Pharmacokinetic effect of ketoconazole on solifenacin in healthy volunteers

Solifenacin succinate (YM905) is a new, once-daily, orally administered muscarinic receptor antagonist designed to treat overactive bladder. The metabolism of solifenacin involves hepatic cytochrome P450 (CYP) 3A4; therefore, the pharmacokinetics of solifenacin may be affected by drugs that inhibit CYP3A4. This study aimed to examine the effects of co-administration of ketoconazole, a potent CYP3A4 inhibitor, on the pharmacokinetics of solifenacin in healthy volunteers. In a single-site, open-label, monosequence, crossover study, 17 healthy men and women aged 18 to 65 years received a single 10 mg oral dose of solifenacin, which is is the highest available dose. After a 14-day wash-out period, they began 20 days of oral ketoconazole at a dose of 200 mg once daily. A single 10 mg dose of solifenacin was administered again on day 7 of ketoconazole treatment. Pharmacokinetics was assessed using the standard measurements of maximum plasma concentration (Cmax), time to Cmax, area under the curve (AUC), and elimination half-life (t1/2). Co-administration of ketoconazole resulted in a 1.43 times increase in the C(max) of solifenacin and an approximately 2 times increase in AUC. The mean t1/2 of solifenacin was extended from 49.3 to 77.5 hr whereas time to Cmax did not change. No substantial increase in the overall rate of adverse events, and no significant effects on vital signs, electrocardiography, clinical laboratory values, or physical examinations were noted. Administration of 200 mg ketoconazole once daily in healthy male volunteers resulted in a 2 times increase in exposure of a single 10 mg dose of solifenacin. Since ketoconazole is one of the strongest inhibitors of CYP3A4, it is expected that co-administration of other CYP3A4 inhibitors will not result in a stronger increase in solifenacin exposure.     

Bioavailability of two new formulations of paracetamol, compared with three marketed formulations, in healthy volunteers

The aim of this study was to compare the main pharmacokinetic characteristics of two new paracetamol formulations, powder sachet and tablet, with that of three commercially available paracetamol formulations: two conventional solid tablets and one effervescent tablet. Twelve healthy volunteers participated in an open, single dose (paracetamol 1,000 mg), randomized, five-way, crossover study. Formulations studied included: formulation A: 2 x 500 mg paracetamol tablets (Laboratorios Belmac S.A.); formulation B: 1 x 1,000 mg paracetamol powder sachets (Laboratorios Belmac, S.A.); formulation C: 2 x 500 mg paracetamol film-coated tablets (Panadol, SmithKline Beecham); formulation D: 2 x 500 mg paracetamol tablets (Tylenol, McNeil); and formulation E: 1 x 1,000 mg effervescent paracetamol tablets (Efferalgan, UPSA). The primary variables were area under the plasma concentration time curve extrapolated to infinity (AUC(0-infinity)), maximum plasma concentration (Cmax), and time to maximum plasma concentration (tmax). Mean AUC(0-infinity) ranged from 52.6 (B) to 56.3 microg x h/ml (D); mean Cmax varied between 17.98 (C) and 20.73 microg/ml (E); mean tmax ranged from 0.40 (E) to 0.88 h (C); and median t(1/2) varied between 2.65 (C) and 2.81 h (A). Formulations A, B and E showed significantly shorter tmax than formulation C. The tmax and Cmax values found for formulations A and B were very similar to that found for E, an effervescent tablet formulation. In conclusion, the two new formulations of paracetamol tested in this study were absorbed rapidly after a single oral dose in healthy volunteers, similar to an effervescent paracetamol formulation and significantly faster than two ordinary commercialized paracetamol tablets.     

