PSYC 450: midterm 1
what two kinds of changes can repeated drug use induce?
Molecular and cellular changes in the brain.
All drugs of abuse are directly or indirectly related to the increase of ___ in the brain.
Dopamine
How do you explain changed behavior that leads to addiction after repeated drug use?
Plastic changes in the brain; tolerance; sensitization.
For opioid addiction, certain drugs like methadone and buprenorphine act as substitutes. What do these chemicals do to receptors?
They bind to opioid receptors, tricking the brain to think it's an opioid.
What can we say does NOT alone contribute to addiction?
Genetics
Name some factors that contribute to addiction.
- Development time at which you take the drug
- Social Environment
- Social interactions
- Eating habits
- Exercise
Define pharmacology.
The branch of medicine that defines the uses, effects, and mode of action of drugs.
What is a drug?
A substance that is used to change any existing process or state, be it psychological, physiological, or biochemical.
For a specific molecule to have an effect, can it bind to any random receptor? Explain.
In order for the drug to have an effect, the Ligand/molecule must bind to the specific receptor that responds only to that molecule.
Name the two branches of pharmacology.
Pharmacokinetics and pharmacodynamics.
Name the three sources of psychoactive agents.
1. Synthetics
2. Semi-synthetics
3. Naturally occurring.
Give an example of naturally occurring drugs and where we can find them.
Opium, sourced from poppy seeds. There is also cocaine, found in the leaves of the coca plant.
Give an example of a semi-synthetic drug.
Heroin from morphine; LSD from fungi.
Give an example of a synthetic drug.
Methadone (synthetic opiate); Amphetamine; Methylphenidate.
What are the ways in which a drug can get its name?
- Street name
- Generic name
- Chemical name
- Brand/Trade name
What is the meaning of an analgesic drug?
One that relieves pain.
In the classification of drugs, what are the various behavioral effects?
- CNS depressants/sedatives
- Stimulants
- Hallucinogenics
- Narcotic analgesics
How many drug schedules are there in the classification of drugs?
Four.
Describe Drug Schedule I.
Requires a prescription to obtain drug by pharmacist, following the diagnosis and professional intervention of a practitioner.
Describe Drug Schedule II:
Prescription is not necessary but drug is only attainable from pharmacist.
Define pharmacokinetics.
Deals with the absorption, distribution, biotransformation, and excretion of drugs
Factors that contribute to pharmacokinetics:
- route of administration
- absorption and distribution
- elimination
- inactivation
For a drug at a specific dose, the time it takes for the body to feel its effects is based on which factor of pharmacokinetics?
Route of administration
Name types of routes of administration.
- Intravenously
- Subcutaneously
- Intranasally
- Orally
- Intramuscular
- Inhalation
Which route of drug administration leads to the highest blood concentration in the shortest amount of time?
Intravenous injection
The drug Half-life varies as a function of route of administration. Define Half-life.
The Half-life is the time at which the blood plasma has fallen to half its peak concentration.
Effects of route of adminstration on absorption are due to 4 factors:
1. Surface area available for absorption
2. Amount of drug that dies immediately
3. Amount of cell layers to blood
4. Blood circulation at adminstration site
What is the most important factor in achieving an active dose at the site of administration?
Drug transport across the cell membranes.
How does drug inactivation occur?
By metabolism/biotransformation. Major site is the liver.
How does drug elimination occur?
Metabolites; feces; sweat; saliva; milk.
Define pharmacodynamics.
The study of biochemical effects of drugs and their mode of activation.
What is the objective of pharmacodynamics?
The objective is to identify the primary actions of drugs.
Use pharmacokinetics and pharmacodynamics to explain the initial biological effects of drugs.
A molecule must bind to a receptor as the intial site of action for biological effect. The act of the molecule getting to the receptor is the realm of pharmacokinetics, and what happens at the site of action (receptor) is the realm of pharmacodynamics.
Explain the D+R = DR complex
Drug + Receptor = Drug-Receptor Interaction. DR leads to a cellular response that is proportional to the number of active receptors.
A drug that affects a horse might not affect a human. Why?
The horse might have a particular receptor for the drug that humans do not possess; therefore there is no interaction and thus no reaction.
When does a dose have its maximal effect?
When all receptors have been occupied
What relationship is described by the dose-effect curve?
The magnitude of a drug effect is proportional to the number of receptors that the drug occupies.
Explain the ED50.
The effective-dose 50% is the halfway mark of the maximal effects of a dose
What is potency and where would it be shown on a graph?
Potency is the amount of a drug (dose) needed to produce the maximum effect. You plot potency on the X axis. In short, different doses of 2 drugs are required to produce the same effects.
Explain efficacy and where it would be shown on the graph.
Efficacy is the dose needed to reach a maximal response. Increases of the dose will not increase or produce a higher response. The is plotted on the Y axis.
Explain why a smaller ED50 is more dangerous than a higher ED50.
A smaller ED50 means that it takes a smaller dose of a particular drug to achieve the same effects of a different drug, at its ED50. For example, heroin has a smaller ED50 than Tylenol, which means that you'd have to take a much larger dose of Tylenol to achieve the same celullar response as a small dose of heroin.
What is the difference between potency and maximum effect?
Potency is related to dose and the ED50. It describes the dose needed to produce a response. The maximum effect is the maximal reaction that can occur from a maximal dose.
Discuss "safe drugs" and their side effects.
On a graph, a drug that is safe to use is one whose side effects are very different from the desired effects. The curvees should be as far away from each other as possible.
Define tolerance.
A higher dose is required to produce the same effects, or repeated adminstration decreases the response.
Define sensitization.
A lower dose is required to produce the original effect; an increased response to repeated administration.
In a dose response graph, what does it mean when the curve shifts to the right compared to when it shifts left?
When the curve shifts to the right, tolerance has occurred. When it shifts to the left, sensitization has occurred.
What is an antagonist drug?
It binds to the receptor, preventing the channel from opening. There are competitive and non-competitive antagonists.
What is an agonist drug?
An agonist prevents the natural ligand from binding to the receptor.
Why is treating drug addiction with an antagonist potentially a good idea?
Because it inactivates the receptor so that binding cannot occur.
Describe the difference between competitive and non-competitive antagonist.
Competitive: binds to the same side of the receptor as the original ligand, but does not have the same effect as the original ligand. Example: Naloxone binds to the same side as fentanyl, thus competing with one another. As a result, you need more of the fentanyl to produce a response.
Non-competitive: molecule binds to the opposite side of the receptor. This means that the molecule and the original molecule cannot compete, and there is no effect of the original molecule.
Why hasn't all addiction been cured with a non-competitive antagonist?
Preventing activation of a receptor may reduce addictive tendencies, but it may consequently impair other functions.
According to behavioral pharmacology, what effects do drugs have on human behavior?
Drugs do not create behavior outside of the human species. They alter the behavior and occurrence of behavior.