Malik Abdul Rub

Mixed Micelle Formation between Amphiphilic Drug Amitriptyline Hydrochloride and Surfactants (Conventional and Gemini) at 293.15−308.15 K

The micellization of amphiphilic drug amitriptyline hydrochloride (AMT, an antidepressant) and conventional as well as gemini surfactants has been studied conductometrically in pure and mixed states in aqueous solutions at different temperatures to derive various physicochemical properties such as critical micelle concentration (cmc), ideal cmc (cmc(id)), counterion dissociation (g), standard Gibbs free energy (DeltaG(m)(0)), enthalpy (DeltaH(m)(0)), and entropy of micellization (DeltaS(m)(0)), micellar mole fractions of surfactant (X1, X1(m)), mole fraction of surfactant in ideal state (X1(id)), interaction parameter (beta), activity coefficients (f1, f2), and excess free energy of mixing (DeltaG(ex)). All the results indicate synergism and attractive interactions in the mixed systems.

Electrochemical determination of olmesartan medoxomil using hydrothermally prepared nanoparticles composed SnO2-Co3O4 nanocubes in tablet dosage forms.

Low-dimensional nanoparticles composed SnO(2)-Co(3)O(4) nanocubes (NCs) were prepared by a hydrothermal method using reducing agents. The doped nanomaterials were investigated by UV/vis, powder X-ray diffraction, FT-IR, energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy, and field-emission scanning electron microscopy. They were deposited on a silver electrode (AgE, surface area, 0.0216 cm(2)) to give a drug sensor with a fast response towards Olmesartan medoxomil (OSM) in 0.1 mol L(-1) phosphate buffer-phases. The sensor also exhibits higher sensitivity, long-term stability, and enhanced electrochemical response. The calibration plot is linear (r(2)=0.9948) over the 0.28 nmol L(-1)-1.4 μM OSM concentration range. The sensitivity is ~2.083 μA cm(-2) mmol L(-1) and the detection limit is 0.17 nmol L(-1) (at an SNR of 3). We discuss the possible potential uses of this nanoparticles doped semiconductor NCs in terms of drug sensing, which could also be employed for the determination of drugs in quality control of formulation.

Effect of Sodium Taurocholate on Aggregation Behavior of Amphiphilic Drug Solution

Abstract The aggregation behavior of promazine hydrochloride (PMZ) and bile salt (sodium taurocholate (NaTC)) mixtures at various compositions and temperature in pure and mixed states were studied using conductometry technique in aqueous solutions. The values of experimental and ideal critical micelle concentration (cmc and cmcid) propose attractive interactions in PMZ-NaTC mixtures. By applying the regular solution theory (RST) various physicochemical parameter such as micellar mole fraction in the mixed (X1) and ideal (X1id) state, interaction parameters (β), thermodynamic parameters of micellization as well as other related parameters have been evaluated and discussed in detail. The results show that the synergistic effect between drug and bile salt plays a crucial role in the redtdprefuction of the overall cmc value in aqueous solution at various composition of NaTC. The thermodynamic parameters recommend the discharge of water from the hydrophobic part of the PMZ at higher temperatures.

Analysis of surface and bulk properties of amphiphilic drug ibuprofen and surfactant mixture in the absence and presence of electrolyte

In the present work, the micellization, adsorption and aggregation behavior of mixed drug-surfactant systems, in the absence and presence of electrolyte (100mM NaCl) were investigated by surface tension and fluorescence measurements. The critical micelle concentrations (cmc) of the mixtures fall between the values of the individual components, which indicate nonideal behavior of mixing of the components. On the basis of regular solution theory (RST), the micellar mole fractions of surfactant (X1) and interaction parameter in solution (β) were evaluated, while their interfacial mole fractions (X1(σ)) and interaction parameters at the interface (β(σ)) were calculated using Rosens model. The results indicate that the surfactants contribution is greater than that of the drug both at the interface and in micelles. The short and rigid hydrophobic structure of the drug resists its participation in micelle formation more than in the monolayer, leading to X1 <X1(σ). Values of the surface excess (Γmax) and minimum area per head group (Amin) indicate attractive interactions. Γmax increases and Amin decreases as the surfactant mole fraction increases. The results have applicability in model drug delivery.

Mixed micelles of amphiphilic drug promethazine hydrochloride and surfactants (conventional and gemini) at 293.15K to 308.15K: Composition, interaction and stability of the aggregates.

Micellization of an amphiphilic phenothiazine drug promethazine hydrochloride (PMT) in presence of conventional (CTAB and TTAB) as well as gemini (16-s-16 and 14-s-14, s=4-6) cationic surfactants has been studied conductometrically at different temperatures. Critical micelle concentration values (cmc and cmc(id)) indicate mixed micelle formation among the two components. Micellar mole fractions of surfactants (X(1), X(1)(M) and X(1)(id)) show greater contribution of surfactants. Interaction parameter, β, suggests attractive interactions in the mixed systems. The thermodynamic parameters suggest dehydration of hydrophobic part of the drug at higher temperatures.

