Solubility of lamotrigine in binary and ternary mixtures of N-methyl pyrrolidone and water with polyethylene glycols 200, 400, and 600 at 298.2K

Comparative Drug Solubility Studies Using Shake-Flask Versus a Laser-Based Robotic Method

Drug solubility is of central importance to the pharmaceutical sciences, but reported values often show discrepancies. Various factors have been discussed in the literature to account for such differences, but the influence of manual testing in comparison to a robotic system has not been studied adequately before. In this study, four expert researchers were asked to measure the solubility of four drugs with various solubility behaviors (i.e., paracetamol, mesalazine, lamotrigine, and ketoconazole) in the same laboratory with the same instruments, method, and material sources and repeated their measurements after a time interval. In addition, the same solubility data were determined using an automated laser-based setup. The results suggest that manual testing leads to a handling influence on measured solubility values, and the results were discussed in more detail as compared to the automated laser-based system. Within the framework of unavoidable uncertainties of solubility testing, it is a possibility to combine minimal experimental testing that is preferably automated with mathematical modeling. That is a practical suggestion to support future pharmaceutical development in a more efficient way.

Study of mesalazine solubility in ternary mixtures of ethanol, propylene glycol, and water at various temperatures

Mesalazine is a low-permeable and low-soluble drug, which makes it a class IV drug in the Biopharmaceutics Classification System. Hence, its solubilization can be helpful for various stages of formulation development. The purpose of this study was to investigate the solubilization manner and thermodynamics of mesalazine in ternary solvent combinations of {ethanol (1) + propylene glycol (2) + water (3)} using the shake-flask technique at (298.2-313.2) K. In the following, the mathematical representation of the acquired solubility data using some popular models was evaluated. The accuracies of the applied models were described by percentages of mean relative deviation (MRD%). Based on obtained results (MRD% < 10.0), it can be concluded that the trained models can adequately predict the solubility of mesalazine in the investigated ternary solvent combinations. The findings also revealed that the solution composition and temperatures greatly influence the solubility of mesalazine. In addition, the thermodynamic characteristics of the mesalazine dissolution process indicate that the mesalazine dissolution process is endothermic and entropy-driven. The generating data in the current work also expands the available solubility database for mesalazine in the solvent mixtures.

Formulation optimization of smart thermosetting lamotrigine loaded hydrogels using response surface methodology, box benhken design and artificial neural networks

The aim of this research was to develop lamotrigine containing thermosetting hydrogel for intranasal administration to manage and treat generalized epilepsy. Thermosetting hydrogels were prepared using different ratios of poloxamer 407 (L127), poloxamer 188 (L68) and Carbopol^® 974 P NF (C974) using the cold production process. The in situ thermosetting hydrogel was optimized using Box Behken design. Co-solvency approach was used to increase the solubility of lamotrigine by dissolving it in propylene glycol and polyethylene glycol 400 (0.2: 0.8) and the resultant solution was incorporated in the hydrogel to manufacture an LTG hydrogel. The presence of a higher amount of L127 resulted in higher viscosity at 22 °C and 34 °C and decreased the overall release of LTG. An increase in the amount of C974 resulted in a decrease in the pH of the hydrogel. The results show that formulations F10, F12, F13, F14, F15, F16 and F17 exhibited acceptable thermosetting behavior, pH and released adequate Lamotrigine above the minimum effective concentration to treat generalized epilepsy. The optimized formulation exhibited acceptable thermosetting behavior, pH and lamotrigine release but formed a stiff gel at 22 °C. The average LTG content of the optimized hydrogel was 5.00 ± 0.0225 mg/ml with % recovery of 99.17%. The amount of LTG released at 12 h from the optimized hydrogel was 3.21 ± 0.0155 mg and will be therapeutically effective in the brain after absorption via the olfactory region in the nasal cavity.

Preparation and characterization of lamotrigine containing nanocapsules for nasal administration

Nanocapsules (NCs) have become one of the most researched nanostructured drug delivery systems due to their advantageous properties and versatility. NCs can enhance the bioavailabiliy of hydrophobic drugs by impoving their solubility and permeability. Also, they can protect these active pharmaceutical agents (APIs) from the physiological environment with preventing e.g. the enzymatic degradation. NCs can be used for many administration routes: e.g. oral, dermal, nasal and ocular formulations are exisiting in liquid and solid forms. The nose is one of the most interesting alternative drug administration route, because local, systemic and direct central nervous system (CNS) delivery can be achived; this could be utilized in the therapy of CNS diseases. Therefore, the goal of this study was to design, prepare and investigate a novel, lamotrigin containing NC formulation for nasal administration. The determination of micrometric parameters (particle size, polydispersity index, surface charge), in vitro (drug loading capacity, release and permeability investigations) and in vivo characterization of the formulations were performed in the study. The results indicate that the formulation could be a promising alternative of lamotrigine (LAM) as the NCs were around 305 nm size with high encapsulation efficiency (58.44%). Moreover, the LAM showed rapid and high release from the NCs in vitro and considerable penetration to the brain tissues was observed during the in vivo study.

