**3.3 Higher photo- and thermal stability**

Another important signature of these excipients is their influence on the chemical stability of pharmaceuticals. Whenever any drug formulation has to be developed, stability parameters and the factors affecting the stability parameters should be kept in mind, and appropriate stability enhancers should be added as per the requirements. CDs are widely known for their capability to reduce the effect of temperature, light, and oxygen, thereby increasing the overall stability [29, 30]. Degradation of the product in the presence of light can lead to the several adverse effects. Higher photo stability was found when a complex of CD and vitamin E was formed. Apart from the protective effect of CD stability, studies are also important to discover the degree to which any formulation can be prevented from the excipient mediated degradation [31].

## **3.4 Improved drug safety**

When CDs increase the solubility, dissolution, and bioavailability of the drugs [28], it means that drug will have the required residence time in the body and will not stay longer, thus reducing the risks of toxic effects [32]. A research was conducted on an anti-viral drug ganciclovir combined with CD, and it was found that toxic effects of the drug were reduced and efficacy was significantly improved. Similarly, irritation caused by both intravenous and ophthalmic products can also be reduced by CDs [33].

### **3.5 Control of drug release**

CDs having ethyl group and acyl group have the potential to prolong drug release [34]. One alternative for controlling drug release is to utilize the epithelial surface of GIT in which per-Obutanoyl *β*-CD is known for its mucoadhesive property. HP-*β*-CDs are being utilized for their gel forming property, thus can extend the release of drug. In controlled drug delivery systems, osmotic pumps are widely utilized as they are unique and provide the uniform concentration of drug in the systemic circulation [35]. Advanced forms of extended delivery systems can be developed by joining the CD conjugates with respective release formulations. This effect was seen when ketoprofen having *β*-CD was combined with ketoprofen, and this formulation was added in CD conjugates, which provided a repeated release profile [36, 37].
