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The Chinese medicinal herb, Epimedium, used traditionally for bone health exerts estrogenic activity (EA) in vitro. A genetically characterized Epimedium brevicornum (EB) extract induced biphasic responses in the mRNA and protein expression of the estrogen-regulated progesterone receptor gene in breast cancer (MCF-7) cells. These changes were mirrored changes in estrogenic receptor (ERalpha) content. In male Sprague-Dawley rats, administration of the estrogenic prodrug, estradiol valerate increased area-under-curve of serum effects for ERalpha (AUC difference: 18,900EA(ERalpha) min; 95% CI: 0-37,800; p = 0.05) and breast cancer cell (MCF-7) growth (AUC difference: 30,200EA(MCF-7) min; 95% CI: 24,200-36,200; p<0.001), compared to placebo. Oral administration of Epimedium brevicornum increased ERalpha activity (1320EA(ERalpha) min, p<0.01). Our data indicate that estrogen-responsive bioassays can measure the pharmacokinetic/pharmacodynamics of estrogenic activity in serum. Epimedium brevicornum extract increases estrogenic activity in serum and human studies are required to evaluate whether Epimedium extracts have utility for estrogen replacement therapy.

Introduction: The aim of this study was to assess the outcome of radical treatment for stage I non-small cell lung cancer (NSCLC) with external beam radiation therapy., Materials and Methods: A retrospective series of 23 patients with stage I NSCLC treated radically with radiotherapy from September 1997 to December 2004 at the National Cancer Centre, Singapore. Eighteen patients had 3D conformal radiotherapy and 5 patients had 2D planning. The median radiation dose delivered was 55 Gy (range, 50 to 67.5 in 20 to 33 fractions). The estimated median BED(10) was 63.9 Gy (range, 57.6 to 70.1). Complete response (CR) rates, overall survival and cause-specific survival rates were analysed for evaluation of treatment results. Local regional failure was defined as disease in the ipsilateral lung and entire mediastinum. Recurrence at the contralateral lung and other distal organs was defined as distant metastases. Survival data were calculated using the Kaplan-Meier method and tested for significance with log-rank statistics., Results: A total of 23 patients (16 males, 7 females) with a median age of 73 years (range, 45 to 88) were analysed. Six (26%) had stage IA and 17 (74%) had stage IB disease. Eleven patients refused surgery and 12 patients were medically inoperable. The median follow-up was 18.9 months (range, 6.2 to 117.4). The overall survival at 2 years and 3 years was 54.7% and 24.3% respectively. The overall cause-specific survival was 57.4% at 2 years and 25.6% at 3 years. Radiological CR was obtained in 6/23 patients (26%) and the median survival was 24.8 months as compared to 20 months in patients who attained partial response (PR) or unknown response (P = 0.24). The median survival for 12 patients who received a BED(10) of > or =63.9Gy was not reached as compared to 20 months in 11 patients with BED(10) of <63.9 Gy (P = 0.03). Sixteen patients died, 14 due to disease recurrence or progression and 2 of unrelated causes. Seven patients (29.2%) remained alive. The longest surviving patient had a follow-up time of 117.4 months. Four of these 7 patients were disease-free and 3 were alive with disease (2 with bone metastases and 1 with recurrence in the primary site)., Conclusion: Our data are consistent with the reported literature for stage I NSCLC treated with radical radiotherapy. Patients who received a higher dose of radiation have a better outcome. The 3-year cause-specific survival of 25.6% is less than ideal and further investigations into dose escalation with modern radiotherapy techniques and perhaps the addition of chemotherapy or new targeted agents to radiation are warranted to improve the outcome.

