Basic & Clinical Pharmacology Questions Complete Marking Scheme

Basic & Clinical Pharmacology Questions Complete Marking Scheme Pharmacodynamics - ANSWER- what the drug does to the body - ANSWERPD & PK - ANSWER- Relationship between dose & effect can be due toRelationship between dose & effect can be due to: Pharmacokinetics - ANSWER- what the body does to the drug ADME (Components of PK) - ANSWER- Absorption Distribution Metabolism Elimination Absorption - PK - ANSWER- Movement of substance from site of administration, across body membranes, to circulation distrubution - ANSWER- Transport of drugs throughout the body into the interstitial and intracellular fluids Metabolism - ANSWER- Chemically converting a drug to a form that is readily removed by the body Elimination/Excretion - ANSWER- Metabolite removed from body Absorption: PK DDIs - ANSWER- Change in pH; Adsorption; Change in GI motility Distribution- PK DDIs - ANSWER- Change in albumin concentration; protein binding interactions Metabolism- PK DDIs - ANSWER- CYP450 Elimination- DDIs - ANSWER- Change in renal excretion Bioavailability - ANSWER- A measure of the extent of drug absorption for a given drug and route (from 0% to 100%). Factors that influence bioavailability: - ANSWER- - first pass metabolism - solubility of drug - chemical instability - drug formulation First Pass Effect - ANSWER- a phenomenon in which drugs given orally are carried directly to the liver after absorption, where they may be largely inactivated by liver enzymes before they can enter the general circulation; oral drugs frequently are given in higher doses than drugs given by other routes because of this early breakdown Bioequivalence drugs: - ANSWER- Share similar rate and extent of absorption Therapeutic Equivalence - ANSWER- Similar drugs in efficacy and safety active transport - ANSWER- Movement of chemical against a concentration or electrochemical gradient; Requires ENERGY from the cell passive diffusion - ANSWER- movement of chemical from area of high concentration to low concentration (HIGH TO LOW); Occurs passively- cell allows it to just happen Endocytosis - ANSWER- Engulfment of drug molecule by cell membrane and transport into the cell; Transports large molecules Factors of drug absorption - ANSWER- - molecular weight & size - dose - route of admin - digestive motility - blood flow - lipid solubility - degree of ionization - partition coefficient Factors influencing GI absorption - ANSWER- - Blood flow - pH - Intestinal Surface area (microvilli) - Contact time with absorptive surface Most drugs are absorbed from: - ANSWER- Lower GI tract Increased peristalsis - ANSWER- = increased drug transit time & DECREASED time for absorption Decreased peristalsis - ANSWER- = decreased transit time & INCREASED time for absorption Distribution of drug delivery - ANSWER- Process in which a drug reversibly leaves blood stream and enters interstitum and/or cells Drug delivery is dependent on: - ANSWER- - Affinity - Blood Flow - Capillary permeability - Drug-protein complexes/competence - Drug Structure - Drug/Food interactions - Hydrophobicity capillary permeability - ANSWER- condition of the capillary wall that enables substances in the blood to pass into tissue spaces or into cells, or visa versa; absent in the brain "Blood-Brain Barrier" Drug Structure - ANSWER- Chemical nature of the drug largely determines ability to cross cell membranes Hydrophobic Drugs - ANSWER- Lipid (fat) soluble drugs that penetrate the lipoidal (fatlike) cell membrane better than hydrophilic drugs. Hydrophilic drugs - ANSWER- Do not easily pass through cell membranes; need slit junctions for passage; "LIKE WATER" Blood Brain Barrier (BBB) - ANSWER- Drugs must pass through endothelial cells of the CNS capillaries or be actively transported; Lipid- soluble drugs are able to penetrate; Ionized or polar drugs cannot pass without slit junction