Lack of acute effect on lidocaine pharmacokinetics from parenteral nutrition

We tested the hypothesis that amino acids in a parenteral nutrition (PN) solution would result in the decreased metabolism of a model compound, lidocaine. One bolus infusion of lidocaine HCl (1 mg/kg) was administered to seven healthy subjects in association with each of three nutrient regimens: (a) a standard PN solution, (b) 10% dextrose water (D10W), and (c) a meal (control) containing similar fluid volume and caloric, protein, and sodium content as the PN solution. Intravenous nutrients were infused consecutively in a random order at 1 L/12 h. Intravenous and control studies were performed 28 days apart. There was no significant difference in the means (+/- SEM) of total body clearance [7.70 +/- 0.70 (PN) versus 6.78 +/- 0.79 (D10W) versus 7.86 +/- 0.93 (control) ml/min kg], half-life [74.0 +/- 12.2 (PN) versus 89.6 +/- 4.35 (D10W) versus 79.2 +/- 7.22 (control) min], volume of distribution [0.82 +/- 0.15 (PN) versus 0.88 +/- 0.13 (D10W) versus 0.78 +/- 0.13 (control) L/kg], and the fraction of unbound lidocaine in the serum [0.34 +/- 0.025 (PN) versus 0.36 +/- 0.019 (D10W) versus 0.33 +/- 0.020 (control)] among the three nutrient regimens. The concentration-time course of the active metabolite, N-ethylglycyl-2,6-xylidide, did not differ significantly regardless of the nutritional regimen used. Our study indicates that amino acids used for PN do not have any acute effect on lidocaine pharmacokinetics in healthy subjects.