Magnesium Aluminometasilicate
An exceptional excipient for nano drug delivery systems
Suryakanta Swain, Amity Institute of Pharmacy, Amity University Kolkata
Apala Chakraborty, Amity Institute of Pharmacy, Amity University Kolkata
Magnesium aluminometasilicate is a water-insoluble excipient used in pharmaceutical preparations. It has a high degree of porosity and liquid and oil adsorption capacity. In comparison to other excipients.It protects and stabilises the adsorbed drug component, as well as increases the bioavailability of poorly water-soluble drugs.
Applications in nanodrug delivery system
This Magnesium aluminometasilicate (Al2O3·MgO·1.7SiO2·xH2O) has a wide range of uses in pharmaceutical formulation design, including tablet binder/disintegrant in solid dosage form, fluidity enhancing agent, adsorber, and stabiliser in the manufacture of self-emulsifying and liquisolid drug delivery systems. In recent study, magnesium aluminometasilicate has been employed as a nanocarrier in nano drug delivery systems, with encouraging results (Gupta et al., 2003; El-Say et al., 2023).
Adsorbent
The shortcomings of the nanoemulsion technology, such as stability and handling issues, can be reduced by converting it to solid dosage form. According to several recent publications, transforming self-nano emulsifying drug delivery systems (SNEDDS) into solid-SNEDDS via adsorption, freeze drying, and spray drying improves the formulation's self-life, simplifies the processability, and scalability (Date et al., 2010). Magnesium aluminometasilicate is an effective liquid adsorbent due to its practical shape (Khalid et al., 2023). The high surface area of magnesium aluminometasilicate allows for equal adsorption of oil and liquid while maintaining good flow properties (Friedl et al., 2021). Aluminometasilicate's microstructural characteristics have been observed to change when a drug particle is incorporated. The increased basal spacing during drug intercalation in the silica layers of the aluminometasilicate is the most likely mechanism of adsorption (Totea et al., 2020). Aluminometasilicate has a better adsorption capacity than other excipients, such as anhydrous dibasic calcium phosphate, since it has nearly 7.5 times more surface area and forms a stronger connection with the medication. The interacting silanol group on the outer side of silicates forms hydrogen bonds with the protons of drug molecules, which is not seen in calcium phosphate (Kutza et al., 2013).
Solubility enhancer
Drugs that are poorly water soluble can be improved by dispersing them on aluminometasilicate. Amorphous solid dispersion of poorly water-soluble medicines in a polymeric matrix enhances particle dissolution. Preparing nanometric solid dispersion ensures faster dissolving and higher bioavailability. Dispersing a medication in amorphous aluminosilicate produces a stable solid dispersion with improved solubility in the 200-400 nm range (Censi et al., 2016). This increased solubility is owing to the greater effective surface area of the excipients over which the medication would be dispersed, which promotes rapid desorption of the poorly water-soluble pharmacological molecule (Sruti et al., 2013).
Stability modifier
Adsorbing pharmaceuticals into amorphous mesoporous materials to increase stabilisation has gained popularity over the last decade because of their numerous benefits. This amorphous material (such as magnesium aluminometasilicate) is inert, has smaller pore diameters of 2 and 50 nm, and unidirectional networking of the mesoporous substance, which helps to suppress the conversion of entrapped drug moiety from amorphous to crystal nature via geometrical constraint method (Azad et al., 2018). According to certain findings, the inclusion of harmless, inert magnesium aluminometasilicate helps to avoid drug desorption into packaging materials. This reduces the interaction between the medicine and the packaging materials, improving the stability of the drug substance. Co-grinding the medication with magnesium aluminometasilicate, which has an adjustable pore size and modifiable surface, increases the drug's physical stability by causing amorphization. It has also been shown that at higher temperatures, drug-magnesium aluminometasilic can form a less volatile and more stable version of the drug excipient complex (Krupa et al., 2010).
Bioavailability enhancer
Improving the bioavailability of weakly water-soluble medicines ensures plasma profile consistency, a reduction in medication dose, and the associated side effects. Improved oral bioavailability can be achieved through a variety of methods, including the development of a self-nanoemulsifying drug delivery system (Udaya et al., 2013). Magnesium aluminometasilicate has been shown to increase medication bioavailability as a nano carrier (Kolammanahalli et al., 2015). The presence of silanol groups on the surface of magnesium aluminometasilicate, which acts as a proton donor cum acceptor, improves drug release in acidic mediums even at low magnesium aluminometasilicate concentrations. Table 1 displays the various grades of magnesium aluminometasilicate, their physiochemical characteristics, and pharmaceutical uses.
Modification for improved functionality
Though magnesium aluminometasilicate shows a promising result as pharmaceutical excipients, the desorption of lipophilic drug from the excipient slowed down with time as observed during the stability study. This problem can be minimised by magnesium aluminometasilicate with polyvinyl alcohol. Polyvinyl alcohol can block the mesoporous area of the silicate, ensure hydration and emulsification of adsorbed oil, followed by better release of the drug from the formulation even after long-term storage (Gumaste et al., 2017). Further, the crosslinking of magnesium aluminometasilicate with sodium alginate, create a thixotropic gel network in drug loaded nanocomposite microbeads with optimum thickness to control release of the drug in intestinal pH environment (Kolammanahalli et al., 2017).
The above-mentioned characteristics of magnesium aluminometasilicate make the product suitable for dispersion of nano drug delivery systems, as observed in various preclinical research as mentioned below in Table 2.
Conclusion
Due to the inertness and safeness, magnesium aluminometasilicate is acceptable by US-FDA and specified in monographs like USP/NF and JPC. The non-reactive nature of the polymer makes it highly stable, and the self-life of the material is 3 years. Furthermore, this excipient has proved its non-interactive nature with a wide range of drug substances including antibiotics, oily drugs, hydrophobic drugs, herbal products, vitamins, etc. Preclinical data suggested as magnesium aluminometasilicate is a very promising adsorbing excipient for BCS class-II as well as Class-IV drugs and have ampoule possibility in successful delivery of nano formulations which need to be explored further in future.
References:
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Author Bio
Prof. (Dr.) Suryakanta Swain is currently a Professor and Head of the Institution at Amity Institute of Pharmacy, Amity University Kolkata, West Bengal, India. Dr. Swain has authored 140 article publications, 45 books/book chapters, and 3 Indian patents. He has received numerous research funding, prizes/awards, and is a member of several professional groups.
Dr. Chakraborty is currently a Asst. Professor at Amity Institute of Pharmacy, Amity University Kolkata, West Bengal, India. Dr. Chakraborty has authored 7 publications, and 7 book chapters and 1 book. She has nearly 5 years of experience in Industrial Formulation & Development. She has received scholarship, prizes, and is a member of several professional groups.