Aim of the Study: This study aims to evaluate the association between hepatitis B virus (HBV) and lymphoma and to characterize HBV-related lymphomas. The efficacy of prophylactic lamivudine on HBV reactivation was also evaluated., Methods: We compared the prevalence rate of HBV infection in 556 patients with lymphoma seen over a 4-yr period with that in a group of 4698 Singapore residents aged 18-69 who participated in the National Health Survey. Next, we compared the clinic-pathologic characteristics of HBV-positive and HBV-negative lymphoma cases., Results: The prevalence rate of HBV infection in our study was 10.3% (57/556), higher than the prevalence rate of 4.1% (192/4698) in the general population (P < or = 0.001). The higher prevalence was observed in both sexes and across different age groups. An association was observed for non-Hodgkin's lymphoma (NHL) but not Hodgkin's lymphoma. The characteristics of HBV-infected patients with lymphoma were similar to those who were HBV-uninfected in terms of age, ECOG, extra-nodal involvement, LDH level, stage, complete remission rate and overall survival. Use of prophylactic lamivudine significantly decreased the incidence of HBV reactivation (13% vs. 38%, P = 0.02) and disruption to chemotherapy (43% vs. 4%, P = 0.02), with a trend towards improved overall survival., Conclusions: Our findings suggest that an association exists between HBV infection and NHL. However, HBV infection does not appear to have a significant impact on the clinical characteristics and prognosis of NHL. Prophylactic lamivudine should be considered in all HBV-infected patients receiving antracycline and/or steroid containing chemotherapy.

Flavonoids present in food, botanicals, and body fluids occur as complex mixtures, and data on their combinatorial estrogenic effects are sparse. Human cell lines that permanently express estrogen receptor (ER) alpha and ERbeta proteins were developed for the measurement of the global estrogenicity of flavonoids in such complex mixtures. The presence of estrogenic ligands, known and unknown, in these mixtures can be detected by activation of an ER-driven luciferase reporter gene. We also examined the effect of hydroxylation on the estrogenic activities of four common flavonoids-apigenin, kaempferol, luteolin, and quercetin, alone and in combination. An inverse relationship was observed between the number of hydroxyl groups in flavonoids and ERalpha bioactivity. When submaximal doses of apigenin, luteolin, kaempferol, genistein, and estradiol were combined in binary and higher order mixtures, the experimental estrogenic effects matched those obtained by summing effects extrapolated from dose-response curves of individual compounds. The estrogenic activities of mixtures containing quercetin were observed to deviate from additivity, suggesting that it was a partial agonist/antagonist. Our assay reveals superagonistic, additive, and antagonistic ERalpha or ERbeta actions of flavonoids and adds to our understanding of the estrogenic effects of phytoestrogens in complex mixtures.

It is known that smoking increases the risk for all histological subtypes of lung cancer. To date, the factors that determine why some patients develop small-cell lung cancer (SCLC) while others develop non-small-cell lung cancer (NSCLC) remain unknown. We compared the characteristics of 774 smokers with SCLC and NSCLC diagnosed during the period January 1999 till December 2002. Multivariate logistic regression was used to estimate the odds ratio (OR) with 95% CI. Testing of linear trend across categories of pack-years was also conducted. Six hundred and sixty-five NSCLC were compared to 109 SCLC. Among SCLC, there were significantly more females (20.2% versus 12.8%), current-smokers (81.7% versus 71.9%) as well as smokers who had smoked more than 40 pack-years (75.6% versus 50.3%). Comparing SCLC with NSCLC among the men only, having smoked more than 40 pack-years was associated with a significantly elevated odds ratio (OR) of 3.71 of developing SCLC (95% CI, 1.05-13.1; p=0.041). There was a decreasing trend in OR with increasing smoking cessation period. When comparing SCLC with adenocarcinoma, the women had a higher OR of 2.37 of developing SCLC (95% CI, 1.05-5.31; p=0.037) compared to the men. Our findings suggest that cumulative smoking exposure in terms of pack-years smoked is an important determining factor for the preferred development of SCLC among smokers.

