1. What are the four main pharmacokinetic processes that determine the fate of a drug in the body? Explain how each process affects the drug concentration and action. - The four main pharmacokinetic processes are absorption, distribution, metabolism, and excretion. Absorption is the process of transferring the drug from the site of administration to the systemic circulation. Distribution is the process of delivering the drug to the tissues and organs. Metabolism is the process of transforming the drug into more polar and less active metabolites. Excretion is the process of eliminating the drug and its metabolites from the body. Each process affects the drug concentration and action by influencing the onset, duration, intensity, and variability of the pharmacological effects. 2. What are the factors that affect drug absorption? Give an example of each factor and explain how it influences the rate and extent of absorption. - The factors that affect drug absorption are physicochemical properties of the drug, formulation and route of administration, physiological factors, and pathological factors. For example, a drug with high lipid solubility, low molecular weight, and non-ionized form can cross biological membranes more easily and have faster and higher absorption. A drug given orally may have lower and slower absorption than a drug given intravenously due to the first-pass effect in the liver. A drug may have altered absorption in patients with gastrointestinal disorders, such as diarrhea, vomiting, or malabsorption syndrome. 3. What are the advantages and disadvantages of oral route of administration? Name two types of oral formulations and explain how they differ in terms of absorption and bioavailability. - The advantages of oral route of administration are convenience, safety, low cost, and suitability for sustained-release formulations. The disadvantages are variability, slow onset, first-pass effect, gastric irritation, food-drug interactions, and patient compliance. Two types of oral formulations are tablets and capsules. Tablets are solid dosage forms that contain one or more active ingredients compressed or molded into a shape. Capsules are gelatin shells that enclose a powder, liquid, or granule. Tablets may have different coatings or disintegrants that affect their dissolution and absorption. Capsules may have different sizes or materials that affect their dissolution and absorption. Generally, capsules have faster and higher absorption and bioavailability than tablets. 4. What is the difference between plasma protein binding and tissue binding of drugs? How do they affect drug distribution and elimination? - Plasma protein binding is the reversible attachment of drugs to plasma proteins, such as albumin or globulins. Tissue binding is the reversible or irreversible attachment of drugs to tissues or organs, such as fat, bone, or brain. Plasma protein binding affects drug distribution by limiting the free fraction of drug that can diffuse across capillary walls and reach the target site. Plasma protein binding also affects drug elimination by prolonging the half-life and reducing the clearance of drugs. Tissue binding affects drug distribution by creating a reservoir or depot for drugs that can maintain a prolonged effect or cause toxicity. Tissue binding also affects drug elimination by delaying the elimination of drugs from the body. 5. What is biotransformation? What are the two main phases of biotransformation? Give an example of each phase and explain ho w it changes the chemical structure and activity of drugs. - Biotransformation is the process of converting drugs into more polar and less active metabolites that can be excreted by the kidneys. The two main phases of biotransformation are phase I and phase II reactions. Phase I reactions are oxidation, reduction, or hydrolysis reactions that introduce or expose a functional group on the drug molecule. Phase II reactions are conjugation reactions that attach a polar molecule to the functional group on the drug molecule. For example, acetaminophen undergoes phase I oxidation by cytochrome P450 enzymes to form N-acetyl-p-benzoquinone imine (NAPQI), which is a toxic metabolite that can cause liver damage. NAPQI then undergoes phase II conjugation with glutathione to form a nontoxic metabolite that can be excreted in urine. 6. What are the factors that affect drug metabolism? Give an example of each factor and explain how it influences the rate and extent of metabolism. - The factors that affect drug metabolism are genetic fa