Pharmacology Flashcards
Define
One-compartment model of pharmacokinetics
Assumes the drug is evenly distributed thoughout the body and the rate of elimination (k) is constant
Define
Two-comparment model of pharmacokinetics
Assumes a drug is taken up by different tissues and the volume of distribution between tissues is different
In the context of comparment models, a drug is only eliminated through the __ comparment
Central
Which compartment model best represents what happens in the body
Multi-comparment model
Define
Open model
The drug is eliminated from the body through the central compartment
Define
Closed model
The drug is recirculated in the body through entero-hepatic circulation
This is rare
Define
Zero order kinetics
The rate at which {drug} changes is constant and independent of drug concentration
Define
First order kinetics
The rate of drug elimination is proportional to the {drug}
List 4 factors influencing the movement of drugs in the body
- Physiochemical properties
- Location/target tissue
- Mechanism of transport
- pH & ion trapping
Remember, drugs cross membranes in their non-ionized form
Define
Pharmacokinetics
What the body does to the drug
Define
Pharmacodynamics
What the drug does to the body
What are the 4 phases of drug pharmacokinetics
Think of the acryonym
- Absorption
- Distribution
- Metabolism
- Excretion
ADME
List 3 routes of parenteral drug administration
- Intravenous
- Intramuscular
- Subcutaneous
Define
Absorption
The passage of the drug from the site of administration to the blood stream
Explain
First pass effect
Describes how a % of drug is lost as it goes through the liver and portal vein to enter systemic circulation
How can you avoid the % of drug loss associated with the first pass effect
By administering the drug rectally or sublingually
Which protein does a drug bind to in the blood?
Albumin
Define
Volume of distribution (Vd)
And what is it directly related to?
The amount of tissue to which a drug distributes
Plasma concentration
What does a Vd of >2kg/kg indicate?
That drug is accumulationg in a specific site or fatty tissue
Where does biotransformation primarily occur?
The liver
Where does excretion primarily occur?
The kidney
Describe the components of
Phase I reactions
Part of biotransformation
Includes hydrolysis, reduction and oxidation
Describe the components of
Phase II reactions
Part of biotransformation
Conjugation (includes acetylation, conjugation to amino acids, and glucuronidation)
What is C0?
In the context of volume of distribution
The drug plasma concentration after equilibrium but before elimination
Define antimicrobial
Agent that kills microbes or inhibits their growth without damaging the host
Define antibiotic
Microbial products that kill or inhibit other micro-organisms
Define antibacterial
Synthetic agents with activity against bacteria
__ do not cause AMR
Antimicrobials
Define inherent resistance
Provide an example
Lack of bacterial activity due to inherent phenotype (i.e., lack of appropriate target)
Mycoplasms are resistant to beta-lactams because they do not have a cell
Define chromosomal resistance
What type of transmission is this?
Mutations in the organism that confer resistance
Vertical transmission
Define transferable resistance
What type of transmission is this?
Resistance genes aquired through mobile genetic elements
Vertical and horizontal transmission
List 3 AMR organisms of concern
- Methicillin resistant staphylococci
- Multidrug resistant cocci
- Multidrug resistant enterbacteriacae
Define a nosocomial infection
An infection aquired through health care
List 3 risk factors for nosocomial AMR
(aquired through healthcare)
- Very young or old animals
- Immunocomprimised patients
- Broad spectrum antibacterial use
What are the 3 most important drivers for antimircobial use in practice?
- Vet prescribing behaviours
- Interactions with clients
- Practice norms
List 5 conditions in which system antimicrobials are not needed as a first line treatment
- Acute vomiting or diarrhoea
- Otitis externa
- Acute conjunctivitis
- Cat bite abscesses
- Feline lower urinary tract disease
List the 7 key concepts for responsible antimicrobial use
- Know there is a bacterial infection
- Do you need systemic AM’s?
- Is treatment required immediately?
- Choose an appropriate AM
- Use the correct dose
- Choose the correct treatment duration
- Improve compliance
List 6 factors affecting PK/PD models
- Poor bioavailability
- Hypovolumic shock
- Renal and/or liver disease
- Increased MIC
- Biofilms
- Pus, debris or foregin materials
List 3 factors that may necessitate the need for higher doses of hydrophilic drugs to ensure theraputic concentrations
- Fluid retention
- IV fluids
- Increases renal clearance
Means theres an alt fluid balance, drugs may be diluted or excreted fast
__ drugs penetrate tissues more effectively
Lipophilic
List one antimicrobial for each category of tissue penetration: excellent, good and poor
Excellent: Doxycycline, metronidazole
Good: Tetracyclines, macrolides
Poor: Penicillins, cephalosporins
List a concentration dependent drug
Most fluoroquinolones
How is the efficacy of concentration dependent drugs measured?
The ratio between the peak concentration and the MIC
How would you dose a concentration dependent drug?
Give the maximum dose every 24 hours
List a time dependent drug
Penicillin
How do you measure the efficacy of a time dependent drug?
Time above MIC
How would you dose a time dependent drug?
Give the appropriate dose every 8-12 hours
List one advantage for both bactericidal and bacteriostatic drugs
Bactericidal: more effective in immunocomprimised patients
Bacteriostatic: release less toxins
List 3 bacteriostatic drugs
- Tetracycline
- Sulphonamides
- Lincosamides
List 3 bactericidal drugs
- Penicillin
- Cephalosporin
- Fluoroquinolones
Which dog breed have a specific risk for ADRs to sulphonamides?
Dobermans
List 3 drugs that are excreted hepatically
- Fluoroquinolones
- Doxycycline
- Rifampicin
List 3 drugs that are excreted both hepatically and renally
- Tetracyclines
- Lincosamides
- Fluoroquinolones
List 3 drugs are excreted renally
- Penicillins
- Cephalosporines
- Trimethoprim-sulphonamides
List 3 ADRs you can see with tetracyclines
- Injection site reactions
- Hepatic enzyme induction
- Oesophageal ulceration
List a pathogen that is most likely causes this infection
Pyoderma
Staphylococci
List a pathogen that is most likely causes this infection
Otitis externa
Staphylococci or pseudomonas