The Influence of Age on Lignocaine Pharmacokinetics in Young Puppies

Eight mongrel puppies were studied at intervals of a few weeks. Lignocaine 4mg/kg was infused over 60 seconds. Frequent samples were taken over 30 minutes for plasma lignocaine assay. Initially the concentrations were significantly higher in the oldest group (178–191 days) but after 10 minutes the youngest group (3–16 days) had significantly higher levels than the other groups.

Pharmacokinetic data derived included the rate constants k₂₁, k₁₂ (drug movement between two compartments), k₁₀ (elimination from the central compartment), and the volume of distribution (V_β). The elimination rate constant k₁₀ was significantly lower in Group 1 (3–16 days) than all other groups and Group 2 (37–57 days) was lower than Group 4 (178–191 days). The calculated β half-life was significantly longer in the youngest group than the others. There was no significant difference in the volume of distribution between these age groups — up to 6 months.