Self-association and micro-environmental properties of sodium salt of ibuprofen with BRIJ-56 under the influence of aqueous/urea solution

ABSTRACT Herein, the interactions between the sodium salt of ibuprofen (IBU) with nonionic surfactant-BRIJ-56 were investigated at the interface as well as in the bulk phase (solution) in the existence and nonexistence of urea (250 mM). In the present study, tensiometric and fluorometric techniques have been utilized to investigate the association and micro-environmental properties of mixed systems. Various models (such as Clint, Rubingh, Maeda, etc.) were employed to obtain information regarding the nature of interaction between the components in bulk as well as at the interface. The critical micelle concentration (cmc) of pure amphiphiles and their mixed system increases in the existence of urea due to enhancement in the surface charge of the micelles. The urea activities have been explored on account of diverse aspects, such as the salvation of head groups and hydrophobic interactions. The aggregation number, micropolarity, and apparent dielectric constant of pure and mixed systems were investigated using steady-state fluorescence spectroscopy. A variety of energetic parameters (for instance the standard Gibbs free energy of micellization, Gibbs free energy of adsorption, and Gibbs excess energy) have been evaluated for further insight of urea action. The Δ values achieved are all negative, both in the absence and in the presence of urea. GRAPHICAL ABSTRACT

Micellization and Interfacial Behavior of the Sodium Salt of Ibuprofen–BRIJ-58 in Aqueous/Brine Solutions

This work deals with the effect of a nonionic surfactant (BRIJ-58) on the physicochemical properties of the sodium salt of ibuprofen, in the absence and presence of salt (NaCl), in order to understand the nature of interactions in IBF–BRIJ-58 aqueous mixtures. Tensiometric measurements were carried out to estimate the critical micelle concentrations (cmc) of drug and surfactant along with their mixtures. A gradual reduction in the surface charge of the micelles was obtained by adding salt followed by the early formation of the micelles; hence, the cmc value of the amphiphiles decreased. Various parameters such as micellar, interfacial, corresponding thermodynamic parameters, etc., have been calculated and are discussed in detail by applying various theoretical models reported in the literature. The theories of Clint, Rubingh, Motomura and Maeda have been applied to investigate interactions among the components. Structural parameters proposed by Tanford have also been also evaluated.

Study of Mixed Micelles of Promethazine Hydrochloride (PMT) and Nonionic Surfactant (TX-100) Mixtures at Different Temperatures and Compositions

Abstract Herein, we have investigated the interaction between a phenothiazine drug promethazine hydrochloride (PMT) and nonionic surfactant t-octylphenoxypolyethoxyethanol (TX-100) in aqueous solutions using a conductometric technique at different temperatures and compositions. The evaluated critical micelle concentration (cmc) values are lower than cmcid values suggesting attractive interactions of mixed micelles components. It is observed that with the increase in temperature, the cmc value increases first and after the value decreases at higher temperature. At 298.15 K, the maximum cmc values were attained in presence or absence of TX-100. The bulk properties of solution were studied by means of different theoretical models reported in the literature such as Clint, Rubingh, Motomura, and Rodenas for explanation and comparison of results of different binary mixtures of the drug and TX-100. The negative values of interaction parameter (β) obtained from the regular solution theory (RST) recommend synergistic interactions. Activity coefficients (f1 and f2) calculated by all theoretical models used herein were obtained to be always below unity indicating nonideality in all binary mixtures. Thermodynamic parameters (like standard Gibbs energy (ΔG°m), enthalpy (ΔH°m), and entropy (ΔS°m)) are also evaluated which propose dehydration of hydrophobic portion of the drug at higher temperatures. The above results obtained may be helpful in model drug delivery systems.

Study of phospholipid-induced phase-separation in amphiphilic drugs

Phase separation of five amphiphilic drugs in 10 mM phosphate buffer with added phospholipids has been studied. The drugs used are tricyclic antidepressants (amitriptyline hydrochloride, imipramine hydrochloride, and clomipramine hydrochloride) and phenothiazines (promethazine hydrochloride and promazine hydrochloride). Depending on the nature and structure of studied compounds, the phospholipids caused different effects on the clouding behavior. Cardiolipin decreased the cloud point for all drugs. With amitriptyline, all the additives lowered the cloud points, whereas the clomipramine showed opposite tendency. Imipramine and promethazine led to similar extremal behaviour of cloud point, although promazine, which is structurally similar to promethazine, did not show the same tendency. Thermodynamic analysis of the experimental data suggested that the process of clouding is entropically driven.

Energetics of Clouding Phenomenon in Amphiphilic Drug Imipramine Hydrochloride with Pharmaceutical Excipients

The clouding behaviour of an amphiphilic antidepressant drug imipramine hydrochloride (IMP) with several additives (hydrotropes, bile salts, fatty acids and sugars) over the entire composition range at pH = 7.6 was investigated in the present study. The magnitude of clouding (increase or decrease) of IMP in the presence of additives (pharmaceutical excipients) depends on the nature and types of additives. Bile salts and fatty acids showed peak behaviour i.e., cloud point (CP) increases at lower concentrations while decrease in cloud points was observed at higher concentrations. Thermodynamics at the CP were also evaluated (except for sugars, because sugars does not form mixed micelles with IMP), assuming that the clouding indicates the solubility limit when phase separation occurs. Thus, the various thermodynamic parameters e.g., standard Gibbs free energy (ΔGso), the enthalpy (ΔHso) and entropy (TΔSso) were calculated at this point. The results showed that the ΔGso, was found to be negative for all the additives, however ΔHso and TΔGso of the clouding phenomenon were found to be positive or negative depending upon the types and nature of additives.