Summary
Nurs 615 Chapter 2 Summary
- Course
- NURS 615
- Institution
- Maryville University Of St. Louis
This is a comprehensive and detailed summary outline of chapter 2; review of basic principles of Pharmacology.
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Chapter 2 – Review of Basic Principles of PharmacologyHow new drugs are developed
- Preclinical stage- the early part of drug development. Identification of promising drugs
and animal testing occurs during this stage. Testing on cells, organs, and tissues also
occurs in the labs.
- Toxicologists specialize in understanding the harmful effects of drugs and predicting as
early as possible in the development process if a drug will harm patients.
- Phase 1 clinical trials establish biological effects, as well as safe dosages and
pharmacokinetics in a small number of healthy patients
- Phase 2 clinical trials new drugs are used to treat disease in a small number of patients
and establish potential of the drug to improve patient outcomes.
- Phase 3 clinical trials will compare the new medication to standard therapy in a larger
number of patients studied in populations across the nation
- After being approved by the FDA, drugs are continually monitored through post market
surveillance, in which health professionals report adverse events, which are studied by
the pharmaceutical companies and the FDA
- Pharmacogenomics = the study of how individual variations in drug targets or
metabolism affect drug therapy. Performed in the post-marketing phase, it can identify
biological factors responsible for predictable beneficial or adverse events in individual
patients.
Drug Responses
- Before a medication can produce a response, it often must overcome homeostatic
mechanisms
- If an adequate drug dose is delivered, there will be a measurable biological response
- Dose response curve:
, o The law of mass action defines chemical interactions and forms the theoretical
foundation for drug responses that occur through receptors that moderate drug
responses.
o The higher the concentration of a drug at its site of action, the more the drug will
bind to the receptor and the greater the response will be.
- 2 types of drug responses: Graded and Quantal
o Graded- biological effects that can be measured continually up to the max
responding capacity of the biological system.
▪ Example – blood pressure is measured in mm Hg
▪ Graded responses are easier to manage because we can see how much a
patient responds to a particular dose if medication, and if needed it can
be altered.
▪ Examples: BP, HR, diuresis, bronchodilation, forced expiratory volume in
1 second, pain on a scale of 1-10, and coma score
o Quantal – responses that may or may not occur
▪ Example – seizures either occur or they do not
▪ If a response is either occurring or absent – it is quantal
▪ Examples: convulsions, pregnancy, rash, sleep, or death
Expressing drug responses
- Dose response curves show the info on the relationship between dosage or
concentration and responses for one or more drugs. Left to right- this represents
increasing dosage or concentration.
- Drug potency- how much a drug is needed to produce a biological response. potency
describes the difference in concentration or dosage of different drugs required to
produce the same effect. Drugs that are more potent require a lower dosage or
concentration to produce the same response as a higher dosage or concentration of a
less potent drug.
, - Drug efficacy- expresses the ability of a drug to produce the max effect at any dosage.
Efficacy is the expression of the max effect a drug can produce.
- Intrinsic activity – represents the ability of a drug to produce a large response. It is used
to describe the ability of a drug to produce a response once it has occupied specific
receptors. Some drugs produce the max receptor stimulation once they occupy the
receptors; their response is limited by how many drug molecules occupy receptor sites.
Therapeutic Index – special ratio describing drug selectivity. It has the ratio of the lethal dose to
the therapeutic dose of a drug.
- provides a fixed comparison for drug safety.
- The index for drugs on the market is always greater than 1
- If the index is less than 1, that means the drug kills before it cures
Receptors
- Drug targets include enzymes, ion channels, cell surface receptors, nuclear hormone
receptors, transporters, and DNA
- Pharmacologists organize drug activity based on receptors through which individual
drugs act
- Chemical energy from drug-receptor interactions is used to change the receptor in some
way that alters physiological processes to produce cellular changes that result in a
measurable response
- The correlation of chemical structure with pharmacological activity is called the
structure activity relationship (SAR)
- There are separate, independent SARs for different drug properties (potency, selectivity,
toxicity), so the fact that any one drug property changes for the better or for worse does
not mean that the change affects the other properties of the drug
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