[Determination of 5-hydroxytryptamine,Adrenalin and Noradrenalin in Human Plasma by Pre-column Derivatization HPLC-MS/MS].

OBJECTIVE: To establish a method for the determination of 5-hydroxy tryptamine (5-HT),adrenalin (AD) and noradrenalin (NA) in human plasma using pre-column derivatization HPLC-MS/MS. Methods Derivatives of the plasma samples were produced with dansyl chloride under pH 10.5,and then extracted and enriched with ethyl acetate. The detected chemicals were separated using Ultimate C18 (50 mm×4.6 mm,5 µm) with acetonitrile-water-formic acid=95∶5∶0.05 (V∶V∶V) at 0.2 mL/min. The HPLC-MS//MS system was operated under a multiple reaction monitoring mode (MRM) using the electrospray ionization technique in positive mode. RESULTS: Linear range of the calibration curve appeared in 250-2.5 ng/mL. The method had a less than 9% intra- and inter-assay relative standard deviation (RSD),95.44%-109.71% recoveries,and 4.86%-12.81% matrix effects. CONCLUSION: This method is simple,accurate,and suitable for detection of 5-HT,AD and NA in human plasma.

[Determination of Voriconazole in Human Plasma and Its Bioequivalence by HPLC-MS/MS].

OBJECTIVE: To develop a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of voriconazole in human plasma and its bioequivalence. METHODS: 48 healthy male volunteers received a single dose of 200 mg voriconazole tablets in a two period (with two preparations) and randomized crossover bioequivalence study. Their plasma voriconazole was determined using HPLC-MS/MS. The pharmacokinetic parameters and bioequivalence of the two preparations were calculated with WinNonlin®6.1. RESULTS: The calibration curve of voriconazole ranged from 1 to 5 000 ng/mL. The HPLC-MS/MS method had less than 11% intra- and inter-day relative standard deviation (RSD),with 100.00% to 109.73% accuracies. The RSD of the matrix effect of voriconazole adjusted with internal standard was less than 15%. The extract recoveries exceeded 50% with good stability. The 90% confidence intervals for the peak concentration (Cmax) and the area under the curve (AUC0-t and AUC0-∞)of voriconazole fell into the bioequivalence range of 80.00%-125.00%. There was no significant difference in peak time (Tmax) between the two preparations. CONCLUSION: HPLC-MS/MS can be used for determination of voriconazole in human plasma. The two tested preparations of voriconazole are bioequivalent.

[Pharmacokinetics Study of Phentolamine Mesylate Injection in Healthy Volunteers].

OBJECTIVE: To study the pharmacokinetic profile of phentolamine mesylate injection in healthy Chinese volunteers. METHODS: A total of 16 healthy volunteers were randomly divided into two groups, each receiving anterior teeth submucosal infiltration anesthesia and inferior alveolar nerve block anesthesia, respectively. The participants were injected with 0.9 mL, 1.8 mL, and 3.6 mL of 2% lidocaine HCl with 1∶100 000 epinephrine over three periods sequentially, followed by corresponding sequential injection of 0.2 mg, 0.4 mg, 0.8 mg of phentolamine mesylate at the same sites 30 min later.Blood samples were drawn from 5 min before injection to 15 h post the injection of phentolamine mesylate (16 time points). Adverse events were closely observed all the time. Plasma phentolamine mesylate was detected using UPLC-MS/MS with isotope as internal standard. WinNolin 6.1 software was used to calculate the pharmacokinetic parameters. RESULTS: Time to peak concerntration (Tmax) ranged from 12 to 13 min. Half-time of elimination (t1/2) ranged from 3.84 to 4.07 h, with a clearance (CL) of 190 L/h. Peak concentration (Cmax), area under concentration-time curves from 0 to t hour and from 0 to infinite time (AUC0-t and AUC0-∞) increased proportionally in the dose range of 0.2 mg to 0.8 mg. The results of confidence interval analysis showed nearly linear dynamic characteristics for the injection of phentolamine mesylate. All participants experienced mild adverse events, including pain at the injection point, dizziness, and palpitations. These adverse events disappeared without treatments. CONCLUSIONS: Phentolamine mesylate injection is effective for reversing oral local anesthetic effects.

