lecture 4 basic principles of pharmacology

drug
substance taken into the body that modifies one or more of its functions.

pharmacokinetics
How the body deals with a drug, absorbed, distributed, eliminated

pharmacodynamics
What a drug does to the body, mechanism of action, benefits and, toxicities

preclinical testing, human (clinical) testing (Phase I,II,III, IV)
what are the drug development stages?

1. initial lab test to determine drug effects and safety
2. lab animals
3. 1-2 years
1. purpose 2.subjects 3. time period
preclinical testing

1. determine effects, safe dosage, pharmokinetics
2. small number (<100) healthy volunteers 3. < 1 year
1. purpose 2.subjects 3. time period
human testing phase I

1. asses drug’s efectivenss in treating a specific disease/disorder
2. limited number (200-300) patients with target disorder
3. 2 years
1. purpose 2.subjects 3. time period
human testing phase II

1. asses safety and effectiveness in a larger patient population
2. larger number (1000-3000) patients targeted
3. 3 years
1. purpose 2.subjects 3. time period
human testing phase III

1. postmarketing surveillance. monitor and problems that occur after New Drug application (NDA) approval
2. general patient population
3. indefinite
1. purpose 2.subjects 3. time period
human testing phase IV

$1.3 billion
what is the average cost of brining a new drug to market?

controlled substances. different schedules from _I__ to _V__ with _I__ having the highest potential for abuse. __II_ drugs are available by prescription
controlled substances. different schedules from ___ to ___ with ___ having the highest potential for abuse. ___ drugs are available by prescription

ceiling effect or maximal efficacy of drug.
the point at which there is no further increase in response

threshold dose
dosage the response begins to occur

1. lower
2. higher
3. unrelated
the more potent drug requires a _1__ dose to produce the same effect as the _2__ dose of a second drug. potency is ___ to maximal efficiency.

1. safer
2. TI=TD_50/ED_50 (median effective dose/median toxic dose)
The bigger the Therapeutic index the _1__the drug. TI=_2___

median effective dose
this is the dose at which 50% of the population respond to the drug in a specified manner

median toxic dose
the dose at which 50% of the group exhibits the adverse effect

first pass effect
when a drug is subject to degradation by liver

advantages: easy, safe, convenient,
disadvantages: must be lipid soluble/acid resistant. limited or erratic absorption of some drugs; chance of first pass inactivation in liver
advantages/disadvantages of oral drug administration

advantages: rapid onset; not subject to first pass inactivation
disadvantages: drug must be easily absorbed from oral mucosa
advantages/disadvantages of sublingual drug administration

advantage: alternative to oral route; local effect on rectal tissue
disadvantage: poor or incomplete absorption; chance of rectal irritation
advantages/disadvantages rectal drug administration

enteral. oral, sublingual & Buccal, rectal
___ is drug administration through alimentary canal. what are the methods that fall under this route.

parenteral
all methods of drug administration that do not use the GI track

advantages: rapid onset; direct application for respiratory disorder; large surface area for systemic absorption
advantages: change of tissue irritation; patient compliance sometimes a problem
inhalation drug administration advantages/disadvantages

advantages: provides more direct administration to target tissues; rapid onset
disadvantages: chance of infection if sterility is not maintained
injection administration advantages ad disadvantages

advantages: local effects on surface of skin
disadvantages: only effective in treating outer layers of skin
topical administration advantages/disadvantages

advantages: introduces drug into body without breaking the skin; can provide steady, prolonged delivery via medicated patch
disadvantages: drug must be able to pass through dermal layers intact
transdermal advantages and disadvantages

iontophoresis
transdermal route via electrical forces driving deeper

phonophoresis
transdermal route via sound forces driving deeper

bioavailability
the extent that a drug reaches the circulation. is a function of absorption and ability to cross cell membranes

passive diffusion
o energy used. Usually fat soluble but not always (lithium). If you slightly ionize the chemical, make it a weak acid or a weak base, you can make the permeability properties more selective. Weak acids will cross membranes more readily in an acid environment and vice versa. This also affects excretion. ALWAYS down the concentration gradient. Ne.ver saturated

facilitated diffusion
Movement of a substance across a usually impermeable membrane by a conformational change in a transmembrane protein carrier. ALWAYS down the concentration gradient. Can be saturated.

