[Preparation, Characterization and Pharmacokinetic Study of Arginine Deiminase Lipid Nanoparticles].

OBJECTIVE: To prepare and characterize D-alpha-Tocopheryl polyethylene glycol 1000 succinate (TPGS) modified arginine deiminase (ADI) sulfobutyl-ß-Cyclodextrin liposome nanoparticles (ATCL), and to investigate the pharmacokinetic characteristics of ATCL in animals. METHODS: The reverse evaporation method was used to prepare ATCL, and the particle size and Zeta potential of ATCL were measured. Thiosemicarbazone-diacetylmonooxime colorimetric method was used to measure the activity of ADI. After intravenous administration, blood was drawn at set intervals of time and the enzyme activity in the plasma was measured. Enzyme activity-time curve was drawn subsequently and Debris Assessment Software (DAS) 2.1.1 was used to analyze the pharmacokinetic characteristics. RESULTS: The particle size and the potential of ATCL were (216.1±13.6) nm and (-19.4±2.1) mV, respectively. The optimal temperature and optimal pH for the catalytic reaction of ADI and ATCL were the same, both being 37 ℃ and pH6.5. Results of the analysis showed that the AUC (0-168 h), MRT (0-168 h), C max, T max, and t 1/2 of ATCL were 3.99, 2.56, 1.58, 3.2, and 9.88 times those of free ADI, respectively. Compared with ADI, the bioavailability of ATCL increased by 298.54%. CONCLUSION: ATCL prepared in the study can effectively improve the enzyme activity and bioavailability of ADI in Sprague-Dawley rats.

[Pharmacokinetics of Curcumin Ethosomes in Rats in vitro].

OBJECTIVES: To study the oral phamacokinetics of curcumin ethosomes in rats. METHODS: Pharmacokinetics parameters were detected by DAS 2.1.1 software analysis through data of blood concentrations harvested from HPLC after oral administration of curcumin ethosomes in rats. RESULTS: Analyzed by non-compartmental method, the area under concentration-time curve from 0 to last time [AUC(0-72h)] of curcumin ethosomes was 1.6 times larger than that of free curcumin, the peak concentration (C max) of curcumin ethosomes was 1.5 times higher than that of free curcumin, the relative bioavailability of curcumin ethosomes was 152.2%. The 90% confidential interval of AUC(0-72 h)was 102.2%-128.5%, which was not in standard interval of bioequialence. Analyzed by compartmental method, the AUC(0-72 h)of curcumin ethosomes was 1.4 times larger than that of free curcumin and the relative bioavailability of curcumin ethosomes was 128.2%. CONCLUSION: The curcumin ethosomes can enhance bioavailability, which has a bioinequivalence with free curcumin.

[Pharmacokinetics and Bioequiavailability of Asparaginase in Asparaginase Nanospheres].

OBJECTIVE: To determine the pharmacokinetics and bioequivalence of self-assembled hyaluronic acid-graft-poly (ethylene glycol)/hydroxypropyl-beta-cyclodextrin hollow nanospheres loaded with asparaginase (AHHPs) in SD rats. METHODS: AHHPs were prepared and observed under transmission electron microscopy. Its size, Zeta potential and entrapment efficiency were detected. Asparaginase (AAS) activities were measured after intravenous injection of AHHPs or free AAS in rats. The pharmacokinetic parameters were calculated using software DAS 2.1.1 for bioequivalence assessment. RESULTS: The self-prepared AHHPs had an average particle size of (367.43 ± 2.72) nm, Zeta potential of (-15. 70 ± 1.25) mV, and average entrapment efficiency of (66.03 ± 3.81)%. The intravenous injection of AHHPs and free AAS produced an area under concentration-time Curve (AUC)(0-48 h) of (162.06 ± 4.01) U/mL · h and (46.38 ± 1.98) U/mL · h, AUC(0-∞) of (203.74 ± 12.91) U/mL · h and (51.44 ± 3.01) U/mL · h, mean residence time (MRT) (0-72h) of (4.35 ± 0.06) h and (1.76 ± 0.06) h, MRT(0-∞) of (7.53 ± 1.05) h and (2.44 ± 0.29) h, peak concentration (Cmax) of (30.37 ± 0.43) U/mL and (26.06 ± 0.88) U/mL, and time to peak concentration (Tmax) of (0.75 ± 0.00) h and (0.08 ± 0.00) h, respectively. Compared with free AAS, the AUC(0-48 h), AUC(0-∞), MRT(0-72 h), MRT(0-∞),Cmax and Tmax of AHHPs increased by 3.5, 4.0, 2.5, 3.1, 1.2 and 9.4 times, respectively. The 90% confidential intervals of AUC(0-48 h), AUC(0.∞) and Cmax of the tested formulation were 72.6%-74.0%, 72.3%-73.7%, 94.7%-96.3%, respectively. CONCLUSION: AHHPs can improve the bioavailability of AAS, extending its biological half-life in rats. AHHPs and free AAS are not bioequivalent.

