RESULTS: No significant difference in plasma propranolol (mean +/- SEM) levels was seen between races six hours after the last dose (Malays, 59.7 +/- 8.8 ng/ml, Indians, 67.6 +/- 19.3 ng/ml, Chinese, 58.4 +/- 7.9 ng/ml). Chinese were least sensitive to the bradycardic and hypotensive effects of propranolol at rest and exercise. Indians and Malays had significant reduction of supine systolic blood pressure with propranolol but not Chinese. Comparison of percentage reductions of systolic blood pressure at supine, sitting and exercise by repeated measure analysis showed the Malays to have significantly higher change compared to the Chinese (p = 0.022). Similarly, comparison of percentage reductions of heart rate at supine, sitting and exercise by repeated measure analysis showed the Malays to have significantly higher change compared to the Chinese (p = 0.040). Average change in potassium concentrations at peak exercise and recovery showed the Indians to have significantly higher increase in potassium levels with propranolol compared to the Malays (p = 0.038). However, no significant interethnic difference was seen in the reduction of glucose levels at rest, peak exercise or recovery. Also, no significant interethnic difference was seen in reduction of FEV1 values.
CONCLUSION: We, therefore, conclude that ethnic differences in response to blockade of beta-receptors exist among racial groups in Malaysia. These differences were seen at similar plasma drug levels between races suggesting ethnic differences in drug sensitivity, rather than differences in drug disposition.
METHODS: Twenty postmenopausal women with a mean age of 54.59 +/- 1.22 years participated in this randomized, crossover, double-blind, placebo-controlled clinical trial. All women received 400 IU of tocopherol daily for 10 weeks or a placebo capsule, before being crossed over for treatment. At intervals of 5 weeks, subjects attended sessions where measurements of arterial stiffness, blood pressure and plasma vitamin E level were taken. Pulse wave velocity measurement, using the automated Complior machine, was used as an index of arterial stiffness.
RESULTS: Plasma vitamin E level was 30.38 +/- 1.56 micromol/l at baseline, after treatment it was 59.01 +/- 3.30 micromol/l and 31.17 +/- 1.37 micromol/l with vitamin E and placebo, respectively (p < 0.001). There was no significant difference in pulse wave velocity after 10-week treatment with placebo and vitamin E (9.14 +/- 0.29 versus 9.04 +/- 0.29 m/s, respectively). Similarly, no difference in systolic and diastolic blood pressure was seen between placebo and vitamin E at the end of 10 weeks.
CONCLUSION: Supplementary vitamin E for 10 weeks at 400 IU daily has no effect on arterial stiffness in healthy postmenopausal women.
METHODOLOGY: This randomised, blinded end-point, placebo-controlled clinical trial with a parallel design involved 36 healthy male subjects who took either an oral placebo or TRE at doses of 80, 160 or 320 mg daily for 2 mo. Baseline and end-of-treatment measurements of vitamin E concentration, arterial compliance [assessed by aortic femoral pulse wave velocity (PWV) and augmentation index (AI)], ASBP, plasma TAS, serum TC and LDL-C were taken.
RESULTS: Baseline tocotrienol isomer concentrations were low and not detectable in some subjects. Upon supplementation, all TRE-treated groups showed significant difference from placebo for their change in alpha, gamma and delta tocotrienol concentrations from baseline to end of treatment. There was a linear dose and blood level relationship for all the isomers. There was no significant difference between groups for their change in PWV, AI, plasma TAS, ASBP, TC or LDL-C from baseline to end of treatment. Groups 160 mg (p = 0.024) and 320 mg (p = 0.049) showed significant reductions in their ASBP. Group 320 mg showed a significant 9.2% improvement in TAS.
CONCLUSION: TRE at doses up to 320 mg daily were well tolerated. Treatment significantly increased alpha, delta, and gamma tocotrienol concentrations but did not significantly affect arterial compliance, plasma TAS, serum TC or LDL-C levels in normal subjects.