[Determination of Warfarin Enantiomers in Human Plasma with HPLC-MS/MS].

OBJECTIVE: To establish a high performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS) method for determination of warfarin enantiomers in human plasma. METHODS: Warfarin enantiomers were extracted with ethyl acetate. The HPLC-MS/MS method used naproxen as internal standard, with methanol : water : formic acid = 85 : 15 : 0.05 as mobile phase, at a flow rate of 0.18 mL/min. R-warfain, S-warfarin and internal standard (IS) were separated on column MS Chiral MS-OD (50 x 2.1 mm, 3 µm). Warfarin enantiomers were protonated with electroapry ionization (ESI) in negative electron ionization mode. The ion pairs being detected were (m/z) 307.2-160.9 (R-warfain and S-warafrin) and (m/z) 228.9 --> 185.1 (IS). RESULTS: The within-run precision relative standard deviations (RSD) and between-run precision RSD of R-warfarin were 3.2%-5.8% and 2.5%-5.1%, respectively. The method recoveries and extraction recoveries of R-warfarin were (96.1 ± 5. 6)%-(105.4 ± 4.7)% and 80.7%-84.4%, respectively. The matrix effect RSD was less than 10%. The within-run precision RSD and between-run precision RSD of S-warfarin were 3.7%-5.2% and 3.2%-4.8%, respectively. The method recoveries and extraction recoveries of 5-warfarin were (98.3 ± 5.1)%-(103.7 ± 3.8)% and 81.3%-84.6%, respectively. The limit of quantification was 0.1 µg/mL for both analytes. CONCLUSION: This new method is fully validated with satisfactory accuracy and adequate reproducibility. Therefore, it can be applied for separating and detecting plasma warfarin enantiomers.

[Bioequivalence of Ubenimex Capsules in Healthy Volunteers].

OBJECTIVE: To evaluate bioequivalence of two specifications of ubenimex capsules in comparison with the Japanese branded product (R). METHODS: The study adopted a 3-way crossover design in twenty-four healthy male volunteers, whose plasma concentrations of ubenimex were determined by UPLC-MS/MS after administration a single oral dose of 30 mg of domestic ubenimex T1 (10 mg/capsule), T2 (30 mg/capsule) and branded ubenimex R (30 mg/capsule) sequentially. The bioequivalence was evaluated using WinNonlin6. 1 statistical analysis software. RESULTS: One volunteer was excluded because of failure to follow medication instructions. The main pharmacokinetic parameters of ubenimex of T1, T2 and R were as follows: C(max) (2 646.73 ± 454.09) ng/mL, (2 675.91 ± 474.32) ng/mL and (2 432.79 ± 544.32) ng/mL, respectively; T(max) (0.68 ± 0.23) h, (0.76 ± 0.19) h and (0.77 ± 0.26) h, respectively; AUC(0-t) (3 925.23 ± 478.34)(ng x h)/mL, (3 804.62 ± 448.84)(ng x h)/mL and (3 789.30 ± 443.15)(ng x h)/mL, respectively; AUC(0-∞)(3 938.31 ± 479.54)(ng x h)/mL, (3 817.26 ± 450.90) (ng x h)/mL and (3 800.90 ± 444.77) (ng x h)/mL, respectively; CL/F (7.72 ± 0.92) L/h, (7.97 ± 0.98) L/h and (7.99 ± 0.90) L/h, respectively; Vd (26.08 ± 9.20 )L, (25.65 ± 10.22) L and (26.03 ± 10.05) L, respectively. The relative bioavailability F(0-t) and F(0-∞) of T1 and T2 against the branded preparation R were (103.90 ± 9.19)% and (100.77± 9.36)%, and (103.93 ± 9.20)% and (100.79 ± 9.33)%, respectively. CONCLUSION: Both ubenimex capsules T1 and T2 are bioequivalent to the Japanese branded products.

[Pharmacokinetics study of injected doripenemin healthy volunteers].

