Multiple-dose cimetidine administration does not influence the single-dose pharmacokinetics of quinapril and its active metabolite (CI-928)

The potential effect of cimetidine on the pharmacokinetic profiles of quinapril and its active metabolite CI-928 was evaluated in eight healthy volunteers. Each subject received a single 40-mg quinapril dose on days 1 and 12 and cimetidine 300 mg four times daily on days 8 through 13. Serial blood and urine samples were collected for assay of quinapril and CI-928 concentrations. No statistically significant differences were observed in quinapril or CI-928 Cmax, tmax, AUC(0-infinity), beta, or percent of dose excreted in urine values for quinapril administered alone and in combination with cimetidine. Therefore, multiple-dose cimetidine administration does not influence the single-dose pharmacokinetics of quinapril and its active metabolite, CI-928, in healthy volunteers.     

SPE-HPLC法测定人血浆中喹那普利和代谢产物及其人体药代动力学研究

目的:建立 SPE—HPLC 法测定人血浆中喹那普利及其代谢产物喹那普利拉的浓度,以研究喹那普利及喹那普利拉在健康志愿者中的药代动力学和相对生物利用度。方法:应用 C_(18)固相萃取柱提取血浆中喹那普利及喹那普利拉,喹那普利色谱条件为:迪马 Diamonsil C_(18)柱(150 mm×4.6 mm,5μm);流动相为乙腈-0.1%醋酸溶液(40:60,v/v);流速1.0 mL·min~(-1)。喹那普利拉色谱条件为:Phenomenex C_(18)柱(150 mm×4.6 mm,5μm);流动相为乙腈-0.005 mol·L~(-1)十二烷基磺酸钠(磷酸调 pH 2.5)(40:60,v/v);流速1.0 mL·min~(-1)。人体药代动力学试验采用单剂双周期交叉设计方案,将18名志愿者随机分为两组,分别口服参比制剂喹那普利片和试验制剂喹那普利胶囊各40 mg,清洗期为1周。结果:喹那普利的线性范围为10～800ng·mL~(-1),r=0.9931,最低定量限为10 ng·mL~(-1);提取回收率与方法回收率分别为82.1%～94.4%,92.6%～99.9%;日内、日间 RSD 均小于10%。喹那普利拉的线性范围为20～1200 ng·mL~(-1),r=0.9995,最低定量限为20 ng·mL~(-1);提取回收率与方法回收率分别为73.3%～94.0%,100.0%～105.9%;日内、日间 RSD 均小于7%。结论:本方法灵敏度高、特异性强、重复性好,测定结果可靠,统计学分析表明2种制剂的主要药代动力学参数无显著性差异,为等效制剂。     

The pharmacokinetics of quinapril and its active metabolite, quinaprilat, in patients with various degrees of renal function.

Single- and multiple-dose pharmacokinetics of quinapril and its active metabolite, quinaprilat, were determined after oral administration of 20 mg quinapril HCl on day 1 and days 4 through 10 in 17 normotensive subjects with various degrees of renal function. Blood and urine samples were collected over 72- and 24-hour periods, respectively, after the first single dose and last multiple dose for measurement of quinapril and quinaprilat concentrations. The renal clearance of quinapril and quinaprilat decreased with increasing renal insufficiency but did not result in significant changes in quinapril pharmacokinetics in patients with renal impairment. In contrast, quinaprilat maximum plasma concentration, trough and peak steady-state plasma concentrations, area under the plasma concentration-time curve, and half-life increased significantly with increasing renal insufficiency. The disposition of quinapril and quinaprilat was unchanged from single to multiple doses. Small changes in the pharmacokinetic disposition of quinapril, together with a decreased rate of quinaprilat elimination, resulted in increased quinaprilat plasma concentrations following administration of both single and multiple quinapril doses to normotensive patients with renal impairment. Thus, quinapril dosage adjustment may be required in some patients with renal impairment.     

