Effect of pitavastatin in different SLCO1B1 backgrounds on repaglinide pharmacokinetics and pharmacodynamics in healthy Chinese males

The effect of pitavastatin and SLCO1B1 genetic background on the pharmacokinetic and pharmacodynamic properties of repaglinide was investigated. In this randomized, placebo-controlled, crossover study, twelve healthy Chinese males were administered with pitavastatin 4 mg/d or the placebo for 5 d followed by repaglinide 4 mg given orally on d 5. Plasma repaglinide and glucose levels were measured by liquid chromatography-tandem mass spectrometry (LC/MS/MS) and the glucose oxidase method, respectively. Treatment with pitavastatin significantly increased the peak plasma concentration (Cmax) of repaglinide (P=0.003) in SLCO1B1*1b homozygotes (P=0.015) and SLCO1B1*15 carriers (P=0.031). Treatment with pitavastatin led to a marginal increase in the area under plasma concentration-time curve from 0 h to infinity (AUC0⇒∞) of repaglinide (P=0.091). There was no significant difference in pharmacokinetic parameters or hypoglycemic effects of repaglinide among SLCO1B1 genotypes in either the pitavastatin or control group. Pitavastatin increased the Cmax of the plasma concentration of repaglinide in an SLCO1B1 genotype dependent manner, but had no apparent effect on the pharmacodynamics of repaglinide in healthy volunteers. The p values for this statement were not reported.

Rapid clinical induction of bupropion hydroxylation by metamizole in healthy Chinese men

AIMS

This study aimed to investigate the effect of metamizole on bupropion hydroxylation related to different CYP2B6 genotype groups in healthy volunteers.

METHODS

Sixteen healthy male volunteers (6 CYP2B6*1/*1, 6 CYP2B6*1/*6 and 4 CYP2B6*6/*6) received orally administered bupropion alone and during daily treatment with metamizole 1500 mg day(-1) (500 mg tablet taken three times daily) for 4 days. Serial blood samples were obtained up to 48 h after each bupropion dose.

RESULTS

After metamizole treatment relative to bupropion alone, the geometric mean ratios (GMRs) and 90% confidence interval (CI) of the AUC(0,∞) ratio of 4-hydroxybupropion over bupropion were 1.99 (1.57, 2.55) for the CYP2B6*1/*1 group, 2.15 (1.53, 3.05) for the CYP2B6*1/*6 group and 1.86 (1.36, 2.57) for the CYP2B6*6/*6 group. The GMRs and 90% CI of bupropion were 0.695 (0.622, 0.774) for AUC(0,∞) and 0.400 (0.353, 0.449) for C(max) , respectively. The corresponding values for 4-hydroxybupropion were 1.43 (1.28, 1.53) and 2.63 (2.07, 2.92). The t(1/2) value was significantly increased for bupropion and decreased for 4-hydroxybupropion. The t(max) values of bupropion and 4-hydroxybupropion were both significantly decreased. The mean percentage changes in pharmacokinetic parameters among the CYP2B6 genotype groups were not significantly different.

CONCLUSIONS

Oral administration of metamizole for 4 days significantly altered the pharmacokinetics of both bupropion and its active metabolite, 4-hydroxybupropion, and significantly increased the CYP2B6-catalyzed bupropion hydroxylation in all of the subjects. Cautions should be taken when metamizole is co-administered with CYP2B6 substrate drugs.

Inhibition of the organic anion-transporting polypeptide 1B1 by quercetin: an in vitro and in vivo assessment

AIM

To investigate the effect of quercetin on organic anion transporting polypeptide 1B1 (OATP1B1) activities in vitro and on the pharmacokinetics of pravastatin, a typical substrate for OATP1B1 in healthy Chinese-Han male subjects.

METHODS

Using human embryonic kidney 293 (HEK293) cells stably expressing OATP1B1, we observed the effect of quercetin on OATP1B1-mediated uptake of estrone-3-sulphate (E3S) and pravastatin. The influence of quercetin on the pharmacokinetics of pravastatin was measured in 16 healthy Chinese-Han male volunteers receiving a single dose of pravastatin (40 mg orally) after co-administration of placebo or 500 mg quercetin capsules (once daily orally for 14 days).