OBJECTIVE: To study the pharmacokinetics of injected doripenem in Chinese healthy volunteers, in order to optimize dosages for patients. METHODS: Twelve healthy volunteers were recruited in the threecross Latin square designed study. Participants received intravenous infusions of 0.25, 0.5 and 1.0 g doripenem sequentially in three periods at a random order. Plasma and urine doripenem were measured by HPLC-UV, using an internal standard method with meropenem for plasma samples and an external standard method for urine samples, respectively. Phoenix WinNonlin 6.1 pharmacokinetic software was used to calculate non-compartment pharmacokinetics parameters. SPSS 19.0 software was used for statistical analysis. RESULTS: A single dose infusion of 0.25, 0.5 and 1.0 g doripenemin 60 min produced the following respective parameters: Cmax (11.81 +/- 1.52), (22.80 +/- 3.80) and (47.26 +/- 8.38) microg/mL, Tmax (60.42 +/- 1.44), (58.33 +/- 5.77) and (60.00 +/- 0) min, t(1/2) (63.48 +/- 10.51), (69.12 +/- 16.72) and (69.30 +/- 11.71) min, AUC(0-1), (1100.86 +/- 150.04), (2111.50 +/- 359.58) and (4359.50 +/- 789.38) microg/(mL x min). Linear Regression and Confidence Interval analyses suggested a linear kinetic characteristic. Doripenem was mainly excreted through kidneys, with 24 h cumulative urine excretion rates ranging from 70% to 75% for the three doses of infusions. It was safe to administer doripenem through infusion in healthy volunteers. Adverse reactions occurred in 19.44% cases of infusions, although all were mild reactions. Tinnitus happened in two cases (8.33%) of infusions, which required close observations. CONCLUSION: Doripenem infusion possesses a linear kinetics. There is no need to adjust the regimenpatients.

[Phase I clinical trial on the safety of injectable cefetamet sodium with a single dose in healthy volunteers].

OBJECTIVE: To investigate the safety and maximum tolerable dosage of injectable cefetamet sodium Sixty healthy volunteers were enrolled in this study. with a single infusion in Chinese healthy volunteers. METHODS: A double-blinded, randomized, placebo-controlled design was adopted. Eight dosages ranging from 100 mg to 5 000 mg were tested. The pharmacokinetics of the drug was analyzed using a Latin square three-cross self-controlled design, with 12 healthy volunteers receiving 500 mg, 1 000 mg and 2 000 mg of injectable cefetamet sodium in a randomized sequence. Blood and urine samples were collected and analyzed using high performance liquid chromatography with UV detection. The main pharmacokinetics parameters were calculated with DAS2.0 software. RESULTS: 59 healthy volunteers completed the tolerance tests. Clinical adverse reactions occurred in 22.73% of participants in the test group and 6.67% of participants in the placebo group; but the difference was not statistically significant. Common adverse events included infusion pain and dizziness. Rare adverse events such as palpitations, diarrhea and rash occurred in participants in the test group. All of the adverse reactions were mild. Abnormal laboratory test results occurred in 43.18% participants in the test group and 53.33% participants in the placebo group; again the difference was not statistically significant. Common abnormal laboratory test results included abnormal bowel flora, stool abnormalities, abnormal urine and elevated serum potassium. After a single infusion of 500 mg, 1 000 mg and 2 000 mg of injectable cefetamet sodium, peak concentration of the drug at 0.5 h reached (37.92 +/- 7.43), (74.90 +/- 10.67) and (148.54 +/- 31.63) mg/L, with areas under concentration-time curve of (72.08 +/- 14.98), (144.28 +/- 24.57) and (286.66 +/- 54.25) (mg x h)/L, respectively. Their elimination half-life was (2.03 +/- 0.38), (2.04 +/- 0.26), and (2.12 +/- 0.26) h, respectively. The disposition of cefetamet was presented as a two-compartment model with linear kinetics. The 24-hour urinary accumulation excretion was 76.6%-67.5%. CONCLUSION: The maximum single tolerated dose of injectable cefetamet sodium is 5 000 mg. The pharmacokinetics is a two-compartment model with linear kinetics within a dose range 500-2 000 mg.

[Determination of dimemorfan in human plasma and urine with HPLC-MS/MS].