Introduction: The survival and epidemiology of small-cell lung cancer (SCLC) in Singapore has not been described. We aim to present the characteristics as well as determine the survival outcome and important prognostic factors for SCLC patients., Materials and Methods: A retrospective analysis of SCLC patients diagnosed from 1999 to 2002 was conducted at the Outram campus, Singapore. Clinical characteristics and treatment data were obtained from case records and survival data were checked with the registry of births and deaths on 30 May 2005., Results: One hundred and eleven patients were analysed. There were 38 (34.2%) limited-disease (LD) patients and 73 (65.8%) extensive-disease (ED) patients. The majority were current or former smokers (94.7% among LD and 94.5% among ED). More patients with LD had good performance status (92% versus 63%, P = 0.0003) and were treated with combined chemotherapy and radiotherapy (82% versus 48%, P = 0.012). The median survival time of LD patients treated with curative chemoradiotherapy was 14.2 months (95% CI, 10.96 to 17.44). Those given prophylactic cranial irradiation had a median survival time of 16.9 months (95% CI, 11.83 to 21.97). For ED patients, the median survival time was 8.17 months (95%CI, 5.44 to 10.89). None of the factors analysed were significant prognostic factors for LD patients while performance status and type of treatment given were significant among ED patients., Conclusions: We found that the characteristics and survival of SCLC patients in Singapore are fairly similar to that of other countries.

Background: The aim of this study was to characterize primary central nervous system lymphoma (PCNSL) among Asian patients and to determine their outcomes with different therapeutic modalities., Patients and Methods: Between 1990 and 2005, 37 patients with PCNSL were analyzed within 5 different treatment groups: radiotherapy alone (arm A), combined chemoradiation (arm B), chemotherapy alone with methotrexate (MTX) > or = 1 g/m2 (arm C), miscellaneous therapy (arm D), and best supportive care (arm E)., Results: The median age at presentation was 59 years, and the majority of patients were male (68%). All patients had aggressive diffuse large B-cell lymphoma. The number of patients in arms A to E were 6, 16, 3, 8 and 4, respectively. The overall median survival was 7.4 months, 54.1 months, not reached, 8.9 months and 0.9 months, respectively. Use of MTX 1-2.5 g/m2 per cycle and an ECOG performance status of 0-2 were each associated with improved survival on univariate analysis (p = 0.022 and p = 0.049, respectively). Compared to radiotherapy alone, use of combined chemo-radiation was associated with a trend towards improved overall median survival (7.4 vs. 54.1 months, p = 0.058)., Conclusion: The clinical characteristics and treatment outcomes in our Asian patients were comparable to those reported in Western series. Use of MTX 1-2.5 g/m2 per cycle and an ECOG performance status of 0-2 were associated with improved survival.

Purpose: Tobacco smoke is a definite causative agent for lung cancer. It is increasingly being recognized that never-smokers can be afflicted with non-small-cell lung cancer (NSCLC). We aim to assess survival differences between smokers and never-smokers with NSCLC., Patients and Methods: We analyzed 975 NSCLC patients who presented from January 1999 to December 2002. Clinical characteristics among current-, former- and never-smokers were tested using chi2 or Kruskal-Wallis test. The hazard ratio (HR) for death and its 95% CI were calculated by Cox regression., Results: Of 975 patients, 59 had no smoking history and 33 had no quit time recorded. Of 883 patients analyzed, 286 patients (32.4%) were never-smokers. One hundred ninety-six never-smokers (68.5%) were females compared with 12% among current- and 13% among former-smokers (P < .001). There was a significant difference in histologic subtype between never-smokers and smokers: 69.9% with adenocarcinoma versus 39.9% (current-smokers) versus 47.3% (former-smokers); 5.9% with squamous cell carcinoma versus 35.7% (current-smokers) versus 28% (former-smokers; P < .001). Smokers had significantly poorer performance status (P = .002) and higher median age at diagnosis (P < .001) while more never-smokers presented with advanced disease (P = .002). Eight hundred and five patients (82.6%) died by May 30, 2005. The HR for smokers was significantly higher on both univariate and multivariate analysis (HR, 1.297; 95% CI, 1.040 to 1.619)., Conclusion: Never-smokers comprised a high proportion of NSCLC patients in Singapore. Definite epidemiologic differences exist between never-smokers and smokers. Differences in survival outcome further suggest that the biology underlying the pathogenesis and behavior of the disease may be different for never-smokers.