[The Pharmacokinetics and Pharmacodynamics of Intravenous Uricase Multivesicular Liposomes].

OBJECTIVE: To determine and compare the pharmacokinetics and pharmacodynamics of uricase-multivesicular liposomes (UOMVLs) with free uricase (UOX) in rats. METHODS: UOMVLs were prepared by the double emulsion method and confirmed with its entrapment efficiency, size and Zeta potential. Twelve healthy rats were randomly divided into two groups: one with i. v. injection of UOMVLs, and the other with i. v. injection of UOX. Their serum activity of uricase was assayed. The pharmacokinetic parameters were calculated using software DAS 2. 1. 1. Another 24 male SD rats were enrolled, the rat model of hyperuricemia was established with hypoxanthine and potassium oxonate, while normal group (n=6) was set as control. Injection of UOMVLs (1 mL, 0. 47 U/mL), UOX (1 mL, 0. 47 U/mL) and nothiy were given 1 h later in UOMVLs group (n=6), UOX group (n=6) and model group (n=6), and their serum uric acid levels were determined 1, 2, 3, 5, 7, 9, 12, 24, 36, 48 h after the establishment of hyperuricemia model. RESULTS: The entrapment efficiency of UOMVLs was (63. 75 ± 3. 65) %, with an average particle size of (22. 56 ± 1. 70) µm and Zeta potential of (-41. 81±6. 59) mV. The pharmacokinetic parameters of UOMVLs and UOX were as follows, respectively: area under time-concentration curve from 0 to infinity time (AUC0-∞) (498. 83 ± 58. 85) U/L . h and (28. 49 ± 9. 95) U/L . h; time to peak concentration (Tmax) (1. 00±0. 00) h and (0. 00±0. 00) h; peak concentration (Cmax) (73. 04±6. 35) U/L and (31. 00±6. 03) U/L; elimination half-life (t1/2) (3. 49±0. 80) h and (1. 17±0. 33) h. The relative bioavailability of UOMVLs was (1 750. 90±206. 56) %. UOMVLs decreased serum uric to normal in 9 h; whereas it took 48 h for the UOX group and the model group to return to normal. CONCLUSION: UOMVLs can prolong tmax and t1/2 and improve the relative bioavailability. UOMVLs decrease serum uric acid levels in rats with hyperuricemia more effectively than UOX.

[Pharmacokinetics and Intestinal Absorption of Curcumin Chitosan Hydrochloride Coated Liposome in Rats].

OBJECTIVE: To investigate the pharmacokinetics and intestinal absorption characteristic of curcumin chitosan hydrochloride coated liposome(CCLP) in SD rats. METHODS: Blood samples were collected after oral administration. Pharmacokinetic parameters were analyzed by DAS program. Rat single pass intestinal perfusion method was employed to investigate the absorption mechanism. RESULTS: The AUC0-t, AUC0-∞, t1/2, and Cmax of CCLP were 1. 73-fold, 1. 95-fold, 1. 56-fold and 1. 91-fold of the free drug. The intestinal absorption rate constant (Ka) of CCLP in duodenum, jejunum, ileum and colon were 1. 48, 1. 28, 1. 17 , and 4. 01 times as much as the free drug and the effective permeability(Peff) of CCLP were 1. 58, 1.-33, 1. 30 and 4. 55 times of the free drug, respectively. CONCLUSION: The bioavailability of CCLP in rats is increased remarkably and Ka is increased in various intestinal segments by CCLP, especially in colon, as well as Peff.

