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Pharmacology wk#1 test#1
Week #1 Notes
Terms in this set (66)
What does pharmacotherapeutics mean?
pharmacotherapeutics deals with the use of drugs in the prevention and treatment of disease.
what is a drug?
any chemical that can affect living processes.
the study of drugs and their interactions with living systems.
the study of drugs in humans
also known as pharmacotherapeutics, is defined as the use of drugs to diagnose, prevent, or treat disease or to prevent pregnancy.
what are the three most important characteristics that any drug can have?
Effectiveness, safety, and selectivity.
What is an effective drug?
an effective drug is one that elicits the responses for which it is given.
What/How is a safe drug?
A safe drug is defined as one that cannot produce harmful effects, even if administered in very high doses and for a very long time.
A selective drug is defined as one that elicits only the response for which it is given. It would not produce side effects. There is no such thing as a selective drug.
what legal regulations govern nursing's role in pharmacotherapy?
Idaho board of nursing, Idaho board of pharmacy, and Idaho board of medicine.
What rules must be followed under the controlled subtances act?
Restricts prescription refills. Tracks prescriptions, dispensing, and purchase of listed subtances. Substances listed based on abuse potential (Schedules I-V)
high abuse potential, no approved medical use (heroin, LSD, marijuana, etc)
written RX required, no automatic refills (most oioids-morphine, codeine, etc)
May be oral or written Rx, refill up to 5 times, within 6 months fo origial order.
may be dispensed without Rx by pharmacist, to adults. (e.g., pseudoephedrine (sudafed) limited in some states)
Which schedule of drugs are kept in locked cabinets and must be signed out and periodically counted to keep track of use?
diverting it from where it belongs
What is the impact of the body on drugs?
What does pharmacokinetics deal with?
It deals with the absorption, distribution, biotransformation (metabolism), and excretion of drugs. These gfactors, coupled with dosage, determine the concentration of a drug at its site of action, and hence, the intesity of its effect as a function of time.
What is the impact of drugs on the body?
What is pharmacodynamics?
the study of biochemical and physiologic effects of drugs and their mechanisms of action.
Variation among the different persons drug responses can most often be explained by the drugs?
Absorption, Distribution, Metabolism, and Excretion.
______all involve the passage of a drug across cellular membranes?
Absorption, Distribution, Metabolism, and Excretion.
In genera do drugs pass through or between cells for absorption and activity?
the movement of a drug from its site of administration into the blood
drug movement from the blood to the interstitial space of tissues.
enzymatically mediated alteration of drug structure.
the movement of drugs and their metabolites out of the body
What are the three ways for a drug to cross a cell membrane?
Passage through channels or pores, passage with the aid of a transport system, and direct penetration of the membrane itself. Of the three direct penetration of the membrane is most common.
What is P-Glycoprotein and what does it do?
It's a trans-membrane protein that transports a wide variety of drugs out of cells. In the liver it transports drugs into the bile for elimination. In the kidney, it transports drugs back into the maternal blood, thereby reducing fetal drug exposure. in the intestine, it transports drugs into the intestinal lumen, and can thereby reduce drug absorption into the blood. and in the brain capillaries, it pumps drugs into the blood, thereby limiting drug access tot he brain.
Drugs crossing the cell membrane by way of channels and pores
Few drugs can. The channels in membranes are extremely small and are specific for certain molecules. only the smallest of compounds can pass, these include ions such as potassium and sodium.
Drugs crossing the cell membrane by way of transport systems
Transport systems are carriers that can move drugs from one side of the cell membrane to the other. Some require energy, others do not. An example would be P-Glycoprotein.
Drugs crossing the cell membrane by way of direct penetration of the membrane
This is the most common, because most drugs are too large to pass through channels and pores and lack transport systems to help them cross all of the membranes that separate them from their sites of action, metabolism, and excretion.
What is passive diffusion?
Water and solute if lipid soluble or small enough molecule move across cell membrane down a concentration gradient (Higher to lower) until steady state achieved where drug concentration is equal intra and extracellularly.
Which type of diffusion is the most dominant method?
Passive diffusion is the most dominant method of drug transport. however, carrier mediated processed can be important too.
_____ is important in transport of endogenous substances whose rate of movement across biologic membranes would be too slow.
Facilitated transport. Facilitated diffusion is carrier mediated but no energy is required.
