Solubility and thermodynamic function of apremilast in different (Transcutol + water) cosolvent mixtures: Measurement, correlation and molecular interactions

Self-Nanoemulsifying Drug Delivery System (SNEDDS) of Apremilast: In Vitro Evaluation and Pharmacokinetics Studies

Psoriatic arthritis is an autoimmune disease of the joints that can lead to persistent inflammation, irreversible joint damage and disability. The current treatments are of limited efficacy and inconvenient. Apremilast (APR) immediate release tablets Otezla® have 20-33% bioavailability compared to the APR absolute bioavailability of 73%. As a result, self-nanoemulsifying drug delivery systems (SNEDDS) of APR were formulated to enhance APR's solubility, dissolution, and oral bioavailability. The drug assay was carried out using a developed and validated HPLC method. Various thermodynamic tests were carried out on APR-SNEDDS. Stable SNEDDS were characterized then subjected to in vitro drug release studies via dialysis membrane. The optimum formulation was F9, which showed the maximum in vitro drug release (94.9%) over 24 h, and this was further investigated in in vivo studies. F9 was composed of 15% oil, 60% Smix, and 25% water and had the lowest droplet size (17.505 ± 0.247 nm), low PDI (0.147 ± 0.014), low ZP (-13.35 mV), highest %T (99.15 ± 0.131) and optimum increases in the relative bioavailability (703.66%) compared to APR suspension (100%) over 24 h. These findings showed that APR-SNEDDS is a possible alternative delivery system for APR. Further studies are warranted to evaluate the major factors that influence the encapsulation efficiency and stability of APR-containing SNEDDS.

Solubility of Cinnarizine in (Transcutol + Water) Mixtures: Determination, Hansen Solubility Parameters, Correlation, and Thermodynamics

Between 293.2 and 313.2 K and at 0.1 MPa, the solubility of the weak base, cinnarizine (CNZ) (3), in various {Transcutol-P (TP) (1) + water (2)} combinations is reported. The Hansen solubility parameters (HSP) of CNZ and various {(TP) (1) + water (2)} mixtures free of CNZ were also predicted using HSPiP software. Five distinct cosolvency-based mathematical models were used to link the experimentally determined solubility data of CNZ. The solubility of CNZ in mole fraction was increased with elevated temperature and TP mass fraction in {(TP) (1) + water (2)} combinations. The maximum solubility of CNZ in mole fraction was achieved in neat TP (5.83 × 10^-2 at 313.2 K) followed by the minimum in neat water (3.91 × 10^-8 at 293.2 K). The values of mean percent deviation (MPD) were estimated as 2.27%, 5.15%, 27.76%, 1.24% and 1.52% for the "Apelblat, van't Hoff, Yalkowsky-Roseman, Jouyban-Acree, and Jouyban-Acree-van't Hoff models", respectively, indicating good correlations. The HSP value of CNZ was closed with that of neat TP, suggesting the maximum solubilization of CNZ in TP compared with neat water and other aqueous mixtures of TP and water. The outcomes of the apparent thermodynamic analysis revealed that CNZ dissolution was endothermic and entropy-driven in all of the {(TP) (1) + water (2)} systems investigated. For {(TP) (1) + water (2)} mixtures, the enthalpy-driven mechanism was determined to be the driven mechanism for CNZ solvation. TP has great potential for solubilizing the weak base, CNZ, in water, as demonstrated by these results.