RESULTS

Quercetin competitively inhibited OATP1B1-mediated E3S uptake with a K(i) value of 17.9 ± 4.6 µm and also inhibited OATP1B1-mediated pravastatin uptake in a concentration dependent manner (IC(50) , 15.9 ± 1.4 µm). In healthy Chinese-Han male subjects, quercetin increased the pravastatin area under the plasma concentration - time curve (AUC(0,10 h) and the peak plasma drug concentration (C(max)) to 24% (95% CI 15, 32%, P < 0.001) and 31% (95% CI 20, 42%, P < 0.001), respectively. After administration of quercetin, the elimination half-life (t(1/2) ) of pravastatin was prolonged by 14% (95% CI 4, 24%, P = 0.027), with no change in the time to reach C(max) (t(max) ). Moreover, quercetin decreased the apparent clearance (CL/F) of pravastatin by 18% (95% CI 75, 89%, P < 0.001).

CONCLUSIONS

These findings suggest that quercetin inhibits the OATP1B1-mediated transport of E3S and pravastatin in vitro and also has a modest inhibitory influence on the pharmacokinetics of pravastatin in healthy Chinese-Han male volunteers. The effects of quercetin on other OATP1B1 substrate drugs deserve further investigation.

Genistein alters caffeine exposure in healthy female volunteers

PURPOSE

This study investigated the effect of 1 g genistein daily for 14 days on caffeine-based metrics of cytochrome P4501A2 (CYP1A2), cytochrome P4502A6 (CYP2A6), N-acetyltransferase 2 (NAT2), and xanthine oxidase (XO).

METHODS

A single dose of 100 mg caffeine was administered once before and once on the last day of a 14-day treatment regime with 1 g genistein once daily to 18 healthy female volunteers. Urine and blood samples were collected up to 12 and 24 h, respectively, after each caffeine dose. Using high-performance liquid chromatography (HPLC), caffeine and 1,7-dimethylxanthine (17X) were quantified in plasma, whereas 17X, 1,7-dimethylurate (17U), 1-methylxanthine (1X), 1-methylurate (1U), and 5-acetylamino-6-formylamine-3-methyluracil (AFMU) were quantified in urine. Urinary metabolite ratios were calculated to assess enzyme activities and compared between administrations using analysis of variance (ANOVA).

RESULTS

Genistein decreased the urinary caffeine metabolite ratio used to assess CYP1A2 activity by 41% [90% confidence interval (CI) 28-51%). The urinary ratio indicating XO activity decreased by 29% (90% CI 24-32%), whereas urinary ratio for CYP2A6 activity increased by 47% (90% CI 29-66%) after 2 weeks of genistein. The NAT2 urinary caffeine metabolite ratio did not change significantly.

CONCLUSIONS

Two weeks of intake of 1 g genistein daily led to decreases in CYP1A2 and XO activity and an increase in CYP2A6 activity, whereas NAT2 activity did not change in healthy Chinese female volunteers. Pharmacokinetics of other substrates of the enzymes investigated here may be influenced in a similar manner.

Liu wei di huang wan, a well-known traditional Chinese medicine, induces CYP1A2 while suppressing CYP2A6 and N-acetyltransferase 2 activities in man

ETHNOPHARMACOLOGICAL RELEVANCE

Liu wei di huang wan (LDW), a well-known traditional Chinese medicine, is frequently combined with other prescription or non-prescription drugs in China.

AIM OF THE STUDY

This study was designed to investigate the effects of LDW on the activities of CYP1A2, CYP2A6, N-acetyltransferase 2 (NAT2) and xanthine oxidase (XO) in healthy subjects, using caffeine as a probe drug.

MATERIALS AND METHODS

Twelve unrelated healthy males were enrolled in a single-blind, randomized, placebo-controlled, two-phase crossover study. Placebo or LDW (12 pills, 0.2 g/pill, twice daily) was given to each participant for 14 continuous days with a wash-out period of 2 weeks. A dose of 100 mg caffeine was given afterwards to test the activities of drug-metabolizing enzymes of interest.

RESULTS

Compared to placebo, LDW significantly induced the CYP1A2 activity, as determined by an increase in the ratio of (AFMU+1U+1X)/17U and the formation of 17X and 1X after taking caffeine. Interestingly, LDW significantly decreased the ratio of 17U/(17U+17X+1X+1U+AFMU) and the formation of 17U (CYP2A6-mediated) (by 39.2%; 95%CI: 23.1-55.3%; P=0.026), and decreased the ratio of AFMU/(AFMU+1U+1X) and the formation of AFMU (NAT2-catalyzed) (by 26.2%; 95%CI: 9.2-61.6%; P=0.038), suggesting a marked inhibition of CYP2A6 and NAT2, respectively.

