS/MS. It was found that plasma clevidipine quickly reached the steady state concentration. The terminal half-life was short (16.8 min), pointing out a rapid elimination after the end of the infusion. The total clearance was 5 mL/(min·kg). In comparison, plasma concentration of H152/81 was increased more slowly and was significantly higher than that of clevidipine. After intravenous administration, clevidipine was distributed rapidly into all tissues examined, with the highest concentrations found in the brain, heart and liver. Maximal concentrations of clevidipine were found in most tissues at 10 min post-dosing. However, the proportion of clevidipine distributed in all tissues was quite small (0.042‰) compared to the total administration dose. It was suggested that clevidipine was mainly distributed in blood and it transformed to inactive metabolite rapidly.
Animals ; Calcium Channel Blockers ; pharmacokinetics ; pharmacology ; Dogs ; Dose-Response Relationship, Drug ; Organ Specificity ; drug effects ; Pyridines ; pharmacokinetics ; pharmacology ; Rats

In this study, UPLC-MS/MS was adopted to determine the contents of five ephedrine alkaloids (Norephedrine, Norpseudoephedrine, Ephedrine, Pseudoephedrine, Methylephedrine) in plasma and urine in rats after the combined administration of Ephedrae Herba-Gypsum Fibrosum and calculate relevant pharmacokinetic parameters, in order to discuss the effect of the combined administration of Ephedrae Herba-Gypsum Fibrosum on plasma pharmacokinetics and urinary excretion characteristics. According to the results, after being combined with Gypsum, the five ephedrine alkaloids showed similar pharmacokinetic changes, such as shortened t(max), accelerated absorption rate, but reduced AUC(0-t) and V(z)/F, which may be related to the increase in urine excretion. Besides, Gypsum was added to enhance C(max) of Pseudoephedrine and prolong MRT(0-t) of Methylephedrine, so as to enhance the anti-asthmatic effect of Ephedrae Herba and resist the toxic effect of Norephedrine and Ephedrine. This study proved the scientific compatibility of Ephedrae Herba-Gypsum Fibrosum and provided a reference for studies on the prescription compatibility regularity and relevant practices.
Alkaloids ; blood ; pharmacokinetics ; urine ; Animals ; Calcium Sulfate ; pharmacokinetics ; Drugs, Chinese Herbal ; pharmacokinetics ; Ephedra ; chemistry ; Male ; Rats ; Rats, Sprague-Dawley ; Urine ; chemistry

OBJECTIVETo observe the release kinetics of methotrexate-loaded calcium phosphate cement (MTX-CPC) implanted in vivo and histologically investigate its resorption and osteogenesis.

METHODSMTX-CPC consisting of 1% methotrexate (MTX) (weight/weight) was pre-set and implanted into femoral muscles of 24 New Zealand rabbits. The in vivo MTX release kinetics was determined on the 1st, 2nd, 5th, 10th, 15th, 20th, 25th, and 30th post-implantation day. The local concentrations and the residual percentage of MTX were determined. Then the pre-set MTX-CPC was implanted into femoral condyle. Calcium phosphate cement (CPC) without MTX was used as a control. The femurs were harvested at the 1st day and the 1st, 3rd, and 6th month and examined by X ray. Then histomorphometric analyses including percentage of newly formed bone and amount of osteoblast and osteoclast were performed.

RESULTSThe MTX release kinetics in vivo confirmed that MTX-CPC was a monolithic matrix system, with a burst effect in the initial stage and a sudden drop thereafter. The local concentration of the released MTX was 0.372 μg/ml on the 30th post-implantation day; with a concentration higher than the effective concentration,the incorporated MTX was expected to be continuously released over the following 2-3 months. Both MTX-CPC and CPC showed good biodegradability and osteoconduction. Although the release of MTX had an inhibitory effect on osteogenesis, especially in the initial stage, the area of newly formed bone, the amount of osteoblasts, and the amount of osteoclasts were not significantly different between MTX-CPC group and CPC group on the 6th post-implantation month.

CONCLUSIONSMPX-CPC system is an effective drug delivery system. Both MTX-CPC and CPC has good biodegradability and osteoconduction. Therefore,MTX-CPC system can be an ideal material for filling defects and controlling local recurrence.

