Ch. 1-4 Flashcards
3 Most Important Properties of an Ideal Drug
- effectiveness: most important
- safety: no harmful effects
- selectivity: drug elicits only the response for which it is given
5 Rights
- drug
- patient
- dose
- time
- route
Pre-admin Assessment
- collection of baseline data to evaluate therapeutic and adverse effects
- identify high–risk patients
- assess of patient’s capacity for self-care
Application of Pharm in Patient Care
- pre-admin assessment
2. dosage and admin
3. evaluating and promoting therapeutic effects
4. minimizing adverse effects
5. minimizing adverse interactions
6. making PRN decisions
7. manage toxicity
P-glycoprotein
- transports a wide variety of drugs out of cells
Passage of Drugs Across Membranes
- to directly penetrate, must be lipophilic
- polar molecules: uneven distribution of a charge; no net charge
- ions: molecules that have a net electrical charge
- Quats: contain at least one atom of nitrogen and carry a positive charge at all times
- pH-dependent ionization: acid is proton DONOR (ionize in basic media); base is a proton ACCEPTOR (ionize in acidic media)
Ion Trapping
- acidic drugs accumulate on alkaine side
- basic drugs accumulate on acidic side
Absorption
- rate= how soon effects will begin
- amount= how intense the effects will be
- rate of diffusion, surface area, blood flow, lipid solubility, and pH partitioning
First Pass Effect
- metabolism of a drug and its passage from liver into circulation
- ex. oral route- could be extensively metabolized by liver before reaching the systemic circulation
- ex. IV bypasses liver, preventing first-pass effect and more drug reaches circulation
Distribution
- blood flow to tissues
- exiting the vascular system
- entering cells
Blood Flow to Tissues
- blood flow determine rate of delivery
- abscesses and tumors: low regional blood flow affects therapy, pus-filled pockets rather than internal blood vessels, solid tumors have a limited blood supply
Exiting Vascular System
- typical capillary beds: drugs pass between capillary cells rather than through
BBB
- tight junctions
- lipid soluble or have a transport system can cross BBB
Placental Drug Transfer
- membranes do NOT constitute an absolute barrier
- birth defects: mental retardation, gross malformations, low birth weight
Protein Binding
- can form reversible bonds with proteins
- albumin is most abundant; large molecule always remains in blood stream
Entering Cells
- binding with receptors on external surface of cell membrane
- do not need to cross the membrane to act
Hepatic Drug-Metabolizing Enzymes
- most that takes place in liver, also known as P450 system
- does not always result in a smaller molecule
Therapeutic Consequences of Drug Metabolism
- accelerated renal drug excretion
- drug inactivation
- increased therapeutic action
- activation of prodrugs
- increased or decreased toxicity
Enterohepatic Recirculation
- repeating cycle in which drug is transported
- limited to drugs that have undergone glucronidation
Renal Routed of Drug Excretion
- glomerular filtratoin, passive tubular reabsorption, active tubular secretion
- factors that modify renal drug excretion: pH-dependent ionization, competition for active tubular transport, and age
Time Course of Drug Response
- Plasma drug levels: minimum effective concentration and toxic concentration (therapeutic range)
- single-dose time course: duration of effects is determined by the combination of metabolism and excretion; for drug levels to min. effective dose, therapeutic response will be maintained
- drug half-life: time required for the amount of drug in the body to decrease by 50%, percentage vs. amount, determine the dosing interval
- drug levels produced with repeated doses: plateau drug levels are achieved, time to plateau, techniques for reducing fluncuations in drug levels, loading doses vs maintenance doses, and decline from plateau