active transport
rt: Must have specificity, expend energy and ability to transport against a concentration gradient. Can be saturated

Tissue permeability, blood flow, binding to plasma proteins, binding to subcellular components. Binding to plasma proteins, usually albumin is especially important.
Amount of plasma protein can vary.
With polypharmacy, there can be competition for binding sites.
factors effecting distribution of drugs

Volume of distribution(Vd)
s the ratio of the amount of drug given to the plasma concentration. This ratio is the theoretical volume of fluid into which the total drug administered would have to be diluted to produce the concentration in plasma. If plasma concentration is lower than you would expect, Vd is high. This concept is used in research.

1. toxicities
2. diminished
3. redistribution
Many drugs tend to sequester themselves in specific tissues in the body that are not the intended target areas such as adipose, bone, muscle or specific organs such as the liver. Consequences are __1_ to the storage tissue, __2_ availability at the target site and prolonged effects due to __3_.

Biotransformation
Chemical changes that take place in the drug after administration. Enzymes within specific tissues are responsible for changing the drug’s structure thus altering its properties either to enhance the drug’s action or, more often, reduce or eliminate the drug’s intended activity. is usually MUCH faster than excretion.

oxidation
refers to the adding of oxygen to a compound or the removal of hydrogen. This is the most common method of drug biotransformation. It actually means adding electrons. Oxygen does not have to be involved.

cytochrome P450 (CYP)
Participates in oxidation reactions
Found primarily in liver endoplasmic reticulum Enzyme induction can degrade drugs more rapidly
Alcohol, cigarettes as well as other drugs Competitive

1. Kidneys
2. Ionized drugs
for excretion __1_ are the primary site with lungs, GI tract and skin as distant alternatives Combinations or biotransformation and excretion are common
__2_or their metabolites are less likely to be reabsorbed and, as such, are more readily excreted.
Drugs can also be actively secreted

proportional
the effectiveness &/or toxicity of a given dosing regimen is ___to the rate of elimination. Any variance off the expected rate can produce disaster.

clearance
is a common way of assessing kidney function. amount of plasma cleared of substance per minute. high indicates more than just excretion. lower indicated reabsorption

half life
amount of time it takes for 50% of the remaining drug in the body to be eliminated.

frequent
The ideal situation is to get a drug to a therapeutic level and keep it there. Unless you have a system of constant release, (and which would those be?), then you are going to get peaks and valleys. the more ___ the dosing the steadier the blood levels. more effective less toxicity

Dose response curve shows the relationship between the drug response and the dose Free drug compared to drugs that are protein bound, molecules that can produce a pharmacologic effect WE WILL WRITE A CUSTOM ESSAY SAMPLE ON ANY TOPIC SPECIFICALLY …

Absorption refers to the movement of drug into the bloodstream, with the rate dependent on the physical characteristics of the drug and its formation. Refers to the passage of drug molecules from the site of administration into the circulation. Active …

What is pharmacotherapeutics? The branch of pharmacology that uses drugs to treat, prevent, and diagnose disease. What are some sources of drugs? Natural sources: Plants, Animal products & Inorganic compounds Synthetic sources WE WILL WRITE A CUSTOM ESSAY SAMPLE ON …

Process by which the body takes in or receives a drug Absorption Action by which a drug is released throughout the body Distribution WE WILL WRITE A CUSTOM ESSAY SAMPLE ON ANY TOPIC SPECIFICALLY FOR YOU FOR ONLY $13.90/PAGE Write …

absorption The process by which one substance is absorbed, or taken in and incorporated, into another, as when the body converts food or drugs into a form it can use. administer To give a drug directly by injection, by mouth, …

Identify 3 sources of drugs Chemical name (ex. molecular formula) Generic name (ex. Acetaminophen) Brand name (ex. Tylenol) What type of drug name is Motrin? Ibruprofen-Brand Name Motrin- Generic WE WILL WRITE A CUSTOM ESSAY SAMPLE ON ANY TOPIC SPECIFICALLY …

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