Animals ; Bone Cements ; Bone Regeneration ; Calcium Phosphates ; Methotrexate ; pharmacokinetics ; Osteogenesis ; Rabbits

Atorvastatin and ezetimibe are frequently co-administered to treat patients with dyslipidemia for the purpose of low-density lipoprotein cholesterol control. However, pharmacokinetic (PK) drug interaction between atorvastatin and ezetimibe has not been evaluated in Korean population. The aim of this study was to investigate PK drug interaction between two drugs in healthy Korean volunteers. An open-label, randomized, multiple-dose, three-treatment, three-period, Williams design crossover study was conducted in 36 healthy male subjects. During each period, the subjects received one of the following three treatments for seven days: atorvastatin 40 mg, ezetimibe 10 mg, or a combination of both. Blood samples were collected up to 96 h after dosing, and PK parameters of atorvastatin, 2-hydroxyatorvastatin, total ezetimibe (free ezetimibe + ezetimibe-glucuronide), and free ezetimibe were estimated by non-compartmental analysis in 32 subjects who completed the study. Geometric mean ratios (GMRs) with 90% confidence intervals (CIs) of the maximum plasma concentration (C(max,ss)) and the area under the curve within a dosing interval at steady state (AUC(τ,ss)) of atorvastatin when administered with and without ezetimibe were 1.1087 (0.9799–1.2544) and 1.1154 (1.0079–1.2344), respectively. The corresponding values for total ezetimibe were 1.0005 (0.9227–1.0849) and 1.0176 (0.9465–1.0941). There was no clinically significant change in safety assessment related to either atorvastatin or ezetimibe. Co-administration of atorvastatin and ezetimibe showed similar PK and safety profile compared with each drug alone. The PK interaction between two drugs was not clinically significant in healthy Korean volunteers.
Atorvastatin Calcium* ; Cholesterol ; Cross-Over Studies ; Drug Interactions* ; Dyslipidemias ; Ezetimibe* ; Humans ; Lipoproteins ; Male ; Pharmacokinetics ; Plasma ; Volunteers*

This study aimed to compare the pharmacokinetics of fixed-dose combination (FDC) tablet of rosuvastatin 20 mg/ezetimibe 10 mg with that of concurrent administration of individual rosuvastatin 20 mg tablet and ezetimibe 10 mg tablet in healthy subjects. A randomized, open label, single-dose, two-way crossover study was conducted. Subjects randomly received test formulation (FDC tablet of rosuvastatin 20 mg/ezetimibe 10 mg) or reference formulation (co-administration of rosuvastatin 20 mg tablet and ezetimibe 10 mg tablet). After 2 weeks of washout, subjects received the other treatment. Blood samples were collected up to 72 hours post-dose in each period. Plasma concentrations of rosuvastatin, ezetimibe and total ezetimibe (ezetimibe + ezetimibe glucuronide) were analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The geometric mean ratio (GMR) of Cmax and AUClast (90% confidence interval, CI) for rosuvastatin was 1.036 (0.979–1.096) and 1.024 (0.981–1.070), respectively. The corresponding values for ezetimibe were 0.963 (0.888–1.043) and 1.021 (0.969–1.074), respectively. The corresponding values for total ezetimibe were 0.886 (0.835–0.940) and 0.983 (0.946–1.022), respectively. FDC tablet containing rosuvastatin 20 mg and ezetimibe 10 mg is bioequivalent to the co-administration of commercially available individual tablets of rosuvastatin and ezetimibe as GMR with 90% CI of Cmax and AUClast of rosuvastatin, ezetimibe and total ezetimibe were contained within conventionally accepted bioequivalence criteria.
Cross-Over Studies ; Ezetimibe ; Healthy Volunteers ; Mass Spectrometry ; Pharmacokinetics ; Plasma ; Rosuvastatin Calcium ; Tablets ; Therapeutic Equivalency

AIMTo investigate the differences of pharmacokinetic behavior and tissue distribution of nimodipine and its two enantiomers in rats.

METHODSA high-performance liquid chromatographic method with an ODS column (150 mm x 4.6 mm ID) and a mobile phase of methanol-water (70:30) was used for racemic nimodipine assay. Another method with a Chiralcel OJ column (250 mm x 4.6 mm ID) and a mixture of n-haxane-ethanol (85:15) as mobile phase was used to determine its two enantiomers. Nimodipine was monitored at 236 nm wavelength.

