1
Q
Definition of Pharmacology
A
the study of drugs
2
Q
Definition of pharmacy
A
drug preparation and dispensing
3
Q
Why do therapists needs an understanding of pharmacology
A
- physical therapy may be MORE effective when
combined or coordinated with pharmacotherapy - PT may be more effective when timed around
drugs
4
Q
PTs should be able to suggest or advise…
A
physician about need for, or modification of, drug administration based on the patient’s performance in the therapy
5
Q
Therapists are in the best position to do what?
A
to observe or note the side effects or drug
interactions
6
Q
Pharmacokinetics
A
- How the body acts on the drug
- Absorption, metabolism, elimination
7
Q
3 phases of drug metabolism
A
absorption, metabolism, elimination
8
Q
absorption
A
- route of administration
- onset
9
Q
metabolism
A
- distribution and bioavailability
- peak and duration
- half life
10
Q
elimination
A
duration
11
Q
half-life
A
time it takes for blood level to decrease by half
12
Q
oral administration
A
- most common
- cheap, easy to administer, convenient
- 1st pass metabolism (liver), must be GI- compatible
- potential for abuse
13
Q
Parenteral
A
administered in a manner other than through the digestive tract
14
Q
Parenteral - IV
A
- into vascular compartment
- Fast, little control, requires sterility
15
Q
Parenteral - Intramuscular
A
- absorption depends on blood supply, concentration and
bioavailability of drug - Absorbs drug more slowly but is affected by exercise
16
Q
Parenteral - Subcutaneous
A
- similar to intramuscular, but typically slower absorption
- not as affected by exercise
17
Q
Transdermal
A
complex pharmacokinetics & inconsistent absorption
18
Q
Inhaled
A
very rapid, may or may not remain local
19
Q
Buccal/sublingual
A
faster than oral, but slower than IV or inhalation, does not require sterilization
20
Q
What is pharmacodynamics?
A
how a drug affects the body
21
Q
What is the clearance of drugs from the body highly dependent on?
A
liver and kidney function
22
Q
Factors affecting pharmacokinetics
A
- Age: older adults and children may metabolize and eliminate certain drugs more slowly
- Liver and kidney dysfunction slow metabolism and elimination of some drugs (both more common in elderly)
- Enzyme-induction in liver may affect drug activity and bioavailability (may develop tolerance)
- Presence of certain chemicals increases or
decreases elimination
23
Q
What does vitamin C do?
A
acidifies urine, increasing exertion of weak bases (may drugs fall into the category of weak acids)
24
Q
Therapeutic Dose
A
- Blood level of a drug will increase with multiple doses until elimination = intake
- Therapeutic dose achieved at 4-5 times the half life
- Loading dose” allows for shorter time course
25
What do pharmacodynamics include?
indications, mechanism of action, side effects
26
Potency
the amount of drug necessary to achieve a given response (determines the size of the pill)
27
Efficacy
The effectiveness of a drug in producing the desired response when given at it’s maximal dose
28
Dose Response Curves
- below threshold for response
- Prescribe at E50
- above threshold: no further response
29
review potency and efficacy charts on slide 19
30
what is determined by the potency of the medication
drug "dose"
A more potent drug will require a lesser dose
31
review frequency response curve
32
Therapeutic Window
- The difference between the effective dose (ED50) and a dose that is lethal (LD50)
- The greater the window the better
33
Drugs with a narrow therapeutic window
– digoxin
– Lithium salts
– phenobarbital
34
Principles Governing Activity of Drugs
- Dose-response Effect
- Absorption
- Distribution (pH differences, lipophilic properties)
- Elimination
35
Dose-response effect:
Effect proportional to dose administered
36
absorption
acid/base properties
37
distribution - lipophilic properties
* Very important for crossing blood-brain
barrier
* Most neuro-active compounds are lipophilic
- Ethanol
- Lipophilic gets into the brain
38
what do most drugs works through?
a known neurotransmitter and a known receptor
39
what is a secondary effect of drugs?