Background: This study reviews the outcome of patients with nasal natural killer (NK)/T-cell lymphoma treated at the Therapeutic Radiology Department, National Cancer Centre, Singapore, from 1997 to 2003., Methods: Twenty-one consecutive patients treated with radiotherapy, with or without chemotherapy, were retrospectively reviewed., Results: The median age was 44 years (range, 27-86 years). Thirteen patients had stage I disease, five had stage II disease, and three had stage IV disease. Immunophenotyping was CD 56+ in 18 patients. Median follow-up for patients still alive was 23.4 months (range, 8.9-78.5 months). A median dose of 50 Gy (range, 35-56 Gy) was delivered. Sixteen patients also received chemotherapy. Two-year overall survival was 52.8%. Five patients had rapidly progressive disease, with a median survival of 89 days from diagnosis. The other 16 patients had complete remission, after which four relapsed. There were two local relapses., Conclusions: This disease often carries a poor prognosis, despite multimodality treatment. Radiotherapy may contribute to local control in some patients., (Copyright 2005 Wiley Periodicals, Inc.)

Purpose: To evaluate the efficacy and toxicity of adjuvant combination of sequential chemotherapy followed by radiotherapy in uterine papillary serous carcinoma (UPSC)., Methods and Materials: From April 1994 to June 2003, 26 patients (median age 61.7 years, range 46.9-78.4) with UPSC were treated with a platinum-based chemoradiation protocol after definitive surgery. 9 patients were assigned as stage I (35%), 4 were stage II (15%), 11 were stage III (42%), and 2 were stage IV (8%) according to the FIGO staging for gynecological cancers. All patients underwent total hysterectomy, salpingo-oophorectomy, pelvic +/- perioartic lymph nodes dissection/sampling, omentectomy, and peritoneal washing. The adjuvant chemoradiation protocol consists of 4 cycles of platinum-based chemotherapy followed by pelvic irradiation and vaginal vault brachytherapy. In selected stage I patients with no or minimal myometrial invasion, only vault brachytherapy was given after adjuvant chemotherapy., Results: After a median follow-up of 28 months (range 9-113 months), 14 (54%) patients were alive and free of disease. 12 out of these 14 patients were FIGO stage I/II. 9 patients (35%) had died (8 from distant metastases). The Kaplan-Meier 2-year and 5-year survival estimates were 69.5% and 57%, respectively. Only 4 (15%) patients had pelvic recurrence. None of the patients developed local vault recurrence. The treatment was well tolerated, only 1 patient developed congestive cardiac failure from the chemotherapy and 6 patients had grade 2 peripheral neuropathy on follow-up., Conclusion: In our series of UPSC patients treated with adjuvant chemotherapy followed by radiotherapy, local control can be achieved in a majority of patients. Distant failure remains the major cause of mortality. Further investigations into finding a more effective systemic therapy are required if improvement in outcome for this form of uterine cancer is to be achieved.

A simple liquid chromatographic method was developed for the simultaneous determination of flavonoids from Orthosiphon stamineus Benth, namely sinensitin, eupatorin and 3'-hydroxy-5,6,7,4'-tetramethoxyflavone, in plasma. Prior to analysis, the flavonoids and the internal standard (naproxen) were extracted from plasma samples using a 1:1 mixture of ethyl acetate and chloroform. The detection and quantification limits for the three flavonoids were similar being 3 and 5 ng/ml, respectively. The within-day and between-day accuracy values, expressed as percentage of true values, for the three flavonoids were between 95 and 107%, while the corresponding precision, expressed as coefficients of variation, for the three flavonoids were less than 14%. In addition, the mean recovery values of the extraction procedure for all the flavonoids were between 92 and 114%. The calibration curves were linear over a concentration range of 5-4000 ng/ml. The present method was applied to analyse plasma samples obtained from a pilot study using rats in which the mean absolute oral bioavailability values for sinensitin, eupatorin and 3'-hydroxy-5,6,7,4'-tetramethoxyflavone was 9.4, 1.0 and 1.5%, respectively.