OBJECTIVE: To develop a sensitive and reproducible HPLC-MS/MS method for analyzing dimemorfan in human plasma and urine. METHODS: Dimemorfan was extracted from plasma and urine by redistilled ether, with lidocaine serving as the internal standard (IS). The analysis was performed on a column of ultimate C18 (50 mm x 4.6 mm, 5 microm) with the mobile phase consisting of methyl alcohol-water-formic acid = 75:25 : 0.05 at a flow rate of 0. 2 mL/min. Dimemorfan was detected by API 3000 mass spectrometer, with multiple reaction monitoring after protonated with ESI in positive electron ionization mode. The ion pairs being detected were (m/z) 256.4-->155. 3 (dimemorfan) and 235.4-->86.1 (lidocaine), respectively. RESULTS: The regression equation for dimemorfan showed excellent linearity (r = 0.995 7) from 0. 025 to 5.0 ng/mL of plasma with detecting limitation of 0.025 ng/mL and perfect linearity (r = 0.9983) from 0.1 to 20.0 ng/mL of urine with detecting limitation of 0.1 ng/mL. The method recoveries of dimemorfan in plasma and urine were ranging from 103.38% to 106.88% and 90.05% to 101.40%, respectively. The maximum intra-day and inter-day relative standard deviations (RSD) of concentration of dimemorfan were 5.92% and 5. 70% (for plasma), 10.35% and 8.80% (for urine), respectively. CONCLUSION: This new method was validated to be accurate and sensitive to determinate the concentration of dimemorfan in plasma and urine samples, and can be applied for pharmacokinetic studies of dimemorfan.

[Pharmacokinetics study of amoxicillin sodium clavulanate potassium (10:1) injection in healthy volunteers].

OBJECTIVE: To study the pharmacokinetics of amoxicillin sodium clavulanate potassium (10:1) injection with different single doses intravenous infusion and one dose repeated intravenous injection in healthy volunteers for guiding the rational clinical regimen. METHODS: Using infusion pump constantly intravenous dripping in 30 min, 4 mL blood samples were collected before and after the administration at 10 min, 20 min, 30 min, 45 min, and 1, 1.25, 1.5, 2, 2.5, 3, 4, 6, 8, 10 h. The plasma concentrations of amoxicillin and clavulanate were detected by high performance liquid chromatography- mass spectrometry/mass spectrometry method. The pharmacokinetic parameters were calculated by DAS2.0.1 software. RESULTS: The dispositions of amoxicillin and clavulanate matched three or two compartment model with the weight coefficient 1/cc. To avoid the biases caused by compartment model fitting, the pharmacokinetic parameters were statistical moment parameters of non-compartment model. The peak concentrations, the areas under curve, the half-lifes and the clearances after single injections of 0. 55 g, 1.1 g and 2.2 g indicated that both amoxillin and clavulanate had linear dynamics characteristics. After 1.1 g single dose and multiple doses infusion, the pharmacokinetic parameters of amoxicillin and clavulanate were close respectively, and the trough concentrations before the 7th to 13th administration were lower than the detection limitation, which implied that the previous administration had cleared out before the next administration, and no accumulation happened after multiple doses. CONCLUSIONS: The amoxicillin sodium clavulanate potassium (10:1) injection possesses the linear kinetics. The dosage regimen of 1.1 g Q8h intravenous infusion could meet the needs of clinical therapy.

[Determination of probucol in human plasma by HPLC-MS/MS].

OBJECTIVE: To develop a specific and sensitive method for the determination of probucol in human plasma using HPLC-MS/MS technique. METHODS: Probucol were extracted from plasma by ethyl ether: dichloromethane (1:1, V/V), with physcion as an internal standard. The analytes went through the column of ultimate CN (50 mm x 4.6 mm, 5 microm) with mobile phase acetonitrile: water: ammonia water = 97:3:0.05 (adjusted pH = 7.2 with formic acid). Probucol was analyzed with a negative mode. The ion pairs being detected were 515.5-->236.1 (probucol) and 283.0-->239.9 physcion, respectively. RESULTS: The established method was able to determine probucol in human plasma over the range of 2.5-6000 ng/mL, with a method recovery ranging from 93.02% to 104.12%. The intra and inter day variances were below 4.67% and 5.72%. CONCLUSION: The HPLC-MS/MS method for analyzing probucol was validated. It is sensitive and suitable for pharmacokinetic studies of probucol.

