Md. Sayem Alam

The Interaction of Cationic Gemini Surfactant 1,4-Butanediyl-α,ω-bis(dimethylcetylammonium bromide) with Primary Linear Alkanols

The critical micelle concentration (CMC) of cationic gemini surfactant 1,4-butanediyl-α, ω-bis(dimethylcetylammonium bromide; C16-C4-C16) with and without additives (primary linear alcohols: butanol (C4OH), pentanol (C5OH), hexanol (C6OH), heptanol (C7OH), octanol (C8OH)) is measured by surface tension measurements using a du Noüy tensiometer in aqueous solution at 303 K. The CMC of C16-C4-C16 decreased with increasing alcohol concentration and the effect followed the order: C8OH > C7OH > C6OH > C5OH > C4OH. The surfactant concentration required to reduce the surface tension of the solvent by 20 mN/m, C20, ratio of C20 and CMC, maximum surface excess, Γmax, and minimum surface area per molecule, Amin, were evaluated from surface tension versus log Ct (Ct is the total surfactant concentration) plots. Mixed micelles were formed and the CMC values of the mixtures were used to compute βm, the interaction parameter for mixed micelle formation in aqueous medium, βσ, the interaction parameter for mixed monolayer formation at the aqueous solution/air interface, and the respective activity coefficients (f1 and f2). The standard Gibbs energy of adsorption was also evaluated. We observed synergism in C16-C4-C16/alkanol systems at all concentration ratios.

Investigation of the role of electrolytes and non-electrolytes on the cloud point and dye solubilization in antidepressant drug imipramine hydrochloride solutions.

Antidepressant drug imipramine hydrochloride (IMP) is amphiphilic which shows surfactant-like behavior in aqueous solutions. We have studied the effect of adding electrolytes and non-electrolytes on the micellar behavior of IMP by making cloud point (CP) and dye solubilization measurements. The CP of a 100mM IMP solution (prepared in 10mM sodium phosphate (SP) buffer) was found to decrease with increasing pH, both in the absence as well as presence of added salts. Increase in pH increased the visible absorbance of Sudan III dye solubilized in the drug micelles, implying micellar growth. Addition of increasing amounts of salts to 100mM IMP solutions (at pH 6.7) caused continuous increase in CP due to micellar growth. On the basis of these studies, the binding-effect orders of counter- and co-ions have been deduced, respectively, as: Br(-)>Cl(-)>F(-) and Li(+)<Na(+)<K(+)<NH(4)(+). The trend of increasing CP with addition of increasing amounts of quaternary salts (tetramethylammonium bromide, TMeAB; tetraethylammonium bromide, TEtAB; tetra-n-propylammonium bromide, TPrAB; tetra-n-butylammonium bromide, TBuAB; tetra-n-pentylammonium bromide, TPeAB) to 100mM IMP solutions (at pH 6.7) was found to be dependent upon the alkyl chain length of the particular salt. Ureas caused CP depression, which was found to be dependent upon the number of methyl groups present in the molecule. Contrary to this, thioureas increased the CP slightly, but the presence of methyl group(s) had effect similar to that of alkylureas. The visible absorbance due to solubilized dye increased/decreased with addition of electrolytes/ureas. The overall behavior has been discussed in terms of electrostatic interactions, micellar growth, and mixed micelle formation.

Influence of additives on the clouding phenomenon of chlorpromazine hydrochloride solutions

Herein we report the effect of various additives (viz. alcohols, cycloalcohols, amino acids, sugars, ureas) on the clouding phenomenon observed in 50mM chlorpromazine hydrochloride (CPZ) drug solutions (prepared in 10mM sodium phosphate buffer). Long chain alcohols (except octanol), cyclohexanol and allylalcohol increased the cloud point (CP) followed by a decrease with the increase in alcohol concentration but short chain alcohols affected the CP insignificantly. Effect of amino acids depended upon their nature: acidic and salts of basic amino acids increased the CP while basic amino acids depressed it; non-polar and uncharged polar amino acids caused small changes in CP. Additives of urea family decreased the CP. All sugars caused a decrease in CP, which is in consonance to their effect on the critical micellar concentration. The overall behavior is explained on the basis of additives affecting the solvent as well as micelle aggregation and/or structure.

Study of the Cloud Point of the Phenothiazine Drug Chlorpromazine Hydrochloride : Effect of Surfactants and Polymers

Surfactants/polymers are used extensively in drug delivery as drug carriers. We herein report the effect of surfactants and polymers on the cloud point (CP) of amphiphilic drug chlorpromazine hydrochloride. At fixed drug concentration (50 mM) and pH (6.7) these additives affect the CP in accordance to their nature and structure: anionic surfactants show an increase followed by a decrease, whereas cationic (conventional as well as gemini) and nonionic surfactants show continous increase. The behavior with polymers is dictated by the number of units present in a particular polymer. Increase in drug concentration and pH, in presence of fixed amounts of CTAB, increases and decreases the CP, respectively. Variation of CP with pH at various fixed gemini concentrations shows that gemini surfactants are better candidates for drug delivery.

