When controlled studies are not available, interactions are based on evidence of pharmacological activity, case reports and other evidence and are largely theoretical.
The following pharmaceutical drugs are suspected to reduce CoQ10 levels, so increased CoQ10 intake may be required with long-term drug therapy:
• beta-adrenergic antagonists
• HMG-CoA-reductase inhibitors: simvastatin, pravastatin and lovastatin reduce both endogenous synthesis of CoQ10 and the serum concentration (Overvad et al 1999). Supplementation with CoQ10 may counter this effect without adversely affecting HMG-CoA-reductase inhibitor efficacy (Bargossi et al 1994a, b, Mortensen et al 1997).
• tricyclic antidepressants WARFARIN
There are three case reports suggesting that CoQ10 may decrease the INR in patients previously stabilised on anticoagulants (Spigset 1994b). However, a double-blind crossover study involving 24 outpatients on stable long-term warfarin found that oral CoQ10 (100 mg) daily had no significant effect on INR or warfarin levels (Engelson 2003). Observe patients using high CoQ10 doses and taking warfarin. Coenzyme Q10 309
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