[Pharmacokinetics Study on Curcumin Hydroxypropyl-ß-Cyclodextrin Phospholipid Complex in Rats].

OBJECTIVE: To compare the in vivo pharmacokinetics of curcumin hydroxypropyl-ß-cyclodextrin phospholipid complex, curcumin hydroxypropyl-ß-cyclodextrin and curcumin phospholipid complex, and to discuss the advantage of hydroxypropyl-ß-cyclodextrin phospholipid complex as carrier. METHODS: Drawing blood after SD rats were oral administered with the above preparations and free drug at 50 mg/kg( corresponding to curcumin) , and the blood concentration were determined by HPLC. RESULTS: The AUC0-∞ of curcumin hydroxypropyl-ß-cyclodextrin phospholipid complex was(1 126. 20 ± 323. 24) g/(L . h), which was 5. 89, 1. 49 and 1. 17 times as curcumin (191. 08 ± 43. 27) µg/( L . h), curcumin phospholipid complex(754. 93 ± 55. 33) µg/(L . h), curcumin hydroxypropyl-ß- cyclodextrin(961. 21 ± 253. 65) µg/(L . h). CONCLUSION: The curcumin hydroxypropyl-ß-cyclodextrin phospholipid complex has a better absorption property than curcumin phospholipid complex and curcumin hydroxypropyl-ß-cyclodextrin, which is more beneficial to improve the bioavailability.

[Study on pharmacokinetics of demethoxycurcumin phospholipid complex in rats].

OBJECTIVE: To study the pharmacokinetics of Demethoxycurcumin phospholipid complex in rats with oral administration. METHODS: Drawing blood from the SD rats after oral administration Demethoxycurcumin phospholipid complex and free demethoxycurcumin. The blood concentration were determined by HPLC. RESULTS: The pharmacokinetics parameter of Demethoxycurcumin phos- pholipid complex were calculated and the results were as follows: AUC0-t (693. 306 ± 128. 55) µg/(L . h),1. 96-fold increase in the area under the plasma concentration versus time curve (AUC0-t) than that of free demethoxycurcumin, and AUC0-∞ (716. 174 ± 123. 18) µg/(L - h), 1. 93-fold increase than that of free demethoxycurcumin. Cmax (95. 044 ± 6. 95) µg/L, Tmax (0. 17 ± 0) h. Conclusion:Demethoxycurcumin phospholipid complex have higher bioavailability than free demethoxycurcumin,and their preparations bioequivalence are unqualified.

[Pharmacokinetics study of curcumin solid lipid nanoparticles by intravenous injection in rats].

OBJECTIVE: To study the intravenous pharmacokinetics of curcumin solid lipid nanoparticles in SD rats. METHODS: Rats were administrated with (iv) curcumin solid lipid nanoparticles and curcumin solution (8.0 mg/kg), respectively. Blood samples were collected and curcumin in blood plasma was determined by HPLC. Compartmental pharmacokinetics was analyzed by DAS software. RESULTS: After intravenous administration, the AUC(0-t), AUC(0-infinity) and t(1/2) of curcumin solid lipid nanoparticles were 1.50-fold, 1.63-fold and 4.08-fold higher than those of curcumin solution as (173.09 ± 44.81) µg x h/L vs. (114.83 ± 13.19) µg x h/L, (196.56 ± 35.25) µg x h/L vs. (120.66 ± 13.95) µg x h/L and (5.95 ± 2.05) h vs. (1.46 ± 0.03) h. CONCLUSION: The curcumin solid lipid nanoparticles is eliminated more slowly. The bioavailability of curcumin in rats increases remarkably compared with that of curcumin solution after intravenous administration.