Bioequivalence evaluation of two brands of ketoconazole tablets (Onofin-K and Nizoral) in a healthy female Mexican population

A randomized, crossover study was conducted in 24 healthy female volunteers to compare the bioavailability of two brands of ketoconazole (200 mg) tablets; Onofin-K (Farmacéuticos Rayere S.A., Mexico) as the test and Nizoral (Janssen-Cilag, Mexico) as the reference products. The study was performed at the Clinical Pharmacology Research Center of the Hospital General de Mexico in Mexico City. Two tablets (400 mg) were administered as a single dose with 250 ml of water after a 12 h overnight fast on two treatment days separated by a 1 week washout period. After dosing, serial blood samples were collected for a period of 12 h. Plasma harvested was analysed for ketoconazole by a modified and validated HPLC method with UV detection in the range 400-14000 ng/ml, using 200 microl of plasma in a full-run time of 2.5 min. The pharmacokinetic parameters AUC(0-t), AUC(0-alpha), Cmax, Tmax and t(1/2) were determined from plasma concentrations of both formulations and the results discussed. AUC(0-t), AUC(0-alpha) and Cmax were tested for bioequivalence after log transformation of data, and no significant differences were found either in 90% classic confidence interval or in the Anderson and Hauck test (p < 0.05). Based on statistical analysis, it is concluded that Onofin-K is bioequivalent to Nizoral.     

食物对两种桂利嗪胶囊人体生物利用度的影响(英文)

目的比较食物对两种桂利嗪胶囊(A和B)人体生物利用度的影响。方法用HPLC紫外检测法测定健康受试者分别在禁食及餐后一次口服50mg桂利嗪胶囊A或B后血清药物浓度。结果胶囊A的Cmax 及AUC不受食物影响 ,胶囊B的吸收受食物影响 ,禁食后的Cmax 和AUC显著低于餐后的Cmax 和AUC。结论胶囊A的制剂优于胶囊B的制剂 ,其人体生物利用度不受食物影响     

Ibopamine (SK&F 100168) pharmacokinetics in relation to the timing of meals.

The effect of the timing of a standard meal relative to a single oral dose of 200 mg ibopamine, on the appearance of its pharmacologically active metabolite, epinine, in plasma was investigated in a randomised crossover study in 12 healthy volunteers. After a 12 h fast, ibopamine was administered either in the fasting state (no meal), or 1 h before, 0.5 h before, immediately after, 2 h after or 3 h after a standardised meal. Blood samples taken immediately before and at intervals for 3 h after dosing were analysed for free epinine. Maximum concentration (Cmax), time to Cmax(tmax), and area under the concentration-time curve (AUC) for free epinine in plasma were calculated. When compared with the fasting state, Cmax and AUC0-3h were significantly reduced when ibopamine was given immediately after or 2 h after a meal. AUC was also reduced for ibopamine given 0.5 h before a meal. tmax was significantly delayed when ibopamine was given immediately after, or 2 or 3 h after a meal. Thus, administration of ibopamine with or shortly after a meal reduced the rate and extent of appearance of free epinine in plasma. The clinical significance of reduced epinine levels on acute dosing in the presence of food is unknown.     

Clinical pharmacokinetics of mizolastine

Mizolastine is a new histamine H1 receptor antagonist. Mizolastine 10 mg/day is effective in allergic rhinitis and chronic idiopathic urticaria. In young healthy volunteers, absorption of mizolastine is rapid with time (tmax) to peak concentration (Cmax) of about 1 hour. The absolute bioavailability of mizolastine 10mg tablets is about 65%. Distribution is rapid with a mean distribution half-life of 1.5 to 1.9 hours. Mizolastine is >98% bound to serum albumin and the apparent volume of distribution is between I and 1.4 L/kg. Mizolastine is extensively metabolised by hepatic glucuronidation and sulphation, with no major active metabolite, and excreted in faeces. The terminal elimination half-life (t1/2beta) is 7.3 to 17.1 hours. The apparent oral clearance after a repeated oral dose of 10mg is 6.02 L/h, with steady state reached from day 3 and no accumulation between days 1 and 7. Cmax and area under the concentration-time curve (AUC) are linearly related to dose. Mizolastine appears in vivo to be a relatively weak inhibitor of cytochrome P450 2E1, 2C9, 2D6 and 3A4. In vivo, no interactions were observed between mizolastine and lorazepam or ethanol. A significant increase in Cmax and trough plasma concentration (Cmin) of digoxin occurred after coadministration with mizolastine, without change in AUC, tmax or clinical parameters. Significant increases in theophylline Cmin and AUC were observed after coadministration with mizolastine. Mizolastine Cmax and AUC were increased when coadministered with erythromycin, with no change in t1/2beta. Concomitant administration of mizolastine and ketoconazole increased mizolastine AUC values with no change in t1/2beta. In a population analysis of the pharmacokinetics of mizolastine in patients with allergies, parameter values were close to those in healthy volunteers, except for duration of absorption, which was almost doubled in the patients. Bodyweight and creatinine clearance were found to have little influence on oral clearance, and no influence of liver transaminases was found on clearance and distribution. Pharmacokinetic parameters of mizolastine in elderly individuals were similar to those observed in healthy young volunteers. In patients with chronic renal insufficiency, t1/2beta was prolonged by 47% compared with young healthy volunteers. In patients with cirrhosis, tmax was longer, Cmax was lower, distribution half-life was prolonged and AUC was 50% higher than in healthy volunteers. In pharmacodynamic-pharmacokinetic trials, the percentage of wheal and flare inhibition was found to correlate with mizolastine Cmin values. No direct relationship was found between drug concentrations in skin blister fluid and antihistamine activity.     

