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RESEARCH JOURNAL OF PHARMACY AND TECHNOLOGY
Year : 2020, Volume : 13, Issue : 12
First page : ( 5716) Last page : ( 5720)
Print ISSN : 0974-3618. Online ISSN : 0974-360X.
Article DOI : 10.5958/0974-360X.2020.00995.6

The thermodynamic parameters of chlorpromazine hydrochloride partitioning into dimyrstoylphosphatidylcholine liposomes

Farah Farah Hamad1*

1Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Ajman University, Ajman P O Box 346, United Arab Emirates.

*Corresponding Author E-mail: f.hamad@ajman.ac.ae

Online published on 15 February, 2021.

Abstract

This study investigates the influence of wide range of concentrations of the model cationic, surface-active drug chlorpromazine hydrochloride (CPZ-HCl) partitioning into dimyrstoylphosphatidylcholine (DMPC) liposomes in phosphate buffer (pH 6.0) as a function of temperature, both below and above the phase transition temperature (Tc) of DMPC, pertinent to calculate various thermodynamic parameters using the Van't Hoff equation. The partitioning of CPZ-HCl into DMPC liposomes was found to be concentration dependent at temperature both below and above the phase transition temperature (Tc). The temperature dependence of the equilibrium partition coefficient (K) over the temperature range 5o-40oC permitted the calculation of free energy (AG (w/l)), enthalpy (AH (w/l)) and entropy (AS (w/l)) of partitioning using the Van't Hoff equation. AG (w/l) values for all concentrations studied were negative indicating that the partitioning of CPZ-HCl into DMPC liposomes over the temperature range of 5–40oC is predominantly entropically controlled. A linear relationship was observed between AS (w/l) and AH (w/l) both below and above the Tc. However a relatively poor correlations were observed between AG (w/l) and AH(w/l) as well as between AG(w/l) and AS(w/l). AG (w/l) values for all CPZ-HCl concentrations studied were negative indicating that the partitioning of CPZ-HCl into DMPC liposomes over the temperature range of 5o-40oC is predominantly entropically controlled. Log K values were observed to increase linearly as a function of log molar CPZ-HCl at concentrations known to cause anesthesia, reflecting a possible relationship between the drug anesthetic potency in-vivo and its ability to partition into phospholipid bilayers.

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Keywords

Partitioning, CPZ-HCl, DMPC liposomes, Free energy, Enthalpy, Entropy.

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