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What are 6 factors that influence the rate of absorption of a drug?
- degree of ionization and pH of tissue
- formulation of the drug (liquid or solid)
- drug's concentration
- circulation to the area
- area of absorptive surface
- route of administration
do liquid or solid formulations of drugs result in an increased rate of absorption of a drug (and more rapid onset of action)?
__________ formulations delay dissolution of tablets until they have moved from the stomach into the upper small intestine, reducing the adverse gastric side effects
are high or low concentrated drugs absorbed faster?
The greater the blood flow to the tissue, the ______ the rate of absorption. What are 3 organs with significant blood flow?
What are the 2 classifications of routes of administration of drugs?
what type of drugs are placed directly into the GI tract by oral or rectal administration and must pass through the liver before distribution to the site of action?
what type of drugs bypass the GI tract and include various injection, inhalation, and topical routes?
What are 5 features of the oral route of drug administration?
- safest route
- most common route
- most conveniente route
- most economical route
- most unpredictable route
What are 6 factors that influence drug absorption rate when it is administered enterally?
- inherent characteristics of the drug
- pH of GI tract
- presence of food in the stomach
- gastric motility
- degree of splanchnic blood flow (blood flow through intstinal viscera)
- patience compliance in taking the prescribed drug regime
the close anatomical relationship between the liver and the GI tract and the abundant blood supply of these organs has important effects on the bioavailabiliyt of some drugs; the liver is situated between enteric sites of absorption and systemic circulation, so it can provoundly influence the amount of drug in circulation when the drug is administered orally
The first-pass effect may _______ concentration of drug molecules
What are 5 ways that parenteral drugs can be administered?
- intravenous (IV)
- subcutaneous (SC)
- intramuscular (IM)
What are 5 features of the IV route of drug administration?
- bypasses absorption; causing immediate effect
- most predictable route
- used in emergency situations
- less safe than oral route
- injection site reactions are possible
drug distribution is achieved primarily through the ___________ system. In most cases, the therapeutic effect of a drug in tissues correlates well with the concentration in the _________.
___________ may affect the duration of a drug effect
a nonselective process of the distribution of drugs. it tends to reduce the availability of drugs for diffusion into target organs because, in general, only the free or unbound drug is capable of crossing biologic membranes.
plasma protein bonding
the distribution of drugs to the CNS and cerebrospinal fluid is restricted by what?
In pregnant women, drugs pass across what by simple diffusion, and the result is that the fetus becomes medicated along with the mother
placenta as a barrier
rarely does a drug enter the body and leave it without some sort of modification. The majority of this process happens in the liver
biotransformation has 2 phases, and can alter drugs in what 4 ways?
- convert an active drug into an inactive drug
- convert an active drug into an active or toxic metabolite
- convert an inactive drug to an active drug
- convert an unexcretable drug into an excretable metabolite
In what phase of biotransformation is a drug's chemical structure modified through oxidation, reduction or hydrolysis which requires very little energy and the most commonly used pathway is the hepatic microsomatl cytochrome
Phase I reactions
In what phase of biotransformation is the chemical structure of a drug modified by conjugation to a large polar endogenous molecule, and almost always results in inactivation of the parent drug?
phase II reactions
what system can be induced to increase drug metabolism or inhibited to reduce the rate of a drug's metabolism and is responsible for many adverse drug-drug interactions?
the CYP450 enzyme system
__________ excretion is the most common and important mechanism of drug elimination from the body. Biotransformation prepares the molecule, and the kidney eliminates it via urination
What is the primary location for drug elimination to occur?
what depends on renal blood flow, ____ ______ rate, and plasma protein binding, and contributes to reduced drug elimination?
________ _____________ __________ facilitates the movement of the drug from the blood stream into the renal tubular fluid by a nonselective carrier system for organic ions.
active tubular secretion
______ ________ reabsorption of nonionized drugs results in net passive reabsorption. many drugs exhibit pH trapping in the distal tubules and are efficiently eliminated in the urine
What are 3 other ways that drugs can be excreted from the body besides glomerular filtration in the kidneys?
- enterohpatic recirculation
- other mechanisms
some metabolites formed in the liver are excreted via the bile into the intestinal tract to be eliminatede in the feces. if these metabolites are subsequently hydrolyzed and reabsorbed from the gut, drug action can be restablished; is describing what?
pulmonary excretion is important for the elimination of anesthetic gases and vapors; is describing what?
true or false. drugs can be excreted in lactation and are potential sources of unwanted pharmacologic effects in nursing infants
the rate of exponential kinetics may be expressed by its constant (k), the fractional change per unit time, or it's ______ (expressed as t1/2)
What is the time required for the plasma concentration of a drug to decrease by 50%
following the administration of multiple therapeutic dosages of a drug at time intervals equal to or shorter than the drug's half-life, a plateau level of drug accumulates; this is called what?
How many half lifes does it take to eliminate a drug?
a constant amount of the drug is eliminated per unit of time