Layered Silicate-Alginate Composite Particles for the pH-Mediated Release of Theophylline

Abstract

Numerous natural and synthetic clay minerals have proven to be excellent drug carriers for high drug-loaded and sustained release formulations due to their considerable ion exchange, adsorption, and swelling capacities. Moreover, the synthetic smectite clays have added advantages in terms of compositional purity and controlled cation exchange capacity in comparison to natural clays. This study involves the intercalation of theophylline (TP) in a synthetic clay, Laponite® (LP), followed by the inclusion of the resulting intercalates into sodium alginate (SA) beads to achieve pH-controlled drug release. Maximum intercalated drug incorporation of 68 mg/g was obtained by ion exchange at pH 1.2 and confirmed by an increase in basal spacing of the clay from 12.9 to 15.5 Å. TP release from the binary LP-TP intercalates in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was found to be 40% and 70%, respectively. LP-TP particles were also incorporated in an SA matrix via polymer crosslinking using CaCl2(aq) to improve the pH selective release. The ternary polymer-clay-drug composite particles effectively prevented the release of TP at low pH in SGF and resulted in sustained release in SIF, with 40% dissolution within 120 min.

Laponite‐Based Nanomaterials for Drug Delivery

“…[29,32,33] As described more extensively in Section 3.3.3, the capacity of Laponite to hold exchangeable cations is called the cation exchange capacity (CEC) which is an inherent characteristic of Laponite. [34] Another important physicochemical property of Laponite is its swellability, which depends not only on the cations present in the interlayer space, but also on the chemical potential of its aqueous solution (the potential to absorb or release energy based on the concentration of Laponite in the solution). [35] The dispersion, aggregation, or coagulation of Laponite can be changed by adjusting its concentration in an aqueous solution or the ionic strength of the solution itself.…”

“…This system bypassed the rapid release of the drug in the stomach and provided a prolonged release in the small intestine, increasing the efficacy of the drug and reducing the side effects. [ 34 ]…”

Laponite for biomedical applications: An ophthalmological perspective

“…This suggested Laponite to be beneficial in confining bacterial infection and inflammation [ 75 ]. In addition, anti-inflammatory agents such as theophylline and vitamin B12 were co-delivered [ 76 ], and dexamethasone exhibited sustained release in vitreous gel in rabbit eyes [ 48 ].…”

Tuning Compressive Young’s Moduli and Antibacterial Activities of Alginate/Poly(N-isopropylacrylamide) Hydrogels with Laponite Layers and Cerium Ions

“…The FTIR spectrum of LP RD shows a broad peak centered at 3400 cm –1 due to the O–H stretching vibrations of −SiOH groups and interlayer water molecules. The band at 990 cm –1 is due to the Si–O stretching vibration, while the peaks at 650 and 430 cm –1 correspond to Mg–O–Mg and Si–O–Mg bending, respectively. , …”

“…The band at 990 cm –1 is due to the Si–O stretching vibration, while the peaks at 650 and 430 cm –1 correspond to Mg–O–Mg and Si–O–Mg bending, respectively. 2 , 41 …”