Pharmacokinetics of quinapril and its active metabolite, quinaprilat, in patients on chronic hemodialysis

The pharmacokinetics of quinapril and its active metabolite, quinaprilat, were evaluated in 12 patients with end-stage renal disease (ESRD) on chronic hemodialysis. Each subject received a single 20-mg oral dose of quinapril 4 hours before a 4-hour hemodialysis treatment. Serial dialysate and blood samples were obtained over 4 and 96 hours, respectively. Samples were analyzed for quinapril and quinaprilat concentrations by gas chromatography. Mean tmax and Cmax values for quinapril were 1.2 hours and 129 ng/mL, respectively. Only one patient had detectable quinapril dialysate concentrations which accounted for 2.8% of the quinapril dose. Mean apparent plasma clearance for quinapril was 1275 mL/min with a mean half-life of 1.7 hours. Quinapril was extensively de-esterified to its diacid metabolite, quinaprilat. Mean tmax and Cmax for quinaprilat were 4.5 hours and 671 ng/mL, respectively. Mean apparent plasma clearance for quinaprilat was 24.0 mL/min with a mean half-life of 17.5 hours. As with quinapril, quinaprilat was not readily dialyzable. Only 5.4% of the administered quinapril dose was recovered as quinaprilat during a single hemodialysis treatment. In view of these results, supplemental quinapril doses need not be routinely given to patients following hemodialysis. Overall, quinapril and quinaprilat pharmacokinetics in patients with ESRD on chronic hemodialysis were not markedly different from those previously observed in patients with moderate to severe renal dysfunction (CLcr less than 29 mL/min) not yet requiring hemodialysis (RDND).     

Multiple-dose propranolol administration does not influence the single dose pharmacokinetics of quinapril and its active metabolite (quinaprilat)

To evaluate the influence of multiple dose propranolol administration on the single dose pharmacokinetics of quinapril and its active metabolite, quinaprilat, a drug-drug interaction study was performed in ten healthy volunteers. Each subject received a single 20 mg quinapril oral dose on Days 1 and 16 of the study. Oral propranolol doses of 40 mg BID were initiated on Day 3, titrated gradually to 80 mg TID by Day 10, and continued at 80 mg TID through Day 17. Comparable mean quinapril pharmacokinetic parameter values as well as comparable mean quinaprilat pharmacokinetic parameter values determined following quinapril administered alone and following quinapril administered with propranolol, indicate that propranolol does not alter the single dose pharmacokinetics of quinapril or quinaprilat.     

Pharmacokinetics of quinapril and its active metabolite quinaprilat during continuous ambulatory peritoneal dialysis

The pharmacokinetics of quinapril, a novel angiotensin converting enzyme (ACE) inhibitor, and its active metabolite, quinaprilat, were determined following a single 20-mg oral dose of quinapril in six patients with chronic renal failure maintained on continuous ambulatory peritoneal dialysis (CAPD). Overall, quinapril was well tolerated by these CAPD patients, with mild and transient side effects, not unexpected in this clinical setting, which included pruritus, headache, nausea, and cough. Blood pressure reduction was observed in four of six patients, with onset reliably two to four hours after dosing and duration up to 48 hours, associated with quinaprilat concentrations in plasma above 90 ng/mL for at least 33 hours postdose. Two patients experienced significant hypotension, systolic blood pressure below 90 mm Hg, which responded promptly to oral fluid administration and/or reduction in dialysate tonicity. The pharmacokinetic profile of quinapril in these CAPD patients was not significantly different from that previously observed in healthy subjects with normal renal function and in patients with moderate to severe renal dysfunction not yet requiring dialysis (RDND). The apparent elimination half-life of quinapril was approximately one hour, with negligible dialysate excretion. The pharmacokinetic profile of quinaprilat in these CAPD patients was similar to that previously observed in patients with RDND. The elimination half-life of quinaprilat was markedly prolonged when compared to that in healthy subjects and averaged 20 hours, with only a small amount of quinaprilat excreted in dialysate (mean = 2.6% of total dose).(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of CYP2C19 polymorphism on the pharmacokinetics of nelfinavir and its active metabolite

AIMS

This study reports the pharmacokinetics of nelfinavir, its active metabolite, M8, and active moiety (nelfinavir + M8) in volunteers genotyped for CYP2C19 as extensive metabolizer (*1*1; n = 38), heterozygous poor metabolizer (PM) (*1*2; n = 22) and homozygous PM (*2*2; n = 6).

METHODS

Subjects received nelfinavir at normal dose (3.5 days of 1250 mg q12h) or high dose (1250 mg q12h for 3 days and single dose of 3125 mg on day 4). Steady-state plasma samples were analysed by high-performance liquid chromatography/ultraviolet assay to determine pharmacokinetics.