[Correlation between in vitro release and in vivo absorption of sustained-releasing tablets of neostigmine bromide].

OBJECTIVE: To determine the correlation between in vitro release and in vivo absorption of sustained-releasing tablets of neostigmine bromide. METHODS: Water was used as dissolution medium to measured in vitro release of neostigmine bromide. After a single oral administration of 100 mg neostigmine bromide to rabbits, the plasma concentrations of neostigmine bromide in the rabbits were determined by HPLC. The compartment model and deconvolution method were employed to explain the in vitro-in vivo correlation. RESULTS: Using Y as cumulative in vitro release and Fa as percentage of absorption, the regression equation was established: Fa = 0.9298Y + 4.6074, r = 0.9961. The input function of R = 2.0163Y-11.242,r = 0.9270. CONCLUSION: The correlation between in vitro release and in vivo absorption of neostigmine bromide is good.

[Pharmacokinetics of mestinon-phospholipid complex in rats].

OBJECTIVE: To determine the pharmacokinetics characteristics of mestinon-phospholipid complex (PBPLC) in rats. METHODS: This study adopted a single-dose, randomized, open-label, two-period crossover trial design. Twelve healthy rats were randomly divided into two groups. One group was orally administered with mestinon-phospholipid complex, and the other group was orally administered with reference mestinon solution (1.5 mg/kg of mestinon). The plasma concentrations of the drugs in ophthalmic vein bloods were determined using HPLC. The pharmacokinetic parameters were calculated with the aid of DAS2.1.1 software. RESULTS: Pharmacokinetic parameters of mestinon-phospholipid complex were Tmax 2 h, Cmax 22.79 microg x min/mL and AUC(0-infinity) 7128.21 microg x min/mL, which were different from those of free mestinon--Tmax, 2 h, Cmax 6.00 microg/mL and AUC(0-infinity) 1772.36 microg x min/mL. The relative bioavailability of mestinon-phospholipid complex was 410.98% of free mestinon. CONCLUSION: The oral bioavailability of mestinon increases remarkably when administered as mestinon-phospholipid complex.

[Preparation and quality control of pyridostigmine bromide orally disintegrating tablet].

OBJECTIVE: To prepare orally disintegrating tablets containing pyridostigmine bromide and optimize formulations. METHODS: Solid dispersion was prepared using solvent evaporation-deposition method. The formulation was optimized by central composite design-response surface methodology (RSM plus CCD) with disintegration time as a reference parameter. RESULTS: The orally disintegrating tablets showed integrity and were smooth with desirable taste and feel in mouth. The disintegration time was less than 30 s. The cumulative drug dissolution was around 8.5% (around 2.5 mg which was less than bitterness threshold of pyridostigmine bromide of 3 mg) within 5 min in water while the cumulative drug dissolution was higher than 95% within 2 min in 0.1 N HCl. CONCLUSION: The orally disintegrating tablets are reasonable in formulation, feasible in technology and patient-friendly.

[Pharmacokinetics and relative bioavailability of neostigmine bromide sustained-release tablets].

OBJECTIVE: To study the pharmacokinetics and relative bioavailability of neostigmine bromide conventional tablets and sustained-release tablets in rabbits. METHODS: Six healthy rabbits were randomly divided into two groups for a cross self-contrast trial. RP-HPLC was used to detect plasma concentrations of neostigmine bromide. The pharmacokinetic parameters were calculated with the aid of DAS 2.0 software. RESULTS: The main pharmacokinetics parameters of the sustained-release tablets and conventional tablets were as follows, respectively: T(max)(3.67 +/- 1.51) hand (1.58 +/- 0.38) h; C(max) (5.04 +/- 1.19) mg/L and (4.56 +/- 1.70) mg/L; AUC(0 --> infinity) (32.82 +/- 9.88) mg/L x h and (29.84 +/- 14.27) mg/L x h. The relative bioavailability of the neostigmine bromide sustained-release tablets was 115.4%. CONCLUSION: The pharmacokinetics of neostigmine bromide accords with two compartments model, showing constant plasma concentration and relatively high bioavailability.