[Determination of donepezil enantiomer in human plasma by normal-HPLC-MS/MS].

OBJECTIVE: To develop and validate a normal phase HPLC-MS/MS method for the determination of donepezil enantiomer in human plasma. METHODS: Donepezil was extracted from plasma by n-hexane:isopropanol (98:2, V/V) with lidocaine serving as an internal standard. The analytes went through the column of CHIRALCEL OJ-H (250 mm x 4.6 mm, 5 microm) with mobile phase n-hexane:n-propanol:diethylamine (60:40: 0.1, V/V/V). Donepezil enantiomer was determined by API 3000 in MRM mode. RESULTS: The retention time of S-DN and R-DN were 15.56 min and 18.41 min, respectively. The calibration curves were linear in a range from 0.051 to 7.596 ng/mL for S-DN, and from 0.049 to 7.404 ng/mL for R-DN, respectively, both with more than 0.99 correlation coefficients. The relative recovery were 95.10%-103.70% for S-DN and 93.58%-98.00% for R-DN, respectively; the pretreatment recovery were 58.42%-61.08% for S-DN and 53.24%-61.87% for R-DN, respectively; the within-day RSD ranged from 8.35% to 11.28% for S-DN and from 6.78% to 11.58% for R-DN, respectively; the between-day RSD ranged from 5.82% to 9.02% for S-DN and from 6.87% to 9.19% for R-DN, respectively. CONCLUSION: This normal phase HPLC-MS/MS method is simple, rapid, sensitive and accurate for the determination of donepezil enantiomer in human plasma and is suitable for pharmacokinetic studies of donepezil enantiomers.

[Determination of ubenimex in human plasma by HPLC-MS/MS].

OBJECTIVE: To establish a liquid chromatography tandem mass spectrometry method for the determination of ubenimex in human plasma. METHODS: The essay was conducted with an API 3000 HPLC-MS/MS system consisted of a Ultimate C18 column (50 mm x 4.6 mm, 5 microm). The mobile phase consisted of methanol-water-formic acid (70 : 30 : 0.05, V/V/V) at a flow rate of 0.2 mL/min. Granisetron was used as the internal standard. The sample was extracted by solid phase extraction column and was operated under the multiple reaction monitoring mode using the electrospray ionization technique in positive mode. RESULTS: The linear range of ubenimex was 0.4-4000 ng/mL. The limit of quantity was set at 0.4 ng/mL. The within-day and between-day variations were less than 6%. CONCLUSION: This method for the quantitative determination of ubenimex was proved to be accurate, sensitive, selective and convenient and can be applied in the determination of ubenimex in human plasma.

[Pharmacokinetics of injected cefozopran hydrochloride in healthy volunteers].

OBJECTIVE: To study the pharmacokinetics of injected cefozopran hydrochloride in healthy volunteers. METHODS: 24 healthy volunteers were enrolled to receive low (0.5 g), middle (1.0 g), high (2.0 g) doses of single injection and multiple doses (1.0 g) injection of cefozopran hydrochloride in an open randomized study. The plasma concentrations of cefozopran were determined by RP-HPLC. The DAS2.0 was used to fit the concentration-time data and to calculate the pharmacokinetic parameters. RESULTS: The main pharmaeokinetic parameters for a single injection of low, middle and high doses of cefozopran were as follows: Cmax (48.27 +/- 9.84), (77.99 +/- 15.08) and (171.59 +/- 18.27) mg/L; Tmax (0.50 +/- 0.00), (0.51 +/- 0.02) and (0.51 + 0.02) h; AUCo-t (92.43 +/- 24.02), (152.45 +/- 16.26) and (341.03 +/- 44.16) mg x h/L; t1/2beta (1.97 +/- 0.19), (2.44 +/- 0.24) and (2.18 +/- 0.31) h, respectively. The main pharmacokinetic parameters for a multiple doses injection of cefozopran were as follows: Cmax (80.39 +/- 11.86) mg/L; Tmax (0.51 +/- 0.02) h; AUCo-t (159.74 +/- 15.06) mg x h/L; t1/2beta (2.55 +/- 0.55) h. The accumulative rate of cefozopran through urine pathway within 24 h was (89.4 +/- 15.5)%. The statistical analysis showed that Cmax, AUCo-t, and AUCo-infinity increased significantly with increased doses of injection (P < 0.05). Those parameters were linearly correlated with the doses of injection (r = 0.9950, 0.9960, 0.9963). However, dosage did not have an impact on other pharmacokinetic parameters (P > 0.05). No gender differences in the parameters were found (P > 0.05). CONCLUSION: Cefozopran hydrochloride performs a linear kinetics in healthy volunteers. The main pharmacokinetic parameters have no significant gender differences, and there is no drug accumulated with multiple doses of injection.

