Doxvex 50 Mechanism of Action

Pharmacological Classification: A 26 Antineoplastic (Cytostatic agent).
Pharmacology: Pharmacodynamics: Doxorubicin is an antimitotic and cytostatic antibiotic, isolated from cultures of Streptomyces peucetius var. caesius, with an antineoplastic action. Its exact mechanism of action of antineoplastic activity is unknown but may involve binding to DNA by intercalation between base pairs and inhibition of DNA and RNA synthesis by template disordering and steric obstruction. Other possible mechanisms of antineoplastic activity include binding to cell membrane lipids, thus altering a variety of cellular functions and interacting with topoisomerase II to form DNA-cleavable complexes.
Pharmacokinetics: Distribution: Doxorubicin is quickly and widely distributed into the extravascular compartments, as indicated by a rapid (5 to 10 min) distribution half-life and by a steady state distribution volume in excess of 20 to 30 litres/kg. However, doxorubicin does not cross the blood-brain barrier in detectable amounts but may cross the placenta and is distributed into breast milk. Binding of doxorubicin to plasma protein is extensive.
Metabolism: Doxorubicin is metabolised to a significant extent by the liver. The major active metabolite is 13-OH-doxorubicinol.
Excretion: The elimination half-life of doxorubicin and 13-OH-doxorubicinol is 20 to 48 hours. Forty to fifty percent of the administered dose is recovered in the bile or in the faeces in seven days, of which about half is as unchanged drug. Renal excretion is modest, accounting for only 5-10 percent of the administered dose in 5 days.