[A preliminary study of pharmacokinetics of evodiamine hydroxypropyl-ß-cyclodextrin inclusion complex].

OBJECTIVE: To compare the pharmacokinetic parameters of evodiamine hydroxypropyl-ß-cyclodextrin inclusion complex and free evodiamine suspension in rats, and investigate the pharmacokinetic characteristics of evodiamine inclusion complex. METHODS: Both water solubility and cumulative release percentage of EHD were tested with evodiamine as the control. Blood samples were collected from the venous plexus of SD rats after intravenous administration with evodiamine inclusion complex and free evodiamine at 100 mg/kg (equivalent evodiamine dose). Plasma concentrations of evodiamine were determined by high-performance liquid chromatography (HPLC), and the pharmacokinetic parameters were calculated using DAS 2.1.1. RESULTS: The evodiamine inclusion complex showed a better water solubility (18.46±0.36 µg/mL) and a higher cumulative release percentage [(76.8±4.9)%] than free evodiamine. The pharmacokinetic parameters of evodiamine inclusion complex and free evodiamine in rats were as follows: Cmax, 252.5±12.43 vs 161.3±3.45 µg/L; T(max), 4.00±0 vs 4.07±0 h; MRT(0-∞), 8.46±0.91 vs 4.43±0.74 h; AUC(0-t), 2266.40±28.64 vs 911.92±8.53 µg·L(-1)·h(-1); AUC(0-∞), 2359.76±31.58 vs 919.16±9.73 µg·L(-1)·h(-1). The relative bioavailability of evodiamine inclusion complex was 256.73%. CONCLUSION: Compared with free evodiamine, evodiamine inclusion complex has a higher bioavailability.

Role of a novel pyridostigmine bromide-phospholipid nanocomplex in improving oral bioavailability.

A novel pyridostigmine bromide (PB)-phospholipid nanocomplex (PBPLC) was prepared to increase the bioavailability of PB. A central composite design approach was employed for process optimization. The physicochemical properties of PBPLC were investigated by means of differential scanning calorimetry, ultraviolet spectroscopy, Fourier transformed infrared spectroscopy and the n-octano/water partition coefficient. The intestinal permeability of PBPLC was observed via a single pass intestinal perfusion in rats. After oral administration of PBPLC, the concentrations of PB at predetermined time points were determined by HPLC, and the pharmacokinetic parameters were computed by DAS 2.1.1 software. Multiple linear regression analysis for process optimization revealed that the optimal PBPLC was obtained when the values of X(1), X(2), and X(3) were 8, 40°C, and 4 mg/mL, respectively. The average particle size and zeta potential of PBPLC with the optimized formulation were 204.60 nm and -25.12 mV, respectively. Non-covalent interactions between PB and phospholipids were found in the PBPLC. The n-octanol/water partition coefficient of PBPLC was substantially increased. PBPLC had better intestinal permeability in comparison with free PB. Mean plasma drug concentration-time curves of PBPLC and free PB after oral administration were both in accordance with the two-compartment open model. The values of pharmacokinetic parameters of PBPLC and free PB were the peak time (T(max)) 2 h vs 2 h, the maximum concentration (C(max)) 22.79 µg/mL vs 6.00 µg/mL, and the value of the area under the concentration vs time curve (AUC(0-∞)) 7128.21 µg·min/mL vs 1772.36 µg·min/mL, respectively. In conclusion, compared with free PB, PBPLC remarkably improves the oral bioavailability of PB, which is likely due to its higher lipophilicity and permeability.

Improved biological properties and hypouricemic effects of uricase from Candida utilis loaded in novel alkaline enzymosomes.

