Pharmacokinetics, pharmacodynamics and safety of LPM3480392 in two phase I clinical trials in healthy Chinese male subjects

Drugs for acute postoperative pain and breakthrough cancer pain are still urgent in clinical. LPM3480392 is a G-protein-biased ligand at the μ-opioid receptor and showed potent analgesia in nonclinical studies. Two phase I studies of LPM3480392 were conducted in healthy Chinese male volunteers to explore its tolerability, pharmacokinetics and pharmacodynamics under single ascending doses (Study I 0.1-3.0 mg, 30 min) and different infusion times (Study II, 0.6-1.0 mg, 2-15 min). There was one serious adverse event (AE) observed in Study II, and the rest AEs were mild or moderate in severity and resolved by the end of the study. Plasma LPM3480392 maximum concentration (Cmax ) (under lower infusion rate) and area under the plasma concentration-time curve (AUCs) were generally increased with dose. Moreover, LPM3480392 at a dose of 0.6 mg under a 2 min infusion rate elicited effective analgesia as the peak effect within 10-30 min, which was measured by cold pain test and pupillometry. These findings suggest that LPM3480392 could be a potential treatment for acute pain management.

Pharmacokinetic and Bioequivalence Evaluation of 2 Tadalafil Tablets in Healthy Male Chinese Subjects Under Fasting and Fed Conditions

Tadalafil is an effective, reversible, and competitive phosphodiesterase 5 inhibitor mainly used to treat erectile dysfunction. This study investigated the bioequivalence of generic and marketed formulations of 10-mg tadalafil tablets under fasted and fed conditions. This open-label, randomized, single-dose, 2-period crossover study included 53 healthy Chinese men (aged 20-43 years). Plasma samples were collected from 0.5 hours before treatment to 72 hours after each dose and analyzed using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry. Pharmacokinetic parameters were calculated using noncompartmental analysis. Safety assessments were performed throughout the study. For the fasted state, the 90% confidence intervals of the geometric mean ratios between the generic and marketed formulations were 86.1% to 99.1% for the maximum plasma concentration and 88.4% to 100.3% for the area under the plasma concentration-time curve from time 0 to infinity, and the corresponding values under the fed state were and 99.9% to 108.4% and 95.7% to 104.3%, respectively. All data were within the accepted bioequivalence range of 80% to 125%. After consuming high-fat, high-calorie meals in the fed condition, the time to the maximum plasma concentration was similar between the formulations, and area under the plasma concentration-time curve from time 0 to infinity and maximum plasma concentration were 10.2% and 6.55% higher, respectively, for the marketed formulation. Thus, food had no clinically relevant effect on tadalafil exposure following a single oral dose in healthy Chinese men. No serious adverse reactions were reported. These results indicated that the analyzed generic and marketed tadalafil tablets were bioequivalent with similar safety profiles.

CYP2C9*3(1075A > C), ABCB1 and SLCO1B1 genetic polymorphisms and gender are determinants of inter-subject variability in pitavastatin pharmacokinetics

A pharmacokinetics study was conducted in 12 Chinese volunteers following a single dose of 1 mg, 2 mg and 4 mg of pitavastatin calcium in an open-label, randomized, three-period crossover design. Plasma concentrations of pitavastatin acid and pitavastatin lactone were determined by a HPLC method. Single-nucleotide polymorphisms (SNPs) in ABCB1, ABCG2, SLCO1B1, CYP2C9 and CYP3A5 were determined by TaqMan (MGB) genotyping assay. An analysis was performed on the relationship between the aforementioned SNPs and dose-normalized (based on 1 mg) area under the plasma concentration-time curve extrapolated to infinity [AUC(0-infinity)] and peak plasma concentration (Cmax) values of the acid and lactone forms of pitavastatin. Pitavastatin exhibited linear pharmacokinetics and great inter-subject variability. Compared to CYP2C9*1/*1 carriers, CYP2C9*1/*3 carriers had higher AUC(0-infinity) and Cmax of pitavastatin acid and AUC(0-infinity) of pitavastatin lactone (P<0.05). With respect to ABCB1 G2677T/A, non-G carriers had higher Cmax and AUC(0-infinity) of pitavastatin acid, and Cmax of pitavastatin lactone compared to GT, GA or GG genotype carriers (P<0.05). Gene-dose effects of SLCO1B1 c.521T> C and g.11187G > A on pharmacokinetics of the acid and lactone forms were observed. Compared to non-SLCO1B1*17 carriers, SLCO1B1*17 carriers had higher Cmax and AUC(0-infinity) of the acid and lactone forms (P<0.05). Significant sex difference was observed for pharmacokinetics of the lactone. Female SLCO1B1 521TT subjects had higher Cmax and AUC(0-infinity) of pitavastatin lactone compared to male 521TT subjects, however, such gender difference disappeared in 521 TC and 521CC subjects. Pitavastatin pharmacokinetics was not significantly affected by ABCB1 C1236T, ABCB1C3435T, CYP3A5*3, ABCG2 c.34G > A, c.421C > A, SLCO1B1 c.388A>G, c.571T>C and c.597C>T. We conclude that CYP2C9*3, ABCB1 G2677T/A, SLCO1B1 c.521T>C, SLCO1B1 g.11187G > A, SLCO1B1*17 and gender contribute to inter-subject variability in pitavastatin pharmacokinetics. Personalized medicine should be necessary for hypercholesterolaemic patients receiving pitavastatin.

