Clinical evaluation of a drug in humans is a systematic process conducted to ensure the safety, efficacy, and quality of a new pharmaceutical compound before it is approved for general medical use. This process is an essential component of drugs regulatory affairs, as regulatory authorities require scientific evidence from human studies before granting marketing authorization. Clinical evaluation is usually divided into several phases, commonly known as Phase I, Phase II, Phase III, and Phase IV trials. Each phase serves a specific purpose and involves increasing numbers of human subjects, beginning with a small group of healthy volunteers and eventually expanding to large patient populations. Phase I clinical trials represent the first stage of testing a new drug in humans. These trials are primarily focused on evaluating the safety profile of the drug rather than its therapeutic effectiveness. Phase I studies usually involve a small number of healthy volunteers, typically between 20 and 100 participants. The main objectives include determining the maximum tolerated dose, identifying potential side effects, studying pharmacokinetics, and understanding how the drug is absorbed, distributed, metabolized, and excreted from the human body. Researchers closely monitor participants to observe any adverse reactions. Dose escalation studies are commonly conducted during this phase, where subjects are given gradually increasing doses of the drug to identify safe dosage limits. The information obtained from Phase I trials is critical for planning subsequent clinical phases. Phase II clinical trials are conducted after establishing preliminary safety data from