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
T/F: Nitroglycerine is an example of sublingual drug. It takes effect in less than a minute.
True. Nitroglycerine is for pts who suffered myocardial schemia; taken when prescribed for chest pain to buy time to travel to the E.R
T/F: There are no anti-hypertensive drugs that can be done sublingually
False. There are some anti-Htn drugs that use this route
Identify which route is being described in each item
- Direct effect
- Not expected to go into the systemic circulation
- Local Effect
- Beyond the epidermis and allows systemic absorption
- Bronchodilators and Nebulizers are exmaples of drugs that use this route
A. Oral
B. Sublingual
C. Rectal
D. Inhalational
E. Topical
F. Transdermal
G. Injection
- D
- E
- E
- F
- D
Why is administering drugs through the rectal route unpredictable? Give three (3) reasons
- Because of the rectum’s anatomy
○ upper 2⁄3 of the rectum are drained by the superior rectal vein → drains to hepatic/portal system resulting in first pass effect - Possible drainage into middle and inferior rectal vein that could lead to systemic circulation
○ Put the suppositories at the lower 1⁄3 of the rectum → drained into middle and inferior rectal vein → systemic circulation - Due to possible presence of feces
○ Remove fecal material before inserting the suppository
Identify which route is being described in each item
- Meant to go through the skin
- Drug examples under this route are Nitroglycerin patch and Nicotine patch
- Pharmacological effects happen in seconds
- Difficult to self-administer
- Must be in aqueous solution
- Ointments, creans, eye drops, ear drops, and nasal drops are examples of drug that are under this type of route
A. Oral
B. Sublingual
C. Rectal
D. Inhalational
E. Topical
F. Transdermal
G. Injection
- F
- F
- G
- G
- G
- E
VARIATION OF INJECTIONS
Most direct systemic effects
Intravenous
VARIATION OF INJECTIONS
Bypasses absorption barriers
Most hazardous (once you inject it, it cannot be
reversed)
Intravenous
VARIATION OF INJECTIONS
In contrast to oral, you can aspirate the drug from stomach
Intravenous
VARIATION OF INJECTIONS
Achieves a high local to a tissue
Intraarterial
VARIATION OF INJECTIONS
Very rarely, for cancer patients
Intraarterial
VARIATION OF INJECTIONS
1. Slow absorption (slowly released)
2. Longer needle
3. For pain relief and anti-inflammatory effects
4. Tissue damage
5. Large volumes are not feasible
A. Subcutaneous
B. Intramuscular
C. Steroids Local Anesthetics
- A
- B
- C
- B
- A
VARIATION OF INJECTIONS
1. Painful
2. The needle is short to ensure it only reaches the subcutaneous fat
3. User friendly and overdosing does not often happen (graded control doses)
4. Best and cheapest form (economical)
5. Examples: Insulin
A. Subcutaneous
B. Intramuscular
C. Steroids Local Anesthetics
- B
- A
- A
- B
- A
VARIATION OF INJECTIONS
1. Examples: vaccines and anti inflammatory drugs
2. Common at knees, shoulder, & achilles tendon
3. Painful procedure
A. Subcutaneous
B. Intramuscular
C. Steroids Local Anesthetics
- B
- C
- C
T/F: Subcutaneous injections have longer needles than intramuscular
False. Subcutaneous injections have shorter needles than intramuscular
OTHER TYPES OF INJECTIONS
Examples: cancer therapeutic drugs for
leukemia or liver
Subarachnoid
OTHER TYPES UNDER INTRAMUSCULAR INJECTIONS
Delivered on epidural space; local anesthetics
Epidural
Most popular is labor analgesia during painful
uterine contractions; inhibit sensory impulses
OTHER TYPES OF INJECTIONS
For inflamed joints; target intervertebral space
Tendon Sheath or Bursa
OTHER TYPES OF INJECTIONS
Steroids (very common), local anesthetics
Tendon Sheath or Bursa
What are the procedures done for Platelet Rich Plasma (PRP) Injection?
● Get blood from the pt themselves →
centrifuge (to separate plasma) → inject
plasma into the joints
This type of injection is for small tears on tendons/ligaments, severe/chronic OA
Platelet Rich Plasma (PRP) Injection. Platelets have anti-inflammatory effects.
DRUG ABSORPTION
What is the fraction of the unchanged drug reaching the systemic circulation following administration by any route?
Bioavailability
DRUG ABSORPTION
Bioavailability is affected by five (5) factors. What are they?
- GI Absorption - First pass effect
- Plasma protein binding
- Adipose tissue storage
- Biotransformation
- Elimination
T/F: If the drug is bound to albumin, then bioavailability decreases
True. This is related with plasma protein binding.
T/F: Gets stored in the fat, bioavailability is maintained
False. Bioavailability decreases in this case
T/F: If already metabolized, ready for excretion, then bioavailability is decreases
True
T/F: The moment you take in drug, the process of metabolism and elimination happens already which leads to decrease bioavailability
True
MEMBRANE STRUCTURE AND FUNCTION
Cell membrane is composed of lipids and some
protein molecules, for a drug to go through this, it needs to be in its lipid form
Fluid Mosaic Model
MEMBRANE STRUCTURE AND FUNCTION
What explains the blood brain barrier?
It is a selective barrier that is good for preventing any drugs to cross it, protective of the brain.
Some drugs make you feel drowsy which could mean it crossed the said barrier
MOVEMENT ACROSS THE MEMBRANE BARRIER
Identify what is being asked
1.Crossing of drug molecules accross cell membrane
2. Can have mechanisms that can make the cell membrane change and just engulf the drug into the cell
3. There are molecules inside the cell that can help bring the drug outside
4. Is related to the following concepts: Permeability coefficient, concentration gradient, area, and thickness
5. Needs ATP to have the drug cross the cell membrane
A. Passive Diffusion
B. Active Transport
C. Facilitated Diffusion
D. Endocytosis/Exocytosis
- A
- D
- D
- A
- B
MOVEMENT ACROSS THE MEMBRANE BARRIER
T/F: There are some drugs that need a carrier protein so that the drug could go from outside to the inside. This is called your Facilitated Diffusion.
True
MOVEMENT ACROSS THE MEMBRANE BARRIER
T/F: PASSIVE DIFFUSION: It depends on the permeability coefficient if a drug is permeable to a membrane
True
MOVEMENT ACROSS THE MEMBRANE BARRIER
T/F: PASSIVE DIFFUSION: More area = lesser diffusion
False. More area - better diffusion
MOVEMENT ACROSS THE MEMBRANE BARRIER
T/F: PASSIVE DIFFUSION: Thicker cell membrane = poorer difffusion
True
MOVEMENT ACROSS THE MEMBRANE BARRIER
T/F: PASSIVE DIFFUSION: Concentration gradient is from higher concentration to lower
True
MOVEMENT ACROSS THE MEMBRANE BARRIER
T/F: PASSIVE DIFFUSION: Poorer diffusion is achieved if there is a higher concentration from the outside to the inside
False. Better diffusion if there is a higher concentration from the outside to the inside