Solubilization, Hansen solubility parameters, and thermodynamic studies of delafloxacin in (transcutol + 1-butyl-3-methyl imidazolium hexafluorophosphate) mixtures

The solubilization, Hansen solubility parameters (HSPs), and thermodynamic properties of delafloxacin (DLN) in various unique combination of Transcutol-HP® (THP) and 1-butyl-3-methyl imidazolium hexafluorophosphate ionic liquid (BMIM-PF₆) mixtures were evaluated for the first time in this research. The 'mole fraction solubilities (x₃)' of DLN in different (THP + BMIM-PF₆) compositions were determined at 'T = 298.2-318.2 K' and 'p = 0.1 MPa'. The HSPs of DLN, neat THP, neat BMIM-PF₆, and binary (THP + BMIM-PF₆) compositions free of DLN were also determined. The x₃ data of DLN was regressed using 'van't Hoff, Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-van't Hoff models' with overall error values of less than 3.0%. The highest and lowest x₃ value of DLN was recorded in neat THP (5.48 × 10^-3 at T = 318.2 K) and neat BMIM-PF₆ (6.50 × 10^-4 at T = 298.2 K), respectively. The solubility of DLN was found to be enhanced significantly with an arise in temperature in all (THP + BMIM-PF₆) compositions including pure THP and pure BMIM-PF₆. However, there was slight increase in DLN solubility with increase in THP mass fraction in all (THP + BMIM-PF₆) mixtures. The HSP of pure THP and pure BMIM-PF₆ were found very close to each other, suggesting the great potential of both solvents in DLN solubilization. The maximum solute-solvent interactions at molecular level were recorded in DLN-THP compared to DLN-BMIM-PF₆. An 'apparent thermodynamic analysis' study indicated an 'endothermic and entropy-driven dissolution' of DLN in all (THP + BMIM-PF₆) compositions including neat THP and BMIM-PF₆.

Solubilization, Hansen solubility parameters and apparent thermodynamic parameters of Osimertinib in (propylene glycol + water) cosolvent mixtures

The solubilization, Hansen solubility parameters (HSPs) and apparent thermodynamic parameters of a novel anticancer medicine osimertinib (OMT) in binary propylene glycol (P) + water (W) cosolvent mixtures were evaluated. The mole fraction solubility (x e) of OMT in various (P + W) cosolvent mixtures including neat P and neat W was determined at T = 298.2–318.2 K and p = 0.1 MPa by applying a saturation shake flask method. HSPs of OMT, neat P, neat W and (P + W) cosolvent compositions free of OMT were also estimated. The x e values of OMT were regressed with Van’t Hoff, modified Apelblat, Yalkowsky-Roseman, Jouyban-Acree and Jouyban-Acree-Van’t Hoff models with an average errors of <3.0 %. The highest and lowest x e value of OMT was estimated in neat P (2.70 × 10−3 at T = 318.2 K) and neat W (1.81 × 10−5 at T = 298.2 K), respectively. Moreover, HSP of OMT was found to be closed with that of neat P. The solubility of OMT was found to be increased significantly with an increase in temperature and P mass fraction in all (P + W) cosolvent compositions including neat P and neat W. The results of activity coefficients suggested higher molecular interactions in OMT-P combination compared with OMT-W combination. The results of thermodynamic studies indicated an endothermic and entropy-driven dissolution of OMT in all (P + W) cosolvent compositions including neat P and neat W.

Solubilization, Hansen Solubility Parameters, Solution Thermodynamics and Solvation Behavior of Flufenamic Acid in (Carbitol + Water) Mixtures

The solubilization, solution thermodynamics, solvation behavior and Hansen solubility parameters (HSPs) of an anti-inflammatory medicine flufenamic acid (FFA) in various Carbitol + water mixtures were evaluated in this study. The experimental solubility of FFA in mole fraction (xe) was measured at T = 298.2–318.2 K and p = 0.1 MPa using a static equilibrium method. The xe values of FFA in various Carbitol + water mixtures were correlated with van’t Hoff, Apelblat, Yalkowsky–Roseman, Jouyban–Acree and Jouyban–Acree–van’t Hoff models. All the studied models showed good correlation with mean error values of less than 2%. The xe value of FFA was found to increase significantly with the increase in temperature and Carbitol mass fraction in all Carbitol + water mixtures evaluated. The maximum and minimum xe values of FFA were recorded in pure Carbitol (2.81 × 10−1) at T = 318.2 K and pure water (5.80 × 10−7) at T = 298.2 K, respectively. Moreover, the HSP of FFA was found to be more closed with that of pure Carbitol, indicating the maximum solubility of FFA in pure Carbitol. The estimated values of activity coefficients showed higher molecular interactions in FFA–Carbitol combinations compared with FFA–water combinations. Thermodynamic studies indicated an endothermic and entropy-driven dissolution of FFA in all Carbitol + water mixtures. The solvation behavior of FFA was observed as enthalpy driven in all Carbitol + water combinations evaluated.

