Evaluation and Optimization of the Conditions for an Improved Ferulic Acid Intercalation into a Synthetic Lamellar Anionic Clay

Polymeric Bioadhesive Patch Based on Ketoprofen-Hydrotalcite Hybrid for Local Treatments

Ketoprofen (KET) represents one of the most common drugs used in the topical treatment of pain and inflammations. However, its potential is rather limited due to the very low solubility and photochemical instability. The local administration of KET by conventional products, such as gels, emulgels, creams, and foams, does not guarantee an efficacious and safe treatment because of its low absorption (due to low solubility) and its sensitivity to UV rays. The photodegradation of KET makes many photoproducts responsible for different adverse effects. In the present work, KET was intercalated into the lamellar anionic clay ZnAl-hydrotalcite (ZnAl-HTlc), obtaining the hybrid ZnAl-KET with improved stability to UV rays and water solubility in comparison to the crystalline form (not intercalated KET). The hybrid was then formulated in autoadhesive patches for local pain treatment. The patches were prepared by casting method starting from a hydrogel based on the biocompatible and bioadhesive polymer NaCMC (Sodium carboxymethycellulose) and glycerol as a plasticizing agent. The introduction of ZnAl-KET in the patch composition demonstrated the improvement in the mechanical properties of the formulation. Moreover, a sustained and complete KET release was obtained within 8 h. This allowed reducing the frequency of anti-inflammatory administration, compared to the conventional formulations.

Dynamics of Clay-Intercalated Ibuprofen Studied by Solid State Nuclear Magnetic Resonance

In designing drug delivery systems with improved release properties and bioavailability, the dynamic features of the active pharmaceutical ingredient can be crucial for the final product properties. In this work, we aimed at obtaining the first characterization of the molecular dynamic properties of one of the most common nonsteroidal anti-inflammatory drug, ibuprofen, intercalated in hydrotalcite, an interesting inorganic carrier. By exploiting a variety of solid state NMR techniques, including ¹H and ¹³C MAS spectra and T₁ relaxation measurements, performed at variable temperature and carrying out a synergic analysis of all results, it has been possible to ascertain that the mobility of ibuprofen within the carrier is remarkably increased. In particular, strong indications have been obtained that ibuprofen molecules, in addition to internal interconformational dynamics, experience an overall molecular motion. Also considering that ibuprofen is "anchored" to the charged surface of the hydrotalcite layers through its carboxylate moiety, such motion could be a wobbling-in-a-cone. Activation energies and correlation times of all the motions of intercalated ibuprofen have been determined.