Bioequivalence study of tramadol by intramuscular administration in healthy volunteers

Tramadol hydrochloride (CAS 36282-47-0) is a centrally acting analgesic agent binding to mu opiate receptors. The bioavailability of a new tramadol hydrochloride injection (Limadol) was compared with a commercially available reference product by intramuscular administration in twelve healthy Chinese male volunteers by a standard two-way cross-over trial. Each volunteer received a single 100 mg injection of tramadol HCl in each phase. The bioavailability was compared using the area under the plasma concentration-time curve from time 0 to 30 h (AUC0-30), the area under the plasma concentration-time curve from time 0 to infinity (AUC0-infinity), peak plasma concentration (Cmax), and time to reach peak plasma concentration (Tmax). No statistically significant difference was observed between the Tmax, Cmax, AUC0-30 and AUC0-infinity of the two preparations. It is concluded that test and reference formulations of tramadol hydrochloride are bioequivalent for both the extent and rate of absorption after a single intramuscular injection.     

Pharmacokinetics of halofantrine in man: effects of food and dose size.

1. Plasma concentrations of halofantrine (Hf) and its putative principal plasma metabolite desbutyl halofantrine (Hfm) have been measured in two separate studies after oral administration of the hydrochloride salt. 2. Six healthy male volunteers each received single oral doses of 250, 500 and 1000 mg administered after an overnight fast. A washout period of at least 6 weeks was allowed between each dose. A further 250 mg single oral dose was administered to the same six subjects in a fasting state and after a standardised fatty meal in a randomised study, again with a washout period of at least 6 weeks. 3. AUC and maximum plasma concentration (Cmax) for Hf increased in proportion to the dose from 250-500 mg. This increase was non-proportional when the dose was increased from 500 to 1000 mg. For Hfm, in the dose range 250-500 mg, AUC but not Cmax increased in proportion in the increase in dose size. The increase in these parameters was non-proportional when the dose was increased from 500 to 1000 mg. Time to reach peak concentrations for Hf and Hfm and the elimination half-life of Hf remained unchanged across the dosage range. 4. Following a fatty meal, Cmax for Hf was increased from 184 +/- 115 micrograms l-1 (fasting) to 1218 +/- 464 micrograms l-1 (fed). AUC for Hf was increased from 3.9 +/- 2.6 mg l-1 h (fasting) to 11.3 +/- 3.5 mg l-1 h following a fatty meal.(ABSTRACT TRUNCATED AT 250 WORDS)     

LC-MS determination and bioavailability study of loperamide hydrochloride after oral administration of loperamide capsule in human volunteers

