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Describe the properties of an ideal drug.
- reversible action
- ease of administration
- freedom of drug
- low costs
- chemical stability
- possession of a simple generic name.
What is Half-Life?
- the time required for the amount of drug in
- the body to decrease by 50%.
- Ex. If Morphine has a half-life of 3 hours, and there is 50mg of morphine in the body, 25mg (50%) will be lost in 3 hours.
- Drugs with short half-lives leave the body quicker. Longer half-lives leave the body slower.
- description of drug using a nomenclature of
- Innapropriate for everyday use b/c of complexity
- Assigned by the US Adapted Names Council.
- Each drug has only one generic name
- Also known as propriety or brand names.
- Are the names under which a drug is marketed.
- These names are created by drug
- companies and must be approved by FDA.
The movement of a drug from its site ofadministration into the blood
- *rate affects how soon drug will kick in
- *amount absorbed affects how intense effects will be
Rate of Dissolution
- Before a drug can be absorbed, it must first
- Rapid dissolution means faster onset.
Major determinant of the rate of absorption
- Surface Area.
- Larger surface area, faster absorption
- Drugs usually absorbed from small intestine rather than stomach b/c greater surface area.
- highly lipid-soluble drugs are absorbed more
- rapidly than drugs whose lipid solubility is low beacuse they can readily cross the membranes that separate them from the blood.
- *Works right away!
Which way of administration of drugs has no barriers to absorption and is instantaneous.
Advantages with IV.
- Rapis onset (ideal for emergencies)
- Precise control over drug levels
- permits use of irritant drugs
Disadvantages of IV.
- Risk of fluid overload, Infection and Embolism
- Drug must be water-soluble
Which way of administration of drugs only barrier to absorption is the capillary
wall. Rapid absorption with water-soluble drugs.
- Intramuscular (IM) <----- Parenternal
- and Subcutaneous
Advantages of IM
- Permits use of poorly soluble drugs and depot preperations.
- ( Depending on the
- depot formulation, the effects of a single injection may persist for days,
- weeks, or even months.)
Disadvantages of IM
- Possible dicomfort
- Potential for injury
Barriers to absorption include 1) epithelial lining of GI tract and 2) Capillary wall.
Slow and Variable absorption pattern.
Oral <-------- Enternal
Advantages to Oral administration.
- Easy and convenient
- Ideal for self-medication
- potentially reversible
Disadvantages of Oral Administration
- Inactivation of some drugs by gastric and digestive enzymes
- Possible nausea and vomiting
The rate at which drugs are delievered to a particular tissue is determined by........?
The blood flow to tissue
Large gaps exist exists between the cells that compose the capillary wall. Drugs and molecules can pass freely into and out of the bloodstream through theses gaps
Typical capillary beds
Junctions between the cells that compose the calls of most capillaries in the CNS are so tight that they prevent passage , so in order to leave the blood and reach sites of action within the brain, a drug must be able to pass through the capillary wall. Only drugs that are lipid-soluble or have a transport system can cross the......?
Blood- Brain Barrier
Drugs that can form reversible bonds with various proteins in the body
Protein Binding Drugs
*Albumin: (protein present in the blood) helps carry the drug molecules.
The enzymatic alteration of drug structure
- Most drug metabolism takes place in the
hepatic microsomal enzyme system
- the cytochrome P450 is not a single molecular
- entity, but rather a group of closely related enzyme families
capable of catalyzing a wide variety of
reactions using drugs as substrates.
Hepatic mocrosmal enzymes
*The nurse is giving a medication that has a high first-pass effect. The physician has changed the route
from IV to PO. The nurse expects
the oral dose to be:
A.[Higher because of
the first-pass effect]
B.[Lower because of the
C.[The same as the IV
- A.[Higher because of
- the first-pass effect]
*What are 3 way to cross a cell membrane
- Channels and pores
- Traansport system- P-Glycoprotein
- Direct penetration of the membrane
*First Pass Effect
- How much of a drug is absorbed the first time it goes through.
- -healthy liver has a 90% first pass
- affect, which means only 10% passes through into the blood stream.
- If drug is bound to protein it has
- less of a chance of exiting the vascular system and into the bloodstream (drug
- needs to be free)
body releases a little at a time (time released) out of the vascular system so you have longer lasting affects of the drug.
A patient is complaint of severe pain and has orders for morphine sulfate. The nurse knows that the route that would give the quickest pain relief would be:
What is Idiosyncratic?
What is Iatrogenic?
What is the ability of a drug to
reach the systemic circulation from its site of administration?
-Special “chemicals” in the body that most
drugs interact with to produce effects.
-Any functional macromolecule in a cell to
which a drug binds to produce its effects.
-most important group of macromolecules
through which drugs act
A noxious, unintended, and undesired effect that occurs at normal drug dosages.
Adverse drug reactions
Who's predisposed to adverse drug reactions?