RESULTS

At steady state, the mean C_max was 42% [95% confidence interval (CI) 19, 69] and 63% (95% CI 20, 122) higher, and mean AUC was 51% (95% CI 24, 83) and 85% (95% CI 32, 159) higher for *1*2 and *2*2 compared with *1*1 subjects, respectively. For M8, the mean C_max and AUC were 35% (95% CI 6, 55) and 33% (95% CI −3, 56), respectively, lower for *1*2 compared with *1*1 subjects. M8 was not detectable in *2*2 subjects. The mean C_max and AUC values for the active moiety were higher by 30–35% for the *1*2 and *2*2 compared with *1*1 subjects.

CONCLUSIONS

Mutation in CYP2C19 increased the systemic exposure of nelfinavir and reduced the exposure of M8. No significant differences were noted among the heterozygous (*1*2) and homozygous (*2*2) PMs. These changes are not considered to be clinically relevant and hence the use of nelfinavir does not require prior assessment of CYP2C19 genotype.     

高脂饮食对阿雷地平及其活性代谢产物人体药动学特征的影响

目的评价高脂餐对阿雷地平及其活性代谢产物羟基阿雷地平在健康中国人体内药动学的影响。方法10名健康男性受试者空腹口服阿雷地平10 mg,经过1 wk清洗期后,受试者高脂餐后口服阿雷地平10 mg。采用液相色谱-串联质谱联用法测定血浆中阿雷地平及其活性代谢产物羟基阿雷地平的浓度。结果空腹和高脂餐后口服阿雷地平,阿雷地平的c_(max)分别为(2.4±s0.8)和(4.4±2.9)μg·L~(-1),羟基阿雷地平的c_(max)分别为(41±10)和(51±19)μg·L~(-1);空腹和高脂餐后阿雷地平和羟基阿雷地平的c_(max)无显著差异。空腹和高脂餐后口服阿雷地平,阿雷地平的AUC_(0～36)分别为(10.3±2.3)和(15±7)μg·h·L~(-1),羟基阿雷地平的AUC_(0～36)分别为(305±108)和(389±129)μg·h·L~(-1);阿雷地平的t_(max)分别为(4.4±1.0)和(9±6)h,羟基阿雷地平的f_(max)分别为(5.0±1.6)和(11±7)h;空腹和高脂餐后阿雷地平和羟基阿雷地平的AUC_(0～36)和t_(max)均存在显著差异,AUC显著增加,t_(max)显著延长。结论高脂餐后,阿雷地平的吸收出现延迟现象,吸收程度有所增加;羟基阿雷地平的体内生成延迟,但生成的量增加。     

Effect of food on pharmacokinetics of chlorambucil and its main metabolite,phenylacetic acid mustard

Summary The influence of food intake on the pharmacokinetics of chlorambucil (C) and its cytotoxic metabolite, phenylacetic acid mustard (PAM), has been studied in man after oral doses of chlorambucil. The administration of chlorambucil with food resulted in slower absorption than when fasting. However, the area under the plasma concentration-time curve (AUC) was unaffected. The mean ratio AUC_PAM/AUC_C was 2.8 (range 1.4–7.1) under fasting and 3.3 (range 1.3–7.4) under nonfasting conditions. The metabolite very probably plays an important role in the cytotoxic effects observed after administration of C, since calculations show that a major fraction of the metabolite is eliminated by alkylation reactions.     

Effect of quercetin on the pharmacokinetics of selexipag and its active metabolite in beagles

ContextAs an inhibitor cytochrome P450 family 2 subfamily C polypeptide 8 (CYP2C8), quercetin is a naturally occurring flavonoid with its glycosides consumed at least 100 mg per day in food. However, it is still unknown whether quercetin and selexipag interact.ObjectiveThe study investigated the effect of quercetin on the pharmacokinetics of selexipag and ACT-333679 in beagles.Materials and methodsThe ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to investigate the pharmacokinetics of orally administered selexipag (2 mg/kg) with and without quercetin (2 mg/kg/day for 7 days) pre-treatment in beagles. The effect of quercetin on the pharmacokinetics of selexipag and its potential mechanism was studied through the pharmacokinetic parameters.ResultsThe assay method was validated for selexipag and ACT-333679, and the lower limit of quantification for both was 1 ng/mL. The recovery and the matrix effect of selexipag were 84.5–91.58% and 94.98–99.67%, while for ACT-333679 were 81.21–93.90% and 93.17–99.23%. The UPLC-MS/MS method was sensitive, accurate and precise, and had been applied to the herb-drug interaction study of quercetin with selexipag and ACT-333679. Treatment with quercetin led to an increased in C_max and AUC_0–t of selexipag by about 43.08% and 26.92%, respectively. While the ACT-333679 was about 11.11% and 18.87%, respectively.Discussion and conclusionThe study indicated that quercetin could inhibit the metabolism of selexipag and ACT-333679 when co-administration. Therefore, the clinical dose of selexipag should be used with caution when co-administered with foods high in quercetin.     