CONCLUSIONS

LDW can induce CYP1A2 and suppress CYP2A6 and NAT2 activities, and affect caffeine metabolism in vivo.

Effects of Ginkgo biloba extract on the pharmacokinetics of bupropion in healthy volunteers

AIMS

To assess the effects of Ginkgo biloba extract on the pharmacokinetics of bupropion in healthy volunteers.

METHODS

Fourteen healthy male volunteers (age range 19-25 years) received orally administered bupropion (150 mg) alone and during treatment with G. biloba 240 mg day(-1) (two 60-mg capsules taken twice daily) for 14 days. Serial blood samples were obtained over 72 h after each bupropion dose, and used to derive pharmacokinetic parameters of bupropion and its CYP2B6-catalysed metabolite, hydroxybupropion.

RESULTS

Ginkgo biloba extract administration resulted in no significant effects on the AUC(0-infinity) of bupropion and hydroxybupropion. Bupropion mean AUC(0-infinity) value was 1.4 microg.h ml(-1)[95% confidence interval (CI) 1.2, 1.6] prior to G. biloba treatment and 1.2 microg.h ml(-1) (95% CI 1.1, 1.4) after 14 days of treatment. Hydroxybupropion mean AUC(0-infinity) value was 8.2 microg.h ml(-1) (95% CI 6.5, 10.4) before G. biloba administration and 8.7 microg.h ml(-1) (95% CI 7.1, 10.6) after treatment. The C(max) of hydroxybupropion increased from 221.8 ng ml(-1) (95% CI 176.6, 278.6) to 272.7 ng ml(-1) (95% CI 215.0, 345.8) (P = 0.038) and the t(1/2) of hydroxybupropion fell from 25.0 h (95% CI 22.7, 27.5) to 21.9 h (95% CI 19.9, 24.1) (P = 0.000).

CONCLUSIONS

Ginkgo biloba extract administration for 14 days does not significantly alter the basic pharmacokinetic parameters of bupropion in healthy volunteers. Although G. biloba extract treatment appears to reduce significantly the t(1/2) and increase the C(max) of hydroxybupropion, no bupropion dose adjustments appear warranted when the drug is administered orally with G. biloba extract, due to the lack of significant change observed in AUC for either bupropion or hydroxybupropion.

Lack of effect of Ginkgo biloba on voriconazole pharmacokinetics in Chinese volunteers identified as CYP2C19 poor and extensive metabolizers

BACKGROUND

Ginkgo biloba is one of the most popular herbal supplements in the world. The supplement has been shown to induce the enzymatic activity of CYP2C19, the main cytochrome P450 isozyme involved in voriconazole metabolism. Because this enzyme exhibits genetic polymorphism, the inductive effect was expected to be modulated by the CYP2C19 metabolizer status.

OBJECTIVE

To examine the possible effects of Ginkgo biloba as an inducer of CYP2C19 on single-dose pharmacokinetics of voriconazole in Chinese volunteers genotyped as either CYP2C19 extensive or poor metabolizers.

METHODS

Fourteen healthy, nonsmoking volunteers-7 CYP2C19 extensive metabolizers (2C19(*)1/2C19(*)1) and 7 poor metabolizers (2C19(*)2/2C19(*)2)-were selected to participate in this study. Pharmacokinetics of oral voriconazole 200 mg after administration of Ginkgo biloba 120 mg twice daily for 12 days were determined for up to 24 hours by liquid chromatography-electrospray tandem mass spectrometry in a 2-phase randomized crossover study with 4-week washout between phases.

RESULTS

For extensive metabolizers, the median value for voriconazole area under the plasma concentration-time curve from zero to infinity (AUC(0-)(infinity)) was 5.17 microg.h/mL after administration of voriconazole alone and 4.28 microg.h/mL after voriconazole with Ginkgo biloba (p > 0.05). The other pharmacokinetic parameters of voriconazole such as AUC(0-24), time to reach maximum concentration, half-life, and apparent clearance also did not change significantly for extensive metabolizers in the presence of Ginkgo biloba. Pharmacokinetic parameters followed a similar pattern for poor metabolizers.

