CoQ10

Absorption CoQ10 in the pure form is a crystalline powder insoluble in water. Absorption as a pharmacological substance follows the same process as that of lipids; the uptake mechanism appears to be similar to that of vitamin E, another lipid-soluble nutrient. This process in the human body involves secretion into the small intestine of pancreatic enzymes and bile, which facilitates emulsification and micelle formation required for absorption of lipophilic substances. Food intake (and the presence of lipids) stimulates bodily biliary excretion of bile acids and greatly enhances absorption of CoQ10. Exogenous CoQ10 is absorbed from the small intestine and is best absorbed if taken with a meal. Serum concentration of CoQ10 in fed condition is higher than in fasting conditions.

Metabolism CoQ10 is metabolized in all tissues, with the metabolites phosphorylated in cells. CoQ10 is reduced to ubiquinol during or after absorption in the small intestine. It is absorbed by chylomicrons, and redistributed in the blood within lipoproteins. Its elimination occurs via biliary and fecal excretion.

Pharmacokinetics Some reports have been published on the pharmacokinetics of CoQ10. The plasma peak can be observed 6–8 hours after oral administration when taken as a pharmacological substance. In some studies, a second plasma peak was observed approximately 24 hours after administration, probably due to enterohepatic recycling and redistribution from the liver to circulation.

Deuterium-labeled crystalline CoQ10 was used to investigate pharmacokinetics in humans to determine an elimination half-time of 33 hours.

Bioavailability In contrast to the intake of CoQ10 as a constituent of food, such as nuts or meat, from which CoQ10 is normally absorbed, there is a concern about CoQ10 bioavailability when it is taken as a dietary supplement. Bioavailability of CoQ10 supplements may be reduced due to the lipophilic nature of its molecule and large molecular weight.

Reduction of particle size Nanoparticles have been explored as a delivery system for various drugs, such as improving the oral bioavailability of drugs with poor absorption characteristics. However, this has not proved successful with CoQ10, although reports have differed widely. The use of aqueous suspension of finely powdered CoQ10 in pure water also reveals only a minor effect.

Water-solubility Facilitating drug absorption by increasing its solubility in water is a common pharmaceutical strategy and also is successful for CoQ10. Various approaches have been developed to achieve this goal, with many of them producing significantly better results over oil-based soft gel capsules despite the many attempts to optimize their composition. Examples of such approaches are use of the aqueous dispersion of solid CoQ10 with the polymer tyloxapol, formulations based on various solubilising agents, such as hydrogenated lecithin, and complexation with cyclodextrins; among the latter, the complex with β-cyclodextrin has been found to have highly increased bioavailability and also is used in pharmaceutical and food industries for CoQ10-fortification.

Coenzyme Q10 was first discovered in 1957 by Frederick Crane at the University of Wisconsin, who isolated it from beef heart mitochondria. Peter Mitchell, who received the Nobel Prize in Chemistry in 1978 for his chemiosmotic theory, elucidated CoQ10's role in the electron transport chain. Karl Folkers at the University of Texas further characterized its chemistry and advocated for its clinical use.

The clinical significance of CoQ10 was established through decades of research, particularly in Japan, where it was approved as a treatment for heart failure in 1974. The connection to statin medications emerged when it was recognized that statins inhibit the mevalonate pathway, which is required for both cholesterol and CoQ10 synthesis, explaining statin-related muscle pain.

The development of ubiquinol (reduced CoQ10) supplements in the early 2000s by Kaneka Corporation addressed the poor bioavailability of conventional ubiquinone, providing 3-8x better absorption.