The purpose of the present study was to develop a standard protocol for loperamide hydrochloride bioequivalence testing. For this purpose, a simple rapid and selective LC-MS method utilizing a single quadrupole mass spectrometer was developed and validated for the determination of loperamide hydrochloride in human plasma, and we followed this with a bioavailability study. Methyl tert-butylether (MTBE) was used to extract loperamide hydrochloride and ketoconazole (internal standard (IS)) from an alkaline plasma sample. LC separation was performed on a Zorbax RX C18 column (5 microm, 2.1 mm x 150 mm) using acetonitrile-water-formic acid (50:50:0.1 (v/v)) as a mobile phase. The retention times of loperamide hydrochloride and IS were 1.2 and 0.8 min, respectively. Quadrupole MS detection was by monitoring at m/z 477 (M + 1) corresponding to loperamide hydrochloride and at m/z 531 (M + 1) for IS. The described assay method showed acceptable precision, accuracy, linearity, stability, and specificity. The bioavailability of loperamide hydrochloride was evaluated in eight healthy male volunteers. The following pharmacokinetic parameters were elucidated after administering a single dose of four 2mg capsules of loperamide: the area under the plasma concentration versus time curve from time 0 to 72 h (AUC72 h) 19.26 +/- 7.79 ng h/ml; peak plasma concentration (Cmax) 1.18 +/- 0.37 ng/ml; time to Cmax (Tmax) 5.38 +/- 0.74 h; and elimination half-life (t1/2) 11.35 +/- 2.06 h. The developed method was successfully used to study the bioavailability of a low dose (8 mg) of loperamide hydrochloride.     

pH-Related Changes in the Absorption of Dipyridamole in the Elderly

The bioavailability of dipyridamole, a poorly soluble weak base, was evaluated in 11 healthy, older subjects (65 years), 6 with a low fasting gastric pH (control) and 5 with a fasting gastric pH > 5 (achlorhydric), in a randomized, crossover design. Subjects received 50 mg dipyridamole as a single oral dose both with and without pretreatment with 40 mg famotidine (control subjects) or 1360 mg glutamic acid HC1 (achlorhydric subjects). Gastric pH was monitored by Heidelberg radiotelemetric capsule. Gastric emptying of ^99mTc-radiolabeled orange juice was measured. Gastric pH appeared to be a primary determinant in dipyridamole absorption in the elderly. Elevated gastric pH resulted in compromised dipyridamole absorption compared to low-gastric pH conditions in all cases. The administration of glutamic acid hydrochloride to achlorhydric subjects prior to the dose of dipyridamole corrected for the decreased C _max and AUC(0–36) exhibited in achlorhydric subjects without pretreatment. T_max and k _a were slower in achlorhydrics, although pretreatment with glutamic acid HC1 tended to normalize these parameters. Based on these results, it would be beneficial for achlorhydrics to take glutamic acid hydrochloride prior to taking dipyridamole and other medications which need a low gastric pH for complete absorption. The administration of 40 mg famotidine was successful in elevating the gastric pH to >5 in all subjects and maintained it at >5 for at least 3 hr in all subjects tested. The lack of differences in C _max and AUC(0–36) with significant differences in T _max and k _a indicated that control subjects after treatment with famotidine may serve as an adequate model for achlorhydrics with respect to the extent of absorption, but not with respect to the rate of absorption. Gastric emptying of a nutrient liquid was significantly slower in achlorhydric subjects than in control subjects. Finally, fasting serum gastrin appeared to be a relatively reliable and easy method for screening for achlorhydria in the elderly.     

Effect of a high-fat meal on the bioavailability of a polymer-coated erythromycin particle tablet formulation

The effect of food on the relative bioavailability of an erythromycin particles-in-tablet formulation was studied in 27 healthy volunteers, using a four-way, crossover study design with the following treatments: one or two erythromycin capsules USP (Eryc, Parke-Davis), or one polymer-coated erythromycin particles-in-tablet (PCE, Abbott) administered fasting or with a high-fat meal. Under fasting conditions the erythromycin particles-in-tablet and erythromycin capsule formulations are bioequivalent based on similar tmax and dose-normalized Cmax and AUC values. The rate and extent of absorption from the particles-in-tablet formulation, however, are dramatically reduced following administration with a meal. Mean Cmax and AUC values decreased by 73% and 72%, respectively, and seven subjects had no detectable erythromycin plasma concentrations for 16 hours following administration of the particles-in-tablet formulation with the high-fat meal. Greater than 40% of the subjects had nonfasting Cmax and AUC values that were less than 10% of those values following administration of the dose fasting. Cmax and AUC values in nonfasting subjects were within 75% to 125% of fasting values in only two and one of 27 subjects, respectively. The erythromycin particles-in-tablet formulation therefore should not be administered with meals.     

