Development of enteric-coated fixed dose combinations of amorphous solid dispersions of ezetimibe and lovastatin: Investigation of formulation and process parameters.

Enteric-coated fixed-dose combinations of ezetimibe and lovastatin were prepared by fluid bed coating aiming to avoid the acidic conversion of lovastatin to its hydroxyacid derivative. In a two-step process, sucrose beads were layered with a glass solution of ezetimibe, lovastatin and Soluplus®, top-coated with an enteric layer. The impact of different bead size, enteric polymers (Eudragit L100® and Eudragit L100-55®) and coating time was investigated. Samples were evaluated by X-ray diffraction, scanning electron microscopy, laser diffraction and in vitro studies in 0.1M HCl and phosphate buffer pH 6.8. Results showed that smaller beads tend to agglomerate and release was jeopardized in acidic conditions, most likely due to irregular coating layer. Eudragit L100-55® required longer processing, but thinner coating layers provided lower drug release. Both polymers showed low drug release in acidic environment and fast release at pH 6.8. The off-line measurement of the coating thickness determined the ideal coating time as 15 and 30min for Eudragit L100-55® and Eudragit L100®-based samples, respectively. Both compounds were molecularly dispersed in Soluplus®, and Eudragit L100® formulations showed concave pores on the surface, presenting higher drug release in acidic conditions. Stability studies after 6 months showed unaltered physical properties and drug release.

New Perspectives for Fixed Dose Combinations of Poorly Water-Soluble Compounds: a Case Study with Ezetimibe and Lovastatin.

PURPOSE: Aiming to improve the dissolution rate of ezetimibe (EZE) and lovastatin (LOV) in a fixed dose combination (FDC), co-amorphous systems and ternary solid dispersions were prepared by quench cooling and spray drying, respectively. METHODS: Formulations were characterized through X-ray diffraction, modulated differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy and laser diffraction, and evaluated by 'in vitro' dissolution. Stability studies were conducted at different conditions during 30 days with the ternary solid dispersion composed of 75% of Soluplus® (ELS 1:1 75%). RESULTS: Single phase co-amorphous systems made up of the pure drugs were not able to increase the dissolution rate of EZE and LOV. However, ternary solid dispersions achieved high dissolution for both compounds, especially when Soluplus® was used as carrier. The dissolution efficiency increased up to 18 (EZE) and 6 (LOV) times in ternary solid dispersions, compared to the crystalline drugs. ELS 1:1 75% preserved its amorphous state during 30 days, in different stability conditions. CONCLUSIONS: A spray dried ternary solid dispersion able to enhance the dissolution rate of two poorly soluble, therapeutically complementary drugs, is reported for the first time. These promising results open new perspectives for the development of more advanced FDCs.

Development and evaluation of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and polycaprolactone microparticles of nimodipine.

Polymeric microparticles containing the calcium channel blocker nimodipine were successfully obtained through simple emulsion/ organic solvent evaporating method. The extended release formulations, composed by the polymers poly(3-hydroxybutyrate-co-3- hydroxyvalerate) (PHBV) and polycaprolactone (PCL), were submitted to characterization through X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TG), Fourier transform infrared analysis (FT-IR) and determination of the mean particle diameter. All formulations obtained revealed an amorphous characteristic, proven through XRPD and DSC results. Besides, no chemical interaction was observed between drug and polymer in polymeric microparticles. PHBV-NMP formulation showed a higher drug entrapment, a larger particle size, a thermal degradation behavior similar to that observed for nimodipine and a longer drug release time, being selected for in vivo evaluation. The PHBV-NMP polymeric microparticles were able to keep the pharmacological antihypertensive effect for a longer period of time, becoming a good alternative to control nimodipine release in hypertension treatment.

Determination of nimodipine in the presence of its degradation products and overall kinetics through a stability-indicating LC method.

The determination of nimodipine in the presence of its degradation products, formed through photolysis, acidic and alkaline hydrolysis, and the drug degradation kinetics under these conditions, was investigated through a validated liquid chromatography method. Separation was achieved using a Phenomenex Luna C18 column (250 × 4.6 mm i.d., 5 µm) with a mobile phase consisting of acetonitrile-methanol-water (55:11:34, v/v/v), at 0.5 mL/min and with ultraviolet detection at 235 nm. The method was considered to be specific, accurate, precise, robust and linear over the concentration range of 5.0 to 35.0 µg/mL. The drug followed a first-order reaction for both hydrolysis and photolysis in methanol, and zero-order for photolysis in acetonitrile and water. The calculated activation energies were 10.899 and 23.442 kcal/mol for alkaline and acidic hydrolysis, respectively. No degradation was observed under thermal and oxidative stress conditions.