Amorphization of Atorvastatin Calcium by Mechanical Process: Characterization and Stabilization Within Polymeric Matrix

Fast-Dissolving Nifedipine and Atorvastatin Calcium Electrospun Nanofibers as a Potential Buccal Delivery System

Geriatric patients are more likely to suffer from multiple chronic diseases that require using several drugs, which are commonly ingested. However, to enhance geriatric patients’ convenience, the electrospun nanofiber system was previously proven to be a successful alternative for the existing oral dosage forms, i.e., tablets and capsules. These nanofibers prepared either as single- or multi-layered fibers could hold at least one active compound in each layer. They might also be fabricated as ultra-disintegrated fibrous films for oral cavity administration, i.e., buccal or sublingual, to improve the bioavailability and intake of the administered drugs. Therefore, in this work, a combination of nifedipine and atorvastatin calcium, which are frequently prescribed for hypertension and hyperlipidemia patients, respectively, was prepared in a coaxial electrospinning system for buccal administration. Scanning electron microscopy image showed the successful preparation of smooth, non-beaded, and non-porous surfaces of the drug-loaded nanofibers with an average fiber diameter of 968 ± 198 nm. In contrast, transmission electron microscopy distinguished the inner and outer layers of those nanofibers. The disintegration of the drug-loaded nanofibers was ≤12 s, allowing the rapid release of nifedipine and atorvastatin calcium to 61% and 47%, respectively, after 10 min, while a complete drug release was achieved after 120 min. In vitro, a drug permeation study using Franz diffusion showed that the permeation of both drugs from the core–shell nanofibers was enhanced significantly (p < 0.05) compared to the drugs in a solution form. In conclusion, the development of drug-loaded nanofibers containing nifedipine and atorvastatin calcium can be a potential buccal delivery system.

Does the trihydrate of atorvastatin calcium possess a melting point?

To decide whether an active pharmaceutical ingredient can be used in its amorphous form in drug formulations, often the glass transition is studied in relation to the melting point of the pharmaceutical. If the glass transition temperature is high enough and found relatively close to the melting point, the pharmaceutical is considered to be a good glass former. However, it is obviously important that the observed melting point and glass transition involve exactly the same system, otherwise the two temperatures cannot be compared. Although this may seem trivial, in the case of hydrates, where water may leave the system on heating, the composition of the system may not be evident. Atorvastatin calcium is a case in point, where confusing terminology, absence of a proper anhydrate form, and loss of water on heating lead to several doubtful conclusions in the literature. However, considering that no anhydrate crystal has ever been observed and that the glass transition of the anhydrous system is found at 144 °C, it can be concluded that if the system is kept isolated from water, the chances that atorvastatin calcium crystallises at room temperature is negligible. The paper discusses the various thermal effects of atorvastatin calcium on heating and proposes a tentative binary phase diagram with water.

In vitro and in vivo evaluation of cyclodextrin-based nanosponges for enhancing oral bioavailability of atorvastatin calcium

The aim of this study was to explore the feasibility of complexing the poorly water-soluble drug atorvastatin calcium (AC) with β-cyclodextrin (β-CD) based nanosponges (NS), which offer advantages of improving dissolution rate and eventually oral bioavailability. Blank NS were fabricated at first by reacting β-CD with the cross-linker carbonyldiimidazole at different molar ratios (1:2, 1:4, and 1:8), then NS of highest solubilization extent for AC were complexed with AC. AC loaded NS (AC-NS) were characterized for various physicochemical properties. Pharmacokinetic, pharmacodynamics and histological finding of AC-NS were performed in rats. The prepared AC-NS showed particles size ranged from 408.7 ± 12.9 to 423 ± 15.9 nm while zeta potential values varied from -21.7 ± 0.90 to -22.7 ± 0.85 mV. The loading capacity varied from 17.9 ± 1.21 to 34.1 ± 1.16%. DSC, FT-IR, and PXRD studies confirmed the complexation of AC with NS and amorphous state of the drug in the complex. AC-NS displayed a biphasic release pattern with increase in the dissolution rate of AC as compared to plain AC. Oral administration of AC-NS (1:4 w/w, drug: NS) to rats led to 2.13-folds increase in the bioavailability as compared to AC suspension. Pharmacodynamics studies in rats with fatty liver revealed significant reduction (p < .05) in total cholesterol, triglyceride, LDL-C and increased level of beneficial HDL-C along with improvement in the associated liver steatosis as confirmed through photomicrographs of liver sections. In this study, we confirmed that complexation of AC with NS would be a viable approach for improving oral bioavailability and in vivo performance of AC.