Influence of food on tianeptine and its main metabolite kinetics

The influence of a test meal on the absorption and disposition of tianeptine (Stablon), a new antidepressant, was investigated in 12 healthy subjects in a two-way, randomized, open cross-over study. Single 12.5-mg oral doses of tianeptine were administered following a night of fasting or immediately after a standardized breakfast. When subjects received tianeptine under fasting conditions the lag time before absorption onset, and the time of the maximum plasma concentration were 0.55 +/- 0.26 hours and 1.29 +/- 0.29 hours, respectively. The maximum plasma concentration was 322 +/- 44 ng/mL, and the total area under the curve 994 +/- 248 ng/hr/mL. When tianeptine was given at the end of the meal, several significant changes were found for tianeptine kinetic parameters; the lag time increased by 0.3 hour and the maximum plasma concentration was lowered (decreased by 25%) and occurred later (tmax increased by 0.5 hour). However, no significant change was found in the area under the plasma concentration-time curve. The trend and extent of changes in the MC5 metabolite parameters were similar to those observed for the parent drug. Absorption of tianeptine is slightly delayed and slowed down without modification of its extent when tianeptine is given at the end of a meal. These slight changes are not clinically relevant for an antidepressant administered three times a day. Despite the changes observed, tianeptine may be given at meal times to improve compliance with treatment.     

Effect of lamotrigine on the pharmacokinetics of carbamazepine and its active metabolite in dogs.

The effect of lamotrigine (LTG) on the pharmacokinetics of carbamazepine (CBZ) and its active metabolite; carbamazepine-epoxine (CBZ-E), was investigated in dogs. Five male dogs received CBZ (2 x 200 mg tab, p.o.) daily for a period of 1 week. After the end of this period, blood samples were collected serially for up to 24 hrs. After a wash-out period of I week, LTG (100 mg tab, p.o.) was coadministered with the CBZ dose (2 x 200 mg tab, p.o.) for 7 days. Blood samples were again serially collected and plasma levels of CBZ and CBZ-E were analysed by high performance liquid chromatography (HPLC). Concurrent administration of LTG with CBZ did not have any significant effect on the pharmacokinetic parameters of CBZ. There was also no significant difference between the plasma concentration ratio (CBZ-E to CBZ) vs time profiles in the two schedules of drug administration signifying the absence of pharmacokinetic interaction between LTG and CBZ or its active metabolite in this animal model.     

Effects of chronic renal failure on the pharmacokinetics of ruboxistaurin and its active metabolite 338522

BACKGROUND: Ruboxistaurin, a specific inhibitor of the beta(1) and beta(2) isoforms of protein kinase C, is currently in clinical development for the treatment of several diabetic microvascular complications. The major metabolite, N-desmethyl ruboxistaurin (metabolite 338522), is equipotent in its inhibitory activity. The elimination of ruboxistaurin and its metabolites is primarily through bile and the faecal route, with urinary excretion constituting only a minor route. OBJECTIVE: To assess the effects of chronic renal insufficiency on the pharmacokinetics of ruboxistaurin and metabolite 338522. METHODS: Six healthy subjects (creatinine clearance >80 mL/min/1.73 m(2)) and six end-stage renal disease (ESRD) subjects requiring long-term haemodialysis were studied. All subjects received a single oral dose of ruboxistaurin 32 mg followed by serial blood sampling up to 72 hours. ESRD subjects underwent haemodialysis approximately 58 hours after dosing, with blood samples obtained immediately before and after dialysis. RESULTS: No differences were observed in the pharmacokinetic parameters (area under the plasma concentration-time curve from time zero to infinity [AUC(infinity)], maximum plasma concentration [C(max)] and elimination half-life [t(1/2)]) of ruboxistaurin and metabolite 338522 between healthy and ESRD subjects Plasma concentrations of ruboxistaurin were below the lower limit of quantification by the time of haemodialysis. The predicted post-dialysis plasma concentrations of metabolite 338522 were not statistically different from the observed values (p=0.163). Ruboxistaurin was well tolerated in both groups of subjects. CONCLUSION: These results indicate that the kidney is not an important route of metabolism or excretion for ruboxistaurin and metabolite 338522. Based on the pharmacokinetic and tolerability findings, no formal dosage adjustment of ruboxistaurin should be required for patients with any degree of renal impairment who are undergoing haemodialysis.     