Effect of Alkylamine Chain Length on the Critical Micelle Concentration of Cationic Gemini Butanediyl-α, ω-bis(dimethylcetylammonium bromide) Surfactant

Herein we report the effect of chain length of alkyl amines on the critical micelle concentration (CMC) of cationic gemini surfactant butanediyl-α, ω-bis(dimethylcetylammonium bromide) (abbreviated as C16-C4-C16). The CMC of different mixtures has been measured by surface tension using a du Noüy tensiometer in aqueous solution at 303 K. A synergistic effect was observed in all instances that were found to be correlated with chain length. It was found that the CMC of C16-C4-C16 decreased with increasing amine concentrations and the extent of effect followed the sequence: octylamine (C8NH2) > heptylamine (C7NH2) > hexylamine (C6NH2) > pentylamine (C5NH2) > butylamine (C4NH2). C20 (the surfactant concentration required to reduce the surface tension of the solvent by 20 mN/m), ratio of C20 and CMC, maximum surface excess (Γmax) and minimum surface area per molecule (Amin) were evaluated from surface tension versus log C (C is concentration) plots. Mixed micelles were formed with the gemini surfactant and the CMC values of the mixtures were used to compute βm (the interaction parameter for mixed micelle formation in aqueous medium), βσ (the interaction parameter for mixed monolayer formation at the aqueous solution/air interface), and the activity coefficients (f1 and f2). The standard Gibbs energy of adsorption ( ) was also evaluated.

Cloud Point Phenomenon in Amphiphilic Drug Promethazine Hydrochloride+Electrolyte Systems

Herein we report clouding phenomenon occurring in amphiphilic drug promethazine hydrochloride (PMT) in the presence of electrolytes. The CP of 50 mM drug solution, prepared in 10 mM sodium phosphate buffer, was found to decrease with increasing pH due to deprotonation of drug molecules at high pH. Addition of inorganic salts (KF, KCl and KBr) to drug solutions at fixed pH (6.7) and drug concentration (50 mM) caused an increase in CP. The results have been discussed on the desorption/adsorption of counterions to the headgroups. Cations also increased the CP by affecting the water structure with their effectiveness being in the order: Li+<Na+<K+<NH4 +. In the presence of NaCl, increase in drug concentration increased the CP while increase in pH showed an opposite trend.

Influence of Electrolytes on the Micellar Growth of Amphiphilic Drug Chlorpromazine Hydrochloride

Abstract The effect of electrolytes on the micellar behavior of an amphiphilic drug, chlorpromazine (CPZ) hydrochloride, was studied using cloud point (CP) and dye solubilization techniques. In the presence of KBr, increase in pH led to decrease in the CP of 50 mmol·L–1 drug solution (prepared in 10 mmol·L–1 sodium phosphate (SP) buffer) because of deprotonation of drug molecules at high pH. The visible absorbance increased (due to dye solubilization) with the increase in pH from 6.5 to 6.9, which indicated micellar growth. At fixed pH (6.7), addition of inorganic salts (KF, KCl, and KBr) to drug solutions (50 mmol·L–1) caused an increase in the CP as well as in the visible absorbance, with effectiveness being in the order: F– Na+ > K+, which was explained by considering cognizance of their hydrated radii. Compared with anions, their effect was small. Increase in [CPZ] caused micellar growth and hence the CP as well as the visible absorbance increased. The overall behavior was discussed in terms of electrostatic interactions and micellar growth.

Phase Separation Study of Imipramine Hydrochloride-Additive Systems

Phase separation study of an antidepressant drug, imipramine hydrochloride (IMP), in presence of various additives (i.e., alcohols, sugars, amino acids) has been made by cloud point (CP) measurements. Whereas the CP remained constant with lower alcohols, higher ones (due to their hydrophobic nature) decreased it and medium chain alcohols showed peaked behavior. With diols, the CP remained constant but showed peaked behavior with cycloalkanols. Sugars have a CP decreasing effect because of their water structure making property. All the amino acids increased the CP but to different extent. At different fixed [hexanol], the CP decreased with increasing pH while increase in drug concentration increased the CP. The results are discussed in terms of additive effects on bulk solvent (water) and drug morphology. In the presence and absence of C6OH, the thermodynamic parameters ( , and ) of IMP at CP are found to be positive up to a certain C6OH concentration (90 mM), and above this concentration, the values become negative.

Micellization and Clouding Phenomenon of Phenothiazine Drug Promethazine Hydrochloride: Effect of NaCl and Urea Addition

Herein we report the micellization and clouding behavior of promethazine hydrochloride (PMT) in absence and presence of NaCl/ureas. The critical micelle concentration (CMC) of PMT is measured by conductivity method and the values decrease with increasing the NaCl concentration. With increasing the temperature, the CMC first increases then decreases. At 25°C, the maximum CMC values were obtained (with or without NaCl). The thermodynamic parameters are evaluated which indicate more stability of the PMT solution in presence of NaCl. PMT shows phase separation also. The cloud point (CP) of PMT decreases with increase in pH due to deprotonation of the drug molecules. Ureas decreased the CP and the behavior is explained on the basis of removal of water from the head group region.