Improved Dissolution of Dipyridamole with the Combination of pH-Modifier and Solid Dispersion Technology

Melting point depression for enhanced dissolution rate of eslicarbazepine acetate

BACKGROUND

Eslicarbazepine acetate (ESL) is antiepileptic agent which is approved for use as single therapy or in combination with other drugs. However, it suffers from poor oral bioavailability. Modulation of drug crystallinity can be utilized as an approach for enhancing drug dissolution.

OBJECTIVE

Accordingly, the aim of this study was to investigate possible eutectic system formation between eslicarbazepine with either tartaric acid or citric acid.

METHODOLOGY

Eslicarbazepine acetate was subjected to wet co-grinding with tartaric acid or citric acid at different molar ratios. The prepared formulations were assessed using Fourier-transform infrared (FTIR), X-ray powder diffraction (XRPD), differential scanning calorimetry in addition to dissolution studies.

RESULTS

The characterization techniques confirmed eutectic system formation with tartaric and citric acid with the optimum molar ratio for eutexia being 1:1 for both substances. Development of eutectic systems significantly enhanced the dissolution rate of ESL. Increasing the ratio of tartaric acid higher than the optimum ratio for eutexia resulted in additional increase in drug dissolution rate. This suggested the impact of pH modification on drug dissolution rate. The enhanced dissolution rate in case of the formulations containing ESL and citric acid was accredited to combined effect of eutaxia and pH modulation. These explanations were proven from investigating the dissolution rate of the physical mixtures which were inferior in their dissolution rate compared with the prepared formulations.

CONCLUSION

co-processing of ESL with either citric acid or tartaric acid resulted in hastened dissolution rate which was accredited to combined effect of eutexia with pH modification.

Innovations in Thermal Processing: Hot-Melt Extrusion and KinetiSol® Dispersing

Thermal processing has gained much interest in the pharmaceutical industry, particularly for the enhancement of solubility, bioavailability, and dissolution of active pharmaceutical ingredients (APIs) with poor aqueous solubility. Formulation scientists have developed various techniques which may include physical and chemical modifications to achieve solubility enhancement. One of the most commonly used methods for solubility enhancement is through the use of amorphous solid dispersions (ASDs). Examples of commercialized ASDs include Kaletra®, Kalydeco®, and Onmel®. Various technologies produce ASDs; some of the approaches, such as spray-drying, solvent evaporation, and lyophilization, involve the use of solvents, whereas thermal approaches often do not require solvents. Processes that do not require solvents are usually preferred, as some solvents may induce toxicity due to residual solvents and are often considered to be damaging to the environment. The purpose of this review is to provide an update on recent innovations reported for using hot-melt extrusion and KinetiSol® Dispersing technologies to formulate poorly water-soluble APIs in amorphous solid dispersions. We will address development challenges for poorly water-soluble APIs and how these two processes meet these challenges.

Enhanced pharmacokinetic performance of dapoxetine hydrochloride via the formulation of instantly-dissolving buccal films with acidic pH modifier and hydrophilic cyclodextrin: Factorial analysis, in vitro and in vivo assessment

Instantly dissolving buccal films have gained attention owing to their easy administration and capability to surmount the hepatic first pass effect of drugs. Dapoxetine hydrochloride (DPX) has a low oral bioavailability due to significant hepatic first pass metabolism. In addition, DPX is a weakly basic drug with a pH dependent solubility that could limit its dissolution in the body neutral fluids. In order to surpass these challenges, this work aimed at enhancing DPX bioavailability via the formulation of instantly dissolving buccal films comprising a pH modifier and a hydrophilic cyclodextrin. Tartaric acid and hydroxypropyl beta-cyclodextrin were selected as dual solubilizing agents based on the screening study. 3² factorial design was employed for the formulation and optimization of DPX films. Statistical analysis revealed that hydroxypropyl methyl cellulose E5: maltodextrin ratio and propylene glycol concentrations have significant effects on mechanical properties, percent DPX dissolved after 5 min, and in vivo mouth dissolving time at P  < 0.05. The optimized film [HPMC E5: MDX, 1:1 and 1% PG] showed no significant change of properties or drug dissolution upon storage at 40 °C/75% RH for a period of 3 months. In addition, the optimized film showed significantly enhanced absorption relative to the oral reference tablet. Therefore, the optimized film could be considered a promising delivery system for DPX with expected improved patient compliance and enhanced pharmacokinetic performance.