The capacity and effectiveness of diosmectite and charcoal in trapping the compounds causing the most frequent intoxications in acute medicine: A comparative study

Montmorillonite promoted photodegradation of amlodipine in natural water via formation of surface complexes

The photolysis of amlodipine (AML) as a ubiquitous pollutant in natural water has been extensively studied. Montmorillonite (MMT), a major component of suspended particles in surface aquifers, plays key roles in the natural transportation and transformation of organic contaminants in the environment. However, literature has scarcely focused on whether and how suspended particles affect the phototransformation of AML. This study systematically investigated the phototransformation behavior of AML in MMT suspensions under simulated sunlight. The results obtained showed that MMT significantly enhanced the photolysis of AML. The photodegradation of AML in 0.05 g/L MMT suspension reached 92.2 % after 3 h irradiation under the simulated sunlight. The photodecomposition followed the pseudo-first-order kinetic with a rate constant of 0.803 h^-1 in the presence of 0.05 g/L MMT, which is about 19 times larger than that in the absence of MMT (0.0421 h^-1). Further mechanistic investigation suggested that MMT accelerated the photolysis of AML by the formation of surface complexes between cationic amino groups of AML and the negatively charged sites on MMT surface, which greatly facilitated light absorption and electron transfer for the production of cationic radical AML^+·. Meanwhile, the hydroxyl radicals generated by irradiated MMT also played an important role in the photocatalytic degradation of AML. The probable photodegradation pathways of AML in MMT suspension further supported the proposed mechanisms. The toxicity evaluation of phototransformation products of AML with ECOSAR program indicated that photolysis could reduce its potential threats. These findings reveal an important and previously overlooked phototransformation mechanisms of AML in the presence of MMT clays, which is of importance in assessing the environmental fate of other similar organic contaminants.

Intercalated theophylline-smectite hybrid for pH-mediated delivery

On the basis of their large specific surface areas, high adsorption and cation exchange capacities, swelling potential and low toxicity, natural smectite clays are attractive substrates for the gastric protection of neutral and cationic drugs. Theophylline is an amphoteric xanthine derivative that is widely used as a bronchodilator in the treatment of asthma and chronic obstructive pulmonary disease. This study considers the in vitro uptake and release characteristics of the binary theophylline-smectite system. The cationic form of theophylline was readily ion exchanged into smectite clay at pH 1.2 with a maximum uptake of 67 ± 2 mg g-1. Characterisation of the drug-clay hybrid system by powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and scanning electron microscopy confirmed that the theophylline had been exclusively intercalated into the clay system in an amorphous form. The drug remained bound within the clay under simulated gastric conditions at pH 1.2; and the prolonged release of approximately 40% of the drug was observed in simulated intestinal fluid at pH 6.8 and 7.4 within a 2-h timeframe. The incomplete reversibility of the intercalation process was attributed to chemisorption of the drug within the clay lattice. These findings indicate that smectite clay is a potentially suitable vehicle for the safe passage of theophylline into the duodenum. Protection from absorption in the stomach and subsequent prolonged release in the small intestine are advantageous in reducing fluctuations in serum concentration which may impact therapeutic effect and toxicity.