普卢利沙星活性代谢产物NM394的检测及其药动学特征

目的建立人血浆中普卢利沙星活性代谢产物NM394检测的HPLC法,并进行其在人体内药动学的研究。方法10名健康受试者单剂量口服200mg普卢利沙星片后,采集一系列血样,检测其血药浓度。血浆经高氯酸沉淀蛋白,以ZORBAX Eclipse XDB—C18（150mm×4．6mm,5μm）为色谱柱,流动相为乙腈-2％醋酸-水=20：40：40（V/V/V）,流速为0．8mL·min-1,柱温为25℃,检测波长为278nm。结果NM394在血药浓度0．05-7．50mg·L^-1内线性关系良好（r=0．9999）,定量下限为0．05mg·L^-1;低、中、高3个浓度的相对回收率（n=5）分别为（105．16±1．86）％、（105．01±1．94）％、（100．40±4．53）％,日内RSD（n=5）分别为5．57％、2．36％、2．31％,日间RSD（n=5）分别为3．25％、2．22％、4．26％。药动学参数分别为：ρmax（1．480±0．329）mg·L^-1,tmax（0．825±0．374）h,AUC0→t（6．853±1．679）mg·h·L^-1,AUC0→∞（7．488±1．687）mg·h·L^-1。结论本方法简便、灵敏、快速、准确,适用于人血浆中普卢利沙星活性代谢产物NM394浓度的检测及其药动学研究。     

Enantioselective pharmacokinetics in animals of pazinaclone,a new isoindoline anxiolytic,and its active metabolite

The enantioselective pharmacokinetics of a new anxiolytic, pazinaclone (DN-2327), and its active metabolite, M-II, were studied in animals. In rats and dogs given racemic pazinaclone intravenously, the total clearance and volume of distribution of (S)-pazinaclone were lower than those of (R)-pazinaclone, whereas the opposite results were obtained in monkeys. The differences in disposition were consistent with enantioselective protein binding, where the unbound fraction was greater for (R)-pazinaclone than that for the (S)-enantiomer in rats and dogs; the reverse was noted in monkeys. Lower clearance and distribution for (S)-pazinaclone in rats and dogs, and for the (R)-enantiomer in monkeys, resulted in comparable plasma profiles for the pazinaclone enantiomers and thereby those of the corresponding enantiomers of M-II. The unbound clearance (CL_u) of (S)-pazinaclone was, however, greater than that of the antipode in rats and dogs and the CL_u of each enantiomer was similar in monkeys. Thus, enantioselectivity in the kinetics of (S)- and (R)-pazinaclone appears to reside largely in plasma binding differences and is unrelated to variations in intrinsic clearance. The first-pass metabolism of (S)- and (R)-pazinaclone on oral administration of the racemate was enantioselective, with respective bioavailabilities of 1.7 and 0.8% in rats, 10.4 and 1.9% in dogs, and 0 and 11.4% in monkeys. Therefore, the enantioselectivity was more pronounced after oral dosing.     

Effects of woohwangcheongsimwon suspension on the pharmacokinetics of bupropion and its active metabolite, 4-hydroxybupropion, in healthy subjects

AIMS

To examine the effects of woohwangcheongsimwon suspension on the pharmacokinetics of bupropion and its active metabolite, 4-hydroxybupropion, formed via CYP2B6 in vivo.

METHODS

A two-way crossover clinical trial with a 2 week washout period was conducted in 14 healthy volunteers. In phases I and II, subjects received 150 mg bupropion with or without woohwangcheongsimwon suspension four times (at −0.17, 3.5, 23.5 and 47.5 h, with the time of bupropion administration taken as 0 h) in a randomized balanced crossover order. Bupropion and 4-hydroxybupropion plasma concentrations were measured for up to 72 h by LC-MS/MS. Urine was collected up to 24 h to calculate the renal clearance. In addition, the CYP2B6*6 genotype was also analyzed.

