Hemmi N. Bhagavan

Coenzyme Q10: Absorption, tissue uptake, metabolism and pharmacokinetics

Available data on the absorption, metabolism and pharmacokinetics of coenzyme Q10 (CoQ10) are reviewed in this paper. CoQ10 has a fundamental role in cellular bioenergetics. CoQ10 is also an important antioxidant. Because of its hydrophobicity and large molecular weight, absorption of dietary CoQ10 is slow and limited. In the case of dietary supplements, solubilized CoQ10 formulations show enhanced bioavailability. The Tmax is around 6 h, with an elimination half-life of about 33 h. The reference intervals for plasma CoQ10 range from 0.40 to 1.91 μmol/l in healthy adults. With CoQ10 supplements there is reasonable correlation between increase in plasma CoQ10 and ingested dose up to a certain point. Animal data show that CoQ10 in large doses is taken up by all tissues including heart and brain mitochondria. This has implications for therapeutic applications in human diseases, and there is evidence for its beneficial effect in cardiovascular and neurodegenerative diseases. CoQ10 has an excellent safety record.

Ascorbic acid and gastrointestinal cancer.

A literature review was made to critically evaluate the ability of ascorbic acid to modulate the incidence of gastrointestinal cancer. A comparison of preclinical, clinical, and epidemiological studies indicated that evidence for ascorbic acid as an inhibitor of carcinogenesis is stronger with regard to gastric cancer and weaker with regard to esophageal and colon/rectal cancer. Insufficient evidence currently exists regarding the oral cavity and the use of ascorbic acid in precancerous conditions such as polyposis and leukoplakia.

Bioavailability Assessment of Oral Coenzyme Q10 Formulations in Dogs

ABSTRACT The purpose of this investigation was to compare the bioavailability of three coenzyme Q10 (CoQ10) formulations in dogs using an open, randomized, multiple-dose crossover design. The formulations included a powder-filled capsule (A, control) and two soft gelatin formulations (Q-Gel ® as the water-miscible form of CoQ10, B and Q-Nol™as the water-miscible form of ubiquinol, the reduced form of CoQ10, C). Formulations were evaluated in pairs, allowing a washout period of 14 days prior to crossing over. Blood samples were collected from each animal prior to dosing to determine the endogenous plasma CoQ10 concentrations. Serial blood samples were collected for 72 hr and plasma CoQ10 concentrations were determined by high-performance liquid chromatography. Plasma concentration–time profiles were corrected for endogenous CoQ10 concentrations. Results showed that the relative bioavailabilities of formulations B and C were approximately 3.6 and 6.2-fold higher than that of control formulation A. The AUC(µg. hr/mL)±SD, Cmax(µg/mL)±SD, and Tmax(hr)± SD for formulations A, B, and C were 1.695±0.06, 6.097±0.08, and 10.510±0.10; 0.096±0.035, 0.169±0.038, and 0.402±0.102; and 4.2±1.48, 4.1±1.57, and 4.5±0.58, respectively. While no significant differences were observed between Tmax values of the three formulations, the AUC and Cmax values for formulations B and C were significantly higher than those of the control (p<0.05). The present investigation demonstrates that soft gelatin capsules containing water-miscible CoQ10 formulations B (Q-Gel®) and C (Q-Nol™) are superior to powder-filled formulations with regard to their biopharmaceutical characteristics.