Propranolol CYP2D6 substrate

FIGURE 4.13 Structures of the CYP2D6 substrates, amitriptyline, codeine, haloperidol, and propranolol, and their metabolites. 

No important interactions normally appear to occur with venlafaxine and ACE inhibitors, beta blockers or diuretics, but an isolated report suggests that propranolol, particularly if it is given with other CYP2D6 substrates, may affect the metabolism of venlafaxine. 

Not understood. The elinieal pietuie is that of exeessive beta-bloekade, and additive pharmaeodynamie effeets are possible. In addition, amiodar-one inereases the levels of metoprolol via inhibition of the eytoehrome P450 isoenzyme CYP2D6, and this may be signifieant in fast metabolis-ers. See Genetie faetors , (p.4), for more information about fast metabo-lisers. Other beta bloekers that are also substrates of CYP2D6, and whieh eould therefore be similarly affeeted, inelude earvedilol and propranolol. 

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