S1L2: Pharmacodynamics Flashcards
Pharmacology
1. Maximum response to a drug
2. Amount/dosage of drug needed to produce a given effect
3. Peak response we can get from a drug
4. First thing to look for in a drug
A. Potency
B. Efficacy
- B
- A
- B
- B
PHARMACOLOGY: POTENCY VS. EFFICACY
Drug that is less ____ would need a ______ amount to produce a given effect, while a drug that is more _____ would need a ______ amount to produce its effect
Drug that is less potent would need a greater amount to produce a given effect, while a drug that is more potent would need a lesser amount to produce its effect
DOSE-RESPONSE CURVE
What values are found in the x-axis?
Doses of Drugs
DOSE-RESPONSE CURVE
What values are found in the y-axis?
Different effects of the drugs
What does “subtherapeutic dose/effect” mean?
Subtherapeutic dose/effect means that the drug would not be able to provide its desired effect
DOSE-RESPONSE CURVE
What do we have to remember in the “peak effect/efficacy/maximum efficacy”? (Give 4)
■ The drug no longer increases its effects
■ Increased risk of adverse effects
■ Doesn’t achieve better than the given dose
■ Do not want to go beyond these doses as it is not safe and is not necessary anymore
Identify the Curve/Graph
- What curve or graph does not look at the effects but at the percent of individuals responding?
- Ratio of median toxic dose (TD50) to median effective dose (ED50)
- Dose required to produce a toxic effect in 50% of the population
- AKA Quantal Dose Response Curve
- Measures the TD50 & therapeutic effect
A. Median Effective Dose
B. Median Toxic Dose
C. Therapeutic Index
- A
- C
- B
- A
- C
T/F: TI = TD50/ED50
True
Do regulated drugs have narrowed TI?
Yes. Because of this regulated drugs & have to be monitored by physicians. The therapeutic effect is near the toxic effect.
Give two examples of drugs that have a narrowed therapeutic index.
Chemotherapy and Digoxin
Chemotherapy - Dose to kill cancer cells would be close to the dose that would produce toxic effects i.e. hair loss, body wasting, vomiting, weakness, nausea, not feeling very well
Digoxin - Anti-arrhythmic drug
Choose the best answer
- Range of doses by which we see the efficacy of the drug without seeing the toxic effects of the drug
- Over-the-counter drugs
- Dose that can kill
A. Therapeutic Window
B. Median Lethal Dose
- A
- A
- B
T/F: Drugs with narrow indices may have toxic effects that are very near the therapeutic dose (which produces therapeutic effects)
True
Modified T/F: The therapeutic window is the one that we want to target. Drugs having a narrow TI might be difficult to find that dose range that will just produce the therapeutic effects without manifesting the toxic effects of the drug
A. 1st statement is true
B. 2nd statement is true
C. Both statements are true
D. Both statements are false
C
T/F: As much as possible we would want to avoid between ED50 & TD50
False. As much as possible we would want to stay between ED50 (Median Effective Dose) & TD50 (Median Toxic Dose)
T/F: Lethal effect usually goes far away from the ED50 and TD50
True
PHARMACOKINETICS
What are the two (2) routes of administration?
Alimentary (GI tract) and Non-alimentary (outside GI tract)
Identify which route is being described in each item
- Are not given to uncooperative pts & those who frequently vomit
- Convenient
- Placed under the tongue due to the venous plexus located there goes directly to the systemic circulation
- Avoids first pass effect
- SALIVATION: Recommended to not swallow until drug has already dissolved
A. Oral
B. Sublingual
C. Rectal
D. Inhalational
E. Topical
F. Transdermal
G. Injection
- A
- A
- B
- B
- B
Identify which route is being described in each item
- Effective alternative
- Self-administered
- Rapid onset
- Fairly rapid onset (~20 - 30 mins after you swallow the drug)
- Peak effect of drug at 3 hrs
A. Oral
B. Sublingual
C. Rectal
D. Inhalational
E. Topical
F. Transdermal
G. Injection
- C
- A
- D
- B
- B
Identify which route is being described in each item
- ECONOMICAL: By formulation, they are the cheapest to manufacture
- GASTRIC IRRITATION: Usually some drugs are advised taken with or after a meal to lessen irritance
- Unpredictable
- Local irritation (some pts complain local irritation after utilizing this route)
- Quickest Onset
A. Oral
B. Sublingual
C. Rectal
D. Inhalational
E. Topical
F. Transdermal
G. Injection
- A
- A
- C
- C
- G
What is the main limitation of oral drugs?
First pass effect
- Anything taken by the mouth gets absorbed by the hepatic circulation (stomach → small intestines)
- It passes through the liver before reaching the
systemic circulation
T/F: There is decrease to the dose of the drug that goes to systemic circulation because of the first pass effect
True
Identify which route is being described in each item
- GASTRIC CONTENTS: Some drugs are affected by food → lesser bioavailability when food is present
- Has first pass effect
- EXAMPLE IN WHICH THIS ROUTE IS PREFERRED: Polio vaccine
- Compliance can be a factor because some pts do not know how to use it or may have
forgotten how & when to use it - EXAMPLES OF DRUGS THAT USE THIS ROUTE: Barbiturates & Pediatric paracetamol
A. Oral
B. Sublingual
C. Rectal
D. Inhalational
E. Topical
F. Transdermal
G. Injection
- A
- A
- B (but sometimes polio vacccines are given in the buccal mucosa)
- D
- C