Simvastatin pharmacokinetics in healthy Chinese subjects and its relations with CYP2C9, CYP3A5, ABCB1, ABCG2 and SLCO1B1 polymorphisms

A pharmacokinetic study of simvastatin (single oral dose, 40 mg) was conducted in 17 healthy Chinese volunteers. Plasma concentrations of simvastatin were determined by an LC-ESI-MS-MS method. The pharmacokinetic parameters of simvastatin were derived with a non-compartmental method. The polymorphisms of CYP2C9, CYP3A5, ABCB1 (encoding P-gp), ABCG2 (encoding BCRP) and SLCO1B1 (encoding OATP1B1) were determined by TaqMan genotyping assay and the impacts of these SNPs on the pharmacokinetics of simvastatin were analyzed. Major pharmacokinetic parameters were as follows: Tmax 1.44 +/- 0.39 h, Cmax 9.83 +/- 2.41 microg x L(-1), t1/2 4.85 +/- 1.23 h and AUC(0-infinity) 40.32 +/- 6.82 microg x h x L(-1). Effect of ABCB1 G2677T/A SNP on dispostion of simvastatin was observed. Significant differences in t1/2, but not Cmax and AUC(0-infinity), were observed between G/A, G/T or G/G carriers and non-G carriers (5.65 +/- 0.50 h vs 4.41 +/- 1.31 h, P < 0.05). There were no significant effects on simvastatin pharmacokinetics by SNPs such as CYP2C9*3 (1075A > C), CYP3A5*3 g.6986A > G, ABCB1 C3435T, ABCG2 c.34G > A, ABCG2 c.421C>A, SLCO1B1 c.388 A > G, SLCO1B1 c.521 T > C, SLCO1B1 g.11187 G > A, SLCO1B1 c.571 T > C and SLCO1B1 c.597 C > T. We conclude here that there is a small inter-subject variation in simvastatin pharmacokinetics in healthy Chinese volunteers. P-gp, OATP1 B1 and BCRP seem unlikely to play an important role in the pharmacokinetics of simvastatin. The gene-dose effects of ABCG2 c.421 C > A and CYP3A5*3 g.6986A > G on simvastatin pharmacokinetics are not strong enough in Chinese subjects.

ABCB1 gene polymorphisms, ABCB1 haplotypes and ABCG2 c.421c > A are determinants of inter-subject variability in rosuvastatin pharmacokinetics

A randomized cross-over pharmacokinetic study of rosuvastatin calcium (single dose: 5 mg, 10 mg and 20 mg; multiple doses: 10mg once daily for 7 days) was conducted in 12 healthy Chinese volunteers. Plasma concentrations of rosuvastatin were determined by an LC-ESI-MS-MS method. Single-nucleotide polymorphisms (SNPs) in ABCB1, ABCG2, SLCOB1, CYP2C9 and CYP3A5 were determined by TaqMan (MGB) genotyping assay. An impact of the aforementioned SNPs on steady state pharmacokinetic parameters [average steady state concentration (Cav,ss) and area under the plasma concentration versus time curve during the dosing interval at steady state (AUCss)], dose-normalized (based on 5 mg) pharmacokinetic parameters of single-dose rosuvastatin were further analyzed. Rosuvastatin exhibited linear pharmacokinetics and great inter-subject variability. Cav,ss, AUCss and dose-normalized peak plasma concentration (Cmax) and AUC(0-infinity) of single-dose rosuvastatin were significantly related with ABCB1 C1236T, G2677T/A and C3435T polymorphisms and ABCB1 haplotypes. Compared to homozygous wild type and heterozygous mutation gene carriers, subjects carrying the variant ABCB1 1236TT, 2677 non-G or 3435TT genotype had higher Cav,ss, AUCss, Cmax and AUC(0-infinity) (p < 0.05). ABCB1 haplotype (1236TT-2677TT-3435TT) had significant influence on dose-normalized pharmacokinetics of single-dose rosuvastatin. ABCB1 haplotype (1236TT-2677TT-3435TT) carriers (n = 12) had obvious higher Cmax (11.16 +/- 3.10 microg x L(-1) vs 8.35 +/- 3.31 microg x L(-1), p < 0.05) and AUC(0-infinity) (86.61 +/- 24.32 microg x h x L(-1) vs 62.60 +/- 26.19 microg x h x L(-1), p < 0.05) compared to non-1236TT-2677TT-3435TT carriers (n = 24). ABCG2 c.421C > A had a significant impact on rosuvastatin pharmacokinetics. Homozygotes (AA) carriers had obvious higher Cmax (12.20 +/- 4.09 microg x L(-1) vs 8.70 +/- 3.09 microg x L(-1), p < 0.05) and AUC(0-infinity) (98.74 +/- 25.36 microg x h x L(-1) vs 64.97 +/- 24.90 microg x h x L(-1), p < 0.05) values compared to heterozygotes (CA) and homozygotes (CC) carriers. There were no significant effects on single-dose and steady-state pharmacokinetics of rosuvastatin by CYP2C9*3 (1075A > C), CYP3A5*3 g.6986A > G, ABCG2 c.34G > A, SLCO1B1 c.521 T > C, c.388 A > G, g.11187 G > A, c.571 T > C and c.597 C > T. In addition, no difference in rosuvastatin pharmacokinetics was observed among subjects of different genders. We conclude that ABCB1 C1236T, G2677T/A and C3435T polymorphism, ABCB1 haplotypes and ABCG2 c.421C > A are determinants of inter-subject variability in rosuvastatin pharmacokinetics in healthy Chinese volunteers, and potentially affect the efficacy and toxicity of statin therapy.