[Determination of biapenem in human plasma by high performance liquid chromatography].

OBJECTIVE: To establish a method to determine biapenem in human plasma with high performance liquid chromatography. METHODS: Chromatographic separation was performed on a YMC-C18 column (150 mmX 4. 6 mm, 5 microm) eluted with a mobile phase comprising 98 : 2 (V = V) of sodium acetate (0.1 mol/L, adjust with acetic acid to pH 4.5) and acetonitrile with a flow rate of 1.0 mL/min. The detection wavelength was set at 300 nm. Temperature was controlled at 35 degrees C. The plasma samples were precipitated with acetonitrile. The supernatant was vortexed with dichloromethane and 0.03 mL of the aqueous layer was injected for analysis. RESULTS: The method was valid to detect biapenem in a range of 0.0625 mg/L to 80 mg/L (correlation coefficient 0.999). The pretreatment recovery of biapenem ranged from 96.11% to 98.76%. The methodological recovery of biapenem ranged from 99.14% to 109.69%. The inter-day RSD ranged from 0.92% to 2.79%. The intra-day RSD ranged from 2.46% to 4.08%. Less than 7% change of results was observed after the sample was stored in room temperature for 5 h, frozen and defrozen 3 times, stored at -30 degrees C for 28 d, stayed in autosampler for 24 h, and injected twice. CONCLUSION: The method is sensitive, accurate and easy to perform, which offers a satisfactory tool for the determination and pharmacokinetic study of biapenem.

[Determination of lidocaine and its metabolites in human plasma by liquid chromatography in combination with tandem mass spectrometry].

OBJECTIVE: To establish a liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method for the determination of lidocaine (LDC) and its metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX), in human plasma. METHODS; The assay was conducted with an API 3000 HPLC-MS/MS system consisted of a Ultimate C18 column (50 x 4.6 mm, 5 microm). The mobile phase consisted of methanol: 5 mmol/ L ammonium acetate (50:50, pH was adjusted to 5.0 by formic acid) and the flow rate was set at 0.2 mL/min. The alkalinized sample was extracted with ethyl acetate. After evaporation of the organic layer, the residue was dissolved in mobile phase and the drug was determined by HPLC-MS/MS using electrospray ionization. RESULTS: The calibration curve was linear in a range from 15.625 to 2000 ng/mL for LDC. Linear calibration curves were obtained in the range of 1.5625 to 200 ng/mL for both for MEGX and GX. The limit of quantification for LDC, MEGX and GX was set at 15.625, 1.5625 and 1.5625 ng/mL. CONCLUSION: This method for the quantitative determination of lidocaine and its metabolites in human plasma is simple, rapid, sensitive and accurate. Therefore it can be used for the determination of lidocaine and its metabolites in clinical practice.

[Detecting penehyclidine hydrochloride in rats plasma and tissues with HPLC-MS/MS].

