Rheological Behavior of a New Mucoadhesive Oral Formulation Based on Sodium Chondroitin Sulfate, Xyloglucan and Glycerol.

Background: The study aimed at assessing the mucoadhesive properties and the barrier effect of a formulation, labelled as AL2106, containing sodium chondroitin sulfate (ChS), xyloglucan from tamarind seed extract, and glycerol, by evaluating the capacity to adhere to a layer of mucin, the rheological synergism and the barrier effect in comparison to the marketed Esoxx One medical device. AL2106 is a medical device distributed by Alfasigma SpA, Italy with REF FTP57 (Manufacturer: Labomar SpA); it is analogous to Esoxx One medical device: the two products are drinkable solutions that, after swallowing, adhere to the esophageal mucosa, protecting it from the corrosive effect of the gastric acid reflux. AL2106 has been conceived to be better performing in terms of duration of the barrier effect compared to Esoxx One. Methods: The mucoadhesive properties, rheological behavior, buffering capacity against acidity, and film-forming ability with the resultant protecting effect on esophagus mucosa (caffeine permeation test) was compared between the two products. Results: The mucoadhesivity of the formulations was shown in vitro: both remained adherent to a mucin layer, also when the support was rotated by 90°, and when the film layer was washed with water, intended to simulate the washout due to swallowing. AL2106 showed a good buffering efficacy, being able to absorb at least 50% of its weight of 0.03 M HCl while maintaining the pH above 4. The film-forming effect and barrier properties of AL2106 and Esoxx One were confirmed by an in vitro study on reconstructed human esophageal epithelium. A greater film-forming efficacy of AL2106, lasting for at least 5 h, than Esoxx One was observed. Noteworthy, the barrier function of esophageal tissues was shown to be preserved after the application of both formulations. Conclusions: The combination of ChS with the mucoadhesive glycerol-xyloglucan complex and other excipients, which contribute to the barrier effect and to mucoadhesion, contained in AL2106, allowed a longer-lasting protective effect than Esoxx One, proving its effectivity and safety for oral use.

Diferencias farmacocinéticas entre rifaximina alfa y una rifaximina genérica / Pharmacokinetic differences between alpha rifaximin and a generic rifaximin

Resumen: ANTECEDENTES: Los fármacos que tienen polimorfismo, como la rifaximina, pueden tener diferencias farmacocinéticas según el polimorfo. La rifaximina polimorfa-α (alfa) es un antibiótico no absorbible. OBJETIVO: Investigar si la farmacocinética de la rifaximina de referencia (α) es distinta de la de una rifaximina genérica en el mercado mexicano. MATERIAL Y MÉTODO: Estudio prospectivo experimental del polimorfo con difracción de rayos X, su perfil de solubilidad y la farmacocinética de una dosis única de 100 mg/ kg de cada rifaximina administrada por vía oral en perros Beagle. RESULTADOS: La rifaximina de referencia fue polimorfo-α (alfa) y la rifaximina genérica resultó polimorfo-к (kappa). El perfil de solubilidad fue diferente porque el polimorfo-к fue más soluble que el α. La concentración plasmática máxima (Cmáx), la concentración durante 24 horas (AUC0-t) y la biodisponibilidad relativa fueron 8 a 10 veces mayores con rifaximina genérica (к) que con la de referencia (α). CONCLUSIÓN: La rifaximina genérica estudiada tiene farmacocinética distinta del producto de referencia y no puede considerarse del todo un antibiótico no absorbible. Se discuten las posibles implicaciones terapéuticas, especialmente en la seguridad.

Abstract: BACKGROUND: Drugs with polimorphism, as rifaximin, may have different pharmacokinetic depending on the polymorph. Rifaximin polymorph-α (alfa) is a non-absorbable antibiotic. OBJECTIVE: To investigate if pharmacokinetic of reference rifaximin (α) is different from a generic rifaximin of the Mexican market. MATERIAL AND METHOD: A prospective experimental study was done assessing polymorphism with X-ray diffraction, solubility test and pharmacokinetics in Beagle dogs after unique oral dose of 100 mg/kg of each rifaximin. RESULTS: Reference rifaximin was a polymorph-α (alfa), while generic rifaximin resulted a polymorph-к (kappa). Solubility profile of both was different, solubility of generic was major than reference rifaximin. Plasma peak concentration (Cmax), area under curve (AUC0-t) and relative bioavailability were 8 to 10 folds higher with generic rifaximin (к) than reference drug (α). CONCLUSION: Generic rifaximin has a different pharmacokinetic from the reference rifaximin and the former cannot be considered a non-absorbable antibiotic.

Solubility and transdermal permeation properties of a dehydroepiandrosterone cyclodextrin complex from hydrophilic and lipophilic vehicles.

The permeation ability of a compound is due principally to its concentration in the vehicle and to its aptitude to cross the stratum corneum of the skin. In this work ex-vivo permeation studies on newly developed formulations containing dehydroepiandrosterone (DHEA) were carried out to investigate vehicles that increase drug permeation through the skin. To enhance the solubility of DHEA, its complex form with alpha-cyclodextrin was used. In addition, the two forms (pure drug and complex form) were introduced in hydrophilic (water), lipophilic (paraffin oil), and microemulsion vehicles to evaluate the synergic effect of cyclodextrins and microemulsion vehicles on solubility and permeation. From the results, DHEA solubility is notably conditioned by the type of the vehicle used: the highest solubilities (both for pure and complex drug forms) were obtained with microemulsion, followed by paraffin oil and water. Moreover, in all the studied vehicles, the c-DHEA was more soluble than DHEA. Permeation profile fluxes showed very interesting differences. That reflect the varying drug forms (pure drug and complex form), vehicles used, and drug concentrations in the vehicles. The major flux was obtained in complex of DHEA with alpha-cyclodextrins in the microemulsion vehicle. Therefore, this type of vehicle and drug form would be very useful in the development of a topical formulation containing DHEA.

Skin permeation study of dehydroepiandrosterone (DHEA) compared with its alpha-cyclodextrin complex form.

Several studies have shown that dehydroepiandrosterone (DHEA) has promising uses in a large range of pathologies including age-related illnesses (osteoporosis, atherosclerosis), immune dysfunctions, and cancer. A long-term oral dosage form would be favorable, but this type of medication has not been developed yet because of the important first-pass effect and low and variable bioavailability. A proposed alternative strategy is the preparation of DHEA for transdermal permeation, allowing direct absorption in the systemic circulation. DHEA has shown good permeation properties through the stratum corneum, however its poor water solubility limits its dosage form concentration and represents the major obstacle to the formulation of a reservoir transdermal system. However, alpha-cyclodextrins have been shown to improve the solubility, the dissolution properties, and the partition coefficient of DHEA. This paper deals with the formulation and evaluation of a transdermal gel containing an alpha-cyclodextrin complex with DHEA. In in vitro permeation tests on porcine skin, the formulation containing the complex improved the permeation flux of DHEA. The study also shows that a gel formulation improved drug permeation with respect to simple water suspension.