A single dose comparative bioavailability study was conducted to evaluate the bioavailability of tocotrienols from two self-emulsifying formulations, one of which produced an emulsion that readily lipolysed under in vitro condition (SES-A), while the other produced a finer dispersion with negligible lipolysis (SES-B) in comparison with that of a non-self-emulsifying formulation in soya oil. The study was conducted according to a three-way crossover design using six healthy human volunteers. Statistically significant differences were observed between the logarithmic transformed peak plasma concentration (Cmax) and total area under the plasma concentration-time curve (AUC(0-infinity)) values of both SES-A and -B compared to NSES-C indicating that SES-A and -B achieved a higher extent of absorption compared to NSES-C. Moreover, the 90% confidence interval of the AUC(0-infinity) values of both SES-A and -B over those of NSES-C were between 2-3 suggesting an increase in bioavailability of about two-three times compared to NSES-C. Both SES-A and -B also achieved a faster onset of absorption. However, both SES-A and -B had comparable bioavailability, despite the fact that SES-B was able to form emulsions with smaller droplet size. Thus, it appeared that both droplet sizes as well as the rate and extent of lipolysis of the emulsion products formed were important for enhancing the bioavailability of the tocotrienols from the self-emulsifying systems.

Purpose: To analyze the results of concurrent chemoradiotherapy in patients with locoregional recurrent nasopharyngeal carcinoma., Methods and Materials: We performed a retrospective analysis of 35 patients with locoregional recurrent nasopharyngeal carcinoma referred to our department between March 1994 and November 2002. Most patients were male (77%), Chinese (97%), and had undifferentiated carcinoma (89%). Most had extensive locally recurrent Stage rT3-T4 disease (66%) with a median age at recurrence of 49 years (range, 35-69 years). A repeat course of radiotherapy was given concurrently with cisplatin, with cisplatin/5-fluorouracil as consolidation treatment. Significant morbidities were present, including cranial nerve palsies due to extensive recurrent local disease before treatment of the recurrence., Results: The response rate to concurrent chemoradiotherapy was 58% (29% complete response and 29% partial response). The 5-year progression-free and overall survival rate, calculated using the Kaplan-Meier method, was 15% and 26%, respectively. Only 3 patients developed systemic metastases. Grade 3-4 acute toxicities included emesis (9%) and neutropenia (14%), and Grade 3-4 late toxicities consisted of temporal lobe necrosis (3%), cranial neuropathy (6%), and endocrine abnormalities (14%)., Conclusion: Concurrent chemoradiotherapy is feasible in a selected group of patients with locoregional recurrent NPC, but the risk of major late toxicities is significant.