RESULTSThe linearity, recoveries and the detection limits of the methods were found to be suitable for the determinations. The average results of within-day and between-day RSDs were 5.64% and 7.85% respectively, the mean recovery was 97.66% for the concentration ranges studied. The pharmacokinetic parameters Tmax, Cmax, AUC and CLs were: S-(-)-nimodipine (2.1 +/- 0.3) h, (197 +/- 5) microgram.L-1, (656 +/- 18) mL.min-1, (0.30 +/- 0.03) microgram.h.L-1, and R-(+)-nimodipine (1.7 +/- 0.5) h, (128 +/- 4) microgram.L-1, (381 +/- 4) mL.min-1, (0.53 +/- 0.03) microgram.h.L-1, respectively. The S-(-)-nimodipine concentration was 2.23 and 1.97 times as high as that of R-(+)-nimodipine in heart and in cerebrum respectively and there was almost only S-(-)-nimodipine in cerebellum. But R-(+)-nimodipine concentration was 1.57, 3.69 and 4.20 times as high as that of S-(-)-nimodipine in major excretion organs such as kidney, spleen and liver respectively.

CONCLUSIONThe experimental results obtained by using the achiral and chiral liquid chromatography showed that the differences between enantiomers were apparent for the pharmacokinetics in rat plasma, and very significant for the distributions in major target tissues: heart, cerebrum and cerebellum, and main elimination tissues: kidney, spleen and liver.

Animals ; Area Under Curve ; Calcium Channel Blockers ; blood ; chemistry ; pharmacokinetics ; Chromatography, High Pressure Liquid ; methods ; Female ; Male ; Nimodipine ; blood ; chemistry ; pharmacokinetics ; Rats ; Stereoisomerism ; Tissue Distribution

OBJECTIVETo prepare floating sustained-release pellets of capsaicin based on nanometer CaCO3.

METHODThe floating sustained-release pellets were prepared by the dropping method with sodium alginate as matrix. The effects of the concentration of sodium alginate, the ratio of capsaicin to sodium alginate and the ratio of nanometer CaCO3 to sodium alginate on pellets were detected in the single-factor test. On that basis, central composite design-response surface method were used to optimize the formula, with the floating capacity, drug-loading rate and in vitro drug release property of pellets as indicators.

RESULTIn the optimal formula, CaCl2 accounted for 1.87%, the ratio of nanometer CaCO3 to sodium alginate was 2.16:1, and the ratio of capsaicin to sodium alginate was 2.36: 1, respectively. Capsaicin sustained-release pellets prepared under the conditions featured round granule, even particle size. It could float on artificial gastric fluid for over 15 hours, showing good sustained-release effect. Its accumulative drug-release percent of pellets in vitro at 12 h were 89.93%.

CONCLUSIONThe floating sustained-release pellets of capsaicin show good floating capacity and sustained-release effect after being optimized with central composite design-response surface method.

Alginates ; chemistry ; Calcium Carbonate ; chemistry ; Capsaicin ; chemistry ; pharmacokinetics ; Chemistry, Pharmaceutical ; instrumentation ; methods ; Delayed-Action Preparations ; chemistry ; pharmacokinetics ; Glucuronic Acid ; chemistry ; Hexuronic Acids ; chemistry ; Nanoparticles ; chemistry ; Particle Size

AIMTo study the pharmacokinetics of m-nifedipine (m-Nif) in Beagle dogs.

METHODSThe Beagle dogs were divided into two groups. m-Nif was intravenously administered to the Beagle dogs in group 1 at the dose of 0. 288 mg x kg(-1), and it was orally administered to the Beagle dogs in group 2, 3 and 4 at the dose of 1.152, 3.456 and 10.370 mg x kg(-1), respectively. m-Nif in plasma was detected by reversed phase high performance liquid chromatography. The pharmacokinetic parameters were calculated by 3P97 software.

RESULTSWhen m-Nif was intravenously administered, the plasma concentration-time curve was fit to a two-compartment model and T1/2beta was 117 min. When m-Nif was orally administered, the plasma concentration-time curve was fit to a one-compartment model. T1/2 (Ke) and Cmax were 147 min and 20 microg x L(-1); at the low dose of 1.152 mg x kg(-1). T1/2 (Ke) was 122 min and Cmax was 36 microg x L(-1) at the middle dose of 3.456 mg x kg(-1). T1/2 (Ke) was 144 min and Cmax was 69 microg x L(-1) at the high dose of 10.37 mg x kg(-1), respectively.

CONCLUSIONIt was showed that the speed of elimination of m-Nif was high in Beagle dogs. The absolute bioavailability of m-Nif given orally was very low.

Administration, Oral ; Animals ; Area Under Curve ; Biological Availability ; Calcium Channel Blockers ; administration & dosage ; pharmacokinetics ; Dogs ; Injections, Intravenous ; Isomerism ; Nifedipine ; administration & dosage ; pharmacokinetics