Effect of different additives on the phase separation behavior and thermodynamics of p-tert-alkylphenoxy poly (oxyethylene) ether in absence and presence of drug

Cloud point(CP) determinations of 4-(1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol(TX-100(nonionic surfactant)) was carried out in aqueous as well as in the attendance of drug(ceftriaxone sodium trihydrate(CFT))/(CFT + different inorganic salts) and discussed thoroughly. Nonionic surfactants are employed extensively in different formulations. In aqueous solution, the values of CP of TX-100 are obtained to increase by means of enhancing of their concentration in the solution. The CP values of TX-100 solutions were found to decrease in the presence of drug and their values decrease more with rising concentrations of the drug. The values of CP of CFT and TX-100 mixtures were found to further decrease in the attendance of inorganic salts in comparison to their absence. The effect of different sodium salts in decreasing CP values of TX-100 was achieved in the following order: NaCO_3 > Na_2SO_4 > Na Cl. However, in the case of potassium and ammonium salts, the decreasing order obtained is K_2SO_4 > KCO_3 > KCl and(NH4)2 SO_4 > Na_2CO_3 > NH_4Cl respectively. Various thermodynamic parameters for example standard free energy(ΔG_c~Θ), standard enthalpy(ΔH_c~Θ) as well as standard entropy(Δ Sc?)changes of phase separation were also evaluated and discussed in detail on the basis of their behavior.

Interaction of cetyltrimethylammonium bromide with cefixime trihydrate drug at different temperatures and compositions: Effect of different electrolytes

Herein,conductivity measurements have been carried out to explore the interaction between cetyltrimethylammonium bromide(CTAB,a cationic surfactant) and antibiotic drug(cefixime trihydrate(CMT)) in water and also in occurrence of inorganic salts(NaCl,Na2 SO4 and Na3 PO4) over the temperature range of 303.15-323.15 K with an interval of 5 K.In all cases,two critical micelle concentrations(c^*) were achieved for the CMT-surfactant system.Addition of CMT drug to CTAB solution decreases the values of c^* which indicates the interaction between CMT and CTAB.Both values of c^* for CMT-CTAB mixture in the presence of salts are lower in magnitude compared to the aqueous medium which indicates that micellization of the CMT-CTAB mixed system is favorable in salt solution.The values of △Gm^0 were obtained to be negative indicating the spontaneity of the micellization process and the extent of spontaneity further increases by means of rising temperature.The obtained outcomes from the ΔHm^0 and ΔSm^0 values disclose that the interactions between CMT and CTAB are mostly electrostatic along with hydrophobic in nature.The thermodynamic parameters of transfer and enthalpy-entropy compensation phenomenon were also determined and discussed in detail.