Celecoxib does not significantly alter the pharmacokinetics or hypoprothrombinemic effect of warfarin in healthy subjects

The objective of this study was to determine the effects of celecoxib, an anti-inflammatory/analgesic agent that primarily inhibits COX-2 and not COX-1 at therapeutic doses, on the steady-state pharmacokinetic profile and hypoprothrombinemic effect of racemic warfarin in healthy volunteers. Twenty-four healthy adult volunteers on maintenance doses of racemic warfarin (2-5 mg daily), stabilized to prothrombin times (PT) 1.2 to 1.7 times pretreatment PT values for 3 consecutive days, were randomized to receive concomitant celecoxib (200 mg bid) or placebo for 7 days in an open-label, multiple-dose, randomized, placebo-controlled, parallel-group study of warfarin pharmacokinetics and PT. Steady-state exposure of S- and R-warfarin (area under the curve [AUC]) and maximum plasma concentration (Cmax) in subjects receiving celecoxib were within 2% to 8% of the warfarin AUC and Cmax in subjects receiving placebo during the concomitant treatment period. In addition, PT values were not significantly different in subjects receiving warfarin and celecoxib concomitantly compared with subjects receiving warfarin and placebo. In conclusion, concomitant administration of celecoxib has no significant effect on PT or steady-state pharmacokinetics of S- or R-warfarin in healthy volunteers.     

Pharmacokinetic properties of tramadol sustained release capsules. 1st communication: investigation of dose linearity.

The relationship between the dose and the pharmacokinetic characteristics. AUC(0-infinity) and Cmax was investigated with respect to linearity in 12 healthy male volunteers. Single doses of 50 mg, 100 mg and 200 mg tramadol (CAS 27203-92-5) hydrochloride were administered as sustained release capsules in an open, randomized three-period crossover study. Tramadol plasma concentrations were determined by a validated gas chromatography method. Statistical analysis after logarithmic transformation of the dose-adjusted characteristics mentioned above yielded bioequivalence for all doses applied. Therefore, dose linearity for the range investigated could be concluded.     

盐酸二甲双胍片在中国健康人体的生物等效性

目的评价2种国产盐酸二甲双胍片(口服降糖药)在中国健康人体的生物等效性。方法 20名健康男性受试者随机交叉单剂量口服盐酸二甲双胍片试验药物和对照药物,各1.0 g。用高效液相色谱法测定血浆中盐酸二甲双胍的浓度,用DAS 2.0软件计算药代动力学参数,并对2种药物进行生物等效性评价。结果试验药物和对照药物的主要药代动力学参数如下:Cmax为(2.83±0.53),(2.57±0.57)mg.L-1;Tmax为(1.55±0.39),(1.63±0.36)h;t1/2为(3.70±1.76),(3.36±0.72)h;AUC0-24为(10.20±1.95),(9.71±2.56)mg.h.L-1。AUC0-24、AUC0-∞、Cmax的90%可信区间分别为99.1%～114.6%、99.1%～113.8%和100.6%～110.4%。试验药物相对于对照药物的生物利用度F为(108.3±20.5)%。结论试验药物和对照药物生物等效。     

Effect of food on the relative bioavailability of two oral formulations of posaconazole in healthy adults

AIMS: This randomized, crossover, single-dose study evaluated the relative oral bioavailability of posaconazole suspension and coprecipitate tablet formulations. Additionally, the study determined whether systemic exposure to posaconazole was affected by prandial status or by the fat content of a meal. METHODS: This was a randomized, open-label, four-way crossover, single-dose study in 20 healthy men. Posaconazole pharmacokinetics were evaluated over 72 h following a single oral dose of posaconazole suspension (200 mg/5 ml) administered with a high-fat meal, a nonfat breakfast, or after a 10 h fast, or posaconazole tablets (2 x 100 mg) administered with a high-fat meal. RESULTS: The posaconazole suspension showed a significant increase in bioavailability compared with the tablet (increase in AUC(0,72 h) = 137% (90% confidence interval (CI) 119%, 156% and Cmax = 123% (90% CI 104%, 146%). The mean increases in AUC(0,72 h) and Cmax values were about 400% when administered with a high-fat meal compared with administration of the suspension in the fasting state (AUC(0,72 h) 90% CI 343%, 448%; Cmax 90% CI 352%, 493%). Administration of the suspension with a nonfat meal enhanced exposure, resulting in an increase in AUC(0,72 h) of 264% (90% CI 231%, 302%) and in Cmax of 296% (90% CI 250%, 350%) relative to the fasted state. CONCLUSIONS: The suspension formulation of posaconazole was associated with enhanced systemic exposure and increased relative bioavailability compared with the tablet. Food substantially enhanced the rate and extent of posaconazole absorption in healthy subjects.     

