Lotram Mechanism of Action

Opioid Analgesic.
Pharmacology: Pharmacokinetics: Tramadol HCl is a centrally acting analgesic, chemically not related to opiates. Though its mechanism of action is not fully understood, binding to neuronal opioid receptor and inhibition of neuronal reuptake of norepinephrine and serotonin appears to be involved in its analgesic actions. Its metabolite desmethyltramadol (M1) is up to 200 times more potent than tramadol in binding to opioid receptors and is pharmacologically active, but its contribution to analgesia of tramadol in humans is unknown. Tramadol HCl is rapidly and completely absorbed following oral administration. Detectable blood levels are reached within 15 to 45 minutes and mean peak plasma concentrations are achieved in 1.6 to 2 hours post dose. A single oral dose of 100 mg produces mean peak plasma drug concentration of 280 to 308 mcg/L. Mean oral bioavailability after single dose is 68%. Following multiple oral administration, oral bioavailability increases to 90-100% with 16% higher peak plasma concentration. Tramadol HCl is extensively metabolised (up to 85% of the dose) in the liver and excreted via kidneys. About 15-30% is excreted as unchanged drug and 60-85% as metabolites. Among various metabolites, 0-dimethyltramadol (MI) is pharmacologically active. The elimination half life of Tramadol and the active metabolite (MI) in young healthy volunteers is 5.1 to 5.9 hours and 6.7 hours respectively. In subjects above age of 75 years the half life of Tramadol is slightly prolonged (7 hours). In patients with impaired renal function (creatinine clearance between 5-80 mL/min) the half life of Tramadol was 1.5 to 2 times higher. Similarly in patients with liver cirrhosis the plasma concentration and half life is increased by a factor of 2 to 3.