Solubility determination, computational modeling, Hansen solubility parameters and apparent thermodynamic analysis of brigatinib in (ethanol + water) mixtures

The solubility and various thermodynamic parameters of an antitumor drug brigatinib (BRN) in various ethanol (EtOH) + water (H2O) mixtures were determined in this study. The mole fraction solubility (x e) of BRN in various (EtOH + H2O) mixtures including pure EtOH and pure H2O was obtained at T = 298.2–323.2 K and p = 0.1 MPa by adopting a saturation shake flask method. Hansen solubility parameters (HSPs) of BRN, pure EtOH, pure H2O and (EtOH + H2O) mixtures free of BRN were also computed. The x e values of BRN were correlated using Van’t Hoff, Apelblat, Yalkowsky–Roseman, Jouyban–Acree and Jouyban–Acree–Van’t Hoff models with mean errors of <2.0%. The maximum and minimum x e value of BRN was obtained in pure EtOH (1.43 × 10−2 at T = 323.2 K) and pure H2O (3.08 × 10−6 at T = 298.2 K), respectively. The HSP of BRN was also found more closed with that of pure EtOH. The x e value of BRN was obtained as increasing significantly with the rise in temperature and increase in EtOH mass fraction in all (EtOH + H2O) mixtures including pure EtOH and pure H2O. The data of apparent thermodynamic analysis showed an endothermic and entropy-driven dissolution of BRN in all (EtOH + H2O) mixtures including pure EtOH and pure H2O.

Analytical Methods for Determination of Apremilast from Bulk, Dosage Form and Biological Fluids: A Critical Review

Apremilast is an anti-inflammatory agent. It has been a flourishing molecule in the field of dermatology. In the year 2014, Apremilast got its approval for treatment of psoriatic arthritis. Presently it is known to treat a number of other conditions, including atopic dermatitis and plaque psoriasis. Apremilast a phthalimide derivative, is non-hygroscopic in nature. It is practically insoluble in water. Apremilast acts by inhibiting the activity of phosphodiesterase 4 (PDE4), an intracellular enzyme. Analytical method plays a key role to understand the physio-chemical properties of a drug molecule. Because of poor solubility and low permeability, analytical method development and formulation becomes challenging. Till date, there are no standard test methods available to analyze Apremilast. So, a critical review of the analytical techniques of Apremilast was carried out. The literature search was done by screening the papers reporting analytical techniques of Apremilast from year 2014 to 2019. Methodologies particularly UV spectroscopy, HPTLC, HPLC, X-ray diffraction, NMR, LC-MS were collected and reviewed. Interminable efforts are made by the researchers to develop simple, accurate, robust and cost-effective methods of analysis. In pharmaceutical research, this information will aid in the development of new delivery systems. The review will prove beneficial and advantageous pre-formulation studies and will guide the formulation development.

Different types, applications and limits of enabling excipients of pharmaceutical dosage forms

Along with the development of novel drug delivery systems the material science is also advancing. Conventional and novel synthetic or natural excipients provide opportunities to design dosage forms of the required features including their bioavailability. Emerging trends in the design and development of drug products indicate an increasing need for the functionality-related characterization of excipients. The purpose of this review is to provide an overview of different types of excipients in relation to their application possibilities in various dosage forms with special focus on the enabling excipients. The study also summarizes the applied excipient systems of research formulations and dosage forms available on the market.