Pharmacokinetics of ketoconazole administered intravenously to dogs and orally as tablet and solution to humans and dogs

The single-dose pharmacokinetics and bioavailability of three ketoconazole formulations were evaluated using HPLC in five healthy human volunteers and six male mongrel dogs. The human volunteers received 400 mg po of ketoconazole as tablet (Ktab) and solution (Ksol) formulations. The dogs received 400 mg po of Ktab and Ksol, and 376 mg iv of an intravenous dose (Kiv). In humans the AUC value for Ksol (62.21 +/- 21.2 microgram X h/ml; mean +/- SD) was significantly greater than for Ktab (50.0 +/- 15.2 micrograms X h/ml; p less than 0.05). Peak serum concentrations (Cmax), time to peak serum concentrations (tmax), t1/2, and the terminal elimination rate constant (kel) did not differ between Ktab and Ksol. This suggests that the administration of Ksol may be a useful alternative to dosage increases in situations where low bioavailability of ketoconazole in tablet form is suspected. The mean systemic clearance (CLs) of Kiv in dogs was 2.74 +/- 1.10 mL/min/kg, the volume of distribution at steady state (Vdss) was 0.72 +/- 0.28 L/kg, and the half-life was 2.7 +/- 1.6 h. Considerable variability was seen in the AUC of ketoconazole, particularly with the oral preparations. The absolute bioavailability of Ktab was 0.50 +/- 0.38, which did not differ statistically from that of Ksol, 0.56 +/- 0.23. The Ksol showed less variability in AUC, Cmax, and F values than did Ktab, and two dogs with low bioavailability with Ktab (0.04 and 0.07) had substantially greater bioavailability with Ksol (F = 0.96 and 0.57, respectively). Evaluation of Kiv in dogs confirms decreased bioavailability from orally administered tablet formulations of ketoconazole.     

Lack of effect of ketoconazole on the pharmacokinetics of rosuvastatin in healthy subjects

AIMS: To examine in vivo the effect of ketoconazole on the pharmacokinetics of rosuvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor. METHODS: This was a randomized, double-blind, two-way crossover, placebo-controlled trial. Healthy male volunteers (n = 14) received ketoconazole 200 mg or placebo twice daily for 7 days, and rosuvastatin 80 mg was coadministered on day 4 of dosing. Plasma concentrations of rosuvastatin, and active and total HMG-CoA reductase inhibitors were measured up to 96 h postdose. RESULTS: Following coadministration with ketoconazole, rosuvastatin geometric least square mean AUC(0,t) and Cmax were unchanged compared with placebo (treatment ratios (90% confidence intervals): 1.016 (0.839, 1.230), 0.954 (0.722, 1.260), respectively). Rosuvastatin accounted for essentially all of the circulating active HMG-CoA reductase inhibitors and most (> 85%) of the total inhibitors. Ketoconazole did not affect the proportion of circulating active or total inhibitors accounted for by circulating rosuvastatin. CONCLUSIONS: Ketoconazole did not produce any change in rosuvastatin pharmacokinetics in healthy subjects. The data suggest that neither cytochrome P450 3A4 nor P-gp-mediated transport contributes to the elimination of rosuvastatin.     