Intermittent watt-level ultrasonication facilitates vancomycin release from therapeutic acrylic bone cement

Ultrasound holds promise for enhancing the vancomycin release from cement though the length of time when local drug level exceeded the minimum inhibitory concentration (T(>MIC)) was not prolonged by the previous protocol of milliwatt-level ultrasonication. Here vancomycin-loaded cements were subjected to continuous watt-level ultrasonication (CUG), intermittent watt-level ultrasonication (IUG) or no ultrasonication (NUG) for 14 d during immersion in 40-ml phosphate buffered saline (PBS) for 28 d. The T(>MIC) for IUG was more than three times that for NUG. In contrast, T(>MIC) for CUG was slightly shortened. The subtherapeutic release of vancomycin between 15 d and 28 d for IUG was one-ninth that for NUG. The fitting equations indicated a significant enhancement on the burst release and the slow release for IUG; however, the continuous ultrasonication hampered the slow release. SEM images exhibited denser craters and pores with larger diameters and less residual drug in specimens from IUG relative to those from both CUG and NUG. Intermittent watt-level ultrasonication improved the ultrasound-enhanced vancomycin release from cement in view of the prolonged T(>MIC) and the inhibited subtherapeutic release compared with continuous ultrasonication. The mechanisms may be associated with the distinctive effects of detaching forces and pushing forces by acoustic microstreams.

Pharmacokinetics and bioequivalence of ranitidine and bismuth derived from two compound preparations

AIM: To evaluate the bioequivalence of ranitidine and bismuth derived from two compound preparations.

METHODS: The bioavailability was measured in 20 healthy male Chinese volunteers following a single oral dose (equivalent to 200 mg of ranitidine and 220 mg of bismuth) of the test or reference products in the fasting state. Then blood samples were collected for 24 h. Plasma concentrations of ranitidine and bismuth were analyzed by high-performance liquid chromatography and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. The non-compartmental method was used for pharmacokinetic analysis. Log-transformed C_max, AUC_(0-t) and AUC_(0-∞) were tested for bioequivalence using ANOVA and Schuirmann two-one sided t-test. T_max was analyzed by Wilcoxon’s test.

RESULTS: Various pharmacokinetic parameters of ranitidine derived from the two compound preparations, including C_max, AUC_(0-t), AUC_(0-∞), T_max and T_1/2, were nearly consistent with previous observations. These parameters derived from test and reference drug were as follows: C_max (0.67 ± 0.21 vs 0.68 ± 0.22 mg/L), AUC_(0-t) (3.1 ± 0.6 vs 3.0 ± 0.7 mg/L per hour), AUC_(0-∞) (3.3 ± 0.6 vs 3.2 ± 0.8 mg/L per hour), T_max (2.3 ± 0.9 vs 2.1 ± 0.9 h) and T_1/2 (2.8 ± 0.3 vs 3.1 ± 0.4 h). In addition, double-peak absorption profiles of ranitidine were found in some Chinese volunteers. For bismuth, those parameters derived from test and reference drug were as follows: C_max (11.80 ± 7.36 vs 11.40 ± 6.55 μg/L), AUC_(0-t) (46.65 ± 16.97 vs 47.03 ± 21.49 μg/L per hour), T_max (0.50 ± 0.20 vs 0.50 ± 0.20 h) and T_1/2 (10.2 ± 2.3 vs 13.0 ± 6.9 h). Ninety percent of confidence intervals for the test/reference ratio of C_max, AUC_(0-t) and AUC_(0-) derived from both ranitidine and bismuth were found within the bioequivalence acceptable range of 80%-125%. No significant difference was found in T_max derived from both ranitidine and bismuth.

