TY - JOUR
T1 - Relationship of cytochrome P450 pharmacogenetics to the effects of yohimbine on gastrointestinal transit and catecholamines in healthy subjects
AU - Bharucha, A. E.
AU - Skaar, T.
AU - Andrews, C. N.
AU - Camilleri, M.
AU - Philips, S.
AU - Seide, B.
AU - Burton, D.
AU - Baxter, K.
AU - Zinsmeister, A. R.
PY - 2008/8
Y1 - 2008/8
N2 - Alpha-2 adrenergic receptors tonically inhibit colonic motility and the α2-adrenergic antagonist yohimbine, given intravenously, increased colonic tone in humans. However, the effect of yohimbine on colonic transit in humans is unknown. In this study, 30 healthy volunteers were randomized to yohimbine 16.2 mg p.o. t.i.d. or identical placebo for 7 days. We evaluated gastric emptying, small intestinal, and colonic transit by scinitigraphy, bowel habits, haemodynamics and plasma catecholamines. As cytochrome P450 enzymes metabolize yohimbine, P450 genotypes (CYP2D6 and CYP3A4) were determined in 25 of 30 subjects who consented to genetic studies. The relationship between drug metabolizer status predicted by CYP2D6 and CYP3A4 and effects of yohmibine were assessed. Compared to placebo, yohimbine increased (P ≤ 0.02) diastolic blood pressure, plasma noradrenaline concentrations and maximum tolerated volume during the satiation test [yohimbine (1241 ± 88, mean ± SEM) vs placebo (1015 ± 87), P = 0.054]. However, yohimbine did not affect gastrointestinal transit. Based on CYP2D6 and CYP3A4 alleles, seven and 18 subjects were, respectively, extensive (EM) and poor (PM) metabolizers of yohimbine. Compared to EM, PM of yohimbine had a greater increase in plasma noradrenaline (P = 0.1 for PM vs EM), lower maximum tolerated volumes (1120 ± 95 vs 1484 + 131 mL, P = 0.02), and faster colonic transit (i.e. GC24 was 3.0 ± 0.4 vs 2.1 ± 0.5, P = 0.1). These data suggest that CYP2D6 and CYP3A4 genotypes which determine the metabolism of yohimbine may influence its sympathetic and gastrointestinal effects.
AB - Alpha-2 adrenergic receptors tonically inhibit colonic motility and the α2-adrenergic antagonist yohimbine, given intravenously, increased colonic tone in humans. However, the effect of yohimbine on colonic transit in humans is unknown. In this study, 30 healthy volunteers were randomized to yohimbine 16.2 mg p.o. t.i.d. or identical placebo for 7 days. We evaluated gastric emptying, small intestinal, and colonic transit by scinitigraphy, bowel habits, haemodynamics and plasma catecholamines. As cytochrome P450 enzymes metabolize yohimbine, P450 genotypes (CYP2D6 and CYP3A4) were determined in 25 of 30 subjects who consented to genetic studies. The relationship between drug metabolizer status predicted by CYP2D6 and CYP3A4 and effects of yohmibine were assessed. Compared to placebo, yohimbine increased (P ≤ 0.02) diastolic blood pressure, plasma noradrenaline concentrations and maximum tolerated volume during the satiation test [yohimbine (1241 ± 88, mean ± SEM) vs placebo (1015 ± 87), P = 0.054]. However, yohimbine did not affect gastrointestinal transit. Based on CYP2D6 and CYP3A4 alleles, seven and 18 subjects were, respectively, extensive (EM) and poor (PM) metabolizers of yohimbine. Compared to EM, PM of yohimbine had a greater increase in plasma noradrenaline (P = 0.1 for PM vs EM), lower maximum tolerated volumes (1120 ± 95 vs 1484 + 131 mL, P = 0.02), and faster colonic transit (i.e. GC24 was 3.0 ± 0.4 vs 2.1 ± 0.5, P = 0.1). These data suggest that CYP2D6 and CYP3A4 genotypes which determine the metabolism of yohimbine may influence its sympathetic and gastrointestinal effects.
KW - Adrenergic
KW - Catecholamines
KW - Colon
KW - Cytochrome P450
KW - Gastrointestinal transit
KW - Yohimbine
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U2 - 10.1111/j.1365-2982.2008.01124.x
DO - 10.1111/j.1365-2982.2008.01124.x
M3 - Article
C2 - 18433425
AN - SCOPUS:47649131927
SN - 1350-1925
VL - 20
SP - 891
EP - 899
JO - Neurogastroenterology and Motility
JF - Neurogastroenterology and Motility
IS - 8
ER -