OBJECTIVE: Previous studies on various enzymosomes (functional lipid vesicles encapsulating an enzyme) have been mostly carried out in vitro and have focused on preserving catalytic activity and improving the stability of the enzyme. Until now, few studies have focused on their in vivo fate. Similarly, although we have previously reported the increased in vitro uricolytic activity (about 2.2 times higher than that of free uricase, or three times higher than that of PEGylated uricase, Puricase(®), under physiological pH and temperature) and improved stability of the novel alkaline enzymosomes (functional lipid vesicles encapsulating uricase from Candida utilis: uricase-containing lipid vesicles, UOXLVs), it is still necessary to study the biological properties and hypouricemic effects of UOXLVs in vivo. METHODS: The enzyme kinetics, pharmacokinetics, pharmacodynamics, immunogenicity, and preliminary safety of UOXLVs were evaluated. RESULTS: The Michaelis constant (K(m)) value of the UOXLVs was slightly lower than that of the free enzyme. The enzyme release from the UOXLVs lasted over 12 hours and their circulation half-life was about sevenfold longer than that of the free uricase. Meanwhile, the UOXLVs had a 22-fold increase in the area under the curve compared with the free uricase. Furthermore, it took less than 3 hours for the UOXLVs to lower the plasma uric acid concentration from a high to a normal level, compared with 6 hours for the free uricase. In addition, the UOXLVs had much less immunogenicity than free uricase and were well tolerated by all animals throughout the observation period. CONCLUSION: The UOXLVs markedly improved the biological properties and enhanced the hypouricemic effects of uricase in vivo.

[Pharmacokinetic study of a new chewing gum dextromethorphan delivery system].

OBJECTIVE: To establish an high-performance liquid chromatography (HPLC)-based method for analysis of the pharmacokinetics and relative bioavailability of dextromethorphan chewing gum tablets in rabbits. METHODS: The pharmacokinetic parameters and the relative bioavailability of dextromethorphan chewing gum preparation in rabbits were compared with those of the commercially available chewing dextromethorphan tablets using 3P97 software. RESULTS: Pharmacokinetic analysis of the new dextromethorphan chewing gum tablets showed a AUC of 488.76 ∓ 175.00 ng.ml(-1).h, C(max) of 95.45 ∓ 17.53 ng/ml, and t(max) of 1.83 ∓ 0.57 h as compared with the corresponding parameters of 370.13 ∓ 90.56 ng.ml(-1).h, 174.00 ∓ 47.88 ng.ml, and 1.04 ∓ 0.14 h for the commercially available chewing tablets. The relative bioavailability of the new chewing gum medicine system was (140.73 ∓ 65.91)%. CONCLUSION: The new dextromethorphan chewing gum preparation shows an increased AUC((0→)), decreased C(max), and prolonged t(max) in comparison with the commercially available chewing tablets, with also a greatly enhanced relative bioavailability.

[Bioequivalence of pyridostigmine bromide dispersible tablets in rabbits].

OBJECTIVE: To compare the pharmacokinetic parameters of pyridostigmine bromide dispersible tablets and common tablets in rabbits. METHODS: Twelve rabbits were given an oral dose (60 mg) of pyridostigmine bromide dispersible tablets or common tablets in a randomized crossover study. The plasma concentration of pyridostigmine bromide was determined by reversed-phase ion pair chromatography. The pharmacokinetic parameters were calculated using DAS2.1.1 software. RESULTS: The pharmacokinetic parameters showed no significant differences in rabbit plasma between pyridostigmine bromide dispersible tablets and common tablets. The two tablets had a C(max) of 1.83∓0.08 mg·L(-1) and 1.68∓0.03 mg·L(-1), tmax of 2.33∓0.41 h and 2.58∓0.20 h, AUC(0-24) of 15.50∓0.62 mg·h·L(-1) and 15.14∓0.30 mg·h·L(-1), AUC(0-∞) of 15.82∓0.70 mg·h·L(-1) and 15.57∓0.32 mg·h·L(-1), respectively. The relative bioavailability F(0-24) was 102.38% and F(0-∞) was 101.61% for the dispersible tablets. CONCLUSION: The two tablets are bioequivalent in rabbits.