Abstract
Glycyrrhizic acid, or glycyrrhizin (GA), a major active component of licorice root, has been widely used in traditional Chinese and Japanese medicine since ancient times. However, only in the last decades has a novel and unusual property of the GA been discovered to form water-soluble, supramolecular complexes with a variety of lipophilic drugs. These complexes show significant advantages over other known delivery systems, in particular, due to strong pH sensitivity, the properties of GA self-associates. In the present study, a supramolecular complex formation of the hypotensive and antiarrhythmic drug nifedipine with GA has been studied at different pH values, corresponding to the different degrees of GA dissociation, including a fully dissociated state of GA. Both NMR experiments and molecular dynamics simulations demonstrate the existence of the nifedipine complex with GA at all dissociation states of GA. However, optical absorption experiments show the decrease of complex stability and solubility at pH > 6 when the GA molecule is fully deprotonated. It means the higher release rate of the drug in a neutral and basic environment compared with acid media. These results could form the basis of follow-up studies of GA self-associates as pH-controlled drug delivery systems.
Highlights
Encapsulation of lipophilic drugs with different delivery systems is an innovative approach that increases their solubility, stability, and bioavailability
The shift of nifedipine signals corresponding to CH3 groups under the increase of GA concentration was detected (Figure 5b). This shift could be caused by the change of the nifedipine environment due to the formation of complexes with GA
Complex formation of the hypotensive drug nifedipine with glycyrrhizic acid was observed at different pH values, corresponding to the different degrees of GA dissociation, including a fully dissociated state of GA
Summary
Encapsulation of lipophilic drugs with different delivery systems is an innovative approach that increases their solubility, stability, and bioavailability. Another advantage of the encapsulation of drug molecules into nanosized delivery systems is their controlled release in the human body [1]. Targeting of drugs is a significant aspect of drug delivery systems It is classified into active and passive. G., pH of endosomes is 5.5–6.0; pH of lysosomes is 4.5-5.0) [8] For this reason, the pH-dependent behavior of a drug plays an important role in its functioning in the the pH-dependent behavior of a drug plays an important role in its functioning in the body. Effect glycyrrhizin observed, in particular, for nifedipine apeutic es 2021, 26, x FOR PEER REVIEW
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