RESULTS

The geometric mean ratios and 90% confidence interval of bupropion with woohwangcheongsimwon suspension relative to bupropion alone were 0.976 (0.917, 1.04) for AUC(0,∞) and 0.948 (0.830,1.08) for C_max, respectively. The corresponding values for 4-hydroxybupropion were 0.856 (0.802, 0.912) and 0.845 (0.782, 0.914), respectively. The t_max values of bupropion and 4-hydroxybupropion were not significantly different between the two groups (P > 0.05). The pharmacokinetic parameters of bupropion and 4-hydroxybupropion were unaffected by woohwangcheongsimwon suspension.

CONCLUSIONS

These results indicate that woohwangcheongsimwon suspension has a negligible effect on the disposition of a single dose of bupropion in vivo. As a result, temporary co-administration with woohwangcheongsimwon suspension does not seem to require a dosage adjustment of bupropion.     

Clinical pharmacokinetics of the prodrug oseltamivir and its active metabolite Ro 64-0802

Oseltamivir is an ethyl ester prodrug of Ro 64-0802, a selective inhibitor of influenza virus neuraminidase. Oral administration of oseltamivir delivers the active antiviral Ro 64-0802 to the bloodstream, and thus all sites of influenza infection (lung, nasal mucosa, middle ear) are accessible. The pharmacokinetic profile of oseltamivir is simple and predictable, and twice daily treatment results in effective antiviral plasma concentrations over the entire administration interval. After oral administration, oseltamivir is readily absorbed from the gastrointestinal tract and extensively converted to the active metabolite. The absolute bioavailability of the active metabolite from orally administered oseltamivir is 80%. The active metabolite is detectable in plasma within 30 minutes and reaches maximal concentrations after 3 to 4 hours. After peak plasma concentrations are attained, the concentration of the active metabolite declines with an apparent half-life of 6 to 10 hours. Oseltamivir is eliminated primarily by conversion to and renal excretion of the active metabolite. Renal clearance of both compounds exceeds glomerular filtration rate, indicating that renal tubular secretion contributes to their elimination via the anionic pathway. Neither compound interacts with cytochrome P450 mixed-function oxidases or glucuronosyltransferases. The pharmacokinetic profile of the active metabolite is linear and dose-proportional, with less than 2-fold accumulation over a dosage range of oseltamivir 50 to 500 mg twice daily. Steady-state plasma concentrations are achieved within 3 days of twice daily administration, and at a dosage of 75mg twice daily the steady-state plasma trough concentrations of active metabolite remain above the minimum inhibitory concentration for all influenza strains tested. Exposure to the active metabolite at steady state is approximately 25% higher in elderly compared with young individuals; however, no dosage adjustment is necessary. In patients with renal impairment, metabolite clearance decreases linearly with creatinine clearance. A dosage reduction to 75mg once daily is recommended for patients with creatinine clearance <30 ml/min (1.8 L/h). The pharmacokinetics in patients with influenza are qualitatively similar to those in healthy young adults. In vitro and in vivo studies indicate no clinically significant drug interactions. Neither paracetamol (acetaminophen) nor cimetidine altered the pharmacokinetics of Ro 64-0802. Coadministration of probenecid resulted in a 2.5-fold increase in exposure to Ro 64-0802; however, this competition is unlikely to result in clinically relevant effects. These properties make oseltamivir a suitable candidate for use in the prevention and treatment of influenza.     

Gender-related differences in pharmacokinetics of enantiomers of trans-tramadol and its active metabolite, trans-O-demethyltramadol, in rats

AIM: To compare the pharmacokinetics of the enantiomers of trans-tramadol (trans-T) and its active metabolite, trans-O-demethyltramadol (M1), in male and female rats. METHODS: Following a single oral dose of 10 mg/kg trans-T hydrochloride to rats, (+)-trans-T, (-)-trans-T, (+)-M1, and (-)-M1 in plasma were determined by a high performance capillary electrophoresis method. RESULTS: The females showed higher plasma concentrations of (+)-trans-T, (-)-trans-T, and (+)-M1 than the males. The enantiomers of trans-T were absorbed and eliminated more slowly in the females than in the males. (+)-M1 was eliminated more slowly in the females than in the males. All pharmacokinetic parameters but T_(max) of the two enantiomers of trans-T were significantly different in both sex rats. The (+)/(-)-enantiomeric ratios of the pharmacokinetic parameters for trans-T in the males were similar to those in the females. The values of C_(max), AUC_(0-∞) of the two enantiomers of M1 were significantly different in both sex rat