A Pharmacokinetic interaction between propranolol and eurycoma /ongifolia (Tongkat Ali)
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Date
2008
Authors
Ahmed Benslman, Shima'a
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Abstract
The objective of this study is to evaluate the possible pharmacokinetic
interaction between propranolol and Tongkat Ali herbal extract. A randomised
single-blinded crossover study for single dose treatments was conducted in 14
healthy non-smoker young. males. Propranonol (lnderal~ 80 mg tablet was
orally-administered with i) placebo [200 mg Lactose] as control treatment and
with ii) 200 mg of water-based extract of Tongkat Ali [0.0272,:!:0.0026%
eurycomanone] as test treatment following an overnight fasting. Blood samples
were collected at 0, 0.5, 1, 1.5, 2, 3, 4, 6, 8 and 10 hrs. Blood pressure and heart
rate were measured before each blood sampling. Plasma concentrations of
propranolol were estimated using a validated HPLC method and the
pharmacokinetic parameters (AUCo-oo, Cmax. T max and t~) were calculated by noncompartmental
model. The differences in the pharmacokinetic parameters
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between control and test treatments were statistically analyzed using ANOVA for
AUCo-oo, Cmax and t~ and using Wilcoxon Signed Ranks Test for T max· The
differences in the lowest blood pressure and heart rate and their time of
occurrence between test and control treatments were also statistically analysed
using ANOVA The study results demonstrated a decrease in the bioavailability
of propranolol when it was administered with Tongkat Ali extract, its AUCo-u, and
Cmax were significantly decreased by 29% and 42% (p<O.OOS and p<0.002
respectively). The 90% confidence interval of the ratio of the means of AUCo-co
was 52% to 78% and for the Cmax the range was 44% to 64%. These ranges
were outside the bioequivalence range of 80-125%. T max was significantly ·
delayed by 86% (p=0.004). The t% was not significantly different (p >0.1)
between the test and control treatments. Seven subjects were sufficient to give
80% power of study when calculated from Cmax, however fourteen subjects could
only give 66% power, when calculated from AUCo-oo parameter. The difference in
the mean lowest blood pressure and heart rate and their time of occurrence
between the two study phases was not statistically significant. Based on the
results, it is recommended that when the propranolol and Tongkat Ali are
consumed together, their administrations should be separated to avoid
pharmacokinetic interaction. Since the effect on blood pressure and heart rate
were not obvious in single dose study, a long term repeated dose study is
recommended for further evaluation of both the pharmacokinetic and
pharmacodynamic interactions between propranolol and Tongkat Ali.
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Keywords
Propranolol , Eurycoma longifolia , Tongkat Ali