**1. Introduction to herbal formulations**

Plant-based treatments are crucial in achieving Sustainable Development Goal 3 (SDG 3) to ensure healthy lives and promote well-being. Integrating effective and safe herbal medical systems with traditional pharmaceutical systems can significantly enhance essential healthcare services. A survey conducted in Germany revealed that various age groups opt for herbal remedies due to dissatisfaction with allopathic treatments, the synergistic effects of medicinal plants, historical usage, and unique knowledge [1]. In the face of emerging diseases like SARS-COV-2 and mycosis, interest in phytotherapy has been rekindled to strengthen the healthcare system and combat the ongoing epidemic. Immunity-boosting plants, herbal remedies, and AYUSH compositions are being considered as preventive measures. Specific botanical formulations include the aqueous solution of Guduchi and pippali, AYUSH 64, and Guduchi aq. extracts have shown promise for mild to moderate and asymptomatic COVID-19 patients [2]. Ashwagandha and Guduchi extracts are also recommended for preventive use against COVID-19, with Withaferin A potentially acting as a therapeutic agent to inhibit viral spread. However, further research is needed to determine the long-term safety and optimal dosage [3]. Currently, herbal medicines straddle the line between conventional drugs and food. This chapter elucidates their historical significance, integration into modern healthcare, and metabolic and pharmacokinetic profiles within the human body.

## **1.1 Importance of understanding herbal formulations' metabolism and pharmacokinetics**

Researchers are increasingly curious about the impact of herbal formulations on metabolism and pharmacokinetics. Pharmacokinetics (PK), a newly developed approach, is instrumental in studying drug absorption, distribution, metabolism, and excretion in vivo. When combined with other techniques, PK helps determine the active components of medicinal plants [4–6]. Pharmacokinetic measures like biological half-life, clearance, and AUC reveal dynamic processes of these components in vivo. Contrasting pharmacokinetic parameters aids in understanding their characteristics [7, 8]. This has three benefits: precise explanation of herbal formulation effects

#### **Figure 1.**

*Representation of pharmacokinetics studies of active constituents via in vivo. Cmax, maximum plasma concentration; MTC, minimum toxic concentration; Tmax, time to Cmax; AUC, area under curve; MEC, minimum effective concentration.*

by identifying components, clarifying interactions of active substances (**Figure 1**), and demonstrating dynamic actions of active ingredients in vivo (**Figure 1**). These discoveries support the clinical use and understanding of medicinal plants.

Researchers discovered how the active components in medicinal plants produce their therapeutic benefits by thoroughly examining them. For instance, artemisinin was employed as a malaria preventative. Rhein, geniposide, and 6,7-dimethylesculetin were successful treatments for hepatic damage syndrome. Nonbacterial prostatitis was treated with berberine. Additionally, research employing PK has helped us to better understand the dynamic mechanisms of the active components of medicinal plants in vivo [2, 3], shown in **Figure 1**.