CONCLUSIONS

The results suggest that 12 days of treatment with Ginkgo biloba did not significantly alter the single-dose pharmacokinetics of voriconazole in either CYP2C19 extensive or poor metabolizers. Therefore, the pharmacokinetic interactions between voriconazole and Ginkgo biloba may have limited clinical significance.

Association of CYP3A4*18B polymorphisms with the pharmacokinetics of cyclosporine in healthy subjects

The aim of this study is to evaluate the association of the CYP3A4*18B genotype with the cyclosporine metabolism in healthy subjects. We employed PCR-RFLP assays for analysis of the CYP3A4*18B genotype. Each of 26 subjects, comprising 12 CYP3A4*1/*1, 12 CYP3A4*1/*18B and 2 CYP3A4*18B/*18B, was given a single oral dose of cyclosporine (4 mgkg(-1)). The plasma concentrations of cyclosporine were measured for up to 24 h post dose by high-performance liquid chromatography-electrospray mass spectrometry. We found that the mean Cmax (95% confidence intervals) of cyclosporine were 2237 (2905, 1859) (*1/*1), 2247 (2916, 1869) (*1/*18B), and 905 (1192, 506) ng ml(-1) (*18B/*18B)(p = 0.037) and the mean AUCO-4 were 5026 (6181, 4372) (*1/*1), 4434 (5481, 3841) (*1/*18B) and 2561 (3155, 1736) ng ml(-1) h (*18B/*18B) (p=0.021). The CL in the *18B/*18B group was significantly higher than in the *1/*1 group. However, Tmax exhibited no difference among the three genotypes. *18B/*18B group showed 50% reduction in concentration at 2 h post dose compared with *1/*18B (p = 0.062) or *1/*1 (p = 0.047), but no statistical significance was detected between*1/*1 and *1/*18B groups (p > 0.05). The data suggest that the CYP3A4*18B genotype affects cyclosporine pharmacokinetics probably resulting from a higher enzymatic activity of this mutation in healthy subjects.

Sensitive bioassay for the simultaneous determination of pseudoephedrine and cetirizine in human plasma by liquid-chromatography–ion trap spectrometry

A liquid chromatography-ion trap mass spectrometry coupled with electrospray ionization (HPLC-ESI-ion trap mass spectrometry) method for simultaneous determination of cetirizine and pseudoephedrine in human plasma is presented. Chromatographic separation was performed on a Hypurity C18 column (Thermo Hypersil-Keystone 2.1 mm x 150 mm, 5 microm, USA), The mobile phase was composed of 65% methanol and 35% water (contained 0.1% formic acid, 10 mM ammonium formate), which was run with a flow-rate of 0.2 ml/min at 40 degrees C. Quantitation was achieved by monitoring the product ions at m/z 166-->m/z 148 (pseudoephedrine), m/z 389.9-->m/z 201.1 (cetirizine), m/z 264-->m/z 246 (tramadol, IS). The calibration curve of pseudoephedrine and cetirizine was established with standard solutions. The limit of detection for pseudoephedrine and cetirizine each was 5 ng/ml. This simplified analytical method is sensitive, specific and accurate enough for simultaneous determination of pseudoephedrine and cetirizine in human plasma and is successfully applied to the pharmacokinetic study of pseudoephedrine and cetirizine.

Sensitive and selective liquid chromatography-mass spectrometry method for the quantification of rosiglitazone in human plasma

A sensitive and selective high-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (HPLC-ESI-MS-MS) method for determination of rosiglitazone in human plasma has been developed. After the addition of the internal standard, plasma samples were precipitated by acetonitrile. The compounds were separated on a proC18 column using a mixture of ammonium acetate buffer (0.02 M, pH 6.5) and acetonitrile (in the ratio of 47:53, v/v) as mobile phase. A Finnigan LCQdeca plus ion trap mass spectrometer connected to a Finnigan Surveyor HPLC was used to develop and validate the method. Linearity was established for the range of concentrations 1-1000 ng/ml with a coefficient of determination (r(2)) of 0.999. The intra-day accuracy for rosiglitazone ranged from 110.0 to 99.2% at low, medium and high levels. The inter-day accuracy was less than 15%. The lower limit of quantitation (LLOQ) was identified reproducible at 1.0 ng/ml with a precision of 5.7%. After validation, the method was used to study the pharmacokinetic profile of rosiglitazone in five healthy volunteers after administration of a single oral dose (4.0mg). The proposed method enabled the unambiguous evaluation and quantitation of rosiglitazone for pharmacokinetic, bioavailability or drug-drug interaction studies. A possible chromatography peak (m/z 121, its parent ion m/z 344) of N-demethyl rosiglitazone was observed at 3.49 min during determining rosiglitazone. This may be also a potential method for simultaneous determination of rosiglitazone and its metabolite N-demethyl rosiglitazone concentrations in plasma.