OBJECTIVE: To develop a method for detecting penehyclidine hydrochloride (PH) in mouse plasma and tissues using HPLC-MS/MS. METHODS: The plasma and tissue samples were extracted with petroleum ether, ethyl ether (70:30). The isolation of PH was achieved on an Allure C18, (50 x 2.1 mm, 5 microm) column, with methanol/5 mmol/L ammonium acetate/triethylamine = 90/10/0.05 (adjusted pH 5.8 by formic acid as mobile phase. Benzhydramine was used as the internal standard. RESULTS: The calibration curves were linear over the range of 0.39-200 ng/mL for plasma and 0.391-100 ng/mL for tissues. The extraction recovered 67.32-70.80% of PH in plasma, 84.99%-89.27% of PH in lung tissues, and 76.86%-81.98% of PH in brain tissues. The HPLC detected 97.66%-99.97% of PH in extracted samples of plasma, 96.55%-101.65% extracted samples of lung and 95.18%-100.21% of extracted samples of brain. The within-day RSD were 1.94%-2.93%, 1.73%-3.70% and 2.35%-2.79% for plasma, lung, and brain, respectively. The between-day RSD were 3.00%-3.85% 2.86%-3.94% and 2.77%-5.00% for plasma, lung, and brain, respectively. Both the long-term and freeze-thaw stabilities were acceptable. The long-term RSD were 1.52%-5.26%, 1.88%-2.93%, and 2.22%-3.76% for plasma, lung, and brain, respectively. The freeze-thaw RSD were 0.38%-3.55%, 2.79%-9.60%, and 1.35%-2.29% for plasma, lung, and brain, respectively. CONCLUSION: The assay is simple and accurate, with good reproducibility, and can satisfy to the needs of pharmacokinetics and relative bioavailability studies on penehyclidine hydrochloride.

[Determination of nicacid and its metabolites in human plasma by HPLC-MS/MS].

OBJECTIVE: To develop a sensitive HPLC-MS/MS method for the determination of nicacid and its metabolites in human plasma. METHODS: The assay was conducted with an API 3000 LC-MS/MS system comprising of a Genimi C18 column (50 x 3.00 mm, 3 microm), and an eluate of 0.1% acetic acid-methanol-isopropyl alcohol (98: 1:1), and flow rate was 0.2 mL/min. Acetonitrile was used to precipitate protein from the plasma samples. The loading samples contained the residue from the supernatant that were dissolved in the eluate solution and rinsed by dichloromethane was used as the loading samples. The ion pairs of m/z 124.1-->80.0, m/z 123.1-->80.0, m/z 181.1-->135.0 and m/z 138.1-->92.0 were used to quantify nicacid, niacinamide, nicotinuric acid and 6-methyl nicotinic acid (IS), respectively. RESULTS: The standard curves of nicacid, niacinamide and nicotinuric were linear in the range of 1.25-320 microg/L, 1.25-1280 microg/L and 1.25-1280 microg/L, respectivly. All with a low determination limits of 1.25 microg/L and a less than 9% within-day and inter-day RSD. The recovery rates reached 89% to 105%. CONCLUSION: The method is simple, rapid, sensitive, and suitable for the determination of nicacid and its metabolites in human plasma.

[Determination of lovastatin and its active metabolites in human plasma with high performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To develop a sensitive LC-MS/MS method for analyzing lovastatin and its active metabolites lovastatin acid in human plasma. METHODS: Lovastatin and lovastatin acid were extracted from plasma by ethyl ether -dichloromethane (V/V, 1:1), with simvastatin serving as an internal standard. The analytes went through the column of Phenomenex Gemini C18 (50 x 3 mm, 3 microm) with mobile phase acetonitrile-water (85:15), and was analyzed by API3000 after protonated with ESI mode. The ion pairs being detected were 427.4-->325.4, 445.4-->343.4 and 436.4-->325.4, respectively. RESULTS: The established method was able to determine lovastatin in human plasma over the range of 0.03125-64 microg/L, with recovery rates ranging from 96% to 102%. The intra and inter day variances were below 9.3%. CONCLUSION: The LC-MS/MS method for analyzing lovastatin is validated and is suitable for clinical pharmacokinetic studies.

[Correction of secondary deformity of unilateral cleft lip with refined anatomic repair in orbicularis oris muscle].

OBJECTIVE: To investigate the functional repair of secondary deformity of unilateral cleft lip. METHODS: The nasal branch, nasolabial branch, and labial branch of orbicularis oris muscle were dissected and repositioned precisely to correct the secondary deformity of unilateral cleft lip. RESULTS: 96 patients were treated successfully with this method during Jan. 2005 to Oct. 2008. Good cosmetic and functional results were achieved. 85 cases were followed up for 3 months to 5 years with a satisfactory rate of 94.1% (80/85 cases). CONCLUSIONS: The application of refined anatomy and precise reposition in orbicularis oris muscle is important to ensure therapeutic effect in patients with secondary deformity of unilateral cleft lip.