- Geriatric patients
- - contributing factors to drug complications are:
- Altered pharmacokinetics, multiple illnesses, multiple drug therapy, and poor compliance, increased percentage of body fat, decreased percentage of body mass, decreased total body water, reduced concentration of serum albumin.
How to Monitor for adverse drug reactions?
take thorough drug history, low dosing, plasma level monitoring, simpliest regimen, review drug treatment schedule.
- Remote risk of fetal harm.
- Controlled studies in women have been done and have fail to demonstrate a risk of fetal harm during the first trimester, and there is no evidence of risk in later trimesters.
- Slightly more risk than A.
- Animal studies do show a risk of fetal harm, but controlled studies in women have failed to demonstrate a risk during the first trimester, and there is no evidence of risk in later trimesters.
- Greater risk than B
- Animal studies show a risk of fetal harm, but no controlled studies have been done in women.
- Proven risk of fetal harm
- studies in women show proof of fetal damage, but the potential benefits of use during pregnancy may be acceptable despite the risks.A statement on risk will appear in the “WARNINGS” section of drug labeling.
- Proven risk of fetal harm.
- Adverse reaction reports indicate evidence of fetal harm: Studies in women or animals show definate risk of fetal abnormality.Adverse reaction reports indicate evidence of fetal risk. The risks clearly outweigh any possible benefit. A statement on risk will appear in the “CONTRAINDICATIONS” section of drug labeling.
Drawing the serum blood levels after the drug is administered as it distributes rapidly
Drawing the serum blood levels right before the next dose.
trough is usually drawn one hour prior to start infusion and the peak about one hour after the
What is the lowest drug
level that is needed to reach therapeutic range?
- If trough is > than normal the pt is at risk for adverse effects.
- Dr should expand the time interval before ordering the next dose or decrease drug dose.
Point when the amount of drug going in is the
same as the amount of drug getting taken out.
- Steady State
- -Takes somewhere between 5 and 6 half-lives for a medication to reach steady state
What are broad-spectrum antibiotics that
suppress bacterial growth by inhibiting
(These drugs bind to the 30S ribosomal unit, and thereby inhibit binding of transfer RNS to the messenger RNA-robosome complex.)
- (are Bacterostatic and have poor ability to cross mammalian cell
Haults growth of bacteria
A new infection that appears during the course of treatment for a primary infection
ex. yeast infection
antibiotic kills all the normal flora which allows a second infection to occur.
- performed on animals.
- Drugs are evaluated for toxicities, pharmacokinetic properties, and potentially useful biologic effects. May take 1-5 years.
- Once sufficient testing is done, the data collected is presented to the FDA for permission to begin testing on humans.
- If approved, it is awarded Investigational New Drug status and clinical trials may begin.
occurs in 4 phases and may take 2-10 years to complete.
Clinical Testing Phase #: Usually conducted on healthy volunteers. Goals: evaluating drug metabolism, pharmacokinetics, and biologic effects.
Clinical Testing Phase #: usually conducted on patient’s.
Objective: to determine therapeutic effects, dosage range, safety, & effectiveness.
Applies to FDA for conditional approval of a New Drug Application.
Phase 2 and 3
Clinical Testing Phase #: POSTMARKETING SURVEILLANCE The new drug is released for general use, permitting observation of its effects in a large population.
The development and testing of new drugs is an expensive and lengthy process, requiring how many years?
Removal of the parent drug and metabolites from the body
Giving a patient a drug that alters urinary pH can help to keep toxic drugs ionized in the urine and reduce passive reabsorption.
bind to receptors and block postreceptor responses by preventing receptor activation by endogenous ligands and other drugs.
drugs that bind to receptors and mimic the actions of endogenous regulatory molecules such as hormones andneurotransmitters.
enhance interation between drug and the body.
What combination extends the antimicrobial spectrum of the penicillin?
b-lactamase and augmentin or amoxicillin
should be taken on an empty stomach (1 hr before meals, 2 hrs after) & with a full glass of water.
*don't take calcium, if pregers, or if under 8
beta-lactam antibiotics similar in structure and actions to the penicillins.
These drugs are bactericidal, often resistant to beta-lactamases, and active against a broad spectrum of pathogens.
Their toxicity is low.
distribute well to most body fluids and tissues.
poor absorption from the GI tract
most effective against cells undergoing active growth & division.
unique antibiotic approved for single-dose therapy of women w uncomplicated UTIs.
Actions: kills bacteria by disrupting synthesis of the peptidoglycan polymer strands that compose the cell wall.
Done with or without food.
can promote severe antibiotic-associated pseudomembranous colitis, which can be fatal
Actions: binds to the 50S subunit of bacterial ribosomes and thereby inhibits protein synthesis.
Distribution: May be admin. orally, IM, or IV.
Absorption from the GI tract is nearly complete and not affected by food.
Action: binds to the 30S ribosomal unit and thereby suppresses bacterial protein synthesis.
Distribution: administered by IM injection, the drug is NOT absorbed in the GI tract. Most is excreted unchanged in the urine.