In this investigation we describe the preparation, physical characterisation and in vivo behaviour of solid dispersions of a liquid nutraceutical, alpha-tocopherol, in Gelucire 44/14 with a view to establishing whether dispersion in this matrix may provide a means of formulating a liquid drug in a solid dosage form while also improving the oral bioavailability. Using Vitamin E Preparation USP as the source of alpha-tocopherol, dispersions were prepared using a melt-fusion method with active loadings up to 50% (w/w) and characterised using differential scanning calorimetry and optical microscopy. Capsules containing 300 IU alpha-tocopherol were manufactured and the absorption profiles compared to a commercial soft gelatin capsule preparation in healthy human volunteers. Confocal laser scanning microscopy (CLSM) studies were performed in order to elucidate the mechanism by which drug release may be occurring. Differential scanning calorimetry studies indicated that the presence of the active had a negligible effect on the melting profile of the carrier, indicating limited miscibility between the two components, a conclusion supported by the microscopy studies. Similarly, the dispersions were shown to exhibit a glass transition corresponding to the incorporated drug, indicating molecular cooperativity and hence phase separation from the lipid base. Despite the phase separation, it was noted that capsules stored for 18 months under ambient conditions showed no evidence of leakage. Bioavailability studies in six healthy male volunteers indicated that the Gelucire 44/14 formulation showed an approximately two-fold increase in total alpha-tocopherol absorption compared to the commercial preparation. Confocal laser scanning microscopy studies indicated that, on contact with water, the dispersions formed two interfacial layers, from which the Gelucire 44/14 disperses in the liquid medium as small particles. Furthermore, evidence was obtained for the dispersed material becoming incorporated into the hydrated lipid. In conclusion, the dispersion of the liquid drug in Gelucire 44/14 appears to allow the dual advantages of the preparation of a solid formulation and improved bioavailability of this material.

A study was conducted to evaluate the bioavailability of alpha-, gamma- and delta-tocotrienols administered via oral, intravenous, intramuscular and intraperitoneal routes in rats. Three separate experiments, each conducted according to a two-way crossover design, were carried out to compare intravenous and oral, intramuscular and oral, and intraperitoneal and oral administration. Oral absorption of all three tocotrienols was found to be incomplete. Of the three tocotrienols, alpha-tocotrienol had the highest oral bioavailability, at about 27.7+/-9.2%, compared with gamma- and delta-tocotrienols, which had values of 9.1+/-2.4% and 8.5+/-3.5%, respectively. Such biodiscrimination was also observed in their total clearance rates (estimated from the intravenous data). alpha-Tocotrienol showed the lowest clearance rate at about 0.16 L kg(-1) h(-1), whereas that of delta- and gamma-tocotrienols was quite similar, with values of 0.24 and 0.23 L kg(-1) h(-1), respectively. Interestingly, all three tocotrienols were found to be negligibly absorbed when administered intraperitoneally and intramuscularly. Thus, these two routes of administration should be avoided when evaluating the biological activities of the tocotrienols in whole animal experiments.

Background: Treatment of locoregionally recurrent nasopharyngeal carcinoma (NPC) is challenging because of prior radiotherapy, morbidities from disease recurrence, and limited therapeutic options available., Methods: A retrospective study of patients with locoregionally recurrent NPC., Result: Between March 1994 and December 1999, there were 42 patients; most were Chinese (98%) men (81%) with undifferentiated NPC (86%). A repeat course of radiotherapy was feasible in 20 patients and given concurrently with cisplatin followed by adjuvant cisplatin/5-fluorouracil (PF) (group 1). The remaining 22 (group 2) received palliative chemotherapy (PF) with a response rate of 50%. Significant morbidities resulted from cranial nerve palsies. The 2-year progression-free survival of patients in group 1 was expectedly better (58% vs 38%). Six (14%) developed systemic metastases at 12 months (median) from first recurrence., Conclusion: Concurrent chemoradiotherapy for locoregional recurrent NPC seems promising. The morbidity experienced resulted from locoregional disease with few progressing to develop systemic involvement., (Copyright 2002 Wiley Periodicals, Inc.)

A simple high-performance liquid chromatographic method was developed for the determination of omeprazole in human plasma. Omeprazole and the internal standard, chloramphenicol, were extracted from alkalinized plasma samples using dichloromethane. The mobile phase was 0.05 M Na2HPO4-ACN (65:35, v/v) adjusted to pH 6.5. Analysis was run at a flow rate of 1.0 ml/min at a detection wavelength of 302 nm. The method was specific and sensitive with a detection limit of 2.5 ng/ml at a signal-to-noise ratio of 4:1. The limit of quantification was set at 5 ng/ml. The calibration curve was linear over a concentration range of 5-1280 ng/ml. Mean recovery value of the extraction procedure was about 96%, while the within and between day coefficient of variation and percent error values of the assay method were all less than 14%.