Effect of SLCO1B1 genetic polymorphism on the pharmacokinetics of nateglinide

AIMS

Nateglinide is a meglitinide analogue with antidiabetic action. A recent study showed that SLCO1B1 (which codes the OATP1B1 gene, also known as OATP-C, OATP2) is a major determinant which markedly affects the pharmacokinetics of repaglinide. Our objective was to assess the association between single nucleotide polymorphisms (SNPs) of SLCO1B1 and the pharmacokinetics of nateglinide.

METHODS

Seventeen healthy volunteers with different SLCO1B1 genotypes (11 with 521TT, four with 521TC and two with 521CC) were enrolled in this study. Each was given a single oral dose of 90 mg nateglinide. Plasma concentrations of nateglinide were measured up to 8 h by HPLC.

RESULTS

The C(max) and AUC(0,infinity) of nateglinide were 83% (P = 0.002) and 82% (P = 0.001) higher in the SLCO1B1521TC subjects (n = 4), and 76% (P = 0.016) and 108% (P = 0.001) higher in the SLCO1B1521CC subjects (n = 2) than in the SLCO1B1521TT subjects (n = 11), respectively. The t(1/2) of nateglinide in SLCO1B1521CC subjects was 78% longer than that in 521TT subjects (P = 0.036). The difference in t(max) values among the three genotypic groups was not statistically significant.

CONCLUSIONS

Our results suggest that OATP1B1-mediated hepatic uptake of nateglinide may be the prior step for its metabolism and elimination. SLCO1B1521T > C SNP might play an important role in the pharmacokinetics of nateglinide.

Role of BCRP 421C>A polymorphism on rosuvastatin pharmacokinetics in healthy Chinese males

BACKGROUND

Rosuvastatin, a novel potent HMG-CoA reductase inhibitor, is excreted into bile mediated by breast cancer resistance protein (BCRP). Our objective was to determine the association between the most frequent single nucleotide polymorphisms (SNPs) of the BCRP (421C>A) and the pharmacokinetics of rosuvastatin.

METHOD

Pre-screening of SLCO1B1 521TC and CYP2C9*1/*3 were performed before this pharmacokinetic study. Fourteen healthy volunteers who are SLCO1B1 521TT and CYP2C9*1/*1 wild-type homozygotes were selected to participate in this study. Seven were 421CC wild-type of BCRP, the others were carriers with at least one 421C>A mutant allele (five subjects had a genotype of 421CA and two were homozygotes of 421AA). Each was given a single oral dose of 20 mg rosuvastatin. The plasma concentrations of rosuvastatin were measured for up to 72 h by LC-MS.

RESULTS

The pharmacokinetic parameters of rosuvastatin showed a significantly difference between the two genotyped groups. The AUC(0-72) and AUC(0-infinity) of rosuvastatin were lower in the 421CC group than in the 421CA+421AA group (33.8+/-11.4 vs. 59.6+/-22.2 ng.h/ml, P=0.018; 34.9+/-11.9 vs. 62.2+/-23.5 ng.h/ml, P=0.018), respectively. The C(max) value was higher in the 421CA+421AA group than that in the 421CC group (9.9+/-5.4 vs. 5.1+/-2.4 ng/ml, P=0.048). The CL/F value was lower in the 421CA+421AA group than that in the 421CC group (384.7+/-161.2 vs. 674.0+/-297.6 l/h, P=0.043). The T(1/2) and T(max) values showed no difference between these groups.

CONCLUSIONS

The BCRP 421C>A polymorphism may play an important role in the pharmacokinetics of rosuvastatin in healthy Chinese males after the exclusion of impact of SLCO1B1 and CYP2C9 genetic polymorphism.

Effect of the CYP2C9*3 allele on lornoxicam metabolism

BACKGROUND

We investigated whether the CYP2C9 genotypes would affect lornoxicam metabolism in healthy volunteers.

METHODS

Twelve healthy volunteers who had been genotyped for CYP2C9 gene were selected to participate in our study. After 8 mg lornoxicam was taken, blood samples were drawn from 0 to 36 h. The plasma concentrations of lornoxicam and 5'-hydroxylornoxicam were determined by HPLC method. 5'-hydroxylornoxicam was purified from rabbits'urine by semi-preparative HPLC.

