Cell Biochemistry and Biophysics

, Volume 66, Issue 3, pp 461–475

Probing the Combined Effect of Flunitrazepam and Lidocaine on the Stability and Organization of Bilayer Lipid Membranes. A Differential Scanning Calorimetry and Dynamic Light Scattering Study

  • Benjamín Caruso
  • Julieta M. Sánchez
  • Daniel A. García
  • Eneida de Paula
  • María A. Perillo
Original Paper

DOI: 10.1007/s12013-012-9494-3

Cite this article as:
Caruso, B., Sánchez, J.M., García, D.A. et al. Cell Biochem Biophys (2013) 66: 461. doi:10.1007/s12013-012-9494-3

Abstract

Combined effects of flunitrazepam (FNZ) and lidocaine (LDC) were studied on the thermotropic equilibrium of dipalmitoyl phosphatidylcholine (dpPC) bilayers. This adds a thermodynamic dimension to previously reported geometric analysis in the erythrocyte model. LDC decreased the enthalpy and temperature for dpPC pre- and main-transitions (ΔHp, ΔHm, Tp, Tm) and decreased the cooperativity of the main-transition (ΔT1/2,m). FNZ decreased ΔHm and, at least up to 59 μM, also decreased ΔHp. In conjunction with LDC, FNZ induced a recovery of ∆T1/2,m control values and increased ΔHm even above the control level. The deconvolution of the main-transition peak at high LDC concentrations revealed three components possibly represented by: a self-segregated fraction of pure dpPC, a dpPC–LDC mixture and a phase with a lipid structure of intermediate stability associated with LDC self-aggregation within the lipid phase. Some LDC effects on thermodynamic parameters were reverted at proper LDC/FNZ molar ratios, suggesting that FNZ restricts the maximal availability of the LDC partitioned into the lipid phase. Thus, beyond its complexity, the lipid–LDC mixture can be rationalized as an equilibrium of coexisting phases which gains homogeneity in the presence of FNZ. This work stresses the relevance of nonspecific drug–membrane binding on LDC–FNZ pharmacological interactions and would have pharmaceutical applications in liposomal multidrug-delivery.

Keywords

FlunitrazepamLidocaineDipalmitoyl phosphatidylcholineCalorimetryLiposomesThermotropic phase changes

Abbreviations

BZD

Benzodiazepine

dpPC

Dipalmitoyl phosphatidylcholine

DSC

Differential scanning calorimetry

FNZ

Flunitrazepam

LDC

Lidocaine

MLVs

Multilamellar vesicles

Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Benjamín Caruso
    • 1
  • Julieta M. Sánchez
    • 1
  • Daniel A. García
    • 1
  • Eneida de Paula
    • 2
  • María A. Perillo
    • 1
  1. 1.Cátedra de Química Biológica, Departamento de Química, FCEFyNInstituto de Investigaciones Biológicas y Tecnológicas (IIBYT), CONICET-Universidad Nacional de CórdobaCórdobaArgentina
  2. 2.Departamento de Bioquímica, Instituto de BiologiaUniversidade Estadual de CampinasCampinasBrazil