Lehne's Pharmacology Chapter 4 Review Questions And Correct Answers

Lehne's Pharmacology Chapter 4 Review Questions And Correct Answers Pharmacokinetics is derived from what two Greek words? pharmakon (drug or poison) kinesis (motion) Pharmacokinetics is... the study of drug movement throughout the body. Also includes drug metabolism and drug excretion. Four basic pharmacokinetic processes: Absorption Distribution Metabolism Excretion Absorption is defined as... the movement of a drug from its site of administration into the blood. Metabolism (bio-transformation) is defined as... enzymatically medicated alternation of drug structure Distribution is defined as... drug movement from the blood to the interstitial space of tissues and from there into cells. Excretion is... the movement of drugs and their metabolites out of the body. The combination of metabolism plus excretion is called... elimination. The intensity of the response to a drug is directly related to... the concentration of the drug at its site of action. Three ways to cross a cell membrane 1) Passage through channels or pores. Very few drugs can do this due to the extremely small size required. Examples: small ions such as potassium and sodium. 2) Passage with the aid of a transport system. Carriers move drugs from one side of the cell membrane to the other. All transport systems are selective - will carry a drug depending on it's structure. 3) Direct penetration of the membrane itself. Drugs that are lipid soluble can penetrate membranes and do not require transport. P-Glycoprotein A well known multi-drug transporter protein. Transports a wide variety of drugs out of cells. - Liver - transports drugs into the bile for elimination - Kidney - pumps drugs into urine for excretion - Placenta - transports drugs back to maternal blood - Intestine - transports drugs into intestinal lumen - Brain - pumps drugs into the blood Polar molecules are... molecules with uneven distribution of electrical charge. They have no net charge and can dissolve in polar solvents (water) but not non-polar solvents (oil). They are unable to cross membranes unassisted. Ions are... molecules that have a net electrical charge (either positive or negative). Most are unable to cross membranes. Quaternary Ammonium Compounds are... molecules that contain at least one atom of nitrogen and carry a positive charge at all times. Unable to cross most membranes. Whether a weak acid or base carries a charge is determined by... the pH of the surrounding medium An acid is... a compound that can give up a hydrogen ion (proton) - a proton donor. A base is... a compound that can take on a hydrogen ion - a proton acceptor. Ionization is... the process of an acid giving up a proton or a base accepting a proton which converts the acid or base into a charged particle (ion). Acids tend to ionize in... basic (alkaline) media Bases tend to ionize in... acidic media When there is a pH gradient between two sides of a membrane, acidic drugs will ________ and basic drugs will ______. When there is a pH gradient between two sides of a membrane, acidic drugs will accumulate on the alkaline side and basic drugs will accumulate on the acidic side. Ion trapping or pH partitioning is... the process whereby a drug accumulates on the side of a membrane where the pH most favors its ionization.