RESULTS

Lornoxicam and 5'-hydroxylornoxicam both exhibit CYP2C9 genotype-dependent pharmacokinetic profiles. The area under the plasma concentration-time curve (AUC) of lornoxicam increased by 60 +/- 9.78% (P <0.05) and the AUC of 5'-hydroxylornoxicam decreased by 65 +/- 11.75% (p <0.001) in heterozygous CYP2C9*1/*3 subjects (n=6) compared with CYP2C9*1/*1 group (n=6). t1/2 value of lornoxicam and 5'-hydroxylornoxicam prolonged by 39 +/- 8.35% and curtailed by 59 +/- 6.83% respectively in CYP2C9*1/*3 subjects. But no significant differences in Tmax of lornoxicam and 5'-hydroxylornoxicam were observed between these 2 genotypes. In addition, for the first time we exploit the purification method for 5'-hydroxylornoxicam from rabbits' urine.

CONCLUSION

The CYP2C9*3 allele significantly affected the metabolism of lornoxicam. The pharmacokinetic parameters of both lornoxicam and 5'-hydroxylornoxicam were significantly different between these 2 genotypes.

MDR1 genotype do not influence the absorption of a single oral dose of 100 mg talinolol in healthy Chinese males

OBJECTIVE

We investigated the linkage between SNPs in exon 12 (C1236T), exon 21 (G2677T/A) and exon 26 (C3435T) of MDR1, and explored the effect of linked polymorphism on the absorption of talinolol after a single oral dose of 100 mg.

METHODS

The genotype of 192 healthy Chinese volunteers was determined using PCR-RFLP with respect to the MDR1 alleles of interest, C1236T, G2677T/A and C3435T. Linkage disequilibrium was analyzed using PHASE software. Consecutive eligible subjects received a single oral dose of 100 mg talinolol. Venous blood samples were taken at intervals up to 60 h post dose for HPLC analysis of plasma concentration of talinolol to obtain a pharmacokinetic profile.

RESULTS

Linkage disequilibrium existed between exon 21 (G2677T/A) and exon 26 (C3435T), exon 12 (C1236T) and exon 21 (G2677T/A), but not between exon 12 (C1236T) and exon 21 (G2677T/A). AUC (0,3 h), AUC (0, infinity), Cmax and Cmax/AUC (0, infinity), used as indices of talinolol absorption, were not significantly different between the genotype groups of 2677GG/3435TT, 2677TT/3435TT, 2677GT/3435CT and 2677AT/3435CT. For these 4 groups, AUC(0,3 h) were 436.8 +/- 50.1, 510.1 +/- 86.3, 466.1 +/- 77.8 and 437.2 +/- 73.4 (microg x h/l) and the Cmax/AUC (0, infinity) were 0.097 +/- 0.018, 0.093 +/- 0.022, 0.105 +/- 0.014 and 0.102 +/- 0.027 (h(-1)), respectively. (P > 0.05).

CONCLUSIONS

The linked MDR1 polymorphisms in exon 21 G2677T/A and exon 26 C3435T apparently did not contribute to the absorptive pharmacokinetics of a single oral dose of 100 mg talinolol.

Determination of sinomenine in human plasma by HPLC/ESI/ion trap mass spectrum

BACKGROUND

Sinomenine is a pure alkaloid with a variety of pharmacological actions including anti-inflammation, immuno-suppression, analgesia, antihypertension, and antiarrhythmia. Methods have been developed to measure sinomenine in rats and rabbits through high-performance liquid chromatography (HPLC). But only one report described a method for determination of sinomenine in humans.

METHOD

We developed a method to quantitate sinomenine in human plasma based on liquid chromatography-ion trap mass spectrometry coupled with electrospray ionization (HPLC/ESI/ion trap mass spectrum).

RESULTS

The calibration curve (r2=0.9993) of sinomenine was established with standard solutions. The mean inter-day and intra-day CVs<15%. The limit of detection for sinomenine was 0.5 ng/ml. The relative recovery of high, middle and low concentration was 99%, 103%, and 118%, respectively.

CONCLUSION

The method is simple, rapid, sensitive, specific, and accurate enough for determination of sinomenine in human plasma and may be used to investigate the metabolism and pharmacokinetics of sinomenine.