Comparative bioavailability study of cefixime (equivalent to 100 mg/5 ml) suspension (Winex vs Suprax) in healthy male volunteers

This investigation was carried out to evaluate the bioavailability of a new suspension formulation of cefixime (100 mg/5 ml), Winex, relative to the reference product, Suprax (100 mg/5 ml) suspension. The bio-availability study was carried out in 24 healthy male volunteers who received a single oral dose (200 mg) of the test (A) and the reference (B) products on 2 treatment days after an overnight fast of at least 10 hours. The treatment periods were separated by a one-week washout period. A randomized, balanced two-way crossover design was used. After dosing, serial blood samples were collected over a period of 16 hours. Plasma concentrations of cefixime were analyzed using a sensitive high-performance liquid chromatographic assay. The pharmacokinetic parameters for cefixime were determined using standard non-compartmental method. The parameters AUC(0-t), AUC(0-infinity), Cmax, Kel, t1/2 and Cmax/AUC(0-infinity) were analyzed statistically using raw and log-transformed data. The time to maximum concentration (tmax) was analyzed using raw data. The parametric 90% confidence intervals of the mean values of the pnfinity harmacokinetic parameters: AUC(0-t), AUC(0-infinity) Cmax, and Cmax/AUC(0-infinity) were within the range 80 - 125% which is acceptable for bioequivalence (using log-transformed data). The calculated 90% confidence intervals based on the ANOVA analysis for the mean test/reference ratios of AUC(0-t), AUC(0-infinity), Cmax, and Cmax/AUC(0-infinity) were 88.93 - 107.10%, 89.09 - 107.11%, 89.63 - 108.58% and 96.85 - 105.29%, respectively. The test formulation was found bioequivalent to the reference formulation with regard to AUC(0-t), AUC(0-infinity), and Cmax using the Schuirmann's two one-sided t-tests. Therefore, the two formulations were considered to be bioequivalent.     

盐酸左氧氟沙星片的人体生物等效性研究

目的研究盐酸左氧氟沙星片的人体相对生物利用度和生物等效性。方法健康志愿者20名,随机双交叉单剂量口服盐酸左氧氟沙星片试验和参比制剂,剂量分别为200mg,剂间间隔为1周。分别于服药后24h内多点抽取静脉血;用高效液相色谱（HPLC）法测定血浆中左氧氟沙星的浓度。用DAS药代动力学程序计算相对生物利用度并评价两种制剂生物等效性。AUC（0-24）,AUC（0-inf）和Cmax经方差分析和双单侧t检验,Tmax进行秩和检验。结果单剂量口服试验制剂和参比制剂后血浆中的左氧氟沙星的Cmax分别为（2.88±0.61）mg·L^-1和（2.90±0.58）mg·L^-1;Tmax分别为（1.17±0.62）h和（1.09±0.79）h;AUC（0-24）分别为（20.23±3.41）mg/（h·L）和（20.11±3.61）mg/（h·L）;AUC（0-inf）分别为（21.97±3.84）mg/（h·L）和（21.72±4.22）mg/（h·L）。AUC（0-24）、AUC（0-inf）和Cmax的90%可信区间分别为97.5%～104.2%、98.2%～104.9%和92.5%～106.5%。结论试验制剂与参比制剂的人体相对生物利用度为（97．53±18．49）％,2制剂具有生物学等效性。     

The effect of a high-fat meal on the oral bioavailability of the immunosuppressant sirolimus (rapamycin)

The bioavailability of an oral nonaqueous solution of sirolimus was compared under fasting conditions and after a high-fat meal in a randomized, two-way crossover pharmacokinetic study. Healthy volunteers were administered a 15 mg single dose of sirolimus on two occasions, once while fasting and once after consumption of a high-fat breakfast. Whole blood concentrations of sirolimus were assayed by using a validated method with high-performance liquid chromatography/tandem mass spectrometric detection. Sirolimus was absorbed more slowly when administered after a high-fat meal than when administered after fasting, as shown by statistically significant reductions in peak concentration (Cmax) and the ratio of Cmax to the area under the curve (AUC), and lengthening of the time to peak concentration. The oral availability of sirolimus was increased to a modest extent (35%) and in a uniform manner when administered with a high-fat meal; the geometric mean ratio of the fed/fasting AUC values was 1.35, with a 90% confidence interval of 1.26 to 1.46. Food had no effect on the terminal half-life of sirolimus (mean values of 67 to 68 hours). The 35% increase in AUC obtained after a high-fat meal appears small relative to the intersubject and intrasubject variabilities observed in clinical trials. However, to minimize unnecessary fluctuations in trough whole blood sirolimus concentrations, it is advisable that sirolimus be administered consistently in individual patients, either with or without meals.