Pharmacology: Summary of Pharmacokinetics and Pharmacodynamics: Silymarin is extracted from the seeds of milk thistle (Silybum marianum), a medicinal plant which has been known for 2000 years. Experiments have shown this drug to exert a protective effect to liver. The therapeutic action of Silymarin is based on its effect on the permeability of the liver cell membrane and on the excretory as well as the metabolic function of liver.
The vitamins of B-Complex form a functional unit in the intermediate metabolism. Furthermore, the vitamin B-Complex content in the case of hepatopathy is reduced due to a loss of storage capacity of the tissue. Therefore, administration of the B-Complex vitamins can compensate such deficiencies.
Silymarin is mainly excreted via bile after oral administration and passes through the enterohepatic circulation. Its major component, silybin is excreted mainly by the kidney, although metabolites, particularly sulfate and glucuronide conjugates, are present in bile. The excretion of silybin in humans lasts for about 24 hrs and the total amount of silybin excreted in bile is about 20%-40% of the ingested dose. Only 3%-7% of the total dose is excreted renally.
Thiamine is widely distributed to most body tissue. It is not stored to any appreciable extent in the body and amounts in excess of the body requirements are excreted in the urine.
Riboflavin is absorbed from the gastro-intestinal tract. Although riboflavin is widely distributed to body tissues, little is stored in the body. Riboflavin is excreted in urine, partly as metabolites.
Pyridoxine is readily absorbed from the gastro-intestinal tract following oral administration. They are mainly stored in the liver where there is oxidation to 4-pyridoxic acid and other inactive metabolites which are excreted in the urine.
Nicotinamide is readily absorbed from the gastro-intestinal tract following oral administration and widely distributed to body tissues. Small amounts of nicotinamide is excreted unchanged in urine following therapeutic doses; however the amount excreted unchanged is increased with larger doses.
Calcium Pantothenate is readily absorbed from the gastro-intestinal tract following oral administration and widely distributed to body tissues. About 70% of calcium pantothenate is excreted unchanged in urine and about 30% in the faeces.