change in neurotransmitter receptor activity
40
are there "silver bullets?"
no
most neuro-active drugs have a general effect
41
non-specificity of drugs:
many drugs are used to treat different disorders
42
Valium
anti-seizure medication, anti-anxiety medication, anesthetic, sedative-hypnotic used for sleep, muscle relaxer, anti-spasticity drug
43
Lock and Key Model
– The receptor functions like a lock:
* Only a particular molecule (an “agonist”) with a certain structure can “unlock” it --> receptor stimulation
* Other types of molecules can bind to the
receptor that don’t “unlock” it, but instead block
activation (“antagonist”)
44
neurotransmitters and their receptors
Forms basis for most pharmacological
intervention
45
Hormone Receptors
– Membrane receptors: Insulin R, alpha and b-adrenergic receptors
– Intracellular receptors: thyroid hormone and glucocorticoid receptors
46
Common mechanisms in pharmacology
* Molecular interaction agonist/antagonist (Neurotransmitter agonists/antagonists)
* NT Reuptake/breakdown inhibitors
* Inhibit/facilitate synaptic vesicle fusion
* Inhibit/stimulate NT precursors
47
Molecular interaction agonist/antagonists examples
– Clopidogrel: anticoagulant that antagonizes platelet activation
– Dexamthasone: agonist to glucocorticosteroid receptors
48
Neurotransmitter agonist example
Bromocreptine (Parlodel): agonize Dopamine receptors
49
Neurotransmitter antagonist example
Acetophenazine (Thorazine): antagonize Dopamine R’s in limbic system
50
Drug that block re-uptake/breakdown of a NT example
Fluoxetine (Prozac): Serotonin specific re-uptake inhibitor
51
Drugs that facilitates neurotransmitter release example
Amphetamine (Ritalin): increase NE release and prevents re-uptake
52
excitatory post-synaptic potentials
– Decreased K+ or Cl- conductance
– Increased Na+ or Ca+2 conductance
53
inhibitory post synaptic potentials
– Increased K+ or Cl- conductance
– Decreased Na+ or Ca+2conductance
54
what is seizure disorder?
* Hyper-excitable or irritable neurons in cortex causing spontaneous depolarizations
55
what do drugs for seizure disorder focus on?
- suppressing the excitability of cortical neurons that trigger the seizure
– gamma-aminobutyric acid (GABA): inhibitory NT found throughout the brain
– most drugs that suppress seizures work by enhancing the action of GABA
56
Review slide 33
57
Where are adverse drug reactions common?
hospital settings
58
what do adverse drug reactions depend on?
- a variety of factors
- Genetics (polymorphisms), gender, age, health, etc
59
what can side effects be compounded by?
conditions that limit liver/kidney function, such as Aging, heart failure, liver disease, kidney
failure
60
what is polypharmacy?
Duplication of medication or over-medication
through the use of multiple drugs
61
what causes polypharmacy to be more likely?
- more comorbilities
- going to multiple physicians
62
can herbal or over the counter medicines interact with prescription medicines?
yes
63
What are drugs classified by?
action, indication, restriction, effectiveness
64
action
mechanism of drug action (CNS vs PNS, antagonist vs agonist)
65
drug indication
by body system or disease process
66
drug restriction
Schedule of controlled substances:
- Schedule I: most restricted
- Schedule V- least restricted
67
drug effectiveness
“cure” versus manage symptoms
* Most drugs control symptoms rather than cure disease
68
Pregnancy Category C
Animal studies suggest risk, but no trials in pregnant women. Use
only when benefit outweighs risk
69
Controlled Schedule I
High potential for abuse. No acceptable medical use: heroin, LSD, marijuana. Research only.
70
What are the issues in Physical Therapy?
- sedation of patients
- respiratory issues
- cardiovascular issues
- controlling pain, infection, blood glucose
- improve patients outlook
71
respiratory issues
open airway, get patient breathing independently again
72
cardiovascular issues - gain control of
– hemostasis/coagulation
– heart rate, blood pressure & organ perfusion
