ADMET-Absorption, Distribution, Metabolism, Excretion, and Toxicity

StatusFDA approved
AdministrationIV, subcutaneous, topical
PharmacologyA common local anesthetic and antiarrhythmic drug. Lidocaine is used topically to relieve itching, burning and pain from skin inflammations, injected as a dental anesthetic or as a local anesthetic for minor surgery.

Absorption_value98.0
Absorption (description)Readily absorbed from the gastro-intestinal tract, mucous membranes, damaged skin (poor absorption from intact skin), and after IM injection; poorly absorbed orally due to first-pass metabolism.
Caco_2-4.21
Bioavailability35.0

MetabollsmHepatic, 90% CYP1A2-mediated. Metabolism in the liver is rapid with about 90% of a dose being dealkylated to form monoethylglycinexylidide which is 60 to 80% as potent as lidocaine and glycinexylidide which is also active. Both have longer half-lives than lidocaine. Further metabolism occurs and metabolic reactions also include hydrolysis, and ring hydroxylation. Less than 10% of a dose is excreted in the urine as unchanged drug in 24 h, 40 to 70% as 4-hydroxy-2,6-xylidine, and about 4% as the active monoethylglycinexylidide; excretion of unchanged drug is increased if the urine is acid. Other metabolites include 2,6-xylidine, 3′-hydroxylignocaine, and 3′-hydroxymonoethylglycinexylidide. Glycinexylidide and the hydroxy metabolites are excreted as acid-hydrolysable conjugates. Glycinexylidide has also been detected in plasma after prolonged IV infusion. Lidocaine crosses the placenta and the blood–brain barrier and it is excreted in breast milk.
Half life1.8 h

ToxicityToxic effects are associated with plasma concentrations greater than 6 mg/L, and fatalities with blood concentrations greater than 14 mg/L.
LD50 (rat)N/A
LD50 (mouse)N/A