______substances are those that originate from within an organism, tissue, or cell
Factors affecting drug transport include?
molecule size and shape, solubility, degree of ionization, dissolution, concentration of drug at site of absorption, circulation to site of absorption, route of administration and other drugs and food.
______ refers to the rapid hepatic inactivation of certain oral drugs?
First pass effect.
If the capacity of the liver to metabolize a drug is extremely high, the drug can be completely inactivated on its first pass through the liver. What is this called?
First pass effect.
First pass effect, things to remember
Drugs taken orally and absorbed in small intestine. Blood circulates from gut thru liver where drug may suffer metabolism and/or inactivation. The drug must first pass thru the liver. Doses of oral drugs may have to be higher than when given IV. EX: IV propranolol does may be 2mg and oral does is 40mg.
How does circulation to the site of absorption affect drug tansport?
if circulation is increased the drug is more rapidly absorbed. inflamed skin will have an increased absorption of topical agent. with cardiac arrest, drug absorption is poor if CPR is not effective. For fastest absorption, deliver drug to highly vascular tissue.
How other drugs and foods can affect drug transport.
They may bind with the drug, inactivate it, or reduce its absorption. Ex: tetracylin (TCN) and milk products--TCN binds with calcium and forms an insoluble metal chelate. This can affect bioavailability.
What is bioavailability?
the amount of active drug which reaches the blood stream.
What is target tissue?
the tissue the drug is intended to affect. The extent to which the drug is distributed will affect the intensity of its effect. once the drug reaches blood stream, it must get to the target tissue.
Cardiac output and regional blood flow affects distribution how?
Cardiac output and regional blood flow- can you get the drug to the target tissue? as cardiac output increases, distribution increases. so if BP is low distribution is slower and less.
Drug storage sites include?
Plasma proteins, neutral body fat, bone, and other less common sites ( renal tissue)
Drugs that are stored in bone?
primarily metals, especially lead. These drugs tend to be tightly bound and hard to remove. Ex: tetracycline bind with calcium on the enamel of teeth in developing child and discolors teeth.
Drugs that are stored in neutral body fat?
lipid soluble drugs. especially in the obese. Lean person has fever storage sites than obese.
Compartments involved in absorption?
GI tract, can be bypassed with IV
Compartments involved in distribution?
Blood stream, plasma proteins, fat and bone.
compartments involved in metabolism?
kidney and liver.
compartments involved in excretion?
kidney and liver.
This occurs from storage sites as plasma concentrations drop, because they move down the concentration gradient, to maintain a plasma steady state (equilibrium). This explains why some drugs may have long durations of action. Ex: Valium is very lipid soluble, a person may experience a hangover of effects, as drug is redistributed from body fat over several hours.
What is gamma phase?
when drugs leave storage sites
Blood Brain Barrier (blood-CSF)
Most drugs do not cross BBB. Brain tissue highly lipid, thus lipid soluble drugs pass more readily. Drugs may be formulated to increase CSF absorption for effects on CNS or to decrease CNS absorption to avoid effects.
Blood brain barrier and meningitis
In meningitis, BBB is not as effective as a barrier, so drugs may get through. thus, some antibiotics may be effective in treating meningitis that would not cross BBB in healthy brain.
Placenta is a poor barrier and has a rich blood supply therefore----
Drugs pass easily, especially with repeated dosing. It takes about 40 minutes for the serum level of a drug to reach equilibrium between mother and fetus. Problems: 1. fetus has immature liver and cannot metabolize drugs as well or as rapidly. 2. small body weight of fetus vs mother = greater relative concentrations of drug reached in fetus which = greater toxicity.
______ drugs pass through tubular membrane more readily and is more readily reabsorbed.
______ drugs are less readily reabsorbed and will be excreted in urine
Disease states that can affect drug metabolism?
Hepatic disease (hepatitis, severe cirrhosis). Starvation, stress states, renal disease.
What is the major organ for excretion?
Kidney. Other organs include GI tract (bile/stool), mammary glands, sweat glands, respiratory tract.
What is the major organ for metabolism?
Entero Hepatic recycling
The drug is absorbed into the blood stream, circulates through the liver and is then excreted in bile, then it's reabsorbed from the GI tract back into the bloodstream.
Primarily lipid soluble drugs. Breast milk is more acidic than plasma, therefore basic drugs move more readily into breast milk.
Factors modifying excretion
urinary pH, age (infants have immature kidneys, elderly lose renal function), drug interactions, and renal disease (reduced renal circulation).
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