L1 Pharmadynamics Flashcards
The aim of drug therapy is to what?
rapidly deliver and maintain therapeutic, yet nontoxic, levels of the most appropriate drug in the target tissue so that the disease is treated without adversely affecting the patient.
How the drug is delivered will affect what?
how much of the drug reaches its target and how long it remains in the animal
In short the aim of drug therapy is?
- maximize efficacy
- minimize adverse effects
No drug are completely safe or without risks. In order to decide if to use a drug you must use?
A risk benefit analyses
There are 3 approaches when deciding what drugs to use, What are they? List them in order to most reliable to least
1) An evidence‐based approach
2) A pathophysiological approach
3) Anecdotal” approach
Describe the evidence based approach?
Where we have the
scientific evidence and clinical trials to back up our therapeutic decisions. Although this can be rare in vet med.
Describe the pathophysiological approach
information on the disease, we know the pathophysiological mechanisms, and we know certain things about the drugs we are using. Based on these things we make a rational decision but dont have clinical trials to back our decisions.
Describe the anecdotal approach
The least satisfactory option, but commonly used. Someone with status in vet med community says “in this situation I use this drug at this dose”
What is empirical therapy?
Similar to anecdotal therapy. Drug selection based on prior (historical) experience with the specific situation.
Typically used when we dont have a firm diagnosis and are treating to see a response.
What is rational therapy?
Drug selection based on detailed Risk/Cost/Benefit
Considerations. More invloved than patient has X I will treat with Y
What are the three ways to name drugs?
Brand name- many brand names for one drug, often more commonly recognized. Patented
International non‐proprietary name (INN) & generic products- identify pharmaceutical substances or active pharmaceutical ingredients. Non-patent and INN name is recognized globally.
Chemical name- long complicated and rarly used
Doe every drug have a generic name and generic product?
Generic name (what we use in the course) but not necessarily a generic product
What does label use mean?
Using drug specifically what it is approved for (disease, species and dose) . This can vary from country to country, an issue when reading textbooks.
What is extra-label use?
Any deviation for label use (i.e. species, disease, dose, or route of administration). Vets have the privilege to do this.
What are drug formulations?
The base of drugs stay the same but they have different salts, preparations, diluents, etc. The pharmadynamics stay the same but the pharmakenetics change. Therefore have different administrations, routes, doses, withdrawal times, etc
What is pharmadynamics?
What the drug does to the body and how drugs interact with and affect biological systems
What is pharmakinetics?
What the body does to the drug. The processes of absorption, distribution, metabolism and elimination.
In order to understand the pharmadynamics of a drug you must first understand?
The physiology of the system it acts on
Drugs can have different ______ but achieve the same effect
different mechanisms of action
Two drug classes used to treat gastric ulcers in horses
H2 blockers and proton pump inhibitors, even tho have different mechanism of action, they both reduce gastric acid production
Omeprazole
is a selective and irreversible proton pump inhibitor. What does the mean?
- Selective means that it acts only on the proton pump
- irreversible means that once it binds the proton pump it does not come off – to regain proton pump function a new proton pump has to be made by the cell.
What is Structure-Activity Relationship?
Structure‐activity relationship is the term for the physical interaction between a drug and its target, and the effect that has on the drug/target activity. Can have important effects on drug characteristics
What are the 8 principles of Pharmacodynamics?
- Drugs act primarily through molecular targets
- Receptor types determine response to many drugs
- Receptors can be turned “on” or “off”
- Multiple mechanisms of antagonism exist
- Efficacy and potency are not the same
- Receptors are not static
- Selectivity is important
- The body tries to maintain homeostasis
List characteristics of drug targets (ie receptors)
- Can be cell surface or intracellular
- All receptors have endogenous ligands (naturally occurring)
- Receptors can transduce and amplify signals
Describe full agonists, partial agonists, inverse agonists and antagonists
- Full agonists fully activate a
receptor - Partial agonists activate their receptor, but not to it’s full effect
- Inverse agonists bind to their receptor and cause an opposite response from that of its agonist
- Antagonists prevent receptor activation, often by blocking agonists binding. They do not cause
any activation of the receptor themselves.
Describe dose response curves
Demonstrates the different between efficacy and potency.
Typically % biological effect on y axis with drug concentration on x- axis. Can be log transformed or not.
Describe the arrows in this picture
yellow- maximal effective concentration- all of the available receptors are bound and increasing the dose
Red- EC50- The concentration of the drug that gives a response equal to half of the maximal response
Compare the red and black drug
The red drug is more potent but less efficacious. The black drug is the reverse.
