1. What are the main differences between pharmacokinetics and pharmacodynamics? How do they affect drug dosing and efficacy? - Pharmacokinetics is the study of how drugs are absorbed, distributed, metabolized and excreted by the body. Pharmacodynamics is the study of how drugs interact with their targets and produce their effects. Pharmacokinetics and pharmacodynamics affect drug dosing and efficacy by determining the optimal dose, frequency, route and duration of administration, as well as the therapeutic range, side effects, interactions and variability of response. 2. What are the four phases of clinical trials for new drugs? What are the main objectives and challenges of each phase? - Phase I trials are the first human studies of a new drug, usually involving a small number of healthy volunteers. The main objective is to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of the drug. The main challenge is to identify the maximum tolerated dose and dose-limiting toxicities. - Phase II trials are the first studies of a new drug in patients with the target disease or condition, usually involving a larger number of participants. The main objective is to assess the efficacy, safety, optimal dose and schedule of the drug. The main challenge is to demonstrate a statistically significant and clinically meaningful benefit over placebo or standard treatment. - Phase III trials are the large-scale studies of a new drug in patients with the target disease or condition, usually involving thousands of participants in multiple sites and countries. The main objective is to confirm the efficacy, safety, cost-effectiveness and comparative advantage of the drug over existing treatments. The main challenge is to ensure the validity, reliability and generalizability of the results. - Phase IV trials are the post-marketing studies of a new drug after it has been approved by regulatory agencies, usually involving a large number of patients in real-world settings. The main objective is to monitor the long-term safety, effectiveness, quality of life and adverse events of the drug. The main challenge is to detect rare or delayed complications, interactions or outcomes that may not have been observed in previous phases. 3. What are the main types of adverse drug reactions (ADRs)? How can they be prevented, detected and managed? - ADRs are any unwanted or harmful effects caused by a drug. They can be classified into two main types: type A (augmented) and type B (bizarre). Type A reactions are dose-dependent, predictable and related to the pharmacological action of the drug. They can be prevented by adjusting the dose according to individual factors such as age, weight, renal function, liver function, etc. They can be detected by monitoring clinical signs and symptoms, laboratory tests and biomarkers. They can be managed by reducing or stopping the drug, administering antidotes or supportive measures, etc. Type B reactions are dose-independent, unpredictable and unrelated to the pharmacological action of the drug. They can be prevented by identifying risk factors such as genetic predisposition, allergies, co-morbidities, etc. They can be detected by reporting suspected cases to pharmacovigilance systems or registries. They can be managed by discontinuing the drug, treating symptoms or complications, administering immunosuppressants or desensitization agents, etc.