Investigation of the Absorption of Nanosized lamotrigine Containing Nasal Powder via the Nasal Cavity

Nasal drug delivery has become a popular research field in the last years. This is not surprising since the nose possesses unique anatomical and physical properties. Via the nasal mucosa local, systemic, and directly central nerve systemic (CNS) effect is achievable. Powders have favorable physicochemical properties over liquid formulations. Lamotrigine (LAM) is an antiepileptic agent with a relatively mild side effect spectrum, but only available in tablet form on market. Reducing the particle size to the nano range can affect the bioavailability of pharmaceutical products. The aim of this article was to continue the work started, compare the in vitro properties of a nanonized lamotrigine containing nasal powder (nanoLAMpowder) and its physical mixture (PM) that were prepared by dry milling. Moreover, to study their trans-epithelial absorption to reach the blood and target the brain by axonal transport. Due to the dry milling technique, the particle size of LAM, their surface and also their structure changed that led to higher in vitro dissolution and permeability rate. The results of the in vivo tests showed that the axonal transport of the drug was assumable by both intranasal formulations because the drug was present in the brain within a really short time, but the LAM from the nanoLAMpowder liberated even faster.

Solubility and Thermodynamics of 6-Phenyl-4,5-dihydropyridazin-3(2H)-one in Various (PEG 400+Water) Mixtures

The aim of this study was to determine the solubility of pyridazinone derivative 6-phenyl-4,5-dihydropyridazin-3(2H)-one (PDP-6) in different “polyethylene glycol 400 (PEG 400)+water” mixtures at temperatures “T=293.2 K to 313.2 K” and pressure “p=0.1 MPa”. The solubilities of PDP-6 were determined using an isothermal method and correlated with Apelblat, van’t Hoff and Yalkowsky–Roseman models. The maximum solubilities of PDP-6 in mole fraction were obtained in neat PEG 400 (8.46×10−2 at T=313.2 K). However, the minimum one was recorded in neat water (7.50×10−7 at T=293.2 K). Apparent thermodynamic analysis showed an endothermic dissolution of PDP-6 in all (PEG 400 water) mixtures. Based on the solubility data of the current study, PDP-6 has been considered as practically insoluble in water and soluble in PEG 400.

The effect of superdisintegrants on the properties and dissolution profiles of liquisolid tablets containing rosuvastatin

CONTEXT

The preparation of liquisolid systems (LSS) represents a promising method for enhancing a dissolution rate and bioavailability of poorly soluble drugs. The release of the drug from LSS tablets is affected by many factors, including the disintegration time.

OBJECTIVE

The evaluation of differences among LSS containing varying amounts and types of commercially used superdisintegrants (Kollidon® CL-F, Vivasol® and Explotab®).

MATERIALS AND METHODS

LSS were prepared by spraying rosuvastatin solution onto Neusilin® US2 and further processing into tablets. Varying amounts of superdisintegrants were used and the differences among LSS were evaluated. The multiple scatter plot method was used to visualize the relationships within the obtained data.

RESULTS AND DISCUSSION

All disintegrants do not showed negative effect on the flow properties of powder blends. The type and concentration of superdisintegrant had an impact on the disintegration time and dissolution profiles of tablets. Tablets with Explotab® showed the longest disintegration time and the smallest amount of released drug. Fastest disintegration and dissolution rate were observed in tablets containing Kollidon® CL-F (≥2.5% w/w). Also tablets with Vivasol® (2.5-4.0% w/w) showed fast disintegration and complete drug release.

CONCLUSION

Kollidon® CL-F and Vivasol® in concentration ≥2.5% are suitable superdisintegrants for LSS with enhanced release of drug.

Dissolution thermodynamics and solubility of silymarin in PEG 400-water mixtures at different temperatures

An isothermal method was used to measure the solubility of silymarin in binary polyethylene glycol 400 (PEG 400) + water co-solvent mixtures at temperatures T = 298.15-333.15 K and pressure p = 0.1 MPa. Apelblat and Yalkowsky models were used to correlate experimental solubility data. The mole fraction solubility of silymarin was found to increase with increasing the temperature and mass fraction of PEG 400 in co-solvent mixtures. The root mean square deviations were observed in the range of 0.48-5.32% and 1.50-9.65% for the Apelblat equation and Yalkowsky model, respectively. The highest and lowest mole fraction solubility of silymarin was observed in pure PEG 400 (0.243 at 298.15 K) and water (1.46 × 10(-5) at 298.15 K). Finally, thermodynamic parameters were determined by Van't Hoff and Krug analysis, which indicated an endothermic and spontaneous dissolution of silymarin in all co-solvent mixtures.