CoQ10 protected against cardiac toxicity associated with anthracyline treatment in patients with malignancy. In one study, children with acute lymphoblastic leukemia or non-Hodgkin's lymphoma who received CoQ10 (100 mg po bid) with daunorubicin exhibited significantly fewer signs of cardiac dysfunction compared to treatment with daunorubucin alone (Iarussi et al. 1994). Mice treated with a combination of doxorubicin and CoQ10 survived significantly longer (224.1%) than controls; the optimum protective effect was achieved with oral doses of 10 mg/kg/day (Shinozawa et al. 1996). The CoQ10 group had significantly less liver and heart microsomal lipid peroxidation, a potential indicator of cardiac toxicity.

In a randomized, double blind trial, patients with coronary artery disease (CAD) were treated with conventional antihypertensive medications and either CoQ10 (60 mg bid) or B vitamin complex for 8 weeks (Singh et al. 1999). Patients treated with CoQ10 required lower doses of their antihypertensive medications (diltiazem, metoprolol, enalapril maleate, and nitrate). In spontaneously hypertensive rats, chronic pretreatment with CoQ10 (10 mg/kg) prolonged, but did not enhance, the antihypertensive effects of enalapril and nitrendipine (Danysz et al. 1994). More research is needed to determine if CoQ10 affects individual medications.

The combination of pentoxifylline and CoQ10 (10 mg/kg) in rats was more effective than pentoxifylline alone at preventing the decrease in hepatic glutathione levels along with the elevation in lipid peroxidation that is typically associated with ischemia-reperfusion damage in the liver (Portakal and Inal-Erden 1999).

In one study, ten patients with glaucoma were concomitantly administered CoQ10 (90 mg/day po) with either timolol drops or saline for six weeks (Takahashi et al. 1989). CoQ10 reduced cardiovascular side effects by diminishing the beta-blocking action of timolol without affecting intraocular pressure.

Case reports have suggested that CoQ10 decreases the anticoagulant effect of warfarin (Landbo and Almdal 1998; Spigset 1994). In one report, three patients had decreased international normalized ratios (INR) after CoQ10 was added to their warfarin regimens (Spigset 1994). The INR of two of the patients dropped after two weeks of CoQ10 supplementation (30 mg/day). Oral administration of CoQ10 (10 mg/kg/day) for 8 days substantially decreased serum concentrations of warfarin (1.5 mg/kg) and significantly increased levels of major metabolites in rats (Zhou and Chan 1998). CoQ10 may increase the hepatic metabolism of warfarin and thereby reduce its anticoagulant effect.

Danysz A, Oledzka K, Bukowska-Kiliszek M. Influence of coenzyme Q-10 on the hypotensive effects of enalapril and nitrendipine in spontaneously hypertensive rats. Pol J Pharmacol. 1994;46(5):457-461.

Iarussi D, Auricchio U, Agretto A, Murano A, Giuliano M, Casale F, et al. Protective effect of coenzyme Q on anthracylines cardiotoxicity: Control study in children with acute lymphoblastic leukemia and non-hodgkin lymphoma. Molec Aspects Med. 1994;15(Suppl):S207-S212.

Landbo C, Almdal TP. [Interaction between warfarin and coenzyme Q10 (see comments)]. Ugeskr Laeger. 1998;160(22):3225-3227.

Portakal O, Inal-Erden M. Effects of pentoxifylline and coenzyme Q10 in hepatic ischemia/reperfusion injury. Clin Biochem. 1999;32:461-466.

Shinozawa S, Kawasaki H, Gomita Y. [Effect of biological membrane stabilizing drugs (coenzyme Q10, dextran sulfate and reduced glutathione) on adriamycin (doxorubicin)-induced toxicity and microsomal lipid peroxidation in mice]. Gan To Kagaku Ryoho. 1996;23(1):93-98.

Singh RB, Niaz MA, Rastogi SS, Shukla PK, Thakur AS. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease. J Hum Hypertens. 1999;13(3):203-208.

Spigset O. Reduced effect of warfarin caused by ubidecarenone. The Lancet. 1994;344:1372-1373.

Takahashi N, Iwasaka T, Sugiura T, et al. Effect of coenzyme Q10 on hemodynamic response to ocular timolol. J Cardiovasc Pharmacol. 1989;14:462-468.

Zhou Q, Chan E. Accuracy of repeated blood sampling in rats: A new technique applied in pharmacokinetic/pharmacodynamic studies of the interaction between warfarin and Co-enzyme Q10. J Pharmacol Toxicol Methods. 1998;40(4):191-199.