Objective: The aim of the present communication is to provide information regarding the intrasubject coefficent of variation obtained from 30 bioequivalence studies covering 16 drugs which can be used for estimation of sample size. Additionally, an attempt was also made to estimate the test power of each of the studies conducted., Methods: The intrasubject coefficient of variation was estimated from the residual mean square error obtained from analysis of variance of the parameters AUC0-infinity, Cmax and Cmax/AUC0-infinity after logarithmic transformation. The test power in the analyses of the above parameters was subsequently estimated using nomograms provided by Diletti et al. [1991]., Results and Conclusion: Thirty products covering 16 drugs were studied in which 22 were immediate-release (including one dispersible tablet) and 8 were sustained-release formulations. The intrasubject coefficient of variation for the parameter AUC0-infinity was smaller than Cmax, and hence considerably more studies were able to attain a power of greater than 80% using 12 volunteers for the AUC0-infinity, compared to the Cmax. However, the variability in the Cmax could be reduced by using the parameter Cmax/ AUC0-infinity, and thus, provide a more realistic estimation of sample size, since the latter reflects only the rate of absorption and not both the rate and extent as in the case of Cmax [Endrenyi et al. 1991].

We have investigated the pharmacokinetics and bioavailability of alpha-, gamma- and delta-tocotrienols under fed and fasted conditions in eight healthy volunteers. The volunteers were administered a single oral dose of mixed tocotrienols (300 mg) under fed or fasted conditions. The bioavailability of tocotrienols under the two conditions was compared using the parameters peak plasma concentration (Cmax), time to reach peak plasma concentration (Tmax) and total area under the plasma concentration-time curve (AUC(o-infinity)). A statistically significant difference was observed between the fed and fasted logarithmic transformed values of Cmax (P < 0.01) and AUC(0-infinity) (P < 0.01) for all three tocotrienols. In addition, the 90% confidence intervals for the ratio of the logarithmic transformed AUC(0-infinity) values of alpha-, gamma- and delta-tocotrienols under the fed state over those of the fasted state were found to lie between 2.24-3.40, 2.05-4.09 and 1.59-3.81, respectively, while those of the Cmax were between 2.28-4.39, 2.31-5.87 and 1.52-4.05, respectively. However, no statistically significant difference was observed between the fed and fasted Tmax values of the three homologues. The mean apparent elimination half-life (t(1/2)) of alpha-, gamma- and delta-tocotrienols was estimated to be 4.4, 4.3 and 2.3 h, respectively, being between 4.5- to 8.7-fold shorter than that reported for alpha-tocopherol. No statistically significant difference was observed between the fed and fasted t(1/2) values. The mean apparent volume of distribution (Vd/f) values under the fed state were significantly smaller than those of the fasted state, which could be attributed to increased absorption of the tocotrienols in the fed state.

A simple high-performance liquid chromatographic method using fluorescence detection was developed for the determination of vitamin E especially delta-, gamma- and alpha-tocotrienols in human plasma. The method entailed direct injection of plasma sample after deproteinization using a 3:2 mixture of acetonitrile-tetrahydrofuran. The mobile phase comprised 0.5% (v/v) of distilled water in methanol. Analyses were run at a flow-rate of 1.5 ml/min with the detector operating at an excitation wavelength of 296 nm and emission wavelength of 330 nm. This method is specific and sensitive, with a quantification limit of approximately 40, 34 and 16 ng/ml for alpha-, gamma- and delta-tocotrienol, respectively. The mean absolute recovery values were about 98% while the within-day and between-day relative standard deviation and percent error values of the assay method were all less than 12.0% for alpha-, gamma- and delta-tocotrienol. The calibration curve was linear over a concentration range of 40-2500, 30-4000 and 16-1000 ng/ml for alpha-, gamma- and delta-tocotrienol, respectively. Application of the method in a bioavailability study for determination of the above compounds was also demonstrated.