CONCLUSION: The two compound preparations are bioequivalent and may be prescribed interchangeably.

Quantitative determination of rosuvastatin in human plasma by liquid chromatography with electrospray ionization tandem mass spectrometry

A simple and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for determining rosuvastatin in human plasma, a new synthetic hydroxymethylglutaryl-coenzyme A reductase inhibitor. The analyte and internal standard (IS; cilostazol) were extracted by simple one-step liquid/liquid extraction with ether. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40 degrees C. The chromatographic separation was performed on an Atlantis C18 column (2.1 mm x 150 mm, 5.0 microm) with a mobile phase consisting of 0.2% formic acid/methanol (30:70, v/v) at a flow rate of 0.20 mL/min. The analyses were carried out by multiple reaction monitoring (MRM) using the precursor-to-product combinations of m/z 482 --> 258 and m/z 370 --> 288. The areas of peaks from the analyte and the IS were used for quantification of rosuvastatin. The method was validated according to the FDA guidelines on bioanalytical method validation. Validation results indicated that the lower limit of quantification (LLOQ) was 0.2 ng/mL and the assay exhibited a linear range of 0.2-50.0 ng/mL and gave a correlation coefficient (r) of 0.9991 or better. Quality control samples (0.4, 8, 25 and 40 ng/mL) in six replicates from three different runs of analysis demonstrated an intra-assay precision (RSD) 7.97-15.94%, an inter-assay precision 3.19-15.27%, and an overall accuracy (relative error) of < 3.7%. The method can be applied to pharmacokinetic or bioequivalence studies of rosuvastatin.

Heroin abuse and nitric oxide, oxidation, peroxidation, lipoperoxidation

To further reveal the risks of heroin abuse to human body, and to determine the injuries of oxidation, peroxidation and lipoperoxidation induced by nitric oxide and other free radicals to heroin abusers, we determined and compared plasma values of lipoperoxides (LPO), nitric oxide (NO), vitamin C (VC), vitamin E (VE), beta-carotene (beta-CAR) and erythrocyte values of LPO, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in 114 heroin abusers and 100 healthy volunteers. Using linear regression and correlation as well as stepwise regression and correlation, we also analyzed the effect of the abusing duration, and daily abusing quantity on the above-mentioned biochemical parameters in the heroin abusers. The results showed that, compared with the healthy volunteer groups, the average plasma values of LPO, and NO, and the average erythrocyte value of LPO in the heroin abuser group were significantly increased (P < 0.0001), and the average plasma values of VC, VE, and beta-CAR and the average erythrocyte values of SOD, CAT, and GSH-Px were significantly decreased (P < 0.0001). Analysis of linear regression and correlation showed that with prolonged heroin abusing and with increased daily quantity in the heroin abusers, the plasma values of LPO, and NO, and the erythrocyte value of LPO were gradually increased (P < 0.001), whereas the plasma values of VC, VE, and beta-CAR and the erythrocyte values of SOD, CAT, and GSH-Px were gradually decreased (P < 0.001). Analysis of stepwise regression and correlation indicated that the plasma values of NO, VC and VE were closely correlated with the abusing duration and daily abusing quantity. These results indicate that the balance between oxidation and antioxidation in the heroin abusers was seriously disturbed, and the injuries induced by nitric oxide and other free radicals, through oxidation, peroxidation and lipoperoxidation to the bodies of heroin abusers exacerbated. It is therefore necessary that in abstaining from heroin dependence, the heroin abusers should acquire sufficient quantities of antioxidants such as VC, VE and beta-CAR.

Genetic polymorphism of 4'-hydroxylation of S-mephenytoin in 148 Chinese of Han nationality

AIM

To study genetic polymorphism of S-mephenytoin (S-Mep) 4'-hydroxylation in the Chinese population of Han nationality.

METHODS

The lg metabolic ratio (MR) and lg hydroxylation index (HI) in the urine (0-12 h) after oral administration with 100 mg of racemic Mep tablet were determined by HPLC method in 148 consangeously unrelated native Chinese subjects and 21 individuals of 5 families.

RESULTS

The lg MR and lg HI showed a bimodal distribution with an antimode of -1.00 and 1.50, respectively. The occurrence of poor metabolizers (PM) was 13.5% in the population. The pedigree analysis in 5 families indicated that deficient S-Mep hydroxylation was an autosomal recessive trait.

CONCLUSIONS

The occurrence of PM for S-Mep 4-hydroxylation in Chinese was higher than that of